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Talk:Allopatric speciation

Adaptive radiation
How does adaptive radiation differ from allopatric speciation? Allopatry begins when subpopulations of a species become isolated geographically (for example, by habitat fragmentation or migration). The isolated populations are then liable to diverge evolutionarily over many generations. As far as I can tell, this is the same as adaptive radiation, but maybe I am overlooking a fine point. RK 16:08, Aug 12, 2004 (UTC)

 * You're not overlooking a fine point, there's quite a distinct difference. Adaptive radiation occurs when a species is introduced to an ecosystem, hitherto unreachable, and can fill a variety of ecological niches. The most frequently quoted example is Darwin's finches - 14 species evolved from a single species introduced on the Galápagos Islands. Allopatric speciation occurs when two populations of a single species, separated by a physical barrier (eg a channel of water) become isolated both geographically and reproductively to the point that if the barrier breaks down, they are unable to interbreed. So adaptive radiation is just what it says - 1 species radiates into a variety of species, IN ORDER TO fill the niches; allopatric speciation - 1 species effectively becomes 2, THROUGH REPRODUCTIVE/GEOGRAPHIC ISOLATION.

 * Hope that helps. By the way, there was no need to revert my comment, it's just some harmless fun. There's no rule about not making a little joke on the discussion page. It was patronising, and insulting. It's not as though I don't know what I'm doing here. TrianaC 03:49, 15 June 2006 (UTC)

Alright then, another comment. Where did this 8 generations or more number come from (in the example picture of fruitflies)? As you know with certain bacteria that could take place in a day. As far as i was aware speciation had never been observed (asides from perhaps postulation from mDNA 'clocks' i suppose) so its unlikely to be a missing reference. So is this science or speculation on the 8 generations?

 * The image is based on a very similar diagram which simply mentions "many generations pass". I don't know why the artist specified a lower limit of eight generations, but it seems a relatively minor mistake to me.  Speciation has been observed, for instance these examples.  Ppe42 21:53, 22 February 2007 (UTC)

Removing Fruit Flys
I'd really like to remove the fruit fly picture because it does NOT take 8 generations to have a new species of fruit fly. I want to know if this is a good idea. - WarriorFIRESTAR (talk) 20:33, 21 October 2008 (UTC), thanks.

 * Do you have a citation to support your claim? I assume the image is based on the published article it cites. --98.217.8.46 (talk) 21:01, 21 October 2008 (UTC)
 * Disagree with removal in lieu of a citation that it is fundamentally flawed. "Eight generations" is not (yet) specifically cited in the image, but is cited at the more general speciation article. — Lomn 21:12, 21 October 2008 (UTC)

Geographical isolation Suggested Merger
Is Geographical isolation merely a poorly worded version of this topic? It certainly seems that that article as written is relating the same information as Allopatric speciation. If so, should one be redirected?--JimmyButler (talk) 18:31, 7 October 2010 (UTC)
 * After close analysis of the two articles; it seems a possible solution would be to merge the two; although in reality although the content is nearly identical; thus one is merely be deleted.--JimmyButler (talk) 14:07, 8 October 2010 (UTC)
 * I support the merge, or possibly a deletion of Geographical isolation and the establishment of a redirect. As it stands, the two article are very similar.--NYMFan69-86 (talk) 15:54, 8 October 2010 (UTC)

--NYMFan69-86 (talk) 02:23, 9 October 2010 (UTC)
 * Take these two sentences:
 * (From Geographical isolation)-" [...]evolve characteristics different from the parent population (due to genetics/genetic) change following geographical isolation, then if the geographical barriers are removed (perhaps due to human activity), members of the two populations will be unable to successfully mate with each other.''
 * (From Allopatric speciation)-" [...]biological populations are physically isolated by an extrinsic barrier and evolve intrinsic (genetic) reproductive isolation to the extent that if the barrier should ever vanish, individuals of the two populations could no longer interbreed."

 * OK, I performed the merge. There is quite a lot of tension within the text though. --Ettrig (talk) 09:56, 10 October 2010 (UTC)
 * I think it's the right move. Work and expansion to be done.--NYMFan69-86 (talk) 20:48, 10 October 2010 (UTC)

 * Wouldn't geographic isolation also be involved in peripatric speciation? Ucucha 00:59, 19 October 2010 (UTC)
 * Mmmm...good point.--NYMFan69-86 (talk) 17:13, 19 October 2010 (UTC)
 * Quoted: "In parapatric speciation there is no specific extrinsic barrier to gene flow. The population is continuous, but nonetheless, the population does not mate randomly. Individuals are more likely to mate with their geographic neighbors than with individuals in a different part of the population’s range. In this mode divergence may happen because of reduced gene flow within the population and varying selection pressures across the population’s range." I've yet to see a text reference this as a type of geographic isolation - perhaps because there is technically no "isolation" in that there are no geographic barriers only preferential mating. Campbell Biology equates allopatric with geographic isolation - the term seeming to be synonymous. The articles in separation had essentially identical explanations describing the same process and outcome. I think / hope the merge was appropriate.--JimmyButler (talk) 19:14, 19 October 2010 (UTC)
 * I mentioned peripatric, not parapatric speciation. However, peripatric speciation may be a special case of allopatric—and perhaps it is hard to sort out the different concepts that are used in the literature. Ucucha 20:07, 19 October 2010 (UTC)
 * There appears to be a fine line between genetic isolation, allopatric speciation, and peripatric speciation. I think a harder look at scholarly sources will help (as the two articles [allopatric and peripatric speciation] stand right now, refs are slim).--NYMFan69-86 (talk) 01:14, 20 October 2010 (UTC)
 * My "bible" on evolution is Evolutionary Biology, 1998, by Douglas Futuyma. It has very similar illustrations of four models of speciation on p. 483. In the chapter about "Kinds of Allopatric Speciation" it describes peripatric evolution with "The other major mode of allopatric speciation ... Mayr ... called this peripatric speciation". Futuyma refers here to Mechanisms of Speciation, pp. 1-19 in Alan R. Liss, New York, 1982. --Ettrig (talk) 19:55, 20 October 2010 (UTC)
 * Sorry... peri vs. para. I dug through some journals as well - enough to realize that the vocabulary and its application is a contentious topic - reminiscent of the definition and use of the word species. What I can gather - peripatric is a form of allopatric involving speciation among the peri pheral populations at the geographical fringes.--JimmyButler (talk) 13:36, 21 October 2010 (UTC)

Reproductive isolation
Reproductive isolation is not the only definition of species. But much of this article seems to assume it is. --Ettrig (talk) 09:56, 10 October 2010 (UTC)
 * Quite right. The text needs a fair bit of work...not to mention more sources to pull information from.--NYMFan69-86 (talk) 18:59, 10 October 2010 (UTC)
 * If I remember correctly from long-ago courses - hasn't the definition of species always been a source of raging debate among the learned?--JimmyButler (talk) 23:23, 10 October 2010 (UTC)
 * If my 6 weeks of college education have taught me anything, its that two members of the same species (opposite gender of course) can mate and produce a sexually viable offspring while two individuals of different species cannot.--NYMFan69-86 (talk) 00:25, 11 October 2010 (UTC)
 * Yes, raging for a long time, because organisms are not always neatly divided into species. There are many more interesting weeks to come. Consider for example dandelion (apomixis) and bacteria (no real sex, although mixing of genes does occur). --Ettrig (talk) 10:53, 12 October 2010 (UTC)

The finch example
I thought this was the classic example of adaptive radiation, something a bit different than allopatric speciation (or are they really the same)?--NYMFan69-86 (talk) 00:28, 11 October 2010 (UTC)
 * I haven't seen this discussed explicitly. My own interpretation is that allopatric speciation cocerns the "small" event that creates a new species, while adaptive radiation concerns a much wider observation that several daughter species from the same original species tend to be rater different. Spelled out this way, adaptive radiation sounds like a rather trivial concept, and I think it is. Anyway, it is not unreasonable that the same group of organisms is an example of both phenomena. --Ettrig (talk) 11:01, 12 October 2010 (UTC)
 * That makes sense to me. I suppose there's a fine line between the two.--NYMFan69-86 (talk) 23:44, 12 October 2010 (UTC)

Question
From the first paragraph: "At this point, a new species has emerged."--wouldn't it be more correct to say two new species have emerged...each a different species than their common ancestor?--NYMFan69-86 (talk) 01:02, 13 October 2010 (UTC)
 * It may need some tweaking; however, whether two "new" species have emerged depends on whether both undergo evolutionary changes that sufficiently distinguishes them from the ancestral population. I guess it is possible that if you split population "a" into two groups "b" and "c" - and only "c" evolves significant characteristic changes then technically only one new species evolved. Of course "both "b" and "c" may diverge from the original form - in which case two new species would be appropriate. That said - I guess I should go read the context of the sentence in questions. I'd like to keep dorking with article as time allows. It is of interest and could use some work. My apologies for not citing as I go, I'm using lecture notes at the moment; however, I will get around to citing. Yes - shame on me:( PS I got around to reading the painted turtle - very well executed! Are you contemplating FA?--JimmyButler (talk) 01:36, 13 October 2010 (UTC)
 * Yeah...I think before too much contemplation occurs, some references would be good (not to say your beastly lecture material isn't sufficient or anything!). My sights for that article are on GA for now...the Wood turtle is what I have in mind next for FA (perhaps a month or so away from getting around to adding some of the more "abstract content"...if you catch my drift).  The painted turtle is up for peer review as of a few minutes ago.--NYMFan69-86 (talk) 18:15, 13 October 2010 (UTC)

Social change
This section starts with talking about social reasons for allopatric speciation...but than kind of falls off onto another topic. Is the other information to be put somewhere else? --NYMFan69-86 (talk) 18:06, 15 October 2010 (UTC)

Adaptive radiation
I think it is incorrect to say that "adaptive radiation ... is a form of allopatric speciation". These concepts are on different scale. Allopatric speciation is when one new species is generated (or two emerge from one by a split) under a particular condition (allopatry). Adaptive radiation is when many species emerge in a short time. Yes, allopatric speciation may have been the manner in which all the species emerged in the adaptive radiation. Still, this does not make the radiation a form of speciation. Radiation is a form of a (large) group of speciations. --Ettrig (talk) 17:40, 17 October 2010 (UTC)
 * I may be a biology major...but I'm still a freshman! I don't really know...professor?--NYMFan69-86 (talk) 18:02, 17 October 2010 (UTC)
 * I agree. The speciation leads to adaptive radiation, but they are not the same thing. As always, I'm open to being overruled by a an opinion from a reliable source. William Avery (talk) 18:18, 17 October 2010 (UTC)
 * Actually, that was a direct quote; ummmm from where thou. The importance of citing as you go. I'll strike it for now and instead use adaptive radiation in island populations as the classic example of allopatric speciation. Adaptive Radiation is a consequence of allopatric speciation - perhaps that is the point we need to establish?--JimmyButler (talk) 14:05, 18 October 2010 (UTC)

New Section Peripheral populations
The info being added is gleaned from a variety of biology text; I suspect it is common knowledge within the field - however, look for misrepresentation of facts as I reword the text for simplification. I hope to seek out some online sources that are accessible to validate. Some of the original material that I've left in place gets a bit technical. I'll need to understand it before any attempt is made by me to edit or delete. There are numerous examples of allopatric speciation - especially in island populations. I'll work them in or add to example section - although I don't like the heading "Examples". Might be a while before I can get back to it... so a citation needed tag may scar the landscape.--JimmyButler (talk) 15:01, 18 October 2010 (UTC)
 * Providing examples in an effective manner is, I think, going to be the hardest part of this article. It shouldn't be difficult at all to find an adequate number of examples in credible literature, however incorporating them in the article seems like it will be a challenge.--NYMFan69-86 (talk) 16:18, 18 October 2010 (UTC)

Wording

 * I see the phrase "allopatric speciation may occur" a lot in the article. Is the word may always necessary, shouldn't the prose discuss the circumstances under which allopatric speciation do occur?--NYMFan69-86 (talk) 21:29, 22 October 2010 (UTC)

 * "First, the peripheral isolates are likely to possess genes that are different from the parental population since such populations tend to represent the extreme genotypic composition."--I personally know what this sentence is saying, but some may be confused about which population the word "population" is referring to here.--NYMFan69-86 (talk) 21:44, 22 October 2010 (UTC)

 * "However, if it is of founder effects, or if the population becomes isolated in an environment which makes new demands upon it."--was there originally supposed to be another portion to this sentence?--NYMFan69-86 (talk) 21:47, 22 October 2010 (UTC)

Extreme periphery
This passage: the peripheral isolates are likely to possess genes that are different from the parental population since such populations tend to represent the extreme genotypic composition is circular. It says that the genes in the periphery are different because they are extreme. Could it be that the intention is to say that because the edges of the area tend to have extreme properties (for the area), selection tends to produce extreme phenotypes in the periphery. ? --Ettrig (talk) 10:23, 23 October 2010 (UTC)

'Genesis of reproductive barriers' - garbled text.
The current (16 Dec 2010) article includes the text:
 * "However, if it is of founder effects, or if the population becomes isolated in an environment which makes new demands upon it. Research has shown that this is a major reason why so many different species exist throughout the world."

The first "sentence" is garbled, ungrammatical and of no clear meaning (this is not a broken edit, it was garbled like this from first insertion). However, removing this text (possibly) removes the anaphoric referent of the "...this..." in the following sentence. Since this second sentence cites no evidence for its claim, which is extravagent whatever the "this" refers to, I have removed both sentences. If anyone understands the real intent of this text, please insert a clearer version. FredV (talk) 13:05, 16 December 2010 (UTC)
 * The offending sentences seems to have been brought over with Geographic Isolation when the two separate articles were recently merged. Whether it made sense there - who knows. "This" was the evidence needed to finally prove Evolution to the masses. Too bad we have no way of ascertaining what "This" actually was. Thus deletion is appropriate.--JimmyButler (talk) 15:19, 16 December 2010 (UTC)
 * I noted this in my "wording" section, but was hesitant to delete it because it seemed important. However, if it doesn't make sense and isn't cited, what else can one do?--NYMFan69-86 (talk) 17:40, 16 December 2010 (UTC)

3 Suggested Improvements
1. There was no mention of migration or founder effect which can also lead to allopatric speciation. 2. In the first paragraph the author writes "the vicariant populations then undergo genotypic OR phenotypic divergence..." which would be better phrased as "populations then undergo genotypic AND phenotypic divergance..." because to have phenotypic change there must be a change in genotype and for speciation to occur phenotypic changes must occur. 3. One thing that should be added to the article is how scientists define two separate species, which can be a tricky subject and should be explained thoroughly for the readers. — Preceding unsigned comment added by Ryan.332 (talk • contribs) 03:27, 1 October 2014 (UTC)

Elephants
Where is the research showing that these Elephants can't mate? HealthClarity (talk) 20:33, 12 April 2016 (UTC)

Vicariant especiation
Leon Croizat coined the term of vicariant speciation and precisely his proposal is based on a clear distancing from the Darwinian notion of allopatric speciation. Thus "vicariant" is different from "allopatric". Fernando Otalora Luna (talk) 19:06, 4 October 2019 (UTC)

Progression rule
A lot of these different topics all seem to intersect with and duplicate other treatments of same or similar topics. This caption -- "Allopatric speciation can result from mountain topography. Climatic changes can drive species into altitudinal zones—either valleys or peaks. Colored regions indicate distributions. As distributions are modified due to the change in suitable habitats, reproductive isolation can drive the formation of a new species." -- reminded me of Willi Hennig's progression rule, which was extended by botanists Vicki Funk and Warren Lambert Wagner to describe Hawaiian island biogeography, in particular, the pattern of evolutionary history that moves down the chain of Hawaiian islands, from the older ones to the younger ones. How does this version of the progression rule, which incorporates geological history, fit in to allopatric speciation? The image that the caption refers to in this article (allopatric speciation by topography) almost illustrates the progression rule if you apply it to Hawaii and point the arrow in one direction. Viriditas (talk) 22:28, 1 October 2023 (UTC)

title: Talk:Allopatric speciation


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Irritator

Irritator is a genus of spinosaurid dinosaur that lived in what is now Brazil during the Albian stage of the Early Cretaceous Period, about 113 to 110 million years ago. It is known from a nearly complete skull found in the Romualdo Formation of the Araripe Basin. Fossil dealers had acquired this skull and sold it to the State Museum of Natural History Stuttgart. In 1996, the specimen became the holotype of the type species Irritator challengeri. The genus name comes from the word "irritation", reflecting the feelings of paleontologists who found the skull had been heavily damaged and altered by the collectors. The species name is a homage to the fictional character Professor Challenger from Arthur Conan Doyle's novels.

Some paleontologists regard Angaturama limai—known from a snout tip that was described later in 1996—as a potential junior synonym of Irritator. Both animals hail from the same stratigraphic units of the Araripe Basin. It was also previously proposed that Irritator and Angaturama's skull parts belonged to the same specimen. Although this has been cast into doubt, more overlapping fossil material is needed to confirm whether they are the same animal or not. Other spinosaurid skeletal material, some of which could belong to Irritator or Angaturama, was retrieved from the Romualdo Formation, allowing for a replica skeleton to be made and mounted for display at the National Museum of Rio de Janeiro in 2009.

Estimated at between 6 and 8 m in length, Irritator weighed around 1 t, making it one of the smallest spinosaurids known. Its long, shallow and slender snout was lined with straight and unserrated conical teeth. Lengthwise atop the head ran a thin sagittal crest, to which powerful neck muscles were likely anchored. The nostrils were positioned far back from the tip of the snout, and a rigid secondary palate on the roof of the mouth would have strengthened the jaw when feeding. Belonging to a subadult, Irritator challengeri's holotype remains the most completely preserved spinosaurid skull yet found. The Angaturama snout tip expanded to the sides in a rosette-like shape, bearing long teeth and an unusually tall crest. One possible skeleton indicates it, like other spinosaurids, had enlarged first-finger claws and a sail running down its back.

Irritator had been mistaken initially for a pterosaur, and later a maniraptoran dinosaur. In 1996, the animal was identified as a spinosaurid theropod. The holotype skull was thoroughly prepared before being redescribed in 2002, confirming this classification. Both Irritator and Angaturama belong to the Spinosaurinae subfamily. A generalist diet—like that of today's crocodilians—has been suggested; Irritator might have preyed mainly on fish and any other small prey animals it could catch. Fossil evidence is known of an individual that ate a pterosaur, either from hunting or scavenging it. Irritator may have had semiaquatic habits, and inhabited the tropical environment of a coastal lagoon surrounded by dry regions. It coexisted with other carnivorous theropods as well as turtles, crocodyliforms, and a large number of pterosaur and fish species.

History of research

The holotype of Irritator was excavated from a chalk concretion containing the rear of a large skull with lower jaws near the town of Santana do Cariri in northeastern Brazil. This fossil was acquired by dealers who sold it to Rupert Wild of the State Museum of Natural History Stuttgart, Germany. At the time it was assumed to be the skull of a giant basal pterosaur, or flying reptile, since the Chapada do Araripe region is famous for its copious pterosaur finds, and the German museum often bought such pieces. As it promised to be a unique discovery of singular importance, German and British pterosaur experts were contacted to study the exemplar. A paper describing it as a pterosaur had already been submitted for publication when the authors, German paleontologist Eberhard Frey and British paleontologist David Martill, were disabused of this notion by the peer reviewers, who suggested the fossil belonged to a theropod dinosaur.

The skull was flattened sideways somewhat and, as is common with fossils, was partly crushed. The right side was well preserved, while the left was extensively damaged during collection. Some of the skull's hindmost upper surface had eroded, and the lower jaw lacked its front end, both owing to breakage during fossilization. Parts of the specimen were also cracked due to being part of a septarian concretion. The tip of the upper jaw was also missing. Since there were no signs of erosion, it had most probably broken off during or after the fossil's collection. Evident corrosion on certain bones indicates acid preparation had been attempted. A vertical fracture was present across the middle of the skull, which had apparently been sealed with car body filler. In hopes of making it look more complete and valuable, the fossil traders had severely obscured the skull beneath plaster; a widespread practice among local collectors in the Chapada do Araripe, especially on fish fossils. The buyers were unaware of the modifications to the specimen until it was sent to universities in the United Kingdom for CT scan imaging. This revealed the collectors had tried to reconstruct the skull by grafting parts of the maxilla (main upper jaw bone) onto the front of the rostrum (snout). The skull (designated SMNS 58022) became the holotype specimen of the new genus and species Irritator challengeri in February 1996, when it was first scientifically described by paleontologists David M. Martill, Arthur R.I. Cruickshank, Eberhard Frey, Philip G. Small and Maria Clarke. In this paper, Martill and his team wrote that the generic name Irritator came "from irritation, the feeling the authors felt (understated here) when discovering that the snout had been artificially elongated." The type species, Irritator challengeri, was named after Professor Challenger, a character in Arthur Conan Doyle's novels, specifically The Lost World. Two years earlier, Frey and Martill had named a new pterosaur species from the Crato Formation Arthurdactylus conandoylei, after the novelist himself.

When Martill and colleagues first described Irritator challengeri, the holotype was still extensively encased in calcareous rock matrix. Under the supervision of American paleontologist Hans-Dieter Sues, technician Diane M. Scott from the University of Toronto at Mississauga assumed the task of fully extracting the skull bones from the rock, allowing for a detailed redescription in 2002. Published by Sues, Frey, Martill, and Scott, this inspection of the now fully prepared specimen negated many of Martill and colleagues' original observations, which were based on misinterpretations of the damaged and largely concealed skull. The estimated length of the complete skull was 24 cm shorter than previously proposed. What was originally thought to be a prominent head crest proved to be an unattached, indeterminate bone fragment. As in the previous study, Sues and colleagues regarded the African genus Spinosaurus as the most similar taxon to Irritator, because they shared many dental features, including mostly straight conical tooth crowns, thin enamel, well-defined edges with no, and lengthwise fluting. Since little was known of Spinosaurus's skull at the time, these similarities were enough for the authors to suggest a possible junior synonymy of Irritator with Spinosaurus. Sues and colleagues noted that more overlapping skull material was needed for further diagnosis. As more of Spinosaurus's skull became known, later research maintained separation of the two taxa.

Although the site of discovery is uncertain, the specimen most probably stems from the Romualdo Formation (previously designated the Romualdo Member of the then Santana Formation). This assignment was confirmed by microfossils of the ostracod Pattersoncypris, and fish scales from the ichthyodectid Cladocyclus, both found in the Romualdo Formation. Questioning of local fossil dealers hinted at a locality near the village of Buxexé close to Santana Do Cariri at the flank of the Chapada do Araripe, at a height of approximately 650 m. Since the Romualdo Formation is indeed exposed there, and the matrix encasing the holotype has the same color and texture as those rocks, this locality can be regarded as the probable site of the discovery of the fossil. Irritator challengeri was the first dinosaur described from the Romualdo Formation, and its holotype specimen represents the most completely preserved spinosaurid skull known.

Synonymy with Angaturama

Angaturama limai, another spinosaurid from the same time and place as Irritator challengeri, was described by the Brazilian paleontologists Alexander W. A. Kellner and Diogenes de Almeida Campos in February 1996. Kept today under specimen number USP GP/2T-5 at the University of São Paulo, the holotype specimen consists of an isolated snout tip from the Romualdo Formation. It was extracted from a calcareous nodule using a technique originally developed for pterosaur fossils. The generic name Angaturama means "noble" in the aboriginal Tupi Indian language of Brazil. The specific name honors the late Brazilian paleontologist Murilo R. de Lima, who informed Kellner of the specimen in 1991.

In 1997, British paleontologists Alan J. Charig and Angela C. Milner considered Angaturama a likely junior synonym of Irritator, noting that both genera had retracted nostrils, long jaws, and characteristic spinosaurid dentition. Paul Sereno and colleagues in 1998 agreed with this possibility, and additionally observed that the holotype of Angaturama seems to complete that of Irritator (meaning that they could belong to the same specimen). Authors including Éric Buffetaut and Mohamed Ouaja in 2002, Cristiano Dal Sasso and colleagues in 2005, Tor G. Bertin in 2010, Darren Naish in 2013, and Madani Benyoucef and colleagues in 2015 supported this conclusion. In their redescription of Irritator, Sues and colleagues pointed out that both holotypes are equally as narrow, and share transversely round teeth with defined yet unserrated edges. They also noted that a sagittal crest on Angaturamas premaxillae may correspond with that of Irritators nasal bones. Some objection has been raised to these assertions. Kellner and Campos in 2000 and Brazilian paleontologist Elaine B. Machado and Kellner in 2005 expressed the opinion that the fossils come from two different genera, and that the holotype of Angaturama limai was clearly more laterally flattened than that of Irritator challengeri.

A review of both fossils by the Brazilian paleontologists Marcos A. F. Sales and Cesar L. Schultz in 2017 noted that the specimens also differ in other aspects of their preservation: the Irritator specimen is brighter in color and is affected by a vertical crack, while the Angaturama specimen bears many cavities; the damage to the teeth of the Irritator challengeri holotype is also much less severe. Sales and Schultz also identified a possible point of overlap, the third left maxillary tooth, and observed that the skull of Angaturama could have been larger than that of Irritator based on the proportions of the closely related genus Baryonyx. They therefore concluded that the two specimens do not belong to the same individual, Sales and Schultz noted that synonymy at the genus level would need to be verified by more extensively overlapping remains. If Angaturama and Irritator are regarded as a member of the same genus, the latter would be the valid scientific name under rules of priority, since it was named almost a month earlier. The paleontologist Marco Schade and colleagues could not confirm the overlap in tooth positions in 2023 due to interpreting them differently, and could not provide information to resolve the issue.

Postcranial material and additional finds

Besides the skull, the snout fragment, and some isolated teeth, the Romualdo Formation has also yielded l remains that may belong to spinosaurids, many of which are hitherto undescribed, and all of them pertaining to the Spinosaurinae subfamily. In 2004, parts of a spinal column (MN 4743-V) were unearthed at the formation. Brazilian paleontologist Jonathas Bittencourt and Kellner assigned these, due to their structure, to the Spinosauridae. It is uncertain whether this specimen can be referred to Irritator or Angaturama, given that both are based only on skull material. In 2007, Machado and Kellner tentatively referred a rib fragment (MN 7021-V) to the Spinosauridae. However, the most complete spinosaur specimen retrieved from the Romualdo Formation is MN 4819-V, a partial skeleton lacking the skull. First reported in 1991, the specimen was referred by Kellner to the Spinosauridae in 2001 because of its tall sacral neural spines and the enlarged condition of the hand claw. The skeleton was fully described in 2010 in an as-of-yet unpublished master's thesis by Machado. An incomplete hind limb (MPSC R-2089) mentioned in 2013 might also pertain to the Spinosauridae. In 2018, Tito Aureliano and his team described LPP-PV-0042, part of a left tibia from a particularly large individual. As is common with fossils from the Araripe Basin, the majority of spinosaurid material from the Romualdo Formation was collected under uncontrolled circumstances for use in the illegal fossil trade. As such, many specimens are partly damaged and without precise geological field data.

Some of the Romualdo Formation postcrania were used as the basis for the creation of a replica Angaturama skeleton, later mounted at the Federal University-owned Museu Nacional do Rio de Janeiro (National Museum of Rio de Janeiro). The skeleton depicted the animal carrying an anhanguerid pterosaur in its jaws. It was the centerpiece of the Dinossauros no Sertão (Dinosaurs of Sertão) exhibit, which opened to the public in March 2009, becoming the first large carnivorous Brazilian dinosaur to be put on display. Some of the original postcranial elements (including the fossil pelvis and sacral vertebrae) were presented alongside the mount. In press releases of the exhibit's opening, Kellner informally implied MN 4819-V as belonging to Angaturama. This is also reflected in the specimen's inclusion in the skeletal mount. In 2011, a third Brazilian spinosaur, Oxalaia quilombensis, was named and described from the Alcântara Formation of the Itapecuru Group, part of the São Luís Basin. This larger species, known only from an isolated snout tip and upper jaw fragment, lived during the Cenomanian stage, around six to nine million years after Irritator and Angaturama. Oxalaia quilombensis is differentiated from Angaturama limai by its broader, more rounded snout and lack of a sagittal crest on the premaxillae. In September 2018, a fire broke out at the palace housing the Museu Nacional, largely destroying the fossil collections and possibly the exhibited Angaturama skeleton and fossil elements. The holotype of Oxalaia quilombensis, which was stored in the same building, may also have been destroyed.

Description

Even by maximal size estimates, Irritator was smaller than other known spinosaurids. Gregory S. Paul calculated its length at 7.5 m and weight at 1 t. Thomas R. Holtz Jr. published a higher estimate of 8 m, with a weight between 0.9 to 3.6 t. Estimates by Dougal Dixon were lower at 6 m long and 2 m high. When scaled by Aureliano and colleagues, the reconstructions from the study by Sales and Schultz provided a length of 6.5 m for the Irritator challengeri holotype, and 8.3 m for the Angaturama limai holotype. Some of the skull bones of the former holotype had not yet fully co-ossified (fused), indicating that the specimen belonged to a subadult. The partial spinosaurine skeleton MN 4819-V represented a moderately sized individual, estimated by Machado at 5 to 6 m in length. Many elements from this specimen were incorporated into the skeletal mount in the National Museum of Rio de Janeiro, which had a length of 6 m and a height of 2 m. However, spinosaurids from the Romualdo Formation possibly attained greater sizes. Although LPP-PV-0042 is represented only by a tibia fragment, Aureliano and colleagues estimated its length at roughly 10 m. Bone histology indicates that this individual was a subadult, so the mature animal may have been larger.

Anatomy of the Irritator challengeri holotype

The holotype skull of Irritator challengeri, although heavily damaged in certain places, is largely complete; missing only the tip of the snout and the front of the mandible. The preserved skull is 16.5 cm tall and 10 cm wide, its full length has been estimated at 60 cm, based on comparisons with Baryonyx. Irritator's skull was long, narrow, and somewhat triangular in cross section. The was inclined backwards, and deeper than it was long. Extending from it was an elongate and low snout, with both sides relatively flat and slightly angled towards the skull midline. Only the rear ends of the paired (frontmost snout bones) remain intact, forming the front upper and lower borders of the  (bony nostrils). As in all spinosaurids, the (main upper jaw bones) extended below and past the nostrils in a long, low branch that formed the lower border of this opening, consequently separating the premaxillae and  bones in that location. Irritator's maxillary sinuses (located in the body of the maxillae) bore a large oval opening, as in Allosaurus. The nostril openings were oval and, as in all spinosaurids, positioned farther back on the skull than in typical theropods. Irritator's nostrils were both proportionately and absolutely smaller than in Suchomimus and Baryonyx, but larger than those of Spinosaurus. The opening behind the orbit (eye socket), the lateral temporal fenestra, was very large, while the antorbital fenestra, in front of the eyes, was long and elliptical. The orbit itself was deep and wider at the top (where the eyeball was placed) than the bottom. The bone separated the orbit from the antorbital fenestra, forming the upper and lower rear margins of the latter with two processes that enclosed a 40-degree angle; similar to Baryonyx, where it enclosed 35 degrees. Unlike in Baryonyx, Irritator's lacrimal did not form a bony horn core. The prefrontal bones were large and sturdy, while the thinner bones, situated behind them, were smooth and concave on top; both of these bones formed the upper rim of the orbit.

A thin sagittal crest, constructed from the elongate nasal bones, extended along the skull midline before stopping just above the eye in a slightly flattened bulge. Although the complete shape and height of this structure is unknown in Irritator, these head crests were commonplace in spinosaurids, having possibly served a display function when the animal was alive. The preserved part of Irritator's crest is deepest above the antorbital fenestra and lacks the vertical ridges seen in the crest of Spinosaurus. Like others in its family, Irritator possessed a long and bony structure on the roof of its mouth called a secondary palate, separating the oral from the nasal cavity. This is a feature observed in extant crocodilians, but absent in most theropod dinosaurs. Also like its relatives, Irritator had two additional openings on the skull roof (called the postnasal fenestrae) as well as long and only partially diverging (bony extensions connecting the braincase with the palate). The back of the lower jaw was deep, its rear upper surface consisting mainly of the large bone, which  with the shallower  bone below it. The, a sideways-facing opening in the lower jaw, was oval and comparatively large. The (tooth-bearing bone of the mandible) is unknown in Irritator, save for a possible remnant at the front of the surangular. Irritator challengeri's holotype is unique in that it is one of the few non-avian (or non-bird) dinosaur fossils found with a preserved stapes.

Irritator had straight or only faintly recurved conical teeth, bearing sharply defined but unserrated edges. Flutes (lengthwise ridges) were present on its tooth crowns, a common dental trait among spinosaurids. Both sides of Irritator's teeth were fluted, as in Spinosaurus, whereas Baryonyx exhibited them only on the lingual (inward facing) side of its teeth. Irritator's teeth were circular in cross section, as opposed to the laterally flattened condition of most theropod teeth. The enamel (first layer of the teeth) was thin, with a finely wrinkled texture also observed in Baryonyx. Both of Irritator's maxillae preserve nine teeth, although the left maxilla's tooth crowns are more intact, and there are traces of a tenth tooth in the rock matrix. The teeth were deeply inserted into the jaw and widely spaced towards the front of the maxilla. The first and second preserved maxillary teeth were the largest, at 32 mm and 40 mm in crown length. The seven remaining teeth became progressively smaller towards the rear, one of the last ones measuring 6 mm in estimated crown length. CT scans performed on the specimen revealed replacement teeth on both sides of the upper jaw. Their roots ran deep into the maxillae and converged close to the midline, nearly reaching the top of the skull. Based on comparisons with Irritator's relatives, the maxillae were probably lined with a total of 11 teeth each, similar to the number of 12 teeth in MSNM V4047, an upper jaw fossil referred to Spinosaurus. The hindmost tooth of the Irritator specimen's left maxilla was not yet fully erupted, and only the tip of it was visible.

Anatomy of the Angaturama limai holotype

The holotype of Angaturama limai consists only of the front part of the upper jaw, comprising the tips of the paired premaxillae and the frontmost ends of the maxillae. The specimen measures 19.2 cm in height and 11 cm in length, with the width of the palatal region being 4 to 5 mm. The suture between the maxilla and premaxilla was jagged at the front and straightened out towards the rear. The lower margin of the premaxillae was concave, with the concavity reaching its apex at the sixth premaxillary tooth. The front of the snout was expanded, forming the spoon-shaped terminal rosette characteristic of spinosaurids. This concave underside of the premaxillae would have complemented a convex and enlarged mandible tip. The premaxillae connected with each other on the bottom to form Angaturama's secondary palate, which was also partially contributed to by two processes extending from the maxillae. The snout was strongly compressed laterally, and the premaxillae gently tapered towards the top to form a tall sagittal crest 1 to 2 mm in thickness. This crest was larger and extended farther forwards on the snout than in other known spinosaurids. The frontmost upper border of the premaxilla had a small bulge that overhung the base of the crest. This bulge was apparently damaged on its upper surface, indicating that the top of the crest may have extended even farther over and forwards from that point. The front of Angaturama's snout hence had a vertically straight or concave margin, atypical from the more smoothly sloping snouts of other spinosaurs.

In the premaxilla, a broken-off tooth with partial tooth crown was recovered. The strongly extended and straight teeth with unserrated conical crowns, which measured 6 to 40 mm in length, were singly embedded. This indicates continuous tooth replacement where new teeth were pushed up between the old ones. Judging by the (tooth sockets), the premaxilla had seven teeth altogether, the third tooth being the largest. The frontmost three teeth of the maxilla were also preserved. The premaxillary teeth increased in size from the first to third, shrank from the third to the sixth, and enlarged again from the sixth premaxillary to third maxillary positions. A 16 cm diastema (gap in tooth row) was present between the last premaxillary and first maxillary tooth.

Postcrania

Though no skeletal remains were discovered with the original Angaturama snout tip, one partial skeleton (MN 4819-V) from a different location may belong to the genus. But since there is no overlapping material between the two specimens, direct comparisons cannot be made. MN 4819-V comprises a largely intact pelvis, some dorsal (back) and (tail) vertebrae, five  (hip) vertebrae, a partial right  and  (shin and calf bones), most of the right  (thigh bone), and part of an  (forearm bone). It also has the most complete hand known from a spinosaurid, including, , one , and one. Like in all spinosaurids, the claw of the first finger (the "thumb") was enlarged.

The pelvic bones are well preserved, with the right side better articulated than the left. The fused sacral vertebrae are still attached to the pelvis, which lacks the distal ends of both of its and  (lower and rearmost hip bones). The (main hip bone) is 55.3 cm long. The (front expansion) of the ilium was curved on the bottom and was somewhat shorter and deeper than the  (rear expansion). The preacetabular ala were somewhat enlarged at the front, in contrast to the more slender condition of the postacetabular ala. The (groove at the bottom of the postacetabular ala) was concave, as was the rear margin of the ischium. The pubis bore a relatively large and almost closed, an indentation in the lower margin of the rear part of the bone that allowed for the passage of the obturator nerve. The upwards projecting neural spines of the sacrum were elongated, as is typical in spinosaurs. In life, these would have been covered in skin, forming a "sail" down the animal's back. MN 4819-V is distinguished from Suchomimus due to its longer and shallower ilium with a less curved upper margin, and from Baryonyx by having a more developed, a blade-like structure on the bottom of the ischium.

Classification

Martill and his team originally classified Irritator as a maniraptoran dinosaur in the clade Bullatosauria (a group no longer considered monophyletic ), as a close relative to the feathered ornithomimosaurs and troodontids. Given that its dental morphology, particularly long snout, and assumed fin-shaped crest were features unknown in "other" maniraptorans, the researchers erected the new family Irritatoridae within the clade. They recognized Irritators affinities with Spinosaurus, in that they both had similarly shaped and unserrated teeth, but noted that the latter's mandible would not conform with the front of Irritators upper jaw, and that other non-avian dinosaurs like Compsognathus and Ornitholestes also bore no serrations on some or all of their teeth. Some of these claims were questioned in 1996 by Kellner who found that Irritator's skull lacked the one autapomorphy (distinguishing feature) diagnosed in maniraptorans at the time, which was having its (cheek) bone forming part of the antorbital fenestra. He also pointed out that since Irritator challengeris holotype lacked the tip of its snout, it would not be possible to know if Spinosauruss dentary could complement it or not. Based on comparisons with Spinosaurus, Kellner resolved Irritator as a spinosaurid and synonymized Irritatoridae with that family. Irritator was then assigned to the Baryonychidae along with Angaturama, Baryonyx, Suchomimus, and Spinosaurus by Oliver W.M. Rauhut in 2003. Thomas Holtz and colleagues in 2004 considered the Baryonychidae synonymous with Spinosauridae, and moved these genera to the latter family. Most later revisions have upheld these classifications. As spinosaurids, Irritator and Angaturama are placed within the superfamily Megalosauroidea, with Spinosauridae being a possible sister taxon to the Megalosauridae.

In 1998, Sereno and colleagues defined two subfamilies within the Spinosauridae based on craniodental (skull and tooth) characteristics. They were Spinosaurinae, where they placed Spinosaurus and Irritator; and Baryonychinae, to which they assigned Baryonyx, Suchomimus, and Cristatusaurus. Spinosaurines were distinguished by their unserrated, straighter, and more widely spaced teeth, as well as smaller first teeth of the premaxilla.  In 2005, Dal Sasso and colleagues assumed Irritator's nostrils as being located above the middle of the maxillary tooth row; more posteriorly than in baryonychines, but less so than in Spinosaurus. Sales and Schultz in 2017 found that Irritator's nostrils were in fact positioned closer to the front of the jaw, as in Baryonyx and Suchomimus; this more forward nostril placement was typically considered characteristic of baryonychines. Nevertheless, Irritator also bore unserrated teeth, a trait associated with spinosaurines. Sales and Schultz thus noted that the Araripe Basin spinosaurids Irritator and Angaturama might represent intermediate forms between the earlier baryonychines and later spinosaurines, and that further research may eventually render the former a paraphyletic (unnatural) group.

Irritator is further distinguished from Baryonyx, Suchomimus, and Cristatusaurus by having slightly over half as many teeth in the maxilla, and from Spinosaurus due to its comparatively larger and more forwardly positioned nostril openings, which, unlike in Spinosaurus, are also formed by the premaxilla. The narrow sagittal crest, which ends in a knob-like process above the frontals, is another autapomorphy separating Irritator from other spinosaurids. Although Angaturama limai's snout is generally narrower than in other spinosaurids, this might be due to damage sustained by the fossil; the holotype appears partly crushed and broken on its lower margin, with some of the preserved teeth having been sectioned off along their length. Therefore, Angaturama's only valid autapomorphy is its sagittal crest, which extends farther forwards on the rostrum and is more exaggerated than in other known spinosaurid skulls.

Topology A: Benson and colleagues (2009)

Topology B: Sales and Schultz (2017)

Diet and feeding

In 1996, Martill and colleagues theorized that Irritator challengeri, with its elongated snout and unserrated conical teeth, likely had at least a partly piscivorous (fish-eating) diet. Although much of the holotype's morphology turned out to be greatly different than they thought, later studies supported these observations. Spinosaurids had very narrow and elongated jaws with relatively homogeneous pointed teeth, an arrangement found particularly in animals like the Indian gharial—the most piscivorous extant crocodilian. The long conical teeth, which in spinosaurines did not possess serrated edges, were suitable for grabbing and holding prey. They differed from teeth of other theropods, which seemed geared towards tearing or cutting off seized body parts.

Irritator shared with crocodilians a stiff secondary palate and reduced antorbital fenestrae. In 2007, a finite-element analysis study by British paleontologist Emily J. Rayfield and colleagues found that these attributes, present in other spinosaurids as well, made the skull more resistant to torsion from prey item loads when feeding. The authors pointed out that in contrast, most theropods lacked secondary palates and had large antorbital fenestrae, exchanging strength for lighter skull builds. The nostrils of Irritator were shifted far back from the snout tip; this, along with the secondary palate, which separated the animal's nasal passages from the inside of its mouth, made respiration possible even if most of the jaw was underwater or held prey. In particular, the sagittal crest of Irritator is an indication for pronounced neck musculature, which would have been necessary to close the jaws quickly against water resistance and withdraw the head rapidly. In 2015, German paleontologist Serjoscha W. Evers and colleagues found evidence for similar adaptations in the African spinosaur Sigilmassasaurus. The neck vertebrae of this genus have a heavily furrowed undersurface. This is consistent with the attachment of powerful neck muscles for use in fishing or rapidly snatching small prey, a trait also observed in extant crocodilians and birds. Sales and Schultz in 2017 found that Irritator and baryonychines might have relied more on their sense of smell for hunting than Spinosaurus did, since they had larger, less retracted nostrils and more room in their skulls for the nasal cavity. Spinosaurus itself probably made heavier use of senses like vision or the mechanoreceptors on the tip of its snout, like those used by crocodilians to sense prey moving in the water.

Another trait spinosaurs shared with gharials was an enlarged snout tip that wielded a rosette-shaped array of interlocking teeth, adept for impaling and catching fish. Although to a lesser degree than most known spinosaurs, this feature was also present in the Angaturama limai holotype. In 2002, Sues and colleagues pointed out, however, that there would be no reason to assume that the Spinosauridae specialized completely in fishing. They stressed rather that this head morphology indicates a generalistic feeding, particularly on small prey animals. In fact, portions of a young Iguanodon, a terrestrial herbivore, were found inside the fossil skeleton of one Baryonyx. Naish and colleagues in 2004 supported the theory that Irritator hunted both aquatic and terrestrial animals as a generalist within the coastal area and in addition probably searched for carrion. A tooth belonging to Irritator was discovered still inserted into the fossil neck vertebral column of an ornithocheirid pterosaur, likely with a wingspan of 3.3 m. This indicates that Irritator ate pterosaurs as well, although it is not known if it actively hunted these animals or simply scavenged the remains. In 2018, Aureliano and colleagues presented a possible scenario for the food web of the Romualdo Formation. The researchers proposed that spinosaurines from the formation may have also preyed on terrestrial and aquatic crocodyliforms, juveniles of their own species, turtles, and small to medium-sized dinosaurs. This would have made spinosaurines apex predators within this particular ecosystem.

Examinations and digital reconstructions of Irritator published in 2023 by Schade, Rauhut et al., suggests that the lower jaws of this spinosaurid could rotate and open laterally, with a gape similar to that of modern pelicans; this would have allowed the theropod to swallow very large prey items. It was also discovered to have a very weak but rapid bite as a result of this analysis. The study also reaffirms that Irritator likely possessed binocular vision and would have held its snout at an inclined orientation. Additionally, the examinations reaffirmed classification of spinosaurids as megalosauroids and that megalosauroids and allosauroidea were part of a monophyletic Carnosauria, with Monolophosaurus standing as a sister taxon to spinosauridae.

Aquatic habits
Many spinosaurs likely had semiaquatic habits, as has been shown in studies using techniques like isotope analysis and bone histology. It has been found that they probably took advantage of aquatic prey and environments (usually marginal and coastal habitats ) to occupy a distinct ecological niche, therefore avoiding competition with more terrestrial theropods. Spinosaurines appear to have been more adapted for such lifestyles than baryonychines. A 2018 study by British paleontologist Thomas M. S. Arden and colleagues examined the morphology of spinosaurine skull bones for possible aquatic traits. They found that the frontal bones of Irritator, Spinosaurus, and Sigilmassasaurus were similar in being arched, concave on top, and narrowed at the front; features that would have resulted in the eyes being positioned further up on the head than in other theropods. In particular, the broad lower jaw and narrowed frontals of Irritator resulted in the orbits facing at a steep incline towards the midline of the skull, whereas most theropods had laterally facing orbits. These traits would have permitted the animal to see above the waterline when submerged.

In 2018, Aureliano and colleagues conducted an analysis on the Romualdo Formation tibia fragment. CT scanning of the specimen in the University of São Carlos revealed the presence of osteosclerosis (high bone density). This condition had previously only been observed in Spinosaurus aegyptiacus, as a possible way of facilitating submersion in water by making its bones heavier. The presence of this condition on the Brazilian leg fragment showed that compact bones had already evolved in spinosaurines at least 10 million years before the appearance of Spinosaurus in Morocco. According to phylogenetic bracketing—a method used to infer unknown traits in organisms by comparison with their relatives —osteosclerosis therefore might have been the norm in the Spinosaurinae. The significance of these traits was questioned in a later 2018 publication, where Canadian paleobiologist Donald Henderson argued that osteosclerosis would not have changed a theropod's buoyancy to a significant extent.

Neuroanatomy and senses
In 2020, German paleontologist Marco Schade and colleagues analyzed the anatomy of the holotype skull braincase through CT scans, revealing numerous details about behavioral capabilities of Irritator. With the scans, they created a 3D model of the skull and braincase, discovering that Irritator had elongated olfactory tracts and a relatively large floccular recesses (area that pierces through the semicircular canals and connects the brain with the inner ear). The flocculus, itself, is an important element in the coordination and control of head and ocular movements during gaze stabilization (visual ability during head movement), by being involved in the coordination of the vestibulo-ocular (VOR) and vestibulo-collic (VCR) reflexes. The flocculus appears to be enlarged in taxa that rely on quick movements of the head body. In addition, the vestibular part of the endosseous labyrinth has a large anterior semicircular canal with a lateral oriented semicircular canal.

Both floccular recesses and semicircular canal suggest that Irritator could coordinate fast head movements and had a downward inclined snout posture, enabling an unobstructed, stereoscopic forward vision, which is important for distance perception and therefore precise snatching movements of the snout. These inferences seem to be an agreement with a piscivore life-style. They also noted that the relatively well-developed cochlear duct may have enable an average hearing frequency of 1,950 Hz with a frequency band width of 3,196 Hz. However, they considered these ranges as rough estimates and established an overall frequency range of 350–3,550 Hz, making Irritator to be placed under bird hearing but above crocodiles.

Paleoenvironment and paleobiogeography

Irritator and Angaturama are known from the Romualdo Formation, whose rocks are dated to the Albian stage of the Early Cretaceous Period, about 110 million years ago. During this time, the Southern Atlantic Ocean was opening, forming the series of circum-Atlantic basins of southern Brazil and southwestern Africa, but the northeastern part of Brazil and West Africa were still connected. The Romualdo Formation is part of the Santana Group and, at the time Irritator was described, was thought to be a member of what was then considered the Santana Formation. The Romualdo Formation is a Lagerstätte (a sedimentary deposit that preserves fossils in excellent condition) consisting of limestone concretions embedded in shales, and overlies the Crato Formation. It is well known for preserving fossils three-dimensionally in limestone concretions, including many pterosaur fossils. In addition to muscle fibres of pterosaurs and dinosaurs, fish, preserving gills, digestive tracts, and hearts, have been found there. The formation is interpreted as a coastal lagoon with irregular freshwater influence that contended with cycles of transgressing and regressing sea levels. The climate of the formation was tropical and largely corresponded to today's Brazilian climate. The regions surrounding the formation were arid to semi-arid, with most of the local flora being xerophytic (adapted to dry environments). Cycadales and the extinct conifer Brachyphyllum were the most widespread plants.

This environment was dominated by pterosaurs, including: Anhanguera, Araripedactylus, Araripesaurus, Brasileodactylus, Cearadactylus, Coloborhynchus, Santanadactylus, Tapejara, Thalassodromeus, Tupuxuara, Barbosania, Maaradactylus, Tropeognathus, and ''Unwindia.  The known dinosaur fauna besides Irritator was represented by other theropods like the tyrannosauroid Santanaraptor, the compsognathid Mirischia,'' an indeterminate unenlagiine dromaeosaurid, and a megaraptoran. The crocodyliforms Araripesuchus and Caririsuchus, as well as the turtles Brasilemys, Cearachelys, Araripemys, Euraxemys, and Santanachelys, are known from the deposits. There were also clam shrimps, sea urchins, ostracods, and molluscs. Various well-preserved fish fossils record the presence of: hybodont sharks, guitarfish, gars, amiids, ophiopsids, oshuniids, pycnodontids, aspidorhynchids, cladocyclids, bonefishes, chanids, mawsoniids and some uncertain forms. According to Naish and colleagues, the lack of herbivorous dinosaurs could mean that the local vegetation was scant and thus incapable of sustaining a large population of them. The abundant carnivorous theropods would have then likely turned to the lush aquatic life as a primary food source. They also hypothesized that following storm events, pterosaur and fish carcasses might have washed up on the shoreline, providing theropods with plenty of carrion. Multiple piscivorous animals were present in the formation, which might in theory have led to high competition. Aureliano and colleagues stated there must have, therefore, been some degree of niche partitioning, where different animals would have fed on prey of varied sizes and locations within the lagoon.

Similarities between the fauna of the Romualdo and Crato Formations to that of Middle Cretaceous Africa suggest that the Araripe Basin was connected to the Tethys Sea, though this link was likely sporadic, because the lack of marine invertebrates indicates the basin had a non-marine depositional setting. Spinosaurids had already achieved a cosmopolitan distribution during the Early Cretaceous. Sereno and colleagues in 1998 suggested that with the opening of the Tethys Sea, spinosaurines would have evolved in the south (Africa, in Gondwana) and baryonychines in the north (Europe, in Laurasia).  In following, Machado and Kellner theorized in 2005 that spinosaurines would have then spread to South America from Africa. Sereno and colleagues postulated that divergent evolution between spinosaurines in South America and Africa likely occurred as a consequence of the Atlantic Ocean, whose opening gradually separated the continents and contributed to differences between taxa. A similar scenario was suggested in 2014 by Brazilian paleontologist Manuel A. Medeiros and colleagues for the fauna of the Alcântara Formation, where Oxalaia has been found. But the paleobiogeography of spinosaurids remains highly theoretical and uncertain, with discoveries in Asia and Australia indicating that it may have been complex.

Taphonomy
The taphonomy (changes between death and fossilization) of the Irritator challengeri holotype specimen has been discussed by some researchers. The skull was found lying on its side. Preceding fossilization, several bones from the back of the braincase, as well as the dentary, splenial, coronoid, and right angular bones from the lower jaw, were lost. Other bones, mostly from the skull rear, had become and displaced towards alternate regions of the head before burial. Naish and colleagues in 2004 asserted that the Romualdo Formation dinosaur fauna is represented by animals that died near shorelines or rivers before being carried out to sea, where their floating remains were eventually fossilized. In 2018, Aureliano and colleagues argued against this scenario, stating that the Irritator challengeri holotype's mandible was preserved in articulation with the rest of the skull, whereas it would have likely detached had the carcass been floating at sea. They also noted that the corpse would have quickly sunk due to the osteosclerosis of the skeleton. The researchers, therefore, concluded that fossils from the Santana Group represent organisms that were buried in their natural habitat, instead of having been deposited allochthonously (other than at their present position).

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Irritator


text:
GM High Feature engine

The GM High Feature engine (also known as the HFV6, and including the 3600 LY7 and derivative LP1) is a family of modern DOHC V6 engines produced by General Motors. The series was introduced in 2004 with the Cadillac CTS and the Holden Commodore (VZ).

It is a 60° 24-valve design with aluminum block and heads and sequential multi-port fuel injection. Most versions feature continuously variable cam phasing on both intake and exhaust valves and electronic throttle control. Other features include piston oil-jet capability, forged and fillet rolled crankshaft, sinter forged connecting rods, a variable-length intake manifold, twin knock control sensors and coil-on-plug ignition. It was developed by the same international team responsible for the Ecotec, including the Opel engineers responsible for the 54° V6, with involvement with design and development engineering from Ricardo plc.

GM's Australian auto division Holden produced a HFV6 engine under the name "Alloytec."

History
The HFV6 was designed, tested, and produced in a joint program by Holden and Cadillac. A majority of designs into the new alloy construction, transmission pairing, and first use in production were all undertaken in Detroit (and manufactured in St. Catharines, Ontario). Holden was charged with developing smaller engines (Holden 3.2 LP1 and Saab 2.8 Turbo LP9) as well as their own Holden 3.6 and 3.0 HFV6 (called the Alloytec V6) for local models.

Cadillac and Holden both tested variations of these engines in the United States and Australia.

LP1
A 2792 cc LP1 variant was introduced in the 2005 Cadillac CTS. It was also used on the Chinese 2008 CTS. It has a 89x74.8 mm bore and stroke, sequential multi-port fuel injection and a 10.0:1 compression ratio. The LP1 was built in St. Catharines, Ontario.

Applications:

LP9

This engine is also known as a A28NET, Z28NET, Z28NEL or B284.

The LP9 is a 2.8L turbocharged version used for the Saab 9-3, Saab 9-5, and other GM vehicles. It has the same bore and stroke as the naturally aspirated LP1, however the compression ratio is reduced to 9.5:1. The engine is manufactured at Holden's Fishermans Bend engine factory in Port Melbourne, Australia, while GM Powertrain Sweden (formerly Saab Automobile Powertrain) is responsible for turbocharging the engine. Global versions of this engine use the same horsepower rating for both metric and imperial markets – mechanical horsepower – while the Europe-only versions are rated in metric horsepower.

Applications:

LAU
The LAU is GM's new code for the LP9 Turbo engine, its usage starting with the 2010 Cadillac SRX. In 2011, production of the Cadillac SRX with the LAU engine ceased, but the engine remained in use in the Saab 9-4X until 2012, when production of that model came to an end.

Applications:

LF1
The LF1 is a 2994 cc version with a bore and stroke of 89x80.3 mm produced between 2010 and 2014, equipped with spark ignition direct injection (SIDI) and a 11.7:1 compression ratio.

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LFW
The LFW is a flexible fuel version of the LF1, capable of running on E85, gasoline, or any mixture of the two. Output is identical to the LF1.

Applications:

3.2
Holden has built its own 3195 cc version of the High Feature engine in Australia produced between 2005 and 2010 with a bore and stroke of 89x85.6 mm. Branded with the Alloytec name like the 3.6L version, this version produces 227 hp at 6600 rpm and 297 Nm at 3200 rpm. It has a 10.3:1 compression ratio. Its fuel economy is 4–6 km/L in city, and 7–9 km/L on highway.. Holden also produced the 3.2L engines that were used by Alfa Romeo as the basis of its JTS V6 engine.

Applications:
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LY7
The 3564 cc LY7 engine was developed primarily by Holden and introduced in the 2004 Holden VZ Commodore and 2004 Cadillac CTS sedan. It has a 10.2:1 compression ratio, Sequential multi-port fuel injection, and a bore and stroke of 94x85.6 mm. Lower-powered versions only have variable cam phasing on the inlet cam (LE0). Selected models also include variable exhaust. The engine weighs 370 lb as installed.

This engine is produced in several locations: St. Catharines (Ontario), Flint Engine South (Michigan), Melbourne (Australia), Ramos Arizpe (Mexico), and Sagara (Japan) by Suzuki.

Suzuki's engine designation is N36A.

The dual-fuel 235 hp LW2 version was able to run on petrol and autogas. The LW2 engine was based on the low-output LE0 V6. It featured a factory-fitted dual-fuel system developed by IMPCO, different valves, and hardened titanium valve seats. This motor was available exclusively in Holden vehicles from 2005–2012.

Applications:

LLT
The 3564 cc LLT is a direct injected version based on the earlier LY7 engine. It was first unveiled in May 2006, and the DI version was claimed to have 15% greater power, 8% greater torque, and 3% better fuel economy than its port-injected counterpart. The LLT engine has a compression ratio of 11.3:1, and has been certified by the SAE to produce 302 hp at 6300 rpm and 272 lbft of torque at 5200 rpm on regular unleaded (87 octane) gasoline. This engine debuted on the 2008 Cadillac STS and CTS. GM used a LLT in all 2009–2017 Lambda-derived crossover SUVs to allow class-leading fuel economy in light of the new Corporate Average Fuel Economy (CAFE) standards. In these crossovers, the LLT engine produced up to 288 hp and 270 lbft of torque.

Applications:

LFX
The LFX is an enhanced version of the LLT engine developed jointly by Holden and Cadillac. Introduced in the MY2012 Holden Commodore SV6 and the MY2012 Chevrolet Camaro LS/LT, it is 20.5 lbs lighter than the LLT, thanks to a redesigned cylinder head, integrated exhaust manifold, and composite intake manifold. Other components like the fuel injectors, intake valves, and fuel pump have also been updated. They also included the addition of cam phasing and variable valve timing. Power and torque are up slightly from the LLT. The compression ratio is 11.5:1. The LFX also features E85 flex-fuel capability.

Applications:

LWR
The LWR is dedicated LPG 3.6-liter engine. Introduced in the MY2012 Holden Commodore, Based on the 3.6-litre LY7 engine, the LWR had a vapour injection system. The vapour injection system injected gas directly into the air intake runner, thereby preventing excess gas from circulating through the air intake system. Although liquid LPG injection generally produces more power, Holden justified vapour injection on the grounds of lower fuel consumption, lower emissions, reduced pumping and parasitic losses, and start-up reliability in hot weather.

The dedicated LPG LWR engine produced peak power and torque of 180 kW at 6000 rpm and 320 Nm at 2000 rpm. The LWR engine was mated to GM's six-speed 6L45 automatic transmission and, over the combined ADR 81/02 test cycle, the Commodore Omega achieved fuel consumption of 11.8 L/100 km – an improvement of 1.6 L/100 km compared to its dual-fuel LW2 predecessor. Furthermore, the LWR engine exceeded Euro 6 emissions standards. Applications:
 * Specially hardened valves and valve seats.
 * A redesigned cylinder head and manifold for improved air flow.
 * Variable exhaust valve timing (the LW2 engine only had variable intake valve timing)
 * Specially-developed fuel injectors.
 * New pistons with pentroof-style centre-domes and valve eyelets for a higher compression ratio of 12.2:1 (compared to 10.2:1 for the dual fuel engine).
 * A new fuel rail and a new LPG fuel filter.

LCS
The 3564 cc LCS was derived from the direct-injected LLT for use in hybrids, using the two-mode system. Differences from the LLT included a slightly lower compression ratio, 11.3:1, and lower power and torque peaks. It was to debut in the 2009 Saturn Vue Hybrid, where it would have made 262 hp at 6100 rpm and 250 lbft of torque at 4800 rpm. Fuel economy ratings would have been 6–8 km/L in city, and 9–11 km/L on highway. However, GM cancelled its plans for the Saturn Vue Hybrid.

LF3
The 3.6L twin-turbocharged version for the 2014 Cadillac CTS and XTS was announced at the 2013 NYAS.

The engine is rated at 420 hp of power at 5750 rpm and 430 lbft of torque at 3500–4500 rpm (with 90% of torque being available at 2500–5500 rpm) and helps the CTS achieve 0-60 mph time of 4.6 seconds with an 8-speed automatic transmission.

In essence, the twin-turbo 3.6L V6 is the forced-induction variant of the popular LFX V6 found in the Cadillac ATS, XTS, and SRX, among many other GM models, with several important upgrades, including:
 * All-new cylinder block casting
 * All-new cylinder head castings
 * Strengthened connecting rods
 * Forged steel crankshaft
 * Continuously variable valve timing
 * Large 38.3 mm intake valves and 30.6 mm sodium-filled exhaust valves
 * Machined, domed aluminum pistons with top steel ring carrier for greater strength
 * 10.2:1 compression ratio
 * Patented, integrated charge air cooler system with low-volume air ducts
 * Twin turbochargers produce more than 12 psi
 * Vacuum-actuated wastegates with electronic control valves
 * All-new direct injection fuel system
 * Tuned air inlet and outlet resonators, aluminum cam covers, and other features that contribute to exceptional quietness and smoothness

Applications:

LF4
The LF4 is a higher-performance variant of the LF3 for use in the Cadillac ATS-V. Changes to the LF3 include:
 * Turbochargers with low-inertia titanium-aluminide turbines and vacuum-actuated wastegates for more responsive torque production
 * Compressors matched for peak efficiency at peak power levels, for optimal track performance
 * Patent-pending low-volume charge-cooling system that optimizes packaging efficiency and maximizes boost pressure
 * Lightweight titanium connecting rods that reduce inertia of the rotating assembly, complementing the quick-spooling turbochargers
 * Peak boost increased to 18 psi, from 12 psi
 * Higher-flow fuel injectors
 * Oil pan baffling for better oil flow at high cornering speeds

Applications:

LFR
The LFR is a bi-fuel variant of the LFX, although multi-point fuel injection is used for both the gasoline and CNG instead of direct-injection.

Applications:

LFY
The LFY is similar to the LFX, but adds stop-start technology and has improved airflow.

Applications:

Fourth generation
Starting with the 2016 Cadillac models, a new generation of High Feature V6s were developed. These new engines have redesigned block architectures with bore centers increased from 103 mm on prior HFV6 engines to 106 mm and a redesigned cooling system to target the hottest areas while also facilitating faster warm-up. They also incorporate engine start-stop technology, cylinder-deactivation, 2-stage oil pumps, and updated variable valve timing featuring intermediate park technology for late-intake valve closure. Both engines debuted in the 2016 Cadillac CT6.

LGW
Bore and stroke of 86x85.8 mm are used, along with a 9.8:1 compression ratio and twin turbos with titanium-aluminide turbine wheels. Maximum engine speed is 6500 RPM. Premium unleaded fuel is required.

Applications:

LGY
Bore and stroke of 86x85.8 mm are used, along with a 9.8:1 compression ratio and twin turbos with titanium-aluminide turbine wheels. Maximum engine speed is 6500 RPM. Premium unleaded fuel is required.

Applications:

LGX
Along with the increased bore spacing, the new 3.6 L DI V6 has larger bores than before, growing from 94 mm to 95 mm with the same 85.8 mm stroke as the 3.0L LGW, for a displacement of 3649 cc. Intake and exhaust valves are also increased in size along with other changes to the cylinder head. The only part shared with the prior generation is the hydraulic lash adjusters in the valvetrain. The LGX was benchmarked against the 3.7L VQ37VHR of the 2015 Infiniti Q40. Compression ratio is 11.5:1 and maximum engine speed is 7200 RPM.

Compared to GM's LFX/LFY 3.6 L engine, the LGX features active fuel management, NVH enhancements and slightly more torque.

The LGX was on Ward's 10 Best Engines for 2016.

Applications:

LGZ
The LGZ is a variant of the LGX designed for use in the Chevrolet Colorado and GMC Canyon.

Applications:

7.2L V12
On March 21, 2007, AutoWeek reported that GM was planning to develop a 60-degree V12 based on this engine family to power the top version of Cadillac's upcoming flagship sedan. This Cadillac would essentially have had two 3.6L High Feature V6s attached crankshaft-to-crankshaft and would have featured high-end technologies including direct injection and cylinder deactivation. If this engine were developed, it would have displaced 7.2 liters, and produced approximately 600 hp and 540 lbft of torque. Development of the engine was reportedly being conducted in Australia by Holden, with a potential HSV or Statesman application.

In August 2008, GM announced that development of the V12 had been cancelled.

Timing chain issues
Earlier production 2.8L, 3.0L, 3.2L, and 3.6L engines with the three chain design suffered from premature timing chain failures because of a faulty PCV system and extended oil change intervals. Most of the problems occurred on pre-LFX engines.

Holden High Feature engine
Holden sold a HFV6 engine under the name Alloytec. The High Feature moniker on the Holden produced engine is reserved for the twin cam phasing high output version. The block was designed to be expandable from 2.8 L to 4.0 L. High Feature V6 engines were previously produced in Fishermans Bend, Port Melbourne, Australia, and remain in production at the following four manufacturing locations: St. Catharines Engine Plant, St. Catharines, Canada; Flint Engine South in Flint, Michigan, United States; Romulus Engine Plant in Romulus, Michigan; and Ramos Arizpe, Coahuila, Mexico. The assembly lines for the St. Catharines and Flint facilities were manufactured by Hirata Corporation at its powertrain facility in Kumamoto, Japan. Most of the designs of this motor happened in Flint. They were first produced for the Cadillac range. The engine block and cylinder heads are cast at Defiance Foundry in Defiance, Ohio.

title: GM High Feature engine


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Duckwater, Nevada

Duckwater is an unincorporated community located in the central portion of the U.S. state of Nevada, in the Duckwater Valley at about the same latitude as Sacramento, California. It is in Nye County, at the eastern edge of the Duckwater Indian Reservation, near the Red Mountain Wilderness at the end of Nevada State Route 379. The city of Las Vegas is about 200 mi to the south-southeast.

A post office was established at Duckwater in 1873. The community was named for the ducks which frequented wetlands near the original town site.

Education
All children may attend the Nye County School District's Duckwater School, but Native American children may elect to attend the Duckwater Shoshone Elementary School (D.S.E.S.), located on the reservation. D.S.E.S. is tribally-controlled and operated, with funding derived from the Bureau of Indian Education (BIE). The BIE provides most of the tribal school's funding. Both schools are K-8 one-room schools.

By 1975, Duckwater School, with one teacher, had an enrollment of six, since some students had withdrawn upon the opening of the reservation school. Prior to loss of Native American students, the school district provided hot lunches, and there were two teachers. By 1986 enrollment was thirteen, and the relationship between the Duckwater School and Duckwater Shoshone School community had mended. The teacher then had an aide, and used the aide and older students to ensure all students be on task. Of the thirteen students, nine had at least one sibling in their classes. Students came from ranching and mining families.

Duckwater Shoshone is in a building that previously functioned as a church. The school was established circa 1973 by tribal members who were dissatisfied with their children's course in the Nye County School District. The school board was established on July 26 of that year, and it opened on November 26 of that year after the United States Office of Education granted $35,000. In 1975 its student count was 21. In 1982 the school was renovated. It maintains its own zoological garden.

Most students in grades 9-12 attend Eureka County High School, 47 mi north of Duckwater. , the students on the reservation go to high school in Eureka, Eureka County High School of the Eureka County School District. Other high schools taking Duckwater area students, as of 1986, are Lund High School in Lund and White Pine High School in Ely, both of the White Pine County School District. As of 1986, residents of Ely and Eureka often take in high school students from Duckwater, who live with them while they attend high school.

title: Duckwater, Nevada


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Talk:Strategic management

Proposing new edits via BRD
The article is built on solid foundations. Like every other article, it can be improved. I noted several breaches of neutrality in this article as well as potentially important elements that are missing:

(1) Strategic management is not the exclusive prerogative of for-profit corporations with "owners" (i.e. shareholders), as the introductory definition suggests. NGOs, universities, government agencies have strategies too, and managers inside them working to design and implement them. This is uncontroversial and does not constitute an opinion. Implying that strategic management is only relevant to shareholder-owned corporations, by contrast, represents a very strong opinion underpinned by problematic bias, namely the idea that you can't exhibit strategic behavior unless your organization has shareholders. This is a political standpoint that has long been debunked in economics and the social sciences. The leading journal in the field, for instance, recently had a special on public and non-profit organizations (https://cdn.strategicmanagement.net/conferences/smj/overview/special-issues/past-special-issues/_rightColumn/past-special-issues/value-creation/s3file.pdf).

(2) Similarly, the idea that only "top" managers are involved in strategic management has been debunked decades ago. Strategy involves middle management, especially when it comes to implementation, but more generally it involves everyone in the organization since a significant portion of strategy is not a "top-down" thing but "emerging" from the bottom up, as research by Burgelman (among many others) demonstrated almost forty years ago (https://pubsonline.informs.org/doi/abs/10.1287/mnsc.29.12.1349). This is one of the most foundational ideas in the field of strategic management. Not controversial, not an opinion.

(3) Strategic management is intimately tied to the goal of organizational adaptation, as was argued (quite uncontroversially) by strategy scholar Chakravarthy in 1982 (https://journals.aom.org/doi/abs/10.5465/AMR.1982.4285438). The idea that firms and other organizations must "adapt" to survive when their environment changes underpins most strategic management thinking. The emphasis on Porter in the opening paragraph is understandable but also reflective of a strong bias favoring approaches coming from industrial organization and economics. Strategic management is a diverse field that draws on evolutionary theory too (inspired by biology and ecology), not on just on economics. The introduction should reflect that to enhance neutrality.

(4) The prominent promotion of James Collins is debatable. He has never published a single piece of strategic management research in a peer-reviewed outlet. His "airport books" have been very successful, yet their arguments have, for the most part, been debunked by studies that rely on the scientific method (as opposed to rhetoric and the convenient selection of a few illustrative cases plagued the "survivor bias"; see, for example, this critique: https://www.jstor.org/stable/27747475). He's a consultant who's selling his services and this entry is essentially promoting them, despite evidence that they probably shouldn't be (and no evidence that they should be). To my knowledge, no serious business program teaches "Good to Great" as part of its curriculum.

Finally, a note on process: Editors play an important role as stewards. When an addition could be improved, it is great for the contributor to know why it's been reverted. When a contributor then takes into account the reason mentioned by the editor and, based on that, proposes a revised contribution that addresses the issue previously raised, I wonder whether reverting it again is the best way to improve an entry? I'm a strong advocate of a more collaborative approach (as opposed to a top-down "I revert because I can" approach ;)

If an editor justifies a reverting with a comment, and that comment is 1) addressed in a subsequent suggested edit, 2) backed by solid references, 3) incremental and rather uncontroversial, then we would probably be able to build knowledge together in a smoother fashion. As per Wikipedia guidelines, "consider reverting only when necessary" (https://en.wikipedia.org/wiki/Wikipedia:BOLD,_revert,_discuss_cycle).

Also, as a side note, there are other approaches to BRD (https://en.wikipedia.org/wiki/Wikipedia:BOLD,_revert,_discuss_cycle#Alternatives)

Awaiting feedback on 1-2-3-4 in the next few days. Please back with evidence. Will then proceed with edits. Thank you all and looking forward to collaborating respectfully. — Preceding unsigned comment added by LaurAWiki1991 (talk • contribs) 16:20, 6 February 2021 (UTC)

 * Sorry I missed this talk page entry change on my watch list. As far as I can see you are making changes to promote a specific take on strategic management based on a limited reference base - indeed it looks a little like citation spam.   Very happy to look at individual proposals for changes or questons in individual references -Snowded TALK 05:57, 14 February 2021 (UTC)
 * been watching for awhile, this editor appears to be making agf effort to add to and improve the article. Are the sources not RS? Do they not support 's edits? Can you provide specific examples/quotes of what you are objecting to? Thanks - wolf  07:22, 14 February 2021 (UTC)

 * Just to summarize: (1) you missed the talk page entirely (for an entire week) despite being the one requesting it; (2) but you did not miss the opportunity to reverse most changes within hours, despite no one having expressed any issues with them (3) your reversals are without any serious justification, and you are not at all engaging with the very Talk Page that YOU requested. That page backed each suggested edit with robust sources and evidence to which you have nothing to add. From the looks of it, you are merely reversing because you can, which would appear to go against Wikipedia's guidelines. For instance, please provide some solid evidence, references, or quotes by authority figures in Strategic Management who claim that strategic management only and exclusively concerns initiatives implemented "on behalf of owners", de facto excluding all organizations that do not have shareholders (see (1) above in BRD Talk section). If you can't provide such evidence then please let people who actually did the background research and actually follow due Wikipedia process make the needed edits to improve this page. — Preceding unsigned comment added by LaurAWiki1991 (talk • contribs) 10:19, 14 February 2021 (UTC)

 * I have a lot of articles on watch so missing one from time to time will happen. I went through the changes and accepted some of the edits. Otherwise we had he insertion of a definition from one obscure author which limited the definition so I restored the original.  On the question of owners that doesn't as a word mean shareholders so it covers not for profit as well.  I would accept stakeholders as an alternative.  Overall this is a field highly vulnerable to using single sources to promote a specific point of view.  So using Henri's Strategy Safari is one thing - as it is a third party source.  But a single paper by a single academic - no.  To illustrate my point the phrase "Academics and practicing managers have developed numerous models and frameworks" was replaced by a single model based on of adaption based on a single 1982 article entitled "A promising metaphor".

 * And I don't like Porter much either but his view is dominant and notable so its there. -Snowded TALK 12:13, 14 February 2021 (UTC)

 * Brilliant, so please explain to us all, who are the "owners" in a non-profit organization? This law firm specializing on non-profits, for instance, provides an answer that I am expecting you to argue against BEFORE YOU REVERSE MY EDIT AGAIN: "No one person or group of people can own a nonprofit organization", they say, quite uncontroversially (https://cullinanelaw.com/nonprofit-law-basics-who-owns-a-nonprofit). Do non-profits have a strategy? Yes. For example, look up the Chief Strategy Officer of the Bill & Melinda Gates Foundation (https://www.gatesfoundation.org/Who-We-Are/General-Information/Leadership/Executive-Leadership-Team/Ankur-Vora). Does the definition you are aggressively protecting currently cover non-profits and their practice of strategic management? No, and you still are unwilling to explain why it shouldn't. You are aggressively pushing your own opinion here, which is that an organization without owners is not concerned by, and does not exercise strategic management. Furthermore, you are unable to provide any evidence to support your narrow perspective and are in denial of the evidence (and, honestly, commonsense) provided on the Talk Page. You are both incorrect about the facts and in violation of Wikipedia's guidelines for collaborating towards improving entries. I am not sure what your agenda is but your attitude, at this point, is clearly hurting this community. — Preceding unsigned comment added by LaurAWiki1991 (talk • contribs) 14:28, 14 February 2021 (UTC)
 * @Snowded, thanks for the reply. @LaurAWiki1991, please see your talk page for a note about signing your posts and indenting them. Thanks - wolf  16:39, 14 February 2021 (UTC)
 * I'm not obliged to respond to a series of aggressive statements and nonsensical accusations.  Try and keep your comments here to clear proposals for changes and do not comment on the motivation of other editors.-Snowded TALK 17:53, 14 February 2021 (UTC)
 * thank you so much for the tips! managers acting "on behalf of stakeholders"? I must have missed something, who proposed this edit and what consensus was there around it? It would appear to be just you. The wording is so vague that it's essentially the same as "[blank]", which was my initial suggestion... except that your wording precludes a scenario wherein managers might be acting on behalf of no one else but themselves, a scenario that has long been recognized in organizational economics (by agency theory) and that we know exists at scale in the real world. But, as long as you feel good about winning your "revert war"... On a related note, it's interesting to see that your two most significant additions (>1,000 characters) this past month are to your own bio and to the entry about a 2x2 you came up with and seem to be exploiting commercially. For the rest, your track record seems to revolve a lot around deleting others' additions to entries, many of which related somehow to your commercial activity. I guess it puts things in perspective.LaurAWiki1991 (talk) 17:00, 28 February 2021 (UTC)
 * Strike the personal attacks and I'll respond on the content issue. Wikipedia is mediated by behavioural standards and you are breaking them-Snowded TALK 10:05, 1 March 2021 (UTC)

Moving towards a resolution
you two have been at this for awhile now, perhaps it's time to consider other means to move towards a resolution, such as following the steps at WP:Dispute resolution. While I suspect Snowded is already aware of this policy, I would encourage LaurAWiki1991 to read through it carefully. You both should consider the various means available to users there in resolving a dispute. (fyi) - wolf  18:38, 28 February 2021 (UTC)
 * LaurAWiki1991 is a very new editor and obviously passionate but their continued posting of personal attacks and slurs needs to stop if they want to edit here. I made a more open change to the text and explained by reasons for that and for refusing the narrow and largely single sourced material being proposed.  I haven't seen a response to that and when there is one I will respond.  -Snowded TALK 09:59, 1 March 2021 (UTC)

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