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The fifth burmaeshnid dragonfly, Neoaeschna kachinensis gen. et sp. nov., is described based on the basal parts of a pair of fore- and hindwings from Kachin amber, indicating that Burmaeshnidae Huang, Cai, Nel & Bechly, 2017 is the most diverse family of true dragonflies in Kachin amber. The new dragonfly differs from the other genera in having one row of cells present in the postdiscoidal area basal of the midfork, the trigonal planate being obsolete, and one or two crossveins present basal of the CuP-crossing in the submedian space.

Three new species of plate-thigh beetles are described and figured from mid-Cretaceous Kachin amber, all representing the extant genus Eucinetus Germar. The species, Eucinetus debilispinus Li & Cai sp. nov., E. panghongae Li & Cai sp. nov., and E. zhenhuai Li & Cai sp. nov., are distinguished from each other by the forms of the antennomeres, leg spination, and form of the spurs. The genus Eucinetus represents a key example of long-term evolutionary stasis with a subcortical lifestyle. This further demonstrates the role of stable cryptic microhabitats in the persistence of some lineages over vast spans of geological time.

In order to place newly discovered fossil taxa (Palaeosymbius gen. nov. with P. groehni and P. mesozoicus spp. nov.) from the mid-Cretaceous amber from northern Myanmar, we investigated the relations of extant and extinct lineages of the coccinellid group of Coccinelloidea with emphasis on the family Anamorphidae. We assembled a taxonomic sampling of 34 taxa, including 15 genera and 19 species of Anamorphidae, the most comprehensive sampling of Anamorphidae at the generic level in a phylogenetic analysis. A morphological dataset of 47 characters was built as well as a molecular alignment of 7140 bp including fragments of eight genes (12S, 16S, 18S, 28S, COI, COII, H3 and CAD). Five anamorphid and one endomychid species were sequenced for the first time and added to the dataset. We performed parsimony-based analysis of the morphological dataset and Bayesian inference analysis of the combined matrix (morphological plus molecular data). Our results confirm that Palaeosymbius belongs to Anamorphidae and represents the oldest known member of this family so far. Among Anamorphidae, Symbiotes (with extant and known Eocene species) was recovered as the most probable closest relative of Palaeosymbius. Our morphological studies additionally revealed the presence of probable glandular openings in the anterolateral corners of the pronotal margins in Asymbius sp. and Anamorphus sp., representing the first report of secretory openings in the family Anamorphidae. Similar openings are found in other cucujiform beetles such as Cryptophagidae and Boganiidae with possible defensive purposes., (© 2024 Willi Hennig Society.)

Fossilized mating insects are irreplaceable material for comprehending the evolution of the mating behaviours and life-history traits in the deep-time record of insects as well as the potential sexual conflict. However, cases of mating pairs are particularly rare in fossil insects, especially aquatic or semi-aquatic species. Here, we report the first fossil record of a group of water striders in copulation (including three pairs and a single adult male) based on fossils from the mid-Cretaceous of northern Myanmar. The new taxon, Burmogerris gen. nov., likely represents one of the oldest cases of insects related to the marine environment, such as billabongs formed by the tides. It exhibits conspicuous dimorphism associated with sexual conflict: the male is equipped with a specialized protibial comb as a grasping apparatus, likely representing an adaptation to overcome female resistance during struggles. The paired Burmogerris show smaller males riding on the backs of the females, seemingly recording a scene of copulatory struggles between the sexes. Our discovery reveals a mating system dominated by males and sheds light on the potential sexual conflicts of Burmogerris in the Cretaceous. It indicates the mating behaviour remained stable over long-term geological time in these water-walking insects.

The beetle superfamily Elateroidea comprises the most biodiverse bioluminescent insects among terrestrial light-producing animals. Recent exceptional fossils from the Mesozoic era and phylogenomic studies have provided valuable insights into the origin and evolution of bioluminescence in elateroids. However, due to the fragmentary nature of the fossil record, the early evolution of bioluminescence in fireflies (Lampyridae), one of the most charismatic lineages of insects, remains elusive. Here, we report the discovery of the second Mesozoic bioluminescent firefly, Flammarionella hehaikuni Cai, Ballantyne & Kundrata gen. et sp. nov., from the Albian/Cenomanian of northern Myanmar ( ca 99 Ma). Based on the available set of diagnostic characters, we interpret the specimen as a female of stem-group Luciolinae. The fossil possesses deeply impressed oval pits on the apices of antennomeres 3-11, representing specialized sensory organs likely involved in olfaction. The light organ near the abdominal apex of Flammarionella resembles that found in extant light-producing lucioline fireflies. The growing fossil record of lampyrids provides direct evidence that the stunning light displays of fireflies were already established by the late Mesozoic.

A mating pair of Palaeoparasycorax globosus Stebner et al., 2015 from the mid-Cretaceous Burmese amber is illustrated and described. The male is redescribed, and the female genitalia of this species is described for the first time. This discovery allows for a better understanding of this fossil sycoracines characteristics and further demonstrates the bioinclusion richness of the mid-Cretaceous Burmese amber. A list of all Cretaceous Psychodidae is given.

Diplura is a cryptic and edaphic group of hexapod animals characterized by the presence of filiform or pincer-like cerci located at the end of the abdomen. As one of the early diverging lineages of Hexapoda, diplurans play a crucial role in unraveling the origin of the hyperdiverse insects. The fossil record of diplurans, however, is exceptionally limited due to their delicate bodies and habitat requirements. Here we report the discovery of a new japygid, Cretojapyx huangi gen. et sp. nov., entombed in mid-Cretaceous Kachin amber (northern Myanmar). This specimen exhibits distinctive features, including the well-developed carinae on abdominal segment X and cerci, left cercus lacking a prominent tooth and denticles, and right cercus with a postmedian tooth followed by uniseriate round denticles. Our finding provides a unique opportunity to gain valuable insights into the evolutionary history of this ancient lineage and deepen our understanding of terrestrial ecosystems during the Mesozoic.

Ptiliidae (featherwing beetles) is a group of minute staphylinoid beetles with a scarce fossil record. Here a second member of the Mesozoic genus Kekveus Yamamoto et al. is reported from mid-Cretaceous Burmese amber, with detailed morphology obtained through confocal microscopy. Kekveus brevisulcatus Li, Yamamoto, Newton & Cai sp. nov. shares with K. jason Yamamoto et al. the unpaired medial pronotal fovea and narrowly separated transverse metacoxae, but can be separated from the latter based on its less elongate body, shorter pronotal foveae, and much weaker transverse depression on the head. Our phylogenetic analyses support the discheramocephalin affinity of Kekveus , although its relationship with other members of Discheramocephalini cannot be confidently resolved., Competing Interests: The authors declare there are no competing interests., (©2023 Li et al.)

As one of the earliest-diverging lineage of the megadiverse beetle suborder Polyphaga, marsh beetles (Scirtidae) are crucial for reconstructing the ancestor of all polyphagan beetles and the ecomorphological underpinnings of their remarkable evolutionary success. The phylogeny of marsh beetles has nonetheless remained challenging to infer, not least because of their fragmentary Mesozoic fossil record. Here we describe a new scirtid beetle genus and species, Varcalium lawrencei gen. et sp. nov., preserving internal tissue, from Albian-Cenomanian Kachin amber (ca 99 Ma), representing the second member of this family known from the deposit. Based on a formal morphological phylogenetic analysis, Varcalium is recovered within the crown-group of Scirtinae, forming a clade with other genera that possess subocular carinae. The finding suggests that the crown-group of Scirtinae has already diversified by the mid-Cretaceous., (© 2022. The Author(s).)

Artematopodid fossils from the mid-Cretaceous Burmese amber are reported for the first time, represented by three species in two genera. Bipogonia Li, Kundrata Cai gen. nov. with two species, B. trivialis Li, Kundrata Cai sp. nov. and B. fortis Li, Kundrata Cai sp. nov., is mainly characterized by the distinctly serrate antennae, mandibles with both apical and subapical teeth, and prosternum without paired longitudinal ridges. Carinibipogonia xiai Li, Kundrata Cai gen. et sp. nov. shares with Bipogonia the distinctly serrate antennae and mandibles with both apical and subapical teeth but differs mainly in the prosternum with short paired longitudinal ridges. Based on their morphology, the two new genera might be related to the extant Allopogonia; however, this needs to be tested in the future with a phylogenetic framework.

Two new species of the prostomid genus Vetuprostomis Engel Grimaldi (Coleoptera: Tenebrionoidea: Prostomidae), V. angularis Li Cai sp. nov. and V. gaoi Li Cai sp. nov., are described from the mid-Cretaceous Burmese amber. Vetuprostomis is suggested to be more closely related to extant Dryocora Pascoe distributed in Australia and New Zealand, rather than the widespread genus Prostomis Latreille. A key to prostomid genera, as well as species in genus Vetuprostomis, is provided.

The rapid Cretaceous diversification of flowering plants remains Darwin's 'abominable mystery' despite numerous fossil flowers discovered in recent years. Wildfires were frequent in the Cretaceous and many such early flower fossils are represented by charcoalified fragments, lacking complete delicate structures and surface textures, making their similarity to living forms difficult to discern. Furthermore, scarcity of information about the ecology of early angiosperms makes it difficult to test hypotheses about the drivers of their diversification, including the role of fire in shaping flowering plant evolution. We report the discovery of two exquisitely preserved fossil flower species, one identical to the inflorescences of the extant crown-eudicot genus Phylica and the other recovered as a sister group to Phylica, both preserved as inclusions together with burned plant remains in Cretaceous amber from northern Myanmar (~99 million years ago). These specialized flower species, named Phylica piloburmensis sp. nov. and Eophylica priscastellata gen. et sp. nov., exhibit traits identical to those of modern taxa in fire-prone ecosystems such as the fynbos of South Africa, and provide evidence of fire adaptation in angiosperms., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Nosodendridae is a small polyphagan beetle family with a sparse fossil record. Herein, the fossil Nosodendridae from mid-Cretaceous Burmese amber (ca. 99 Ma) are systematically reviewed. Nosodendron cretaceum Deng et al. is transferred into Archaenosodendron Li Cai gen. nov., as A. cretaceum (Deng et al.) comb. nov., primarily based on the morphology of prosternum. Three new species of Archaenosodendron from Burmese amber, A. explanatum Li Cai sp. nov., A. remotidens Li Cai sp. nov., and A. angulare Li Cai sp. nov., are also described and illustrated. A key to nosodendrid genera and species from Burmese amber is provided.

A new lycid beetle, Murcybolus longiantennus gen. et sp. nov., is reported from mid-Cretaceous Burmese amber (ca. 99 Ma). Murcybolus is placed in the recently erected fossil tribe Burmolycini based on the fully metamorphosed female, 10-segmented antennae, and pronotal disc with deep rounded punctures but without carinae. Murcybolus differs from the other genus in Burmolycini, Burmolycus, by its antennal morphology and elytral venation.

Within the hyperdiverse beetle family Staphylinidae, Dasycerinae is one of the smallest and most cryptic subfamilies, comprising a sole extant genus characterized by a latridiid beetle-like body form. Little has been known about their early diversification, character evolution, phylogeny and historical biogeography because of limited fossil material and lack of a phylogeny integrating extant and extinct representatives. Here we report an unexpectedly diverse dasycerine fauna from the mid-Cretaceous of northern Myanmar, including a new genus and four new species. To reconstruct the early evolutionary history of Dasycerinae, we present a phylogenetic framework of the subfamily based on a dataset integrating all extant and extinct taxa using parsimony, maximum-likelihood and Bayesian methods. †Cedasyrus gen. n., characterized by distinct sexual dimorphism in antennal and elytral lengths, is recovered as the basal-most lineage, sister to the remaining two extinct genera and all living Dasycerus species. †Vetudasycerus is recovered as sister to †Protodasycerus + Dasycerus. Among all extinct taxa, †Protodasycerus bears distinctly longer elytra, and appears to represent a transitional form from †Vetudasycerus to Dasycerus. Phylogenetic inferences and ancestral distribution reconstruction support an "Out-of-Orient" model for Dasycerinae. Either the Bering- or North Atlantic Land Bridge may have served as a passageway for dasycerine dispersal between Eurasian and North American continents. An elevation-reconstruction analysis indicated that the ancestor of the extant Dasycerus probably lived at a high altitude and stayed at this elevation through the end of the Miocene. We propose that the extinction of dasycerine ancestors living on the Tethyan islands at low altitude was likely caused by sea-level rise and climatic warming during the Late Cretaceous. The high-altitude areas might have played the role of refugia that harboured subalpine derivatives which eventually gave rise to the extant Dasycerus., (© 2020 The Authors. Cladistics published by John Wiley & Sons Ltd on behalf of Willi Hennig Society.)

Bioluminescent beetles of the superfamily Elateroidea (fireflies, fire beetles, glow-worms) are the most speciose group of terrestrial light-producing animals. The evolution of bioluminescence in elateroids is associated with unusual morphological modifications, such as soft-bodiedness and neoteny, but the fragmentary nature of the fossil record discloses little about the origin of these adaptations. We report the discovery of a new bioluminescent elateroid beetle family from the mid-Cretaceous of northern Myanmar ( ca 99 Ma), Cretophengodidae fam. nov. Cretophengodes azari gen. et sp. nov. belongs to the bioluminescent lampyroid clade, and would appear to represent a transitional fossil linking the soft-bodied Phengodidae + Rhagophthalmidae clade and hard-bodied elateroids. The fossil male possesses a light organ on the abdomen which presumably served a defensive function, documenting a Cretaceous radiation of bioluminescent beetles coinciding with the diversification of major insectivore groups such as frogs and stem-group birds. The discovery adds a key branch to the elateroid tree of life and sheds light on the evolution of soft-bodiedness and the historical biogeography of elateroid beetles.

The Sternorrhyncha, which comprise about 18,700 described recent species, is a suborder of the Hemiptera, one of big five most diverse insect orders. In the modern fauna, these tiny phytophages comprise insects of great ecological and economic importance, like aphids (Aphidomorpha), scale insects (Coccidomorpha), whiteflies (Aleyrodomorpha) and psyllids (Psylloidea). Their evolutionary history can be traced back to the Late Carboniferous, but the early stages of their evolution and diversification is poorly understood, with two known extinct groups-Pincombeomorpha and Naibiomorpha variously placed in classifications and relationships hypotheses. Most of the recent Sternorrhyncha groups radiated rapidly during the Cretaceous. Here we report the new finding of very specialised sternorrhynchans found as inclusions in mid-Cretaceous amber from Kachin state (northern Myanmar), which represent another extinct lineage within this hemipteran suborder. These fossils, proposed to be placed in a new infraorder, are revealed to be related to whiteflies and psyllids. We present, also for the first time, the results of phylogenetic analyses covering extinct and extant lineages of the Sternorrhyncha.

Mesozoic long-proboscid scorpionflies (Mesopsychoidea) provide important clues to ancient plant-pollinator interactions. Among them, the family Aneuretopsychidae is especially important because its mouthparts are vital to deciphering the early evolution of Mesopsychoidea and putatively the origin of fleas (Siphonaptera). However, the identification of mouthpart homologs among Aneuretopsychidae remains controversial because of the lack of three-dimensional anatomical data. Here, we report the first Aneuretopsychidae from Late Cretaceous Burmese amber, which have short maxillary palpi and elongate mouthpart elements consisting of one pair of galeae and one hypopharynx. Their mouthparts are identical to those of Pseudopolycentropodidae (= Dualulidae, new synonym) but are not homologous to those of Siphonaptera. Our phylogenetic analysis provides robust evidence for the debated monophyly of Mesopsychoidea. Our results suggest that the long-proboscid condition has most likely evolved once in Mesopsychoidea, independently from fleas, and further reveal the variety and complexity of mid-Cretaceous pollinating insects., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Insect pollination of flowering plants (angiosperms) is responsible for the majority of the world's flowering plant diversity and is key to the Cretaceous radiation of angiosperms. Although both insects and angiosperms were common by the mid-Cretaceous, direct fossil evidence of insect pollination is lacking. Direct evidence of Cretaceous insect pollination is associated with insect-gymnosperm pollination. Here, we report a specialized beetle-angiosperm pollination mode from mid-Cretaceous Burmese amber (99 mega-annum [Ma]) in which a tumbling flower beetle (Mordellidae), Angimordella burmitina gen. et sp. nov., has many tricolpate pollen grains attached. A. burmitina exhibits several specialized body structures for flower-visiting behavior including its body shape and pollen-feeding mouthparts revealed by X-ray microcomputed tomography (micro-CT). The tricolpate pollen in the amber belongs to the eudicots that comprise the majority of extant angiosperm species. These pollen grains exhibit zoophilous pollination attributes including their ornamentation, size, and clumping characteristics. Tricolpate pollen grains attached to the beetle's hairs are revealed by confocal laser scanning microscopy, which is a powerful tool for investigating pollen in amber. Our findings provide direct evidence of insect pollination of Cretaceous angiosperms, extending the range insect-angiosperm pollination association by at least 50 million years. Our results support the hypothesis that specialized insect pollination modes were present in eudicots 99 million years ago., Competing Interests: The authors declare no competing interest., (Copyright © 2019 the Author(s). Published by PNAS.)

Predation is a major driving force for the evolution of functional forms. Avoidance of visual predators has resulted in different kinds of anti-predator defences, such as: camouflage, crypsis, disruptive coloration, and masquerade or mimesis. Camouflage is one of the forms involving shape, colouration, structure and behaviour when the visual pattern and orientation of an animal can determine whether it lives or dies. Inferring the behaviour and function of an ancient organism from its fossilised remains is a difficult task, but in many cases it closely resembles that of its descendants on uniformitarian grounds. Here we report and discuss examples of morphological and behavioural traits involving camouflage named recently as a flatoidinisation syndrome, shown by the inclusion of a planthopper in mid-Cretaceous Burmese amber. We found a new genus and species of an extinct Cretaceous planthopper family Mimarachnidae showing peculiar complex morphological adaptations to camouflage it on tree bark. Due to convergence, it resembles an unrelated tropiduchid planthopper from Eocene Baltic amber and also a modern representatives of the planthopper family Flatidae. Flattening of the body, the horizontal position of the tegmina at repose, tegmina with an undulating margin and elevated, wavy longitudinal veins, together with colouration and more sedentary behavioral traits enable these different insects to avoid predators. Our discovery reveals flatoidinisation syndrome in mid-Cretaceous Burmese amber which may provide insights into the processes of natural selection and evolution in this ancient forest.

The origin and early evolutionary history of polyphagan beetles have been largely based on evidence from the derived and diverse 'core Polyphaga', whereas little is known about the species-poor basal polyphagan lineages, which include Scirtoidea (Clambidae, Decliniidae, Eucinetidae, and Scirtidae) and Derodontidae. Here, we report two new species Acalyptomerus thayerae sp. nov. and Sphaerothorax uenoi sp. nov., both belonging to extant genera of Clambidae, from mid-Cretaceous Burmese amber. Acalyptomerus thayerae has a close affinity to A. herbertfranzi, a species currently occurring in Mesoamerica and northern South America. Sphaerothorax uenoi is closely related to extant species of Sphaerothorax, which are usually collected in forests of Nothofagus of Australia, Chile, and New Zealand. The discovery of two Cretaceous species from northern Myanmar indicates that both genera had lengthy evolutionary histories, originated at least by the earliest Cenomanian, and were probably more widespread than at present. Remarkable morphological similarities between fossil and living species suggest that both genera changed little over long periods of geological time. The long-term persistence of similar mesic microhabitats such as leaf litter may account for the 99 Myr morphological stasis in Acalyptomerus and Sphaerothorax. Additionally, the extinct staphylinoid family Ptismidae is proposed as a new synonym of Clambidae, and its only included species Ptisma zasukhae is placed as incertae sedis within Clambidae.

Cycads, unlike modern wind-pollinated conifers and Ginkgo, are unusual in that they are an ancient group of gymnosperms pollinated by insects [1-3]. Although it is well documented that cycads were diverse and abundant during the mid-Mesozoic, little is known about their biogeography and pollination before the rise of angiosperms. Direct fossil evidence illuminating the evolutionary history of cycads is extremely rare [4, 5]. Here we report a specialized beetle-mediated pollination mode from the mid-Cretaceous of Myanmar, wherein a new boganiid beetle, Cretoparacucujus cycadophilus, with specialized pollen-feeding adaptations in its mouthparts and legs, was associated with many pollen grains of Cycadopites. Phylogenetic analyses indicate Cretoparacucujus as a sister group to the extant Australian Paracucujus, which pollinate the cycad Macrozamia riedlei. Our discovery, along with the current disjunct distribution of related beetle-herbivore (tribe Paracucujini) and cycad-host (tribe Encephalarteae) pairs in South Africa and Australia, indicate a probable ancient origin of beetle pollination of cycads at least in the Early Jurassic, long before angiosperm dominance and the radiation of flowering-plant pollinators later in the Cretaceous., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Insect faunas are extremely rare near the latest Cretaceous with a 24-million-year gap spanning from the early Campanian to the early Eocene. Here, we report a unique amber biota from the Upper Cretaceous (uppermost Campanian ~72.1 Ma) of Tilin, central Myanmar. The chemical composition of Tilin amber suggests a tree source among conifers, indicating that gymnosperms were still abundant in the latest Campanian equatorial forests. Eight orders and 12 families of insects have been found in Tilin amber so far, making it the latest known diverse insect assemblage in the Mesozoic. The presence of ants of the extant subfamilies Dolichoderinae and Ponerinae supports that tropical forests were the cradle for the diversification of crown-group ants, and suggests that the turnover from stem groups to crown groups had already begun at ~72.1 Ma. Tilin amber biota fills a critical insect faunal gap and provides a rare insight into the latest Campanian forest ecosystem.

Camouflage and mimicry are staples among predator-prey interactions, and evolutionary novelties in behavior, anatomy, and physiology that permit such mimesis are rife throughout the biological world [1, 2]. These specializations allow for prey to better evade capture or permit predators to more easily approach their prey, or in some cases, the mimesis can serve both purposes. Despite the importance of mimesis and camouflage in predator-avoidance or hunting strategies, the long-term history of these traits is often obscured by an insufficient fossil record. Here, we report the discovery of Upper Cretaceous (approximately 100 million years old) green lacewing larvae (Chrysopoidea), preserved in amber from northern Myanmar, anatomically modified to mimic coeval liverworts. Chrysopidae are a diverse lineage of lacewings whose larvae usually camouflage themselves with a uniquely constructed packet of exogenous debris, conveying greater stealth upon them as they hunt prey such as aphids as well as evade their own predators [3, 4]. However, no lacewing larvae today mimic their surroundings. While the anatomy of Phyllochrysa huangi gen. et sp. nov. allowed it to avoid detection, the lack of setae or other anatomical elements for entangling debris as camouflage means its sole defense was its mimicry, and it could have been a stealthy hunter like living and other fossil Chrysopoidea or been an ambush predator aided by its disguise. The present fossils demonstrate a hitherto unknown life-history strategy among these "wolf in sheep's clothing" predators, one that apparently evolved from a camouflaging ancestor but did not persist within the lineage., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Spiders (Araneae) are a hugely successful lineage with a long history. Details of their origins remain obscure, with little knowledge of their stem group and few insights into the sequence of character acquisition during spider evolution. Here, we describe Chimerarachne yingi gen. et sp. nov., a remarkable arachnid from the mid-Cretaceous (approximately 100 million years ago) Burmese amber of Myanmar, which documents a key transition stage in spider evolution. Like uraraneids, the two fossils available retain a segmented opisthosoma bearing a whip-like telson, but also preserve two traditional synapomorphies for Araneae: a male pedipalp modified for sperm transfer and well-defined spinnerets resembling those of modern mesothele spiders. This unique character combination resolves C. yingi within a clade including both Araneae and Uraraneida; however, its exact position relative to these orders is sensitive to different parameters of our phylogenetic analysis. Our new fossil most likely represents the earliest branch of the Araneae, and implies that there was a lineage of tailed spiders that presumably originated in the Palaeozoic and survived at least into the Cretaceous of Southeast Asia.

A fossil palpigrade is described and figured from mid-Cretaceous (Cenomanian) amber from northern Myanmar. Electrokoenenia yaksha Engel and Huang, gen. n. et sp. n., is the first Mesozoic fossil of its order and the only one known as an inclusion in amber, the only other fossil being a series of individuals encased in Pliocene onyx marble and 94-97 million years younger than E. yaksha. The genus is distinguished from other members of the order but is remarkably consistent in observable morphological details when compared to extant relatives, likely reflecting a consistent microhabitat and biological preferences over the last 100 million years.