Donald Davesne
email: donald.davesne@edu.mnhn.fr

Matt Friedman

Veronique Barriel

Guillaume Lecointre

Philippe Janvier

Cyril Gallut

Olga Otero

Early fossils illuminate character evolution and interrelationships of Lampridiformes (Teleostei, Acanthomorpha)

Keywords:

Lampridiformes is a peculiar clade of pelagic marine acanthomorph (spiny-rayed) teleosts. Its phylogenetic position remains ambiguous, and varies depending on the type of data (morphological or molecular) used to infer interrelationships. Because the extreme morphological specializations of lampridiforms may have overwritten the ancestral features of the group with a bearing on its relationships, the inclusion of fossils that exhibit primitive character state combinations for the group as a whole is vital in establishing its phylogenetic position. Therefore, we present an osteological dataset of extant (ten taxa) and fossil (14 taxa) acanthomorphs, including early Late Cretaceous taxa for which a close relationship with extant Lampridiformes has been suggested: †Aipichthyoidea, †Pharmacichthyidae and †Pycnosteroididae. We find that all three taxa plus Lampridiformes form a clade that we call Lampridomorpha. Under this hypothesis, †Aipichthyoidea is paraphyletic. The inclusion of fossils in the analysis changes the topology, highlighting their critical importance in phylogenetic studies of morphological characters. When fossils are included, Lampridomorpha is sister to Euacanthomorpha (all other extant acanthomorphs), concurring with most previous anatomical studies, but conflicting with most molecular results. Lampridomorpha as a whole was a major component of the earliest acanthomorph faunas, notably in the Cenomanian.

INTRODUCTION

Lampridiformes is a peculiar clade of teleosts, strictly marine and pelagic, present in every ocean of the world. Extant lampridiform richness is relatively low, with about 20 species and 11 genera grouped in six families [START_REF] Olney | Lampriformes: development and relationships[END_REF][START_REF] Nelson | Fishes of the World[END_REF][START_REF] Roberts | Systematics, Biology and Distribution of the Species of the Oceanic Oarfish Genus Regalecus (Teleostei, Lampridiformes, Regalecidae)[END_REF]: Veliferidae (velifers), Lamprididae (opahs), Lophotidae (crestfishes), Radiicephalidae (tapertail), Trachipteridae (ribbonfishes) and Regalecidae (oarfishes). Stylephoridae (tubeeye) has been recently excluded from Lampridiformes by congruent molecular and morphological data [START_REF] Miya | Mitochondrial genome and a nuclear gene indicate a novel phylogenetic position of deep-sea tube-eye fish (Stylephoridae)[END_REF][START_REF] Grande | Limits and relationships of Paracanthopterygii: A molecular framework for evaluating past morphological hypotheses[END_REF]. Contrasting with their low specific diversity, lampridiforms exhibit remarkable morphological disparity: from the small, deep-bodied velifers to the very large, ribbon-like oarfish. Deep-bodied forms (veliferids and lampridids) are referred to as "bathysomes", while ribbon-like taxa (lophotids, radiicephalids, trachipterids and regalecids) compose the taeniosomes [START_REF] Regan | On the anatomy, classification, and systematic position of the teleostean fishes of the suborder Allotriognathi[END_REF][START_REF] Olney | Phylogeny of lampridiform fishes[END_REF][START_REF] Wiley | The phylogenetic relationships of lampridiform fishes (Teleostei: Acanthomorpha), based on a total-evidence analysis of morphological and molecular data[END_REF].

Lampridiformes have historically been difficult to classify amongst teleosts. Early works based on anatomy placed them in Acanthomorpha (spiny-rayed teleosts) and Acanthopterygii, close to or within the "perciforms" (e.g. [START_REF] Regan | On the anatomy, classification, and systematic position of the teleostean fishes of the suborder Allotriognathi[END_REF][START_REF] Greenwood | Phyletic studies of teleostean fishes, with a provisional classification of living forms[END_REF]. More recently, most morphological studies placed Lampridiformes as sister to Euacanthomorphathat is, sister to all other acanthomorphs [START_REF] Johnson | Percomorph phylogeny: a survey of acanthomorphs and a new proposal[END_REF][START_REF] Olney | Phylogeny of lampridiform fishes[END_REF][START_REF] Wiley | The phylogenetic relationships of lampridiform fishes (Teleostei: Acanthomorpha), based on a total-evidence analysis of morphological and molecular data[END_REF][START_REF] Wiley | The interrelationships of Acanthomorph fishes: a total evidence approach using molecular and morphological data[END_REF])yet this view has been contested by some [START_REF] Wu | Review of the teleostean adductor mandibulae and its significance to the systematic positions of the Polymixiiformes, Lampridiformes, and Triacanthoidei[END_REF]. Molecular studies are even more equivocal and suggested varying positions for Lampridiformes: sister to Euacanthomorpha [START_REF] Wiley | The phylogenetic relationships of lampridiform fishes (Teleostei: Acanthomorpha), based on a total-evidence analysis of morphological and molecular data[END_REF][START_REF] Wiley | The interrelationships of Acanthomorph fishes: a total evidence approach using molecular and morphological data[END_REF][START_REF] Smith | Venom evolution widespread in fishes: a phylogenetic road map for the bioprospecting of piscine venoms[END_REF]Grande et al., 2013 with parsimony), to Polymixiiformes + Paracanthopterygii [START_REF] Dettaï | Further support for the clades obtained by multiple molecular phylogenies in the acanthomorph bush[END_REF], to Polymixiiformes alone [START_REF] Li | RNF213, a new nuclear marker for acanthomorph phylogeny[END_REF], to Percopsiformes [START_REF] Dettaï | New insights into the organization and evolution of vertebrate IRBP genes and utility of IRBP gene sequences for the phylogenetic study of the Acanthomorpha (Actinopterygii: Teleostei)[END_REF][START_REF] Li | RNF213, a new nuclear marker for acanthomorph phylogeny[END_REF], to Paracanthopterygii (Betancur-R. et al., 2013a) and to Euacanthopterygii [START_REF] Near | Resolution of ray-finned fish phylogeny and timing of diversification[END_REF][START_REF] Near | Phylogeny and tempo of diversification in the superradiation of spiny-rayed fishes[END_REF]Grande et al., 2013 with maximum likelihood;[START_REF] Faircloth | A phylogenomic perspective on the radiation of rayfinned fishes based upon targeted sequencing of ultraconserved elements (UCEs)[END_REF]. Molecular studies based on mitochondrial DNA suggested that Lampridiformes are sister to the nonacanthomorph Ateleopodiformes [START_REF] Miya | Mitogenomic exploration of higher teleostean phylogenies: a case study for moderate-scale evolutionary genomics with 38 newly determined complete mitochondrial DNA sequences[END_REF][START_REF] Miya | Major patterns of higher teleostean phylogenies: a new perspective based on 100 complete mitochondrial DNA sequences[END_REF] or Myctophiformes [START_REF] Miya | The phylogenetic position of toadfishes (order Batrachoidiformes) in the higher ray-finned fish as inferred from partitioned Bayesian analysis of 102 whole mitochondrial genome sequences[END_REF][START_REF] Miya | Mitochondrial genome and a nuclear gene indicate a novel phylogenetic position of deep-sea tube-eye fish (Stylephoridae)[END_REF][START_REF] Poulsen | Mitogenomic sequences and evidence from unique gene rearrangements corroborate evolutionary relationships of myctophiformes (Neoteleostei)[END_REF], thus implying acanthomorph polyphyly.

Anatomically, Lampridiformes are very specialized, with their highly protractile jaws and peculiar fins with poorly developed spines [START_REF] Oelschläger | On the evolution and ecological adaptations of the Allotriognathi[END_REF][START_REF] Oelschläger | Vergleichende und funktionelle Anatomie der Allotriognathi (= Lampridiformes), ein Beitrag zur Evolutionsmorphologie der Knochenfische[END_REF][START_REF] Olney | Phylogeny of lampridiform fishes[END_REF].

Due to their distinctive anatomy, Lampridiformes are difficult to relate to other acanthomorph subgroups. This difficulty in formalizing hypotheses of homology between lampridiforms and other acanthomorphs explains, in part, the uncertainty arising from morphological studies, and difficulty in assessing the results of molecular analyses in the light of anatomical data. The discovery of fossil relatives of lampridiforms might therefore be especially helpful in identifying plesiomorphic conditions with a bearing on the phylogenetic affinities of the clade. Twelve entirely fossil genera of Lampridiformes have been described (for reviews, see [START_REF] Bannikov | A review of fossil Lampridiformes (Teleostei) finds with a description of a new Lophotidae genus and species from the Oligocene of the Northern Caucasus[END_REF][START_REF] Carnevale | The first fossil ribbonfish (Teleostei, Lampridiformes, Trachipteridae)[END_REF]. They have been referred to crown-group Lampridiformes, as they present most of the anatomical specialisations of extant representatives [START_REF] Bannikov | An Eocene veliferoid (Teleostei, Lampridiformes) from Bolca[END_REF][START_REF] Bannikov | A review of fossil Lampridiformes (Teleostei) finds with a description of a new Lophotidae genus and species from the Oligocene of the Northern Caucasus[END_REF][START_REF] Sorbini | The Cretaceous fishes of Nardò. 10°. Nardovelifer altipinnis, gen. nov. et sp. nov. (Teleostei, Lampridiformes, Veliferidae)[END_REF]. As such, these fossils do not bear very distinctive character state combinations that would inform us on the position of the group among Acanthomorpha.

Conversely, other fossil taxa might potentially be informative for the large scale relationships of Lampridiformes. These include several extinct acanthomorph groups that have been described from early Late Cretaceous outcrops in the Near East, England, Slovenia, Mexico, Morocco, and Italy. Most of them are coeval with the oldest known fossil Acanthomorpha, which are Cenomanian in age (93-100 Myr). In contrast, the oldest unequivocal lampridiform is the Campanian-Maastrichtian (70-83 Myr ago): †Nardovelifer altipinnis [START_REF] Sorbini | The Cretaceous fishes of Nardò. 10°. Nardovelifer altipinnis, gen. nov. et sp. nov. (Teleostei, Lampridiformes, Veliferidae)[END_REF], which has been interpreted as a close relative of modern veliferids. These extinct Cretaceous taxa are interesting in the context of lampridiform interrelationships for two reasons. First, they show mosaic character combinations that are not found in modern taxa, suggesting that they can add valuable information if included in a phylogenetic analysis of acanthomorphs. Second, they have been repeatedly nominated as potential sister-groups to Lampridiformes, although their phylogenetic position remains largely untested.

In this paper, we assess the phylogenetic position of Lampridiformes by including Acanthomorpha and closely related outgroup taxanotably the Late Cretaceous fossil candidates as sister-groups of Lampridiformesfor the first time in the same phylogenetic analysis of morphological characters.

POTENTIAL CRETACEOUS RELATIVES OF LAMPRIDIFORMES

Five extinct taxa have been proposed as potential sister groups to lampridiforms: †Araripichthyidae, †Dinopterygidae, †Pycnosteroididae, †Pharmacichthyidae and †Aipichthyoidea. †Araripichthyidae is a monogeneric family comprising four species [START_REF] Alvarado-Ortega | A new species of Araripichthys (Teleostei, Elopocephala) from the Tlayúa Formation (Cretaceous, Albian), Mexico[END_REF] Maisey & Blum (1991: 215), because this genus shows a large ascending process on the premaxilla and absence of pelvic fins (a character present in only some taeniosomes); however, [START_REF] Maisey | A review of the problematic extinct teleost fish Araripichthys, with a description of a new species from the Lower Cretaceous of Venezuela[END_REF] later argued that these features are probably convergent with lampridiforms, because †Araripichthys lacks most acanthomorph, ctenosquamate, and even euteleost synapomorphies. [START_REF] Cavin | Osteology and phylogenetic relationships of the teleost Goulmimichthys arambourgi Cavin, 1995, from the Upper Cretaceous of Goulmima, Morocco[END_REF] performed a phylogenetic analysis showing that †Araripichthys is closer to the non-acanthomorph euteleost Esox than to the acanthomorph †Hoplopteryx.

The four remaining taxa, †Dinopterygidae, †Pycnosteroididae, †Pharmacichthyidae and †Aipichthyoidea were grouped together by [START_REF] Patterson | A review of Mesozoic acanthopterygian fishes, with special reference to those of the English Chalk[END_REF] in the †Dinopterygoidei. In his review of Cretaceous acanthomorphs, he mentioned a possible relationship between lampridiforms and †dinopterygoids (1964: 473), an opinion strengthened by his subsequent work on the caudal skeleton (1968: 97). Oelschläger (1983: fig. 108) concurred with this opinion in his review of lampridiform anatomy. Patterson (1993: 36) later explained that his †Dinopterygoidei was most probably a non-monophyletic assemblage, lacking unique synapomorphies. We agree with Patterson's assessment, and will therefore treat the component groups of †Dinopterygoidei separately. †Dinopterygidae consists of only one species, †Dinopteryx spinosus (Davis, 1887), from the Santonian of Sahel Alma, Lebanon. Little is known about this taxon, due to the poor preservation of the few specimens available, and Patterson (1993: 42) Gayet (1980a), who considered this genus related to modern holocentrids [START_REF] Gayet | Essai de définition des relations phylogénétiques des Holocentroidea nov. et des Trachichthyoidea nov. (Pisces, Acanthopterygii, Béryciformes)[END_REF]. Patterson (1993: 40) maintained the genus as Acanthomorpha incertae sedis. [START_REF] Murray | Four new basal acanthomorph fishes from the Late Cretaceous of Morocco[END_REF] suggested that the whole family is part of the order Polymixiiformes, by finding †Magrebichthys in a polytomy with Polymixia and paracanthopterygians.

There are three species of †Pharmacichthyidae: †Pharmacichthys venenifer Smith Woodward, 1942, †P. numismalis Gayet, 1980a, both from the Cenomanian of Hakel, Lebanon, and †P. judensis Gayet, 1980b from the Cenomanian of Ein Yabrud, Palestine. Gayet (1980a,b,c) argued that †Pharmacichthys is not even an acanthomorph, whereas [START_REF] Rosen | The structure and relationships of the paracanthopterygian fishes[END_REF] and [START_REF] Patterson | An overview of the early fossil record of acanthomorphs[END_REF] listed it amongst possible lampridiform relatives.

The super-family †Aipichthyoidea is a more diverse group, with 13 species included in eight genera and two families (Otero & Gayet, 1996;Alvarado-Ortega & Than-Marchese, 2012;[START_REF] Murray | Four new basal acanthomorph fishes from the Late Cretaceous of Morocco[END_REF]. Family †Aipichthyidae includes †Aipichthys [five species: †A. nuchalis (Dixon, 1850), †A. minor (Pictet, 1850), †A. pretiosus Steindachner, 1860, †A.

velifer Smith Woodward, 1901 and†A. oblongus Gayet, 1980a], †Paraipichthys lusitanicus [START_REF] Gaudant | Contribution à l'étude anatomique et systématique de l'ichthyofaune cénomanienne du Portugal. Première partie: les "acanthoptérygiens[END_REF]†Freigichthys elleipsis Otero, 1997. Family †Aipichthyoididae includes †Aipichthyoides formosus Gayet, 1980b, †A. galeatus Gayet, 1980b (Gayet, 1980b;[START_REF] Otero | Un nouveau genre d'Aipichthyoidea (Teleostei, Acanthomorpha) du Cénomanien inférieur marin de Hgula (Liban) : description et relations phylogénétiques[END_REF], but the five species of †Aipichthys are known from Lebanon, England and Slovenia [START_REF] Patterson | A review of Mesozoic acanthopterygian fishes, with special reference to those of the English Chalk[END_REF][START_REF] Radovčić | Some new Upper Cretaceous teleosts from Yugoslavia with special reference to localities, geology and palaeoenvironment[END_REF]Gayet, 1980a), †Aspesaipichthys is from Italy [START_REF] Taverne | Les poissons crétacés de Nardò. 17°. Aspesaipichthys cavaensis gen. et sp. nov. (Teleostei, Acanthomorpha, Aipichthyoidea)[END_REF], †Paraipichthys from Portugal [START_REF] Gaudant | Contribution à l'étude anatomique et systématique de l'ichthyofaune cénomanienne du Portugal. Première partie: les "acanthoptérygiens[END_REF], †Zoqueichthys from Mexico (Alvarado-Ortega & Than-Marchese, 2012) and finally †Errachidia and †Homalopagus are from Morocco [START_REF] Murray | Four new basal acanthomorph fishes from the Late Cretaceous of Morocco[END_REF]. All of these genera are Cenomanian (or Cenomanian-Turonian) of age, with the exception of †Aspesaipichthys which is younger (Campanian-Maastrichtian). Although [START_REF] Patterson | A review of Mesozoic acanthopterygian fishes, with special reference to those of the English Chalk[END_REF][START_REF] Patterson | An overview of the early fossil record of acanthomorphs[END_REF], [START_REF] Rosen | The structure and relationships of the paracanthopterygian fishes[END_REF] and [START_REF] Oelschläger | Vergleichende und funktionelle Anatomie der Allotriognathi (= Lampridiformes), ein Beitrag zur Evolutionsmorphologie der Knochenfische[END_REF] suggested that †aipichthyids were related to lampridiforms, Gayet (1980a,b) proposed that they were closer to paracanthopterygians. Finally, [START_REF] Otero | Etude phylogénétique des aipichthyides, poissons téléostéens de la Téthys cénomanienne[END_REF], 1996) placed †aipichthyoids as sister to Euacanthomorpha (see below), but not without mentioning a possible lampridiform affinity (1995: 223).

Few phylogenetic studies included these Cretaceous taxa. The first was presented by [START_REF] Otero | Etude phylogénétique des aipichthyides, poissons téléostéens de la Téthys cénomanienne[END_REF], 1996), including only †aipichthyoids among our candidate taxa. They found that the superfamily is monophyletic and composed of two sister-groups: †Aipichthyidae ( †Aipichthys and †Paraipichthys) and †Aipichthyoididae ( †Aipichthyoides).

Their analysis also retrieved †Aipichthyoidea as a sister-group to Euacanthomorpha, but lampridiforms were not included in the study. Alvarado-Ortega & Than-Marchese (2012), then [START_REF] Murray | Four new basal acanthomorph fishes from the Late Cretaceous of Morocco[END_REF] re-analysed Otero & Gayet's matrix, adding new taxa. They included †Freigichthys in †Aipichthyidae and †Aspesaipichthys and †Zoqueichthys in †Aipichthyoididae. Their results did not change the position of †aipichthyoids amongst Acanthomorpha, and lampridiforms were once again unrepresented in the data matrix. Thus, despite the fact that a relationship between Lampridiformes andat least - †aipichthyoids had been repeatedly proposed in the literature before, all previous studies were unable to test this hypothesized relationship. [START_REF] Rosen | The structure and relationships of the paracanthopterygian fishes[END_REF]; but see [START_REF] Newbrey | A new species of the paracanthopterygian Xenyllion from the Mowry Formation (Cenomanian) of Utah, USA[END_REF]. We chose not to include †Araripichthys, judging that [START_REF] Maisey | A review of the problematic extinct teleost fish Araripichthys, with a description of a new species from the Lower Cretaceous of Venezuela[END_REF] and [START_REF] Cavin | Osteology and phylogenetic relationships of the teleost Goulmimichthys arambourgi Cavin, 1995, from the Upper Cretaceous of Goulmima, Morocco[END_REF] provided convincing evidence that this genus is not an acanthomorph. †Dinopteryx was also excluded, because the incompleteness of the available material made most relevant characters impossible to assess [START_REF] Patterson | An overview of the early fossil record of acanthomorphs[END_REF].

MATERIAL AND METHODS

The ten extant taxa were chosen from all major acanthomorph clades and closely related non-acanthomorphs. These include: the aulopiform Synodus intermedius (Spix & Agassiz, 1829) and the myctophiform Gymnoscopelus sp. as non-acanthomorph outgroups; the holocentrid Myripristis sp. for Euacanthopterygii; Polymixia nobilis Lowe, 1836 for Polymixiiformes; the percopsiform Aphredoderus sayanus (Gilliams, 1824) and the gadiform Merluccius merluccius (Linnaeus, 1758) for Paracanthopterygii; the veliferid Metavelifer multiradiatus [START_REF] Regan | On the anatomy, classification, and systematic position of the teleostean fishes of the suborder Allotriognathi[END_REF], the lampridid Lampris spp. and the taeniosomes Regalecus glesne Ascanius, 1772 and Trachipterus spp. for Lampridiformes.

This sampling makes the present study the first to simultaneously include representatives from all extant acanthomorph subgroups (Lampridiformes and Euacanthopterygii were absent from Otero & Gayet, 1996) and Cretaceous fossils. This is also the first time the placements of †Pharmacichthys and †Pycnosteroides have been assessed in a phylogenetic analysis.

The list of specimens examined is available in Table 1. Extant specimens are dry osteological preparations, unless otherwise stated. Taxa not included in Table 1 were coded exclusively from the literature.

PHYLOGENETIC ANALYSES

The character matrix was analysed using PAUP 4.0 [START_REF] Swofford | PAUP*, Phylogenetic Analysis Using Parsimony *and other methods[END_REF]. All characters were unordered and assigned an equal weight of one, because we had no arguments on character ordering and polarity prior to the analyses.

We performed two consecutive phylogenetic analyses. Analysis 1 included the extant taxa only (ten taxa), with trees rooted with one of the outgroups (Synodus). We used the Exhaustive search algorithm for this analysis. Analysis 2 included all 24 taxa (fossil and extant), with trees still rooted with Synodus. Because 24 taxa exceed the capability of exhaustive algorithms, we used the Branch-and-Bound search algorithm in this analysis, with "furthest" addition sequence. Character polarity was determined a posteriori by the outgroup criterion.

Tree descriptions were computed in PAUP 3.1.1 [START_REF] Swofford | PAUP, Phylogenetic Analysis Using Parsimony, Version 3.1[END_REF], for an accurate reconstruction of character states. We calculated the Bremer indexes automatically using a PAUP script generated with TreeRot v.2 [START_REF] Sorenson | TreeRot, version 2[END_REF].

RESULTS

CHARACTERS

The 39 skeletal characters used by [START_REF] Otero | Etude phylogénétique des aipichthyides, poissons téléostéens de la Téthys cénomanienne[END_REF], 1996), and then by Alvarado-Ortega & Than-Marchese (2012) for aipichthyoid phylogeny were coded in our matrix. We also included 14 skeletal characters described by [START_REF] Olney | Phylogeny of lampridiform fishes[END_REF] in their study of lampridiform intrarelationships, that are applicable in fossils. The characters that we used come from every region of the skeleton: cranial (Fig. 1), vertebral, dorsal (Fig. 2) and anal fins, caudal (Fig. 3) and appendicular skeleton (Fig. 4). In total, 67 characters have been coded; they are detailed in Table 2.

Characters 29, 43 and 64 are new, and they are described below. For description of the remaining characters, please refer to the appropriate references in Table 2.

Character 29: Urohyal: 0 = not expanded ventrally; 1 = expanded by a large ventral lamina

The urohyal is a median unpaired membrane bone surrounded laterally by the gill arches and the branchiostegal rays (Fig. 1G-H). In lampridiforms, the ventral edge of the urohyal forms an extensive lamina (Fig. 1H,4C), which is absent in most other acanthomorphs (Fig. 1G).

Character 43:

First soft ray of the dorsal fin elongated and unbranched: 0 = absent; 1 = present The soft rays of the dorsal fin (posterior to the fin spines when they are present) are branched distally in most teleosts. In †aipichthyoids, †Pharmacichthys and lampridiforms, the first soft ray is unbranched and elongated when compared to the other dorsal soft rays.

Character 64:

Internal wings of the pelvic bone: 0 = separated; 1 = joined medially Usually in acanthomorphs (Fig. 4D) and close relatives, both pelvic bones only contact each other at the level of their median processes (Stiassny & Moore, 1992: figs 2, 3). In †Freigichthys, †Zoqueichthys (Fig. 4E), lampridiforms (Fig. 4F) and most euacanthopterygians, the internal wings of the pelvic bones are expanded and make extensive contact with each other on a median line.

The complete data matrix (24 taxa, ten extant and 14 fossil; 67 characters) is available in Table 3. There is 11% missing data, noted as '?' in the matrix: this is mainly a result of incomplete fossils, but is also linked with extant Lampridiformes for characters 9, 14, and 15, because of the bad state of preservation of the collection material that we accessed. As a result of the chosen coding strategy, 2% of the character states are treated as inapplicable. They are noted '-' in the matrix. Only one character, character 18, is uninformative.

PHYLOGENETIC RESULTS

Analysis 1 (extant taxa only) yielded one parsimonious tree, with a tree length of 107 steps, a consistency index (CI) of 0.64, and a retention index (RI) of 0.71 (Fig. 5). Within the monophyletic Acanthomorpha, it places Lampridiformes sister to Paracanthopterygii (Gadiformes + Percopsiformes). This relationship is well-supported by seven unambiguous synapomorphies (see below). In both analyses, Lampridiformes is monophyletic and supported by 12 (analysis 1) and ten (analysis 2) unambiguous synapomorphies, respectively. Our results are consistent with the previous morphological and molecular hypotheses of lampridiform intrarelationships (e.g. [START_REF] Olney | Phylogeny of lampridiform fishes[END_REF][START_REF] Wiley | The phylogenetic relationships of lampridiform fishes (Teleostei: Acanthomorpha), based on a total-evidence analysis of morphological and molecular data[END_REF]: veliferids (exemplified by Metavelifer) are sister to a clade composed by Lampris and taeniosomes (represented here by Trachipterus and

Regalecus).

The complete list of character state changes is given in the Appendix. If inference for a character change on the parsimonious tree (or the strict consensus tree) provided several character distributions (resulting in an ambiguous state for some nodes), every possible optimization was considered before one was selected based on biological considerations.

DISCUSSION TOPOLOGICAL IMPACT OF THE INCLUSION OF FOSSILS

The impact of fossils in phylogenetic reconstruction has been debated ever since the generalisation of cladistic methodology. Following claims that fossil taxa have little impact in topologies (e.g. [START_REF] Patterson | Significance of fossils in determining evolutionary relationships[END_REF], empirical studies have shown that all available taxa (extant and fossils) should be included in an analysis so that it can reflect most closely the interrelationships of characters and taxa [START_REF] Gauthier | Amniote phylogeny and the importance of fossils[END_REF][START_REF] Donoghue | The importance of fossils in phylogeny reconstruction[END_REF][START_REF] Cobbett | Fossils impact as hard as living taxa in parsimony analyses of morphology[END_REF]. Within acanthomorphs, studies have explored the importance of fossils for reconstructing the evolutionary acquisition of complex characters (e.g. [START_REF] Friedman | The evolutionary origin of flatfish asymmetry[END_REF][START_REF] Friedman | An early fossil remora (Echeneoidea) reveals the evolutionary assembly of the adhesion disc[END_REF], studying the sequence of character acquisition (e.g. [START_REF] Murray | Contributions of fossils to the phylogenetic relationships of the percopsiform fishes (Teleostei: Paracanthopterygii): order restored[END_REF] and influencing the topology, even when they are incomplete (e.g. [START_REF] Santini | The importance of even highly incomplete fossil taxa in reconstructing the phylogenetic relationships of the Tetraodontiformes (Acanthomorpha: Pisces)[END_REF].

The case of Lampridiformes is particularly interesting, because no enduring consensus has been reached on their phylogenetic position among acanthomorphs (see "Introduction"). This is especially true with datasets composed of nuclear genes that, in addition, consistently show low support values for the immediately more inclusive clade: for example 54% of bootstrap replicates in Betancur-R. et al. (2013a) and less than 70% in [START_REF] Near | Phylogeny and tempo of diversification in the superradiation of spiny-rayed fishes[END_REF]. Yet, under a certain threshold (for example, 95% according to [START_REF] Felsenstein | Confidence limits on phylogenies: using the bootstrap[END_REF], nodes should in principle be considered as statistically non-significant. New molecular studies, specifically sampling the base of the acanthomorph tree, are needed in order to better understand the source of these low nodal supports and conflicting topologies. In this context, assessing how taxonomic sampling impacts the reconstructions of topology and character evolution is particularly relevant, especially with fossils, which are absent from molecular datasets.

With the present study, we show another empirical case where fossils have a direct impact on a topology including numerous extant taxa. The phylogenetic position of Lampridiformes varies between our two analyses, which otherwise are based on identical datasets.

When only extant taxa are included (analysis 1), Lampridiformes is sister to Paracanthopterygii (Fig. 5), a position that has already been suggested by some molecular studies (e.g. Betancur-R. et al., 2013a), but by no other morphological analyses to date. The Lampridiformes + Paracanthopterygii clade is then supported by at least seven synapomorphies: the loss of the antorbital (character 7, 01), the loss of postabdominal epineurals (character 36, 01), the presence of only one supraneural (character 38, 02), the fusion of the upper hypurals together (character 52, 01) and with the second ural centrum (character 53, 01), the fusion of the lower hypurals (character 54, 01) and the fusion of the postcleithra (character 61, 01).

The inclusion of fossils in analysis 2 (Fig. 6) changes the position of Lampridiformes relative to other extant taxa: their extant sister-group becomes Euacanthomorpha. Support for this hypothesis is also high, with at least five euacanthomorph synapomorphies (see "Taxonomy and character evolution" below).

Such incongruence between the results of both analyses means that at least one of the topologies is misleading and should be rejected, as well as the hypotheses of secondary homology it implies. All synapomorphies that support the Lampridiformes + Paracanthopterygii clade after analysis 1 are linked to reduction or fusion of bones (see above), characters for which primary homology hypotheses are difficult to formalize and which are known to have occurred independently in many different acanthomorph groups. In analysis 2, homology for these character states in Lampridiformes and Paracanthopterygii is rejected by the inclusion of additional data: new character state distributions from fossils.

Thus, convergent appearance of the features in both clades is implied by analysis 2.

Previously, the absence of the fossil taxa mistakenly supported a relationship between these two clades that show a high amount of character transformation (especially reduction), in a way similar to so-called long-branch attraction in molecular phylogenetics.

The result of analysis 2 (including fossils) shows congruence with previous morphological [START_REF] Johnson | Percomorph phylogeny: a survey of acanthomorphs and a new proposal[END_REF][START_REF] Wiley | The interrelationships of Acanthomorph fishes: a total evidence approach using molecular and morphological data[END_REF] as well as molecular analyses [START_REF] Wiley | The interrelationships of Acanthomorph fishes: a total evidence approach using molecular and morphological data[END_REF][START_REF] Smith | Venom evolution widespread in fishes: a phylogenetic road map for the bioprospecting of piscine venoms[END_REF]Grande et al., 2013 with parsimony).However, it contradicts other molecular results. For instance, the monophyly of Acanthomorpha (including Lampridiformes) is recovered unambiguously, in contrast with phylogenies based on the mitogenome [START_REF] Miya | Mitogenomic exploration of higher teleostean phylogenies: a case study for moderate-scale evolutionary genomics with 38 newly determined complete mitochondrial DNA sequences[END_REF][START_REF] Miya | Major patterns of higher teleostean phylogenies: a new perspective based on 100 complete mitochondrial DNA sequences[END_REF][START_REF] Miya | The phylogenetic position of toadfishes (order Batrachoidiformes) in the higher ray-finned fish as inferred from partitioned Bayesian analysis of 102 whole mitochondrial genome sequences[END_REF][START_REF] Poulsen | Mitogenomic sequences and evidence from unique gene rearrangements corroborate evolutionary relationships of myctophiformes (Neoteleostei)[END_REF]. Other large-scale molecular studies using diverse markers and methods proposed a Lampridiformes-Euacanthopterygii clade [START_REF] Near | Resolution of ray-finned fish phylogeny and timing of diversification[END_REF][START_REF] Near | Phylogeny and tempo of diversification in the superradiation of spiny-rayed fishes[END_REF][START_REF] Faircloth | A phylogenomic perspective on the radiation of rayfinned fishes based upon targeted sequencing of ultraconserved elements (UCEs)[END_REF], which is not supported by our data. Should this alternative molecular hypothesis be confirmed by future studies, however, some lampridomorph characters are also found in euacanthopterygians and could be taken as potential evidence of a relationship between both clades. These include the anatomy of the pelvic skeleton (with the pelvic bones joined medially by their internal wings) and the presence of a pelvic spine in several taxa.

TAXONOMY AND CHARACTER EVOLUTION

Works such as [START_REF] Johnson | Percomorph phylogeny: a survey of acanthomorphs and a new proposal[END_REF], [START_REF] Olney | Phylogeny of lampridiform fishes[END_REF] or Otero & Gayet (1996) established a framework for large-scale acanthomorph classification. Once we established that our second analysis (Fig. 6), including both extant Lampridiformes and Cretaceous fossils, efficiently sorted out homology and homoplasy in our character set, we were able to bring forth some new taxonomic hypotheses and confirm some others.

The classification of acanthomorphs we propose is as follows: TELEOSTEI MÜLLER, 1846 NEOTELEOSTEI NELSON, 1969EURYPTERYGII ROSEN, 1973CTENOSQUAMATA ROSEN, 1973ACANTHOMORPHA ROSEN, 1973 Included taxa: Euacanthomorpha (see below); Lampridomorpha (see below).

Eight unambiguous character states support Acanthomorpha.

1. Frontal branch of the sensory canal running through the frontal and pterotic in a groove (character 14, 01).

In non-acanthomorph teleosts, this canal is enclosed within a bony tube. There is a reversal of this character state, at least in †Pharmacichthys numismalis.

Developed sagittal crest (character 16, 01).

The sagittal crest primitively consists of the supraoccipital alone. It is secondarily reduced in taeniosome lampridiforms (exemplified by Trachipterus and Regalecus).

Dorsal limb of the posttemporal firmly bound to the epiotic (character 22, 01).

This acanthomorph synapomorphy has been proposed first by [START_REF] Stiassny | The limits and relationships of the acanthomorph teleosts[END_REF]. 4. Spines in the dorsal fin (character 42, 01).

They are secondarily lost in Merluccius and all lampridiforms, except veliferids.

Hemaxanal complex (character 46, 01).

This fusion of the anterior-most anal pterygiophores is secondarily lost in Merluccius and most lampridiforms. 6. Spines in the anal fin (character 47, 01).

In several acanthomorph groups not included in the analysis (such as batrachoidiforms and nototheniids), spines are present in the dorsal fin only. This suggests that the presence of spines in the anal and dorsal fins is not phylogenetically linked and should be treated as two independent characters. This contradicts character 6 from Otero & Gayet (1996). Like the dorsal fin ones, anal fin spines are lost in Merluccius and lampridiforms excluding veliferids.

7. Loss of the urodermals (character 56, 01). 8. Loss of the dermal caudal scutes (character 57, 01).

Seven out of ten acanthomorph characters from Otero & Gayet (1996) are recovered here as acanthomorph synapomorphies. Their character 5 (neural spines fused to their centra) which is our character 33 (01)is interpreted as a ctenosquamate synapomorphy instead.

Their character 10 (reduction of the number of pelvic fin rays to seven, character 66, 01) is recovered as independently derived in euacanthomorphs (see below), †Aipichthyoides and Clade B (see below). Optimization of their character 3 (our character 15, 01) is ambiguous: it could also be a euacanthomorph synapomorphy.

Postmaxillary process of the premaxilla (character 1, 01).

A posterior notch appears on this process in paracanthopterygians.

Spina occipitalis (character 23, 01).

This character was interpreted as an acanthomorph synapomorphy by [START_REF] Stiassny | The limits and relationships of the acanthomorph teleosts[END_REF], who described it first.

Foramen in the distal ceratohyal (character 27, 10).

A so-called "beryciform" foramen is also present in †Ctenothrissa, †Pycnosteroides, †Pharmacichthys and in veliferid lampridiforms. It is secondarily lost in extant paracanthopterygians.

4. Anterior epineurals originating on vertebral centra or transverse processes (character 35, 01).

The state appears convergently in †Pharmacichthys and †Pycnosteroides.

Seven pelvic soft rays or less (character 66, 10).

This character is interpreted as an acanthomorph synapomorphy by Otero & Gayet (1996, character 10). Otero & Gayet (1996, character 11) proposed that a caudal fin with a maximum of 18 principal rays (our character 58, 01) was another synapomorphy of Euacanthomorpha. The optimization of this character state is ambiguous.

LAMPRIDOMORPHA

We propose to name Lampridomorpha the clade that unites Lampridiformes with †Pycnosteroididae, †Pharmacichthyidae and †Aipichthyoidea (Fig. 6, clade A). This name was already used in several studies (e.g [START_REF] Mccune | Twenty ways to lose your bladder: common natural mutants in zebrafish and widespread convergence of swim bladder loss among teleost fishes[END_REF][START_REF] Dillman | Regressive progression, progressive regression or neither? Phylogeny and evolution of the Percopsiformes (Teleostei, Paracanthopterygii)[END_REF])sometimes as "Lampriomorpha" [START_REF] Nelson | Fishes of the World[END_REF] or "Lampridacea" [START_REF] Wiley | A teleost classification based on monophyletic groups[END_REF], but always as a superorder with a taxonomic composition identical to the order Lampridiformes. Lampridomorpha is sister to Euacanthomorpha, therefore we suggest for subsequent workers to use this name for grouping Lampridiformes and all fossil taxa most closely related to them than to any other extant acanthomorph taxon (i. These taxa present most of the synapomorphies that characterise Lampridomorpha (see below). †Errachidia and †Homalopagus are retained as Lampridomorpha incertae sedis, as Murray & Wilson (2014: fig. 12) found in their analysis (although they considered them to be †Aipichthyoidea incertae sedis and included no living lampridomorphs in their analysis).

Within Lampridomorpha, our topology challenges the taxonomy established by previous studies. Indeed, Otero & Gayet's (1996) †Aipichthyoidea is not monophyletic: some of its representatives are most closely related to crown Lampridiformes, while others are grouped with the †Pycnosteroididae + †Pharmacichthyidae clade. Finally, family †Aipichthyoididae as proposed by these authors is also challenged by our results, †Aipichthyoides and †Aspesaipichthys being part of clade D, but not †Zoqueichthys.

Our results therefore imply that, instead of forming a clade, †Aipichthyoidea as a whole is a paraphyletic assemblage of Late Cretaceous acanthomorphs, more or less closely related to extant lampridiforms.

We found nine potential synapomorphies for Lampridomorpha, including eight whose optimisation is unambiguous.

1. Loss of the antorbital (character 7, 01).

It also occurs convergently in extant paracanthopterygians.

Ascending process on the lachrymal (character 8, 01).

It is present in †'aipichthyoids' and †Pycnosteroides, but appears independently in paracanthopterygians [START_REF] Patterson | The Paracanthopterygii revisited: order and disorder[END_REF]. It is optimised as lost in †pharmacichthyids and lampridiforms.

3. Single-headed cranial articular condyle on the hyomandibula (character 25, 01). Despite Oelschläger's (1983: 108) interpretation of the double-headed articular condyle as an "advanced" feature of percomorphs, the same state (Fig. 1D) occurs in myctophiforms [START_REF] Paxton | Osteology and relationships of the lanternfishes (family Myctophidae)[END_REF] and aulopiforms, suggesting that it is plesiomorphic for acanthomorphs. Therefore, we view the reduction to only one condyle as a derived character state of lampridomorphs (Fig. 1E,F), acquired convergently by some paracanthopterygians [START_REF] Grande | Limits and relationships of Paracanthopterygii: A molecular framework for evaluating past morphological hypotheses[END_REF] and by †Ctenothrissa.

4. All supraneurals anterior to the first neural spine (Fig. 2A,B; character 39, 01).

The state is reversed in †Pycnosteroides.

5. First dorsal pterygiophore inserting anterior to the second neural spine (Fig. 2A,B; character 40, 01). This character is further derived in lampridiforms (Fig. 2B), †Pycnosteroides and two species of †Pharmacichthys, where the first dorsal pterygiophore inserts anterior to the first neural spine.

6. First soft ray of the dorsal fin elongated and unbranched (character 43, 01).

In †Aipichthys (Fig. 2A), for example, the anterior-most dorsal fin ray that is branched is the second one. In taeniosome lampridiforms, all dorsal fin rays are unbranched. In all these cases, the first dorsal ray is also the longest (not visible in Fig. 2).

We infer a reversal in †Pycnosteroides, where all dorsal fin rays are branched.

Pelvic girdle contacting the coracoids medially (character 63, 01).

Contact between the pelvic and pectoral girdles is common in acanthomorphs, as described by [START_REF] Stiassny | A review of the pelvic girdle of acanthomorph fishes, with comments on hypotheses of acanthomorph intrarelationships[END_REF], but it can occur in different ways. In Polymixia and Aphredoderus, there is no contact. In Merluccius (Fig. 4A) and Myripristis, the pelvic girdle contacts the cleithra, but not the coracoids. In fossil lampridomorphs (Fig. 4B), it is unclear if it contacts both coracoids and cleithra, or just coracoids. In Lampridiformes (Fig. 4C) the pelvic girdle contacts an enlarged and ventrally expanded coracoid (Le [START_REF] Danois | Sur la musculature des nageoires pectorales et pelviennes de l'opah (Lampris luna Duhamel)[END_REF])incorrectly referred to as an "hypocoracoid" by [START_REF] Gill | On the relations of the fishes of the family Lamprididae or opahs[END_REF].

Pelvic bones joined medially by their internal wings (character 64, 01).

This character also occurs in most euacanthopterygians, but not in polymixiiforms (Fig. 4D) or paracanthopterygians. While the character state is observable only in two of our fossil taxa ( †Freigichthys and †Zoqueichthys; Fig. 4E), their respective positions in the final tree favours the interpretation that it appeared in the last common ancestor of lampridomorphs.

The following feature can also be optimised as a ctenosquamate synapomorphy: 9. Hypurostegy of the caudal fin rays (character 58, 01).

The character is also present (amongst many others) in myctophids and in numerous euacanthopterygians (e.g. scombrids, carangids, luvarids, xiphioids). It is noteworthy that this ambiguous synapomorphy was the main argument that [START_REF] Patterson | The caudal skeleton in Mesozoic acanthopterygian fishes[END_REF][START_REF] Patterson | An overview of the early fossil record of acanthomorphs[END_REF] and later authors (e.g. [START_REF] Olney | Phylogeny of lampridiform fishes[END_REF] mentioned to justify a relationship between †aipichthyoids (Fig. 3D) and lampridiforms (Fig. 3E). Otero & Gayet (1996) proposed four synapomorphies for their †Aipichthyoidea. Here we demonstrate that three of these (the loss of the antorbital, the anterior insertion of the supraneurals and the contact between pelvic and pectoral girdles) in fact characterize a more inclusive clade: they can be assigned without ambiguity to Lampridomorpha. Their last putative synapomorphy of †aipichthyoids (plate-like process on the hyomandibula: character 26, 01) is unambiguously optimised as a ctenosquamate synapomorphy. Therefore, our data do not support any synapomorphies for †Aipichthyoidea, which we regard as a nonmonophyletic assemblage. Some other character reconstructions of the present study are worth mentioning. For example, the true pelvic spine (character 67, 01) was thought to be a diagnostic character of acanthopterygians [START_REF] Stiassny | A review of the pelvic girdle of acanthomorph fishes, with comments on hypotheses of acanthomorph intrarelationships[END_REF][START_REF] Johnson | Percomorph phylogeny: a survey of acanthomorphs and a new proposal[END_REF]. There is a pelvic spine in at least two lampridomorphs, however: †Pycnosteroides (Fig. 4B) and †Magrebichthys [START_REF] Murray | Four new basal acanthomorph fishes from the Late Cretaceous of Morocco[END_REF]. [START_REF] Murray | Four new basal acanthomorph fishes from the Late Cretaceous of Morocco[END_REF] also described a spine in the pelvic fins of †Errachidia and †Homalopagus, but this interpretation is questionable because the structures are incomplete, and can also be interpreted as enlarged and unbranched soft rays (as in †Aipichthys). Therefore, when our data are considered, pelvic spines appeared at least twice independently: in Euacanthopterygii and in certain lampridomorphs. This clade (Fig. 6,clade C) is supported by two synapomorphies, both unique to it:

1. Frontal bone forming part of the sagittal crest (Fig. 1B,C), which usually (Fig. 1A) consists of the supraoccipital only (character 17, 01).

2. Long sagittal crest (Fig. 1B,C), extending from the nasal area to the occiput (character 20, 01).

Both synapomorphies are unknown in †Aspesaipichthys, due to its incomplete preservation. In acanthomorphs, the mesethmoid is generally located anterior to the lateral ethmoids (Fig. 1A). In †Aipichthyoides, the mesethmoid composes the sagittal crest; dorsally it is median to the lateral ethmoids (Fig. 1B). In lampridiforms (Olney et al., 1993: 148), the mesethmoid is partly median, partly posterior (Fig. 1C), or completely posterior (in taeniosomes) to the lateral ethmoids.

Five hypurals or fewer (character 51, 01).

There is a reversal in veliferids (Fig. 3C), a convergence in euacanthopterygians and some paracanthopterygians.

Lower hypurals fused together (character 54, 01).

In †Aipichthyoides, †Aspesaipichthys (Fig. 3B) and veliferids (Fig. 3C), hypurals one and two are joined together at the base, thus partially fused together. The fusion is complete in Lampris. This state is convergent in Aphredoderus and Merluccius.

LAMPRIDIFORMES GOODRICH, 1909

Synonyms: Allotriognathi [START_REF] Regan | On the anatomy, classification, and systematic position of the teleostean fishes of the suborder Allotriognathi[END_REF]Lampriformes Goodrich, 1909. Remark: A debate exists on whether the order should be named "Lampriformes" or "Lampridiformes". "Lampriformes" has been used several times following the recommendations of [START_REF] Steyskal | The grammar of family-group names as exemplified by those of fishes[END_REF], for example in [START_REF] Olney | Lampriformes: development and relationships[END_REF], [START_REF] Grande | Limits and relationships of Paracanthopterygii: A molecular framework for evaluating past morphological hypotheses[END_REF] and most notably, in Nelson's widely used handbook Fishes of the World [START_REF] Nelson | Fishes of the World[END_REF] as well as in the online database FishBase [START_REF] Froese | FishBase[END_REF]; http://www.fishbase.org). However, Patterson, in an appendix to [START_REF] Olney | Phylogeny of lampridiform fishes[END_REF], advocated the use of "Lampridiformes". This orthography has been followed by the vast majority of recent phylogenetic papers, including the review of teleost classification by [START_REF] Wiley | A teleost classification based on monophyletic groups[END_REF] and the DeepFin-EToL classification (Betancur-R. et al., 2013b).Therefore, we chose to maintain current usage and use the name "Lampridiformes".

Included taxa: see reviews in [START_REF] Olney | Phylogeny of lampridiform fishes[END_REF][START_REF] Roberts | Systematics, Biology and Distribution of the Species of the Oceanic Oarfish Genus Regalecus (Teleostei, Lampridiformes, Regalecidae)[END_REF]. Olney et al. (1993) proposed four osteological synapomorphies for Lampridiformes. All of these were retrieved here (one has an ambiguous optimisation and another is not a discrete character state in our matrix) and we propose additional ones, for a total of 14 synapomorphies (four cannot be unambiguously assigned to the clade because of missing data in the fossil sister groups).

1. Ascending process of the premaxilla equal or longer than the alveolar process (character 2, 01).

An elongate ascending process is a lampridiform synapomorphy according to Olney et al. (1993: 148).

Loss of the supramaxillae (character 3, 02).

It is also the case in modern paracanthopterygians and in myctophids, by convergence.

Loss of the anterior palatine process (character 4, 01).

This lampridiform synapomorphy according to Olney et al. (1993: 147) is here optimised as ambiguous, because the character state data are missing for the immediate fossil outgroups in our matrix.

4. Loss of the ascending process on the lachrymal (character 8, 10). This is a reversal of Lampridomorpha character number one. 5. "Vault" or "cradle" on the frontal, accommodating the premaxilla and the rostral cartilage (character 12, 01). This state is part of Olney et al.'s (1993: 148) synapomorphy number three.

Seven or fewer branchiostegal rays (character 28, 12).

This state is convergent with paracanthopterygians and Polymixia.

7. Urohyal expanded by a large ventral lamina (Fig. 1H; character 29, 01).

The optimisation is ambiguous for this state because of missing data in fossils. A large ventral lamina on the urohyal is also present in many deep-bodied euacanthopterygians not included in the analysis like menids and some carangids.

Epineurals lost on the postabdominal vertebrae (character 36, 01).

This state is convergent with extant paracanthopterygians. 9. Loss of the epipleurals (character 37, 01).

An independent loss occurred in Euacanthopterygii+Paracanthopterygii and in †Pycnosteroides 10. Only two supraneurals (character 38, 02).

All Lampridiformes included in our analysis have one supraneural at most (hence the character state presented here). However, Velifer hypselopterus (not included) is the only extant species with two supraneurals (Fig. 2B), suggesting that the reduction to two supraneurals is the lampridiform synapomorphy. Such a reduction is convergent with paracanthopterygians and Myripristis.

11. First dorsal pterygiophore inserting anterior to the first neural spine (Fig. 2B;character 40,12). This character state is also observed (by convergence) in the †Pharmacichthys + †Pycnosteroides clade (with a reversion in †Pharmacichthys venenifer) and in euacanthopterygians not included in the analysis such as echeneids, pleuronectoids, pataecids and coryphaenids.

12. Upper hypurals fused together (Fig. 3B,C; character 52, 01).

The character can also be considered a synapomorphy of a potential †Aspesaipichthys+Lampridiformes clade (recovered in several parsimonious trees), convergent with modern paracanthopterygians.

13. Upper hypurals fused to the second ural centrum (Fig. 3C; character 53, 01).

While it could also be interpreted as convergent in lampridids and veliferids, we follow [START_REF] Wiley | A teleost classification based on monophyletic groups[END_REF], who favoured this character state as a lampridiform synapomorphyas already noted by [START_REF] Patterson | The caudal skeleton in Mesozoic acanthopterygian fishes[END_REF]. There is a reversal in taeniosomes, which have greatly modified caudal skeletons presumably associated with reduction of the caudal fin. The state is also convergent with extant paracanthopterygians.

Postcleithra fused together (character 61, 01).

This state is convergent with extant paracanthopterygians.

Our results are consistent with the previous ones regarding relationships within Lampridiformes (e.g. [START_REF] Olney | Phylogeny of lampridiform fishes[END_REF][START_REF] Wiley | The phylogenetic relationships of lampridiform fishes (Teleostei: Acanthomorpha), based on a total-evidence analysis of morphological and molecular data[END_REF]: veliferids are sister to a clade composed by lampridids and taeniosomes.

CONCLUSIONS

For the first time, Late Cretaceous acanthomorphs of uncertain affinities are included in a phylogenetic analysis along with representatives of all the major acanthomorph subgroups.

Thanks to this taxonomic sampling allowing a better comprehension of character state distribution among acanthomorphs, we are able to propose here new arguments concerning the phylogenetic position of Lampridiformes. Our results support a topology that is congruent with some previous works, both anatomical [START_REF] Johnson | Percomorph phylogeny: a survey of acanthomorphs and a new proposal[END_REF][START_REF] Olney | Phylogeny of lampridiform fishes[END_REF] and molecular [START_REF] Wiley | The phylogenetic relationships of lampridiform fishes (Teleostei: Acanthomorpha), based on a total-evidence analysis of morphological and molecular data[END_REF][START_REF] Wiley | The interrelationships of Acanthomorph fishes: a total evidence approach using molecular and morphological data[END_REF][START_REF] Smith | Venom evolution widespread in fishes: a phylogenetic road map for the bioprospecting of piscine venoms[END_REF][START_REF] Grande | Limits and relationships of Paracanthopterygii: A molecular framework for evaluating past morphological hypotheses[END_REF]. The present study is thus a new example of the interest of including fossils in phylogenetic studies where the extant taxa have very modified anatomies leading to ambiguities in assessment of potential homologies (e.g. [START_REF] Santini | The importance of even highly incomplete fossil taxa in reconstructing the phylogenetic relationships of the Tetraodontiformes (Acanthomorpha: Pisces)[END_REF][START_REF] Friedman | Osteology of †Heteronectes chaneti (Acanthomorpha, Pleuronectiformes), an Eocene stem flatfish, with a discussion of flatfish sister-group relationships[END_REF].

In addition to the position of Lampridiformes, we were able to clarify the relationships and taxonomy of the Cretaceous fossils we used, suggesting that †"aipichthyoids", †pharmacichthyids and †pycnosteroidids are indeed closely related to modern lampridiforms and demonstrating the paraphyly of †Aipichthyoidea.

The clade Lampridomorpha has been expanded in its composition, as it now includes extinct lineages along with the extant Lampridiformes. Our results show (Fig. 7) that lampridomorphs were already present in the Cenomanian, which is about 20 Myr earlier than the previously accepted oldest occurrence of the group (with †Nardovelifer in the Campanian-Maastrichtian). Thus, the oldest lampridomorphs are the same age as the oldest representatives of the other main acanthomorph subclades: Polymixiiformes ( †Homonotichthys and †Omosoma from England, Lebanon and Morocco), Paracanthopterygii ( †Xenyllion from North America) and Euacanthopterygii (diverse "beryciform" genera from Lebanon, Palestine, England, Portugal, Morocco, Slovenia and Mexico), which are all from the Cenomanian or Turonian [START_REF] Patterson | An overview of the early fossil record of acanthomorphs[END_REF][START_REF] Wilson | Early Cenomanian acanthomorph teleost in the Cretaceous Fish Scale Zone, Albian/Cenomanian boundary, Alberta, Canada[END_REF][START_REF] Newbrey | A new species of the paracanthopterygian Xenyllion from the Mowry Formation (Cenomanian) of Utah, USA[END_REF].

The present study offers a new glimpse of the early evolution of lampridiforms, and of acanthomorphs as a whole. We show that lampridomorphs were a diverse group in the Cretaceous, represented by at least 14 species in the Cenomanian, which is an important part of the total acanthomorph diversity known at the time. Consistent with other acanthomorph groups [START_REF] Friedman | Explosive morphological diversification of spiny-finned teleost fishes in the aftermath of the end-Cretaceous extinction[END_REF][START_REF] Near | Phylogeny and tempo of diversification in the superradiation of spiny-rayed fishes[END_REF], it was later, in the Paleogene, that the clade diversified while developing numerous morphological innovations [START_REF] Bannikov | A review of fossil Lampridiformes (Teleostei) finds with a description of a new Lophotidae genus and species from the Oligocene of the Northern Caucasus[END_REF][START_REF] Carnevale | The first fossil ribbonfish (Teleostei, Lampridiformes, Trachipteridae)[END_REF]. These are the profound modification of the jaws articulations, reduction of spinous component of fins and adaptation to a pelagic environment that are characteristic of the extant Lampridiformes. Ascending process of the premaxilla: 0 = shorter than the alveolar process; 1 = equal to or longer than the alveolar process Olney et al., 1993: character 1996): 0 = three (Fig. 2A); 1 = two (Fig. 2B); 2 = one; 3 = none Table 3: Character matrix used in the study. ' †' denotes an extinct taxon; '?' denotes an unknown character state; '-' denotes an unapplicable character state. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 Synodus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -----0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Gymnoscopelus 0 0 2 0 0 0 0 0 0 1 0 0 0 0 0 0 -----0 0 0 0 1 1 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 †Ctenothrissa 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ? 0 0 1 0 0 0 0 0 0 0 0 0 ? ? 0 0 0 0 0 0 0 0 0 0 0 †Pharmacichthys venenifer 0 0 0 0 1 0 1 0 0 0 0 0 0 ? ? 1 0 0 1 0 0 1 ? ? 1 1 0 1 ? 0 0 0 1 0 1 0 0 1 1 1 0 1 1 0 0 1 1 †P. numismalis 0 0 0 ? 1 0 1 0 0 0 0 0 0 0 0 1 0 0 1 0 0 1 ? ? 1 1 ? ? ? 0 0 0 1 0 1 0 0 1 1 2 0 1 1 0 0 1 1 †P. judensis 0 0 0 0 1 0 1 ? ? 0 0 0 0 ? ? 1 0 0 1 0 0 1 ? ? 1 1 ? ? ? 0 0 0 ? 0 1 0 0 1 1 2 0 1 ? 0 0 1 1 †Aipichthyoides ? 0 0 ? 0 1 1 1 0 0 0 0 0 1 1 1 1 1 0 1 0 1 ? ? 1 1 1 1 ? 0 0 0 1 0 ? 0 0 0 1 1 0 1 1 0 0 1 1 †Paraipichthys 0 ? ? ? 0 0 ? ? 0 ? ? ? 0 ? 0 1 0 0 0 0 0 ? ? ? 1 ? ? ? ? 0 0 0 ? 0 ? ? ? 0 1 ? ? 1 1 0 0 1 1 †Aipichthys velifer 0 0 1 0 0 0 1 1 0 0 0 0 1 1 1 1 0 0 1 0 1 1 ? ? 1 1 1 1 0 0 0 0 1 0 0 0 0 0 1 1 0 1 1 0 0 1 1 †A. oblongus 0 ? ? ? 0 0 1 ? 0 0 0 0 1 1 0 1 0 0 1 0 1 ? ? ? 1 1 ? ? ? 0 0 0 1 0 0 0 0 0 1 1 0 1 1 0 0 1 1 †A. minor 0 0 1 0 0 0 1 1 0 0 0 0 1 1 0 1 0 0 1 0 1 1 ? ? 1 1 1 1 ? 0 0 0 1 0 0 0 0 0 1 1 0 1 1 0 0 1 1 †Freigichthys 0 0 ? 0 0 0 1 1 0 0 ? 0 1 1 1 1 0 0 1 0 1 1 ? ? 1 1 ? ? ? 0 0 0 1 0 0 0 0 0 1 1 0 1 1 0 0 1 1 †Aspesaipichthys 0 0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1 0 1 ? ? 0 0 0 0 ? ? ? ? 0 1 1 0 1 ? 0 0 ? ? †Zoqueichthys 0 0 0 ? 0 0 1 1 ? 0 0 0 0 ? ? 1 1 0 0 1 0 1 ? ? 1 1 ? 1 ? 0 0 0 1 0 0 0 0 0 1 1 0 1 1 0 0 1 1 †Pycnosteroides ? 0 0 0 0 0 1 1 ? 0 0 0 0 1 0 1 0 0 1 0 0 1 ? ? 1 1 0 1 0 0 0 0 1 0 1 0 1 1 0 2 0 1 0 0 0 1 1 Polymixia 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 1 1 0 0 1 0 2 0 0 0 0 1 0 1 0 0 0 0 0 0 1 0 0 0 1 1 †Sphenocephalus 2 0 1 0 0 0 0 1 ? 1 1 0 0 1 1 1 0 0 1 0 0 1 ? ? 1 0 0 2 0 1 1 0 1 1 ? ? ? 2 0 0 0 1 0 0 0 1 1 Aphredoderus 0 0 2 0 0 0 1 1 1 1 1 0 0 1 1 1 0 0 1 0 0 1 1 0 0 0 1 2 0 1 1 0 1 1 1 1 1 2 0 0 0 1 0 0 0 1 1 Merluccius 2 0 2 0 0 0 1 1 1 1 1 0 0 1 1 1 0 0 0 0 0 1 1 1 1 0 1 2 0 1 1 1 1 1 1 1 1 3 -0 0 0 0 0 0 0 0 Myripristis 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 1 1 0 0 0 0 1 0 1 1 0 1 0 1 0 1 1 0 0 0 1 0 0 0 1 1 Metavelifer 0 1 2 1 0 1 1 0 0 0 0 1 0 ? ? 1 1 0 0 1 0 1 0 0 1 1 0 2 1 0 0 0 1 0 0 1 1 2 1 2 0 1 1 0 0 1 1 Lampris 0 1 2 1 0 1 1 0 0 0 0 1 0 ? ? 1 1 0 0 1 0 1 0 1 1 0 1 2 1 0 0 1 1 0 -1 1 2 1 2 0 0 1 0 0 0 0 Trachipterus 0 1 2 1 0 1 1 0 ? 0 0 1 0 ? ? 0 -----1 0 0 1 0 1 2 1 0 0 2 1 1 -1 1 3 -2 1 0 1 1 1 --Regalecus 0 1 2 1 0 1 1 0 ? 0 0 1 0 ? ? 0 -----1 0 0 1 0 1 2 1 0 0 2 1 1 -1 1 3 -2 1 0 1 1 1 -- Synodus 0 0 0 0 0 0 0 0 ? 0 0 0 0 0 0 0 0 0 0 0 Gymnoscopelus 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 †Ctenothrissa 0 0 0 0 0 0 0 0 0 0 0 0 0 ? 0 1 ? ? 0 0 †Pharmacichthys venenifer 0 1 0 0 0 0 0 0 0 1 1 0 0 0 0 1 ? ? 2 0 †P. numismalis 0 1 0 0 0 0 0 0 0 1 1 0 0 0 0 1 ? ? 2 0 †P. judensis 0 1 0 0 0 0 0 0 ? 1 1 0 0 0 ? 1 ? ? 2 0 †Aipichthyoides 0 0 1 1 0 0 1 1 1 1 1 0 0 0 0 1 ? ? 1 0 †Paraipichthys 0 0 0 0 0 0 0 0 1 1 1 0 ? 0 0 1 ? ? 2 0 †Aipichthys velifer 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 ? ? 2 0 †A. oblongus 0 0 0 0 0 0 0 0 1 1 1 ? 0 0 0 1 ? ? ? 0 †A. minor 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 ? ? 2 0 †Freigichthys 0 0 0 ? ? 0 ? 0 1 1 1 ? 0 0 0 1 1 0 1 0 †Aspesaipichthys 0 0 0 1 1 0 1 1 1 1 1 0 ? ? ? ? ? ? ? ? †Zoqueichthys 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 1 0 0 0 †Pycnosteroides 1 0 0 0 0 0 0 0 1 1 1 1 0 0 0 1 ? ? 2 1 Polymixia 1 0 0 0 0 0 0 0 1 1 0 1 0 0 0 0 0 1 1 0 †Sphenocephalus 1 0 1 0 0 0 0 0 1 1 0 1 1 0 0 0 0 1 1 ? Aphredoderus 1 0 1 0 1 1 1 0 1 1 0 1 1 1 0 0 0 1 1 0 Merluccius 1 1 1 1 1 1 1 0 1 1 0 1 1 1 0 0 0 0 1 0 Myripristis 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 0 1 1 Metavelifer 0 0 0 0 1 1 1 0 1 1 1 0 0 1 0 1 1 0 0 0 Lampris 0 0 1 1 1 1 1 0 1 1 1 0 0 1 1 1 1 0 0 0 Trachipterus 1 0 1 1 1 0 1 0 1 1 0 1 0 1 1 1 1 0 2 0

TABLES

  : †Araripichthys castilhoi Silva Santos, 1985 from the Albian of Brazil and Mexico; †A. corythophorus Cavin, 1997 from the Turonian of Morocco; †A. axelrodi Maisey & Moody, 2001 from the Aptian of Venezuela; and †A. weberi Alvarado-Ortega & Brito, 2011 from the Albian of Mexico. A close relationship between †Araripichthys and lampridiforms has been suggested by

  chose to consider it as an acanthomorph incertae sedis. †Pycnosteroididae is represented by two species: †Pycnosteroides levispinosus (Hay, 1903) from the Cenomanian of Hajula, Lebanon and †Magrebichthys nelsoni Murray & Wilson, 2014 from the Cenomanian-Turonian of Agoult, Morocco. †Pycnosteroides has been well-described based on complete specimens, notably by

  Analysis 2 yielded 12 parsimonious trees of 155 steps in length, CI = 0.48 and RI = 0.72. These multiple most parsimonious trees largely reflect uncertain relationships within the genera †Aipichthys and †Pharmacichthys. The strict consensus is shown in Figure6. This analysis supports monophyly of Euacanthomorpha, with Polymixia sister to a clade formed by Euacanthopterygii (Myripristis) and Paracanthopterygii (including †Sphenocephalus). Sister to Euacanthomorpha is a clade including all †Aipichthyoidea, †Pharmacichthyidae and †Pycnosteroides, together with Lampridiformes (clade A). If fossils are not considered, Lampridiformes is therefore sister to Euacanthomorpha. Clade A is supported by eight unambiguous characters. Within clade A, †Paraipichthys, †Aipichthys, †Freigichthys, †Pycnosteroides and †Pharmacichthys form clade B. †Paraipichthys is sister to all the other genera. †Aipichthys and †Freigichthys on one hand, †Pycnosteroides and †Pharmacichthys on the other form subclades. A well-supported clade (clade C) groups together †Aipichthyoididae (sensu Alvarado-Ortega & Than-Marchese, 2012) and Lampridiformes, with †Aipichthyoides and †Aspesaipichthys closer to Lampridiformes (clade D) than to †Zoqueichthys.

  EUACANTHOMORPHA JOHNSON & PATTERSON, 1993 Included taxa: Polymixiiformes (represented by Polymixia); Euacanthopterygii (represented by Myripristis); Paracanthopterygii (represented by †Sphenocephalus, Aphredoderus and Merluccius).

Five

  character states are unambiguously found to support a clade which includes Polymixia, Myripristis, †Sphenocephalus, Aphredoderus and Merluccius, to the exclusion of extant lampridiforms. This clade matches the one named Euacanthomorpha by[START_REF] Johnson | Percomorph phylogeny: a survey of acanthomorphs and a new proposal[END_REF].

Furthermore

  , family †Aipichthyidae sensu Alvarado-Ortega & Than-Marchese (2012), is paraphyletic according to the position of †Paraipichthys as sister to all other members of clade B. The genus †Aipichthys is also paraphyletic, or should include †Freigichthys, a taxonomic revision already suggested by Alvarado-Ortega & Than-Marchese (2012: fig. 8).

  †Pycnosteroides levispinosus (Hay 1903), †Pharmacichthys venenifer Smith Woodward 1942, †P. numismalis Gayet 1980a, †P. judensis Gayet 1980b, †Aipichthys minor (Pictet 1850), †A. velifer Smith Woodward 1901, †A. oblongus Gayet 1980a, †Paraipichthys lusitanicus Gaudant 1978, †Freigichthys elleipsis Otero 1997. Presumably included taxa (not present in our analysis): †Aipichthys nuchalis (Dixon 1850), †A. pretiosus Steindachner 1860; †Magrebichthys nelsoni Murray & Wilson, 2014. This clade (Fig. 6, clade B) is supported by only one synapomorphy: 1. Six or fewer soft rays in the pelvic fin (character 66, 02). The state is reversed in †Freigichthys, and also present in Trachipterus + Regalecus. The state of this character is unknown for †Aipichthys oblongus. UNNAMED CLADE C Included taxa: †Aipichthyoides galeatus Gayet 1980b, †Aspesaipichthys cavaensis Taverne 2004, †Zoqueichthys carolinae Alvarado-Ortega & Than-Marchese 2012, Lampridiformes. Presumably included taxa (not present in our analysis): †Aipichthyoides formosus Gayet 1980b.

  They are reversed in taeniosome lampridiforms (Trachipterus + Regalecus), which are characterised by reduced crests. UNNAMED CLADE D Included taxa: †Aipichthyoides galeatus Gayet 1980b, †Aspesaipichthys cavaensis Taverne 2004, Lampridiformes. Presumably included taxa (not present in our analysis): †Aipichthyoides formosus Gayet 1980b. This clade (Fig. 6, clade D) is supported by three synapomorphies: 1. Mesethmoid median or posterior to the lateral ethmoids (character 6, 01).

512162238

  Lateral ethmoid: 0 = not linked to the palate-quadrate region; 1 = linked to the palate-quadrate region by a narrow processGayet, 1979 6 Mesethmoid: 0 = anterior to the lateral ethmoid (Fig.1A); 1 = median or posterior to the lateral ethmoid (Fig.1B, C)[START_REF] Olney | Phylogeny of lampridiform fishes[END_REF] character Frontal vault or cradle: 0 = absent; 1 = presentOlney et al.,1993: character 3, in part 13 Interfrontal flat: 0 = absent; 1 = present Otero & Gayet, 1996: character 23 14 Frontal branch of the sensory canal: 0 = runs through the frontal and pterotic in a closed tube; 1= runs through the frontal and pterotic in a groove Otero & Gayet, 1996: character 2 15 Preopercular branch of the sensory canal: 0 = opens throughout pores; 1 = opens throughout an indentation Otero & Gayet, 1996: characters 3 & 25; Alvarado-Ortega & Than-Marchese, 2012: character 3 Size of the sagittal crest (composed at least by the supraoccipital): 0 = absent or small crest; 1 = developed sagittal crest Olney et al., 1993: character 14; Otero & Gayet, 1996: character 1 17 Frontal bone forming part of the sagittal crest: 0 = absent (Fig. 1A); 1 = present (Fig. 1B, C) Otero & Gayet, 1996: character 18, in part; Alvarado-Ortega & Than-Marchese, 2012: character 18 absent (Fig. 1A, C); 1 = present (Fig. 1B) Otero & Gayet, 1996: character 18, in part; Alvarado-Ortega & Than-Marchese, 2012: character 19 19 Posterior edge of the sagittal crest: 0 = convex (rounded crest, Fig. 1B, C); 1 = concave (half-boomerang shaped crest, Fig. 1A) Alvarado-Ortega & Than-Marchese, 2012: character 20 20 Length of the sagittal crest: 0 = short, entirely behind the orbit (Fig. 1A); 1 = long, from the nasal area to the occiput (Dorsal limb of the posttemporal: 0 = not firmly bound to the epiotic; 1 = firmly bound to the epiotic Stiassny, 1986; Johnson & Patterson, 1993: character 5 23 Spina occipitalis: 0 = absent; 1 = present Otero & Gayet, 1996: character 12 24 Foramen magnum: 0 = dorsal to the tripartite occipital condyle; 1 = bounded laterally by the exoccipital condyles Olney et al., 1993: character 12 25 Cranio-hyomandibular condyle: 0 = two-headed (Fig. 1D); 1 = single-headed (Fig. 1E, F) Oelschläger, 1983; Grande et al., 0 = not expanded ventrally (Fig. 1G); 1 = expanded by a large ventral lamina (Fig. 1H) New 30 Posterior border of the preopercular: 0 = smooth; 1 = spiny Otero & Gayet, 1996: character 33 31 Posterior border of the opercular: 0 = smooth ; 1 = spiny Otero & Gayet, 1996: character 40 32 Total number of vertebrae: 0 = less than 40; 1 = 40-60; 2 = 60 or more Olney et al., 1993: characters 10 & 25 33 Neural spines of vertebral centra (unknown for the first neural spine of most fossils): 0 = autogenous; 1 = fused with the centrum Otero & Gayet, 1996: character 5 34 Orientation of the first neural spine: 0 = inclined posteriorly; 1 = inclined anteriorly and in close association with the cranium Olney et al., 1993: character 16 35 Point of origin of anterior epineurals: 0 = neural arches or Otero & Gayet, 1996: character 13 spines; 1 = centra or transverse processes 36 Epineurals on the postabdominal vertebrae: Number of supraneurals (predorsals in Otero and Gayet

FIGURESFigure 1 .

 1 FIGURES

Figure 2 .

 2 Figure 2. Dorsal fin skeleton of two studied taxa. A, †Aipichthys velifer, MNHN.F.HAK57. Scale bar: 1 cm. Photo D. Davesne. B, Velifer hypselopterus (Veliferidae), AMS 21840020. Scale bar: 5 mm. Photo courtesy D. Johnson. Abbreviations: dpt, dorsal pterygiophore; dsp, dorsal spine; dsr, dorsal soft ray; ns, neural spine; sn, supraneural.

Figure 3 .

 3 Figure 3. Caudal skeleton of several studied taxa. A, †Aipichthys minor (reconstruction), after Patterson (1968: fig. 11A). Scale bar: 1 mm. B, †Aspesaipichthys cavaensis (reconstruction), after Taverne (2004: fig. 7). Scale bar: 1 mm. C, Velifer hypselopterus (=V. africanus) (Veliferidae), after Oelschläger (1983: Fig. 82). Scale bar: 1 mm. D, †Aipichthys velifer, MNHN.F.HAK57, showing hypurostegy of the caudal fin rays. Scale bar: 5 mm. Photo D. Davesne. E, Lampris guttatus, ZMUC 74, showing hypurostegy of the caudal fin rays. Scale bar: 5 cm. Photo M.A. Krag. Abbreviations: hy, hypural; phy, parhypural; pu, preural vertebral centrum; u, ural vertebral centrum.

Figure 4 .

 4 Figure 4. Appendicular skeleton of several studied taxa. A, pectoral and pelvic girdles of Merluccius merluccius, ZMUC 215x, with shapes of scapula and coracoid outlined. Scale bar: 2 cm. Photo M.A. Krag. B, pectoral and pelvic girdles of †Pycnosteroides levispinosus, MNHN.F.HDJ105. Scale bar: 5 mm. Photo D. Davesne. C, pectoral and pelvic girdles of Lampris guttatus, ZMUC 74, with shape of the pelvic girdle outlined. Scale bar: 5 cm. Photo M.A. Krag. D, pelvic girdle of Polymixia sp. in ventral view, after Stiassny & Moore (1992: fig. 3). Scale bar: 2 mm. E, pelvic girdle of †Zoqueichthys carolinae in ventral view, after Alvarado-Ortega & Than-Marchese (2012: fig. 5). Scale bar: 1 mm. F, pelvic girdle of Metavelifer multiradiatus, AMNH 91800SD, in ventral view. Scale bar: 2 mm. Abbreviations: cle, cleithrum; cor, coracoid; iw, internal wing of the pelvic girdle; mp, median process of the pelvic girdle; pcl, postcleithrum; pel, pelvic girdle; psp, pelvic spine; sca, scapula; uro, urohyal.

Figure 5 .

 5 Figure 5. Most parsimonious tree obtained after analysis 1 (only the ten extant taxa included). Numbers above branches are Bremer indexes. Length = 107, CI = 0.64, RI = 0.71.

Figure 6 .

 6 Figure 6. Strict consensus of the 12 most parsimonious trees obtained after analysis 2 (all 24 taxa, fossil and extant, included). Fossil taxa are indicated by daggers ( †). Numbers above branches are Bremer indexes. Length = 155, CI = 0.48, RI = 0.72.

Figure 7 .

 7 Figure 7. Hypothesis of acanthomorph interrelationships suggested by our results, with ages of taxa highlighted (thick lines). Position of internal nodes does not reflect divergence times.

  , †Aspesaipichthys cavaensis Taverne, 2004 and †Zoqueichthys carolinae Alvarado-Ortega & Than-Marchese, 2012. †Errachidia pentaspinosa Murray & Wilson, 2014 and †Homalopagus multispinosus Murray & Wilson, 2014 are two species with family incertae sedis. †Aipichthyoidea has a large geographical distribution: †Aipichthyoides and †Freigichthys are restricted to the East Mediterranean

  †P. numismalis, †P. venenifer), †Pycnosteroides levispinosus, eight species from six different genera of †Aipichthyoidea ( †Aipichthys minor, †A. oblongus, †A. velifer, †Paraipichthys lusitanicus, †Freigichthys elleipsis, †Aipichthyoides galeatus, †Aspesaipichthys cavaensis, †Zoqueichthys carolinae) and †Sphenocephalus fissicaudus

	TAXONOMIC SAMPLING
	Our data matrix includes 24 taxa. The 14 fossil taxa are early Late Cretaceous in age,
	and they include †Ctenothrissa sp. (outgroup), the three species of †Pharmacichthys ( †P.
	judensis, Agassiz, 1838, one the oldest known paracanthopterygian, known by well-preserved
	specimens

  e. total-group Lampridiformes). Included taxa: †Pycnosteroides levispinosus (Hay, 1903); †Pharmacichthys venenifer Smith Woodward, 1942; †P. numismalis Gayet, 1980a; †P. judensis Gayet, 1980b; †Aipichthys minor (Pictet, 1850); †A. velifer Smith Woodward, 1901; †A. oblongus Gayet, 1980a; †Paraipichthys lusitanicus Gaudant, 1978; †Freigichthys elleipsis Otero, 1997; †Aipichthyoides galeatus Gayet, 1980b; †Aspesaipichthys cavaensis Taverne, 2004; †Zoqueichthys carolinae Alvarado-Ortega & Than-Marchese, 2012; Lampridiformes. Presumably included taxa (not present in our analysis): †Aipichthys nuchalis (Dixon, 1850); †A. pretiosus Steindachner, 1860; †Aipichthyoides formosus Gayet, 1980b; †Errachidia pentaspinosa Murray & Wilson, 2014; †Homalopagus multispinosus Murray & Wilson, 2014; †Magrebichthys nelsoni Murray & Wilson, 2014.

Table 1 :

 1 List of the specimens used to code the characters in the study. Column 1 = taxon name; column 2 = specimen number; column 3 = technique(s) used. Institutional abbreviations: AMNH = American Museum of Natural History, New York City, USA; AMS = Australian Museum, Sydney, Australia; MNHN = Muséum national d'Histoire naturelle, Paris, France; NHMUK = Natural History Museum, London, UK; ZMUC = Zoological Museum -University of Copenhagen, Denmark

	Outgroups
	Synodus intermedius	ZMUC P2394016	direct observation and photos
			dissection, X-ray computed
	Gymnoscopelus sp.	MNHN research collection	tomography
	†Ctenothrissa protodorsalis	MNHN.F.HAK22	binocular microscope
	†Ctenothrissa signifer	NHMUK PV P47524	binocular microscope and photos
	†Ctenothrissa vexillifer	MNHN.F.HAK39	binocular microscope
	†Ctenothrissa vexillifer	MNHN.F.HAK104	binocular microscope
	Potential Cretaceous sister-groups of Lampridiformes
	†Pharmacichthys numismalis	MNHN.F.HAK3	binocular microscope
	†Pharmacichthys venenifer	MNHN.F.HAK7	binocular microscope
	†Aipichthys minor	MNHN.F.HAK1938	binocular microscope
	†Aipichthys minor	MNHN.F.HAK94	binocular microscope
	†Aipichthys velifer	MNHN.F.HAK57	binocular microscope
	†Aipichthys velifer	NHMUK PV P4743	binocular microscope and photos
	†Aipichthys velifer	NHMUK PV P4744	binocular microscope and photos
	†Pycnosteroides levispinosus	MNHN.F.HDJ105	binocular microscope
	†Pycnosteroides levispinosus	NHMUK PV P13901	binocular microscope and photos
	Polymixiiformes
			X-ray radiographs of alcohol
			specimen, X-ray computed
	Polymixia cf.nobilis	MNHN.IC.2006-1740	tomography
	Polymixia nobilis	NHMUK 95.5.28.1	direct observation and photos
	Paracanthopterygii
			X-ray radiographs of alcohol
	Aphredoderus sayanus	MNHN.IC.1987-0864	specimen
	†Sphenocephalus fissicaudus	NHMUK PV P8772	binocular microscope and photos
	†Sphenocephalus fissicaudus	NHMUK PV P8774	binocular microscope and photos
	Merluccius merluccius	Research collection	dissection
	Merluccius merluccius	ZMUC 215	direct observation and photos
	Euacanthopterygii
	Myripristis sp.	Research collection	dissection
	Lampridiformes
			X-ray radiographs of alcohol
			specimens, X-ray computed
	Velifer hypselopterus	MNHN.IC.1982-0025	tomography
	Velifer hypselopterus	AMS 21840020	cleared and stained, photos
	Metavelifer multiradiatus	AMNH 214663 SD	direct observation and photos
	Metavelifer multiradiatus	AMNH 219280 SD	direct observation and photos

Table 2 :

 2 List of the characters used in the study. Column 1 = character number; column 2 = character description; column 3 = references.

	1	Postmaxillary process of the premaxilla: 0 = absent; 1 =	Patterson & Rosen, 1989
		present; 2 = present with a "gadoid" notch
	2

Table 3 (

 3 continued):

48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67

Otero & Gayet, 1996: characters 10 and 22; Alvarado-Ortega & Than-Marchese, 2012: character 10 67 Pelvic spine: 0 = absent; 1 = present (Fig. 4B) Stiassny & Moore, 1992: character 3; Johnson & Patterson, 1993: character 13

ACKNOWLEDGEMENTS

We would like to thank Gaël Clément, Philippe Béarez, Patrice Pruvost, Romain Causse, Zora Gabsi (MNHN), Martha Richter, Zerina Johanson, Emma Bernard, James Maclaine (NHMUK), Marcus A. Krag (ZMUC), David Johnson (NMNH), Barbara Brown and Radford Arrindell (AMNH) for access to collections or specimens under their care. Guy Duhamel and Mélyne Hautecoeur (MNHN) are thanked for providing specimens from the Southern Ocean, as well as Anthony Herrel (MNHN) for access to dissection facilities, François Meunier and Hugo Dutel (MNHN) for help during dissections and Eric Pellé (MNHN) for osteological preparations. CT-scannings were performed at the AST-RX, Plateforme d'accès scientifique à la tomographie à rayons X, UMS 2700 Outils et Méthodes de la Systématique Intégrative (CNRS/MNHN), with the help of Miguel García-Sanz for data acquisition, Florent Goussard and Damien Germain (MNHN) for data treatment. Fabrice Fack (MNHN) provided PAUP 3.0 emulated with SheepShaver, as well as thorough discussion on phylogenetics. Niels Bonde, Bouziane Khalloufi, Bruno Chanet, and Nalani Schnell are warmly thanked for their helpful discussions and comments at different stages of the work. Critical comments and advice by Alison Murray and an anonymous reviewer greatly improved the present paper. D. Davesne is supported by funding from ATM "Formes possibles, formes réalisées" (MNHN).

APPENDIX COMPLETE LIST OF CHARACTER STATE CHANGES

Character state changes in italics are ambiguous optimizations that we chose based on biological considerations. Character state changes in bold are unique to the clade (with no homoplasy outside the clade).