Taposhi Hazra

Benjamin Adroit

Manoshi Hazra

Robert A Spicer

Teresa E V Spicer

Mahasin Subir Bera

Mahasin Ali Khan
email: ali-khan@skbu.ac.in

New discovery of rare insect damage in the Pliocene of India reinforces the biogeographic history of Eurasian ecosystems

Keywords:

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Insect-feeding damage on plants provides insights into plant-insect interactions and has the potential for documenting the effects of extant, and ancient, environmental temporal and spatial gradients in respect of insect herbivory and the evolutionary diversification of the insect groups through geological time [START_REF] Wilson | The Diversity of Life: Cambridge[END_REF][START_REF] Wilf | Response of plant-insect associations to Paleocene-Eocene warming[END_REF][START_REF] Labandeira | The history of associations between plants and animals. Plantanimal interactions: an evolutionary approach[END_REF][START_REF] Schoonhoven | Insect-Plant Biology[END_REF][START_REF] Currano | Sharply increased insect herbivory during the Paleocene-Eocene Thermal Maximum[END_REF][START_REF] Currano | Fossil insect folivory tracks paleotemperature for six million years[END_REF][START_REF] Krassilov | Mine and gall predation as top-down regulation in the plant-insect systems from the Cretaceous of Negev, Israel. Palaeogeogr[END_REF]Adams et al., 2010;[START_REF] Sohn | Morphological and functional diversity of foliar damage on Quercus mongolica Fisch. ex Ledeb. (Fagaceae) by herbivorous insects and pathogenic fungi[END_REF]. Feeding or chewing damage, perhaps the most widely recognised type of insect injury to plants, can take many forms such as hole feeding, margin feeding, surface feeding, galling, mining, skeletonization and so on. Leaf chewing adult insects have mouthparts with two opposing mandibles, or jaws, [START_REF] Labandeira | Insect mouthparts: ascertaining the paleobiology of insect feeding strategies[END_REF] and several insect orders have such chewing mouthparts, including beetles (Coleoptera), caterpillars (Lepidoptera), grasshoppers (Orthoptera), and termites (Isoptera).

Like other foliar feeding damages, one specific interaction between an insect and its host plant is leaf skeletonization. Leaf skeletonization is a type of surface feeding damage generally caused by leaf beetles (Coleoptera), but rarely caused by other insect groups such as Hymenoptera, Diptera and Lepidoptera [START_REF] Hering | Mine producers[END_REF]. The insects feed by removing the soft and tender epidermal tissue leaving behind tough leaf veins. The skeletonized area can be reticulate or striate andgenerally depends on the venation pattern of the leaves of the host plant. However, in many cases, the insects do no not feed over the whole lamina, but leave areas of incomplete skeletonization in which a substantial amount of the lamina tissue remains intact [START_REF] Sohn | Morphological and functional diversity of foliar damage on Quercus mongolica Fisch. ex Ledeb. (Fagaceae) by herbivorous insects and pathogenic fungi[END_REF]. This distinguishes insect induced skeletonisation from that produced from post mortem microbial decay, which tends to affect the whole lamina.

The history of plant-insect associations can be dated back to the Early Devonian [START_REF] Labandeira | The four phases of plant-arthropod associations in deep time[END_REF][START_REF] Labandeira | The origin of herbivory on land: initial patterns of plant tissue consumption by arthropods[END_REF][START_REF] Labandeira | The fossil record of plant-insect dynamics[END_REF][START_REF] Feng | Evidence for insect-mediated skeletonization on an extant fern family from the Upper Triassic of China[END_REF]. There are various records of insect-mediated damage preserved in diverse megafossil remains [START_REF] Straus | Gallen, Minen und andere Fraßspuren im Pliokän von Willershausen am Harz[END_REF][START_REF] Crane | Insect leaf mines from the Palaeocene of southern England[END_REF][START_REF] Lang | Fossil evidence for patterns of leaf-feeding from the late Cretaceous and early Tertiary[END_REF][START_REF] Srivastava | Lower Barakar flora of Raniganj Coalfield and insect-plant relationship[END_REF][START_REF] Srivastava | Fossil records of insects and insects related plant damage in India[END_REF][START_REF] Srivastava | Fossil evidence of gall-inducing arthropod-plant interactions in the Indian subcontinent[END_REF][START_REF] Srivastava | Insect gall impression on fossil angiosperm leaf[END_REF], 2010[START_REF] Srivastava | Insect herbivory in Gondwana plants[END_REF][START_REF] Srivastava | Cecidomyiid leaf galls in Palaeocene leaves from north-eastern India[END_REF][START_REF] Srivastava | Insect traces on Early Permian plant of India[END_REF][START_REF] Labandeira | The history of associations between plants and animals. Plantanimal interactions: an evolutionary approach[END_REF][START_REF] Banerji | Evidence of insect-plant interactions from the Upper Gondwana sequence (Lower Cretaceous) in the Rajmahal Basin, India[END_REF][START_REF] Krassilov | Mine and gall predation as top-down regulation in the plant-insect systems from the Cretaceous of Negev, Israel. Palaeogeogr[END_REF][START_REF] Singh | Late Tertiary flora of Mahuadanr Valley, Latehar District, Jharkhand, India[END_REF][START_REF] Winkler | Distinguishing Agromyzidae (Diptera) leaf mines in the fossil record: new taxa from the Paleogene of North America and Germany and their evolutionary implications[END_REF][START_REF] Carvalho | Insect leaf-chewing damage tracks herbivore richness in modern and ancient forests[END_REF][START_REF] Ding | Biology of a leaf miner (Coleoptera) on Liaoningocladus boii (Coniferales) from the Early Cretaceous of northeastern China and the leafmining biology of possible insect culprit clades[END_REF][START_REF] Feng | Evidence for insect-mediated skeletonization on an extant fern family from the Upper Triassic of China[END_REF]

Materials and methods

The fossil leaf remains displaying skeletonization were collected from an outcrop of latest Neogene (Rajdanda Formation) sediments exposed on the left bank of the Birha River in Mahuadanr Valley (23.3965°N, 84.1066°E; 353 m asl), Jharkhand, eastern India (Fig. 1). The outcrop exposes mostly shale (arenaceous and clayey) and sandstone, while the studied fossil leaves are preserved as impressions and compressions in greyish blue mudstones and light-brown diatomite. Earlier workers [START_REF] Prakash | Fossil wood resembling Sindora from the Tertiary of Palamau District, Bihar[END_REF][START_REF] Srivastava | Fossil woods of Terminalia and Lagerstroemia from the late cenozoic beds of Mahuadanr, Palamu District[END_REF]Hazra et al., 2020a) have considered the age of the Rajdanda Formation to be 'late Tertiary' (Pliocene), but till date no absolute (radiometric) dating has been carried out.

The fossil leaf specimens (Plates I, II, III); Figs. S1, S2, S3) required little preparation before photography as leaves that were not fully exposed in the initial fracture were simply revealed by careful removal of the overlying matrix using fine needles, scalpels and brushes. Macroscopic images of fossil leaf specimens (Plate I, II, III; Figs. S1, S2, S3) were photographed using a digital camera (Canon Power Shot A720IS). After photography, the photographs were edited only for contrast using image editing software Adobe Photoshop CS ver 7. The line drawings for accompanying figures and photographs were made using Corel [START_REF] Khan | Fossil evidence of insect folivory in the eastern Himalayan Neogene Siwalik forests[END_REF][START_REF] Khan | Plant-arthropod associations from the Siwalik forests (middle Miocene) of Darjeeling sub-Himalaya, India[END_REF][START_REF] Ghosh | Leaf galls on Dicroidium hughesii (Feistmantel) Lele from the Triassic of India-a new record[END_REF][START_REF] Sohn | Morphological and functional diversity of foliar damage on Quercus mongolica Fisch. ex Ledeb. (Fagaceae) by herbivorous insects and pathogenic fungi[END_REF][START_REF] Sohn | New leaf-mine fossil from the Geumgwangdong Formation, Pohang Basin, South Korea, associates pygmy moths (Lepidoptera, Nepticulidae) with beech trees (Fagaceae, Fagus) in the Miocene[END_REF][START_REF] Zhang | Plant-insect associations from the upper Miocene of Lincang, Yunnan, China[END_REF]Adroit et al., 2020;Hazra et al., 2020a;[START_REF] Giraldo | Rich and specialized plantinsect associations in a Middle-Late Paleocene (58-60 Ma) neotropical rainforest (Bogotá Formation, Colombia)[END_REF]. Such records provide a primary source of information on the evolutionary history of plant-insect association and the patterns of tissue consumption through geological time [START_REF] Labandeira | Deep-time patterns of tissue consumption by terrestrial arthropod herbivores[END_REF][START_REF] Labandeira | The fossil record of plant-insect dynamics[END_REF][START_REF] Feng | Evidence for insect-mediated skeletonization on an extant fern family from the Upper Triassic of China[END_REF]. [START_REF] Feng | Evidence for insect-mediated skeletonization on an extant fern family from the Upper Triassic of China[END_REF] re-ported the earliest evidence of insect-mediated skeletonization on leaves of Dictyophyllum nathorstii Zeiller, from the Late Triassic Yipinglang flora of south-western China. Leaf skeletonizations have also been reported from K-Pg boundary of Great Plains, USA [START_REF] Donovan | Novel insect leafmining after the end-Cretaceous extinction and the demise of Cretaceous leaf miners, Great Plains, USA[END_REF], but skeletonization is scarcely documented on Cenozoic angiosperm leaves [START_REF] Labandeira | The four phases of plant-arthropod associations in deep time[END_REF][START_REF] Labandeira | The origin of herbivory on land: initial patterns of plant tissue consumption by arthropods[END_REF][START_REF] Vasilenko | Margin feeding damage on the leaves of conifers and Ginkgoales from the Mesozoic of Transbaikalia[END_REF][START_REF] Feng | Evidence for insect-mediated skeletonization on an extant fern family from the Upper Triassic of China[END_REF]Adroit et al., 2020).

Here, we report well-preserved and rare insect-mediated skeleton-izations on Abroma augustum (L.) L. f. (Malvaceae) leaf remains from the Pliocene sediments of Jharkhand, eastern India. Draw ver. 21 (Fig. 2; Fig. S1). We also surveyed the forests adjacent to the fossil exposures looking for similar feeding traces on modern leaves and photographed all the collected skeletonized modern leaves (Plate IV). The rational for doing this is that previous work has shown local floral and climatic similarities between the Pliocene and the modern (Hazra et al., 2020b). We followed the [START_REF] Labandeira | Guide to Insect (and Other) Damage Types on Compressed Plant Fossils[END_REF] guide for identifying and classifying plant-insect interactions in the fossil. Morphological descriptions of fossil leaf specimens follow the terminology and nomenclature proposed by [START_REF] Dilcher | Approaches to the identification of angiosperm leaf remains[END_REF]

Results

We have collected eight leaf specimens with skeletonization feeding traces from the Pliocene sediments of Jharkhand, eastern India. We also reconstructed an insect-mediated damaged leaf remain of Abroma (Fig. 3). The feeding trace recorded in this study did not match any of the fossil DTs described by [START_REF] Labandeira | Guide to Insect (and Other) Damage Types on Compressed Plant Fossils[END_REF]. The skeletonization DTs in this investigation are represented as damage type DT297 of Adroit et al. (2020).

3.1. Damage type (Plates I, II, III; Fig. 2; Fig. S1)

The feeding trace is scattered across the surface of the lamina avoiding only main veins and exhibits elongated to curvilinear skeletonization subdivided in a row of many holes resembling a chain. This elongated to curvilinear structure is approximately 1-2 cm long. Each hole is usually rectangular with rounded corners, ~2 mm length. The number of holes per chain varies from 2 to 15. However, most traces bear 4-10 holes per chain. The lines separating individual holes are very thin, commonly inconspicuous or sometimes missing. The margin of the trace is dark, thick and distinct. This dark scar is due to reaction tissue being produced in the leaf lamina after being attacked by feeding insect [START_REF] Schoonhoven | Insect-Plant Biology[END_REF]. This dark scar makes it possible to distinguish it as a herbivory trace made by an insect during the leaf's lifespan as distinct from a detritivorous trace made after abscission [START_REF] Labandeira | The history of associations between plants and animals. Plantanimal interactions: an evolutionary approach[END_REF] Plate I. Traces of skeletonization on the lamina surface of specimen SKBUH/PPL/JH/136A. (1) elongated to curvilinear skeletonization scattered all over the surface of the lamina;

(2) Enlargement of A (arrows indicate insect mediated skeletonization). Scale bar = 1 cm. [START_REF] Labandeira | Guide to Insect (and Other) Damage Types on Compressed Plant Fossils[END_REF]. Following the Adroit et al. ( 2020) protocol, we measured almost all the DT297 occurrences in terms of length, width and surface area, and counted the number of holes for each occurrence (Table S1). Some damages that could be identified as DT297 have been excluded from these measurements because the preservation was not good enough to be certain about the various dimensions. Overall, the size of DT297 can vary significantly in terms of surface area and length. The smallest damage is ca. 3.4 mm 2 , while the largest ones reach ca. 25.4 mm 2 . However, these raw measurements do not take into account the leaf surface area, because it was not always possible to measure that due to leaf fragmentation and partial preservation. The width is uniform along the length of each damage occurrence and quite similar among the different DT297 instances observed. All detailed measurements can be found in the spreadsheet Table S1.

Host

Abroma augustum (L.) L. f. (Family: Malvaceae) (Plate I; Figs. S2,S3) Leaf symmetrical, lamina well-preserved, complete, mesophyllous, palmately lobed (five lobed), length 10-15 cm; width 10-14 cm; broadly ovate shape; odd-lobed acute apex, base cordate, margin slightly dentate; petiole well preserved, 4-10 cm; primary venation suprabasal actinodromous i.e., seven veins diverging radially from a single point; secondary venation brochidodromous, moderately curved near the margin, irregularly spaced; angle of divergence acute; tertiary venation percurrent, sometimes branched, oblique in relation to primary veins, predominantly alternate and distant; quaternary veins very faint.

Remarks: The large size, lobed laminae, acute apices, cordate bases, suprabasal actinodromous venation with seven primary veins arising from a single point are the important characters of the fossil leaf. The above-mentioned combination of characters shows close resemblance to modern leaves of Gossypium herbaceum L., Sterculia colorata Roxb., Pterygota mildbraedii Engl. and Abroma augustum (L.) L. f. However, the detailed morphological study of the leaves of the above-mentioned species indicates a strong affinity of the fossil leaves to the leaf of extant A. augustum in shape, size and venation pattern.

Abroma Jacq. is a monotypic genus, with the sole species being A. augustum, which is widely distributed in tropical Asia, South and eastern Africa, and Australia [START_REF] Gupta | Abroma augusta Linn f: a review[END_REF][START_REF] Powo | Plants of the World Online[END_REF]. It is found both in the wild and is cultivated, throughout the hot and moist regions of India from the Punjab and Uttar Pradesh eastwards to Arunachal Pradesh, Assam, Meghalaya and Tripura, ascending to 1200 m, and southwards in peninsular India. It is also cultivated for medicine as well as an ornamental. This taxon is also very common in the forests of the Chotanagpur region [START_REF] Wood | Plants of Chotanagpur including Jaspur and Surguja[END_REF].

Discussions

Skeletonization is a distinctive kind of insect feeding behaviour in which an insect feeds on the whole thickness of the leaf including both the upper and lower epidermis, while the tough veins remain intact, so that the skeleton of the leaf is preserved. Feeding on tough veins often results in considerable wear and tear of the mandibles of many insect species and thereby, insects leave the tough veins [START_REF] Crepet | The evolution of insect pollination in angiosperms[END_REF]. Thus, the feeding behaviour of leaf skeletonising insects is quite different from those that cause external foliage, such as hole or margin feeding [START_REF] Feng | Evidence for insect-mediated skeletonization on an extant fern family from the Upper Triassic of China[END_REF]. Not only the feeding behaviour, but leaf nitrogen levels are also regarded as an important determinant of leaf quality for herbivorous insects [START_REF] Sinclair | Leaf miners: the hidden herbivores[END_REF][START_REF] Feng | Evidence for insect-mediated skeletonization on an extant fern family from the Upper Triassic of China[END_REF]. The preference of insects to feed on particular plant tissues can either be enhanced by phagostimulants or reduced by antiherbivore defences such by reducing the digestibility and nutrient content [START_REF] Theis | The evolution of function in plant secondary metabolites[END_REF][START_REF] Feng | Evidence for insect-mediated skeletonization on an extant fern family from the Upper Triassic of China[END_REF]. Different insects prefer to target different portions of the leaf lamina according to the physical and chemical properties of the plant tissues [START_REF] Schoonhoven | Insect-Plant Biology[END_REF]. However, skeletonization tends to be generated mainly by holometabolous insects belonging to Coleoptera [START_REF] Bernays | Saturniid and sphingid caterpillars: two ways to eat leaves[END_REF], even if some members of Hymenoptera, Diptera and Lepidoptera can also skeletonize leaves [START_REF] Bernays | Saturniid and sphingid caterpillars: two ways to eat leaves[END_REF].

Our study documents, for the first-time, the evidence of the rare damage type DT297 on the surface of fossil leaf remains of Abroma recovered from the Pliocene sediments of Jharkhand, eastern India. Our discovery of fossil skeletonised Abroma leaves provides direct evidence of the continuous relationship between plants and herbivorous insects since Pliocene. It is evident from our specimens that the interveinal tissues were selectively targeted, and the larger vascular bundles were conspicuously avoided, probably because of their coarse texture and low nutritive values. The evidence of the feeding pattern on our fossil leaves takes the form of traces characterised by elongate to curvilinear skeletonization in a row of several holes scattered randomly on the surface of lamina, either between or over the veins, and sometimes follows a linear pattern.

This rare DT297 damage type was noticed for the first time in the fossil record by [START_REF] Straus | Gallen, Minen und andere Fraßspuren im Pliokän von Willershausen am Harz[END_REF] on the fossil leaves of Parrotia from the German Willershausen (Pliocene) locality (Fig. 4). Recently, Adroit et al. (2020) discovered this specific type of skeletonization on other Parrotia leaves in both the fossil record (China) and modern forests (Iran). The damage measurements made in this study present DT297 damage that is, on average, significantly larger and longer (ca. 11.8 mm 2 of surface area; 8.2 mm length; 1.3 mm large) than the ones previously measured on Parrotia leaves (ca. 4.1mm 2 of surface area, 5.42 mm of length, 0.62 of large) (Adroit et al., 2020). However, such direct comparison is not fair because for our fossil specimens, the leaf blade could not be measured due to their partial preservation and fragmentation during recovery. It means that our DT297 measurements cannot be related directly to leaf area. Finally, these new observations add to the previous ones and allow us to further refine the description of DT297.

We have extensively surveyed the modern tropical forests adjacent to the fossil exposures to compare our fossil skeletonization leaf feeding traces with those in extant vegetation. We have noticed the existence of similar types of feeding traces on modern leaves from different angiosperm taxa namely, Zizyphus sp. (Rhamnaceae), Desmodium sp. (Fabaceae), Tilia sp. (Malvaceae), Shorea sp. (Dipterocarpaceae), and Solanum sp. (Solanaceae) (Plate IV). In addition, various authors have reported similar types of skeletonization damage patterns in different modern angiosperm taxa, namely Lantana (Verbenaceae), Fabaceae, Cistus sp. (Cistaceae), Ziziphus mauritiana (Rhamnaceae) (Świętojańska et al., 2014). Świętojańska et al. (2014) reported a similar type of skeletonization pattern to that seen in our fossil specimens on various Cistus leaves. So, based on the above-mentioned published data, as well as our survey in the modern forests adjacent to the fossil locality, we suggest that probable damage inducers of our skeletonization on Abroma fossil leaves might be Coleopteran beetles, especially Chrysomelid beetles that cause morphologically similar damage traces on modern leaves of several angiosperm taxa. Our interpretation fits with that of [START_REF] Straus | Gallen, Minen und andere Fraßspuren im Pliokän von Willershausen am Harz[END_REF] who suggested the damage type DT297 on Parrotia fossil leaves from Willershausen (3 Ma, Germany) could have been produced by Chrysomelidae larvae. In addition, such assumptions have been restated by Adroit et al., (2020) who also observed DT297 on Parrotia fossil leaves in Shanwang (15 Ma, China) and on their modern analogues P. persica (Hyrcanian forest, Iran) and P. subaequalis (Yixing forest, China). In the same vein, our comparative study of leaffeeding skeletonization caused by Coleopteran beetles on modern leaves shows they are similar to the feeding patterns seen in our fossil leaves of Abroma, suggesting no marked change in leaf-feeding strategies of this type of herbivorous insect since the Pliocene. Our recent finding also suggests that the same damage inducers (Coleopteran beetles) were active in the monsoon-influenced Pliocene evergreen forest of the Chotanagpur plateau, eastern India. This is consistent with the occurrence of some fossil Coleoptera larva (Grub) from the fossil locality (Fig. S4).

It is interesting to note that at present on the Chotanagpur plateau, these rare skeletonization feeding traces are not found to be associated with the host genus Abroma, but they are still found to be associated with another taxon (Tilia) of the same host family Malvaceae (Plate IV). So, based on modern and present fossil evidence, it seems that in the eastern Indian area Chrysomelid beetles have not changed their host preference at the family level since the Pliocene. Our observations are similar to the ones made by Adroit et al. ( 2020) on the Hamamelidaceae and support the assumption that DT297 could be intimately related to a specific plant family in a geographic area. However, our results are not consistent with a previous assumption that an exclusive relationship between Parrotia and the damage type DT297 might exist. Nevertheless, such specific insect feeding DT297 could relate of similar chemical and/or nutrient quality of these plant taxa (Parrotia, Tilia and Abroma) for the insect, and then could suggest close ecological niche of these plants in their respective geographic areas and times. Specific and specialised insect damages such as the one observed in our study, could reveal similarities between two paleoecosystems that description of plant species alone may not highlight [START_REF] Adroit | Patterns of insect damage types reflect complex environmental signal in miocene forest biomes of central Europe and the Mediterranean[END_REF].

At least, in our case, there are no obvious changes in leaf architecture, such as differences in vein density, that might indicate why there might have been a switch in host preference at the genus level and this suggests external environmental factors may have played a role. Since Pliocene time in this part of eastern India published qualitative [START_REF] Singh | Late Tertiary leaf flora of Mahuadanr valley, Jharkhand[END_REF][START_REF] Krassilov | Mine and gall predation as top-down regulation in the plant-insect systems from the Cretaceous of Negev, Israel. Palaeogeogr[END_REF], 2009a, 2009b, 2009c;[START_REF] Hazra | Pliocene Albizia (Fabaceae) from Jharkhand, eastern India: reappraisal of its biogeography during the Cenozoic in Southeast Asia[END_REF] and quantitative climatic data (Hazra et al., 2020b) suggest that during Pliocene time the monsoon in the Jharkhand area of eastern India was slightly weaker than now, with a wetter dry season.

Fig. 1 .

 1 Fig. 1. (a) Geological map of Mahuadanr, Latehar district, Jharkhand (a part of the district resource map of Palamu district, Bihar published under the direction of Director General, Geological Survey of India, Kolkata), along with the fossil locality map; (b) generalised lithological section made using SedLog 3. 0 software showing litho-units with a composite graphic log of 3 m of exposed sedimentary section.

  ,andthatwasonParrotia (Hamamelidaceae) leaves from the Pliocene sediments of Willer-shausen, Germany and the Miocene sediments of Shanwang forma-tion of China. In this context, our discovery on a different host plant (Abroma) is therefore of significance and is documented for the first time on Indian fossil leaves.

  and Ellis et al. (2009). The eleven fossil leaf specimens (SKBUH/PPL/JH/ 136A; SKBUH/PPL/JH/136B; SKBUH/PPL/JH/137; SKBUH/PPL/JH/138A; SKBUH/PPL/JH/138B; SKBUH/PPL/JH/139; SKBUH/PPL/JH/155; SKBUH/ PPL/JH/156; SKBUH/PPL/JH/157; SKBUH/PPL/JH/158; SKBUH/PPL/JH/ 165) are housed in the Museum of the Palaeobotany and Palynology Laboratory, Department of Botany, Sidho-Kanho-Birsha University (SKBUH), Purulia.

  Plate II. (1-6) Fossil specimens of Abroma showing skeletonization on the lamina surface (marked in white oval). (1, 3, 5 and 6) curvilinear skeletonization divided in a row of many holes resembling a chain (SKBUH/PPL/JH/139; SKBUH/PPL/JH/156; SKBUH/PPL/JH/158 and SKBUH/PPL/JH/165); (2 and 4) linear skeletonization scattered on the lamina surface with row of many holes (SKBUH/PPL/JH/155; SKBUH/PPL/JH/157) Scale bar = 1 cm.

  Plate III. Enlargement of traces of skeletonization. (1-2) curved skeletonization; (3-9) elongated skeletonization. Scale bar = 1 cm.

Fig. 2 .

 2 Fig. 2. Line drawing of various types of elongated to curvilinear skeletonization feeding traces. Scale bar = 1 cm.

  Plate IV. Skeletonization on modern angiosperm leaves inflicted by Coleoptera. (1-3) skeletonization on leaves of Zizyphus induced by the Tortoise beetle Cassida; (4) skeletonization on leaf of Desmodium sp.; (5) elongated rectilinear skeletonization on a leaf of Cistus sp.; (6) elongated to curvilinear skeletonization on a leaf of Shorea sp., (7) skeletonization on a leaf of Tilia sp.; (8) elongated to curvilinear skeletonization on a leaf of Parrotia sp.; (9) skeletonization on leaves of Solanum sp. Scale bar = 1 cm.

Fig. 4 .

 4 Fig. 4. Map of the Eurasian continent showing where the damage type DT297 has been observed on fossil leaves (red dots) and modern leaves (green zones). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Acknowledgments

TH, MH and MAK gratefully acknowledge the Department of Botany, Sidho-Kanho-Birsha University for providing infrastructural facilities to accomplish this work. BA acknowledges Department of Botany, Sidho-Kanho-Birsha University for its kind invitation in order to contribute to that present manuscript. RAS and TEVS were supported by NERC/ NSFC BETR Project NE/P013805/1. SB acknowledges the Centre of

Declaration of Competing Interest

The authors declare that they have no competing interests.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https:// doi. org/10.1016/j.revpalbo.2021.104589.

Adams, J.M., Brusa, A., Soyeong, A., Ainuddin, A.N., 2010. Present-day testing of a paleoecological pattern: is there really a latitudinal difference in leaf-feeding insectdamage diversity? Rev. Palaeobot. Palynol. 162 (1), 63-70. Adroit, B., Zhuang, X., Wappler, T., Terral, J.F., Wang, B., 2020. A case of long-term herbiv-