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Abstract A re-examination of the early Toarcian fish fossils preserved in public paleontological collections in Luxembourg revealed 70 specimens of large Toarcian pachycormid fish with an excellent three-dimensional preservation within calcareous nodules. Six of them are associated with octobrachian coleoid gladii in their oesophagus or stomach, an association not previously described from Luxembourg. The pachycormids are ascribed to Pachycormus macropterus (Blainville, 1818) and Saurostomus esocinus Agassiz, 1843 while the octobrachian gladii are ascribed to Teudopsis bollensis Voltz, 1836, Teudopsis sp. indet. and Loligosepiidae indet. The position and orientation of the gladii provide direct evidence of these fishes feeding on coleoids and thus a teuthophagous diet, rather than an accidental joint burial. Together with evidence from coeval deposits in Germany, these findings suggest that teuthophagy was a widespread feeding strategy at the base of the clade that contains the suspension-feeding pachycormid giants of the Jurassic–Cretaceous.

The modern marine megafauna is known to play important ecological roles and includes many charismatic species that have drawn the attention of both the scientific community and the public. However, the extinct marine megafauna has never been assessed as a whole, nor has it been defined in deep time. Here, we review the literature to define and list the species that constitute the extinct marine megafauna, and to explore biological and ecological patterns throughout the Phanerozoic. We propose a size cut-off of 1 m of length to define the extinct marine megafauna. Based on this definition, we list 706 taxa belonging to eight main groups. We found that the extinct marine megafauna was conspicuous over the Phanerozoic and ubiquitous across all geological eras and periods, with the Mesozoic, especially the Cretaceous, having the greatest number of taxa. Marine reptiles include the largest size recorded (21 m; Shonisaurus sikanniensis) and contain the highest number of extinct marine megafaunal taxa. This contrasts with today’s assemblage, where marine animals achieve sizes of >30 m. The extinct marine megafaunal taxa were found to be well-represented in the Paleobiology Database, but not better sampled than their smaller counterparts. Among the extinct marine megafauna, there appears to be an overall increase in body size through time. Most extinct megafaunal taxa were inferred to be macropredators preferentially living in coastal environments. Across the Phanerozoic, megafaunal species had similar extinction risks as smaller species, in stark contrast to modern oceans where the large species are most affected by human perturbations. Our work represents a first step towards a better understanding of the marine megafauna that lived in the geological past. However, more work is required to expand our list of taxa and their traits so that we can obtain a more complete picture of their ecology and evolution.

Abstract For the understanding of the evolution of jawed vertebrates and jaws and teeth, ‘placoderms’ are crucial as they exhibit an impressive morphological disparity associated with the early stages of this process. The Devonian of Morocco is famous for its rich occurrences of arthrodire ‘placoderms’. While Late Devonian strata are rich in arthrodire remains, they are less common in older strata. Here, we describe a large tooth-bearing jaw element of Leptodontichthys ziregensis gen. et sp. nov., an eubrachythoracid arthrodire from the Middle Devonian of Morocco. This species is based on a large posterior superognathal with a strong dentition. The jawbone displays features considered synapomorphies of Late Devonian eubrachythoracid arthrodires, with one posterior and one lateral row of conical teeth oriented postero-lingually. μCT-images reveal internal structures including pulp cavities and dentinous tissues. The posterior orientation of the teeth and the traces of a putative occlusal contact on the lingual side of the bone imply that these teeth were hardly used for feeding. Similar to Compagopiscis and Plourdosteus, functional teeth were possibly present during an earlier developmental stage and have been worn entirely. The morphological features of the jaw element suggest a close relationship with plourdosteids. Its size implies that the animal was rather large. ZooBank LSID: urn:lsid:zoobank.org:pub:B707FB56-74A8-42C2-8BA0-D5BE1F32AB4A.

Abstract Due to the lower fossilization potential of chitin, non-mineralized cephalopod jaws and arm hooks are much more rarely preserved as fossils than the calcitic lower jaws of ammonites or the calcitized jaw apparatuses of nautilids. Here, we report such non-mineralized fossil jaws and arm hooks from pelagic marly limestones of continental Greece. Two of the specimens lie on the same slab and are assigned to the Ammonitina; they represent upper jaws of the aptychus type, which is corroborated by finds of aptychi. Additionally, one intermediate type and one anaptychus type are documented here. The morphology of all ammonite jaws suggest a desmoceratoid affinity. The other jaws are identified as coleoid jaws. They share the overall U-shape and proportions of the outer and inner lamellae with Jurassic lower jaws of Trachyteuthis (Teudopseina). We also document the first belemnoid arm hooks from the Tethyan Maastrichtian. The fossils described here document the presence of a typical Mesozoic cephalopod assemblage until the end of the Cretaceous in the eastern Tethys.

The actinopterygian crown group (comprising all living ray-finned fishes) originated by the end of the Carboniferous. However, most late Paleozoic taxa are stem actinopterygians, and broadly resemble stratigraphically older taxa. The early Permian †Brachydegma caelatum is notable for its three-dimensional preservation and past phylogenetic interpretations as a nested member of the neopterygian crown. Here, we use computed microtomography to redescribe †Brachydegma, uncovering an unanticipated combination of primitive (e.g., aortic canal; immobile maxilla) and derived (e.g., differentiated occipital ossifications; posterior stem of parasphenoid; two accessory hyoidean ossifications; double jaw joint) dermal and endoskeletal traits relative to most other Paleozoic actinopterygians. Some of these features were previously thought to be restricted to the neopterygian crown. The precise phylogenetic position of †Brachydegma is unclear, with placements either on the polypterid stem or as an early-diverging stem neopterygian. However, our analyses decisively reject previous placements of †Brachydegma in the neopterygian crown. Critically, we demonstrate that key endoskeletal components of the hyoid portion of the suspensorium of crown neopterygians appeared deeper in the tree than previously thought.

The global body-fossil record of marine ‘fishes’ from the time interval immediately preceding the Cretaceous–Paleogene Extinction is markedly poor. This deficiency appears to be further exacerbated with regards to offshore and deep-water taxa, obscuring our understanding of the state and composition of corresponding vertebrate faunas at the onset of this major extinction event. Recent fieldwork in the mid–late Maastrichtian exposures of the Pindos Unit in Gavdos Island, Greece, yielded a small but informative sample of fossil ‘fishes’, which inhabited the Tethys approximately three to four million years before the extinction. In this work we describe this sample, which comprises between eight and nine discrete morphotypes of various size classes, belonging to †Ichthyodectoidei, Aulopiformes (†Dercetidae, †Enchodontidae, †Ichthyotringidae), cf. †Sardinioididae, as well as the hexanchid shark †Gladioserratus sp. The new material expands the faunal list for the Maastrichtian of Gavdos Island, and the Pindos Unit as a whole, and further allows for the description of a new genus and species of †Enchodontidae and a new species of †Ichthyotringidae. The two new taxa are found to be widespread in the Maastrichtian of the Pindos Unit. The overall character of the assemblage agrees with previous interpretations of an offshore and rather deep depositional environment for the fossiliferous horizons. Furthermore, it exhibits a higher diversity than, and little taxonomic overlap with penecontemporaneous teleost assemblages from the Tethys, and informs on the otherwise poorly known Maastrichtian offshore and deep-water marine ichthyofaunas of the region.

Abstract Background †Saurichthyiformes were a successful group of latest Permian–Middle Jurassic predatory actinopterygian fishes and constituted important, widely-distributed components of Triassic marine and freshwater faunas. Their systematic affinities have long been debated, with †saurichthyiforms often being aligned with chondrosteans, a group today comprising sturgeons and paddlefishes. However, their character-rich endocranial anatomy has not been investigated in detail since the first half of the 20th century. Since then, major advances have occurred in terms of our understanding of early actinopterygian anatomy, as well as techniques for extracting morphological data from fossils. Results We used μCT to study the internal cranial anatomy of two of the stratigraphically oldest representatives of †Saurichthys, from the Early Triassic of East Greenland and Nepal. Our work revealed numerous previously unknown characters (e.g., cryptic oticooccipital fissure; intramural diverticula of braincase; nasobasal canals; lateral cranial canal; fused dermohyal), and permitted the reevalution of features relating to the structure of cranial fossae, basicranial circulation and opercular anatomy of the genus. Critically, we reinterpret the former †saurichthyiform opercle as an expanded subopercle. For comparison, we also produced the first digital models of a braincase and endocast of a sturgeon (A. brevirostrum). New information from these taxa was included in a broad phylogenetic analysis of Actinopterygii. †Saurichthyiforms are resolved as close relatives of †Birgeria, forming a clade that constitutes the immediate sister group of crown actinopterygians. However, these and other divergences near the actinopterygian crown node are weakly supported. Conclusions Our phylogeny disagrees with the historically prevalent hypothesis favoring the chondrostean affinities of †saurichthyiforms. Previously-proposed synapomorphies uniting the two clades, such as the closure of the oticooccipital fissure, the posterior extension of the parasphenoid, and the absence of an opercular process, are all widespread amongst actinopterygians. Others, like those relating to basicranial circulation, are found to be based on erroneous interpretations. Our work renders the †saurichthyiform character complex adequately understood, and permits detailed comparisons with other stem and crown actinopterygians. Our phylogenetic scheme highlights outstanding questions concerning the affinity of many early actinopterygians, such as the Paleozoic–early Mesozoic deep-bodied forms, which are largely caused by lack of endoskeletal data.

A re-examination of the early Toarcian fish fossils preserved in public paleontological collections in Luxembourg revealed 70 specimens of large Toarcian pachycormid fish with an excellent three-dimensional preservation within calcareous nodules. Six of them are associated with octobrachian coleoid gladii in their oesophagus or stomach, an association not previously described from Luxembourg. The pachycormids are ascribed to Pachycormus macropterus (Blainville, 1818) and Saurostomus esocinus Agassiz, 1843 while the octobrachian gladii are ascribed to Teudopsis bollensis Voltz, 1836, Teudopsis sp. indet. and Loligosepiidae indet. The position and orientation of the gladii provide direct evidence of these fishes feeding on coleoids and thus a teuthophagous diet, rather than an accidental joint burial. Together with evidence from coeval deposits in Germany, these findings suggest that teuthophagy was a widespread feeding strategy at the base of the clade that contains the suspension-feeding pachycormid giants of the Jurassic–Cretaceous. [ABSTRACT FROM AUTHOR]

Throughout the Silurian and Devonian, cartilaginous fish successively evolved their specialized skeletal and dental characteristics, and increasingly refined their sensory systems. The Late Devonian shark taxon Maghriboselache mohamezanei gen. et sp. n. from the eastern Anti-Atlas of Morocco is known from multiple specimens preserving most of its skeletal features, which in some instances are preserved in three dimensions. Key details of the dentition, jaws, and pectoral skeleton are shared with the iconic genus Cladoselache. Phylogenetic analyses place the family Cladoselachidae as the sister group of symmoriiforms and these groups as sister group of the holocephalans. Further phylogenetic results corroborate that the initial evolutionary radiation of crown chondrichthyans occurred within or before the Late Devonian. Remarkably, this new stem holocephalan is equipped with a wide snout and large laterally separated nasal capsules: the earliest known example of this condition in the chondrichthyan and (perhaps) gnathostome record. This suggests sensory specialization approaching that of extant broad-rostrum elasmobranchs and represents a significant addition to increasingly apparent ecomorphological diversity among early chondrichthyans. [ABSTRACT FROM AUTHOR]

The Paleogene nominal species Osteochilus sanshuiensis, Osteochilus longipinnatus, and Osteochilus laticorpus from Sanshui Basin, China, were originally assigned to the extant genus Osteochilus, in the family Cyprinidae. They were lately considered to belong to Catostomidae or the extinct family Jianghanichthyidae. However, the type specimens of the above nominal species have been deemed to be lost, which hindered the corroborated taxonomic assignment of the species. After multiple attempts and inter-institutional efforts, a series of original type specimens were recovered from a warehouse. We herein report the resurfacing and relocation of the specimens, as well as clarify the taxonomic status of those nominal species. Based on the type specimens and our recently collected specimens in the same locality, we propose to revise the three nominal species as one species †Jianghanichthys sanshuiensis comb. nov. One of the best-preserved original type specimens, SYSU R. 741177 is designated to be the lectotype. [ABSTRACT FROM AUTHOR]

Vertebrate macroevolution has been punctuated by fundamental habitat transitions from shallow marine origins to terrestrial, freshwater, and aerial environments. Invasion of the deep sea is a less well-known ecological shift because of low fossilization potential and continual loss of abyssal fossil record by ocean floor subduction. Therefore, there has been a lack of convincing evidence of bottom-living vertebrates from pre-Paleogene deep seas. Here, we describe trace fossils from abyssal plain turbidites of the Tethys Ocean, which, combined with nannofossil dating, indicate that fishes have occupied the deep seafloor since at least the Early Cretaceous (Hauterivian-Barremian). These structures are identical to those produced by modern demersal fishes that feed by either scratching the substrate or expose their prey by water flow generated by suction or jetting. The trace fossils suggest activity of at least three fish species exploiting a productive abyssal invertebrate sediment fauna. These observations are consistent with Early Cretaceous vertebrate transition to the deep sea triggered by the availability of new food sources. Our results anticipate the appearance of deep-seafloor fishes in the fossil record by over 80 My while reassessing the mode of vertebrate colonization of the deep sea. [ABSTRACT FROM AUTHOR]

A new gyracanthid, Gyracanthus? jasperi, is described based on partially articulated and isolated elements from the Lower Carboniferous (Mississippian) lower Waugh Member of the Ste Genevieve Formation, at the early tetrapod site near Delta, Iowa, U.S.A. Pectoral fin spines of the new gyracanthid are characterized by the insertion on the fin spine being a half to one-third the length of the spine and maximum length:depth ratio 10:1. Ornament ridges on the pectoral fin spine converge at ≥90° along a low leading edge ridge, and ridge tubercles are oriented oblique to the ridge; the distal end of one pectoral is described using micro-computed tomography. The scapulocoracoids have an anteriorly curving bulbous apex, and a base length that is 35–40% of pectoral spine length. The procoracoid is associated with an unornamented ventral plate. A possible isolated dorsal fin spine is more symmetrical and less worn than the pectoral fin spines. Pelvic spines are dorsoventrally flattened, with oblique ridges meeting at approximately 100° proximally and 80° distally, along a smooth leading edge ridge. Scales, found on the partial articulated specimen and as isolated remains, are polyodontode with a flat base. Adults of the new taxon are estimated to have been about one meter long. Deposition was in debris flows, within a sinkhole lake most likely removed from the edge of the ocean. Other Carboniferous gyracanthids from North America are reviewed. [ABSTRACT FROM AUTHOR]

The family Latidae is considered to have originated in marine waters of the Tethys, and the fossil record of this group indicates a widespread occurrence of latid fishes in the past. In the Mediterranean–Paratethyan basins, the genus Lates is represented by a number of fossil species, the youngest of which have been reported from Miocene deposits of Italy and Ukraine. Here we report on Lates fossils recovered from Late Miocene (Pontian) deposits of the Shkodova Gora locality of Ukraine, with a description of a new species †Lates odessanus sp. nov. The new species bears distinct morphological traits, especially on its maxilla, premaxilla, and parasphenoid, not found in other spatiotemporally close relatives. The fossil record shows that much of the latid species diversity was lost after the Late Miocene, and the newly described species, †L. odessanus, appears to be the last known extinct representative of this group in low salinity deposits of the Mediterranean–Paratethyan basins. The only extant Lates species in the Mediterranean, L. niloticus, has survived in estuarine environments of the southern shore. [ABSTRACT FROM AUTHOR]

Cannibalism (conspecific predation) is a surprisingly common and widespread behavior in modern ecosystems; however, direct evidence for cannibalism is strongly lacking in the fossil record. Identifying cannibalism is important to help better understand recondite trophic interactions between extinct species, as well as to detect potential resource pressures and competition in their ecosystems. Here, I describe the first direct evidence for a cannibalistic diet in a pachycormiform fish, based on three exceptionally well-preserved specimens of Pachycormus macropterus (de Blainville, 1818) with conspecific gut contents from the Early Jurassic (Toarcian) of Normandy (France). The generalist diet of Pachycormus is proven to be more complex than previously considered, which has recently been shown to include vampyropod squids, belemnoteuthids, ammonites, and small teleosts. All of the prey fishes were ingested whole in a longitudinal orientation, revealing that Pachycormus actively hunted juveniles of its own kind and was an indiscriminate opportunistic predator. The cannibal individuals themselves are also juveniles, further supporting previous findings for a dietary shift in Pachycormus from piscivorous to teuthophagous over ontogeny. Despite a widespread European distribution of Pachycormus, only specimens from the Normandy area show evidence for cannibalism, suggesting that the more conventional prey resources were either scarce or restricted at the site, prompting Pachycormus juveniles to indiscriminately predate on one another. [ABSTRACT FROM AUTHOR]

Isolated fossil bones from freshwater Upper Cretaceous (Maastrichtian) deposits in the Mahajanga Basin of northwestern Madagascar are identified as belonging to a gonorynchiform fish. Multiple elements representing the same bone, including opercles, hyomandibulae, frontals, and basioccipitals, indicate that only a single gonorynchiform species is present. The most diagnostic element is here named as a new genus and species, †Vango fahiny; the other elements likely belong to the same taxon. The Madagascan gonorynchiform material shares features with members of the subfamily Chaninae and is assigned to that group. It is similar to the extant milkfish Chanos chanos but can be easily distinguished from that species by numerous features, such as the basioccipital and maxilla being relatively shorter than those of C. chanos, and the opercle being overall rounder and having a shorter auricular process. The presence of a chanid in Madagascar in the Maastrichtian most likely represents an invasion of a marine lineage into fresh waters. The previously known Cretaceous fossils of gonorynchiforms are spread throughout the Tethys Sea in mid-latitude to northern regions from the east (e.g., Lebanon, Europe) through to the southwest (e.g., Mexico, Brazil). †Vango faniny gen. et sp. nov. represents the first Mesozoic/Paleogene record of gonorynchiforms in East Gondwana, comprising primarily Antarctica, Australia, Madagascar, and the Indian subcontinent. [ABSTRACT FROM AUTHOR]

A new species of Eusthenodon from the Upper Devonian (Famennian) Catskill Formation was collected from associated talus blocks excavated during road construction along the northbound lanes of U.S. Route 15/Interstate 99 near Trout Run in Lycoming County, Pennsylvania, U.S.A. The new species is represented by isolated or partially articulated cranial bones, an anocleithrum, and body scales from several individuals. The new discovery is the second species of Eusthenodon described from the Catskill Formation after Eusthenodon bourdoni, a species found only at the Cogan House Exit Ramp locality, north of and up section from the Trout Run site. The new species is of a larger size category and exhibits qualities that distinguish it from E. bourdoni including a contact between posterior supraorbital and lacrimal bones that excludes the jugal from the orbital margin and scales with an ornamental field incised by radiating grooves. The clarity offered by the Catskill Formation Eusthenodon species informs an historical review of reports on Eusthenodon occurrence that suggests a polydemic but not cosmopolitan distribution of the taxon. A phylogenetic analysis of Tristichopteridae is presented that includes the new species presented here. The Eusthenodon species at Trout Run is the fifth tristichopterid species described from the Catskill Formation and all five are found to belong to a highly nested clade of largely Famennian tristichopterids. With a growing fauna that additionally includes rhizodontids, dipnoans, holoptychiid porolepiforms, megalichthyids, and limbed tetrapodomorphs, the Catskill Formation of Pennsylvania continues to be an important focus for the study of Late Devonian sarcopterygian evolution. [ABSTRACT FROM AUTHOR]

A new genus and species of stromateiform fish, Butyrumichthys henricii gen. et sp. nov., from the Eocene Fur Formation of Denmark is described. The description is based on six well-preserved, almost complete articulated skeletons plus a well-preserved head. All the specimens originate from the carbonate concretion horizons of the Fur Formation. The fossils were investigated also through element-mapping of strontium and phosphorus using a micro-XRF spectrometer in order to expose and enhance the skeletal anatomy. Butyrumichthys gen. nov. exhibits a unique combination of characters that support its recognition as a new stromateoiform genus, including jaws with uniserially arranged, small conical teeth, preopercle with at least 15 prominent spines, 37–38 (17–18 + 20) vertebrae, dorsal fin with 5–6 weak spines and 27–28 soft rays, and anal fin with two spines and 19–20 soft rays. The new fossil stromateoid described herein shows several morphological similarities to certain species of the genus SchedophilusCocco, 1839, especially S. pemarco (Poll, 1959) and S. medusophagus (Cocco, 1839), and is tentatively referred to the family Centrolophidae. The exceptionally preserved fossil fishes of the Fur Formation increase our knowledge of the diversity of Paleogene marine teleosts, also providing some of the earliest occurrences of modern lineages based on articulated skeletal remains, including that of the stromateiforms. [ABSTRACT FROM AUTHOR]

The global body-fossil record of marine 'fishes' from the time interval immediately preceding the Cretaceous–Paleogene Extinction is markedly poor. This deficiency appears to be further exacerbated with regards to offshore and deep-water taxa, obscuring our understanding of the state and composition of corresponding vertebrate faunas at the onset of this major extinction event. Recent fieldwork in the mid–late Maastrichtian exposures of the Pindos Unit in Gavdos Island, Greece, yielded a small but informative sample of fossil 'fishes', which inhabited the Tethys approximately three to four million years before the extinction. In this work we describe this sample, which comprises between eight and nine discrete morphotypes of various size classes, belonging to †Ichthyodectoidei, Aulopiformes (†Dercetidae, †Enchodontidae, †Ichthyotringidae), cf. †Sardinioididae, as well as the hexanchid shark †Gladioserratus sp. The new material expands the faunal list for the Maastrichtian of Gavdos Island, and the Pindos Unit as a whole, and further allows for the description of a new genus and species of †Enchodontidae and a new species of †Ichthyotringidae. The two new taxa are found to be widespread in the Maastrichtian of the Pindos Unit. The overall character of the assemblage agrees with previous interpretations of an offshore and rather deep depositional environment for the fossiliferous horizons. Furthermore, it exhibits a higher diversity than, and little taxonomic overlap with penecontemporaneous teleost assemblages from the Tethys, and informs on the otherwise poorly known Maastrichtian offshore and deep-water marine ichthyofaunas of the region. [ABSTRACT FROM AUTHOR]

A new enchodontoid, †Spinascutichthys pankowskiae gen. et sp. nov. is described from the marine Cenomanian deposits of the En Nammoura locality, Lebanon. The enchodontoid is small, but fully ossified, and armoured with rows of scutes bearing strong spines along the back, flanks, and ventral surface of the tail. The long, slender body and elongate jaws are similar to those of dercetids, but the predorsal scutes and ventral prongs on the dentary indicate relationship with enchodontids. Although more, or better, characters are needed to resolve the phylogeny and monophyly of the †Enchodontoidei, the family †Enchodontidae is found to be monophyletic, but a monophyletic †Dercetidae is not recovered. The new taxon is resolved in a phylogenetic analysis as the sister group to †Nardorex. This small, armoured fish supports the interpretation of En Nammoura as having a shallower water environment than that represented at the two similarly aged Lebanese deposits of Hakel and Hadjula. [ABSTRACT FROM AUTHOR]

A large mawsoniid coelacanth from the lower part of the marine Kimmeridge Clay Formation of England (Kimmeridgian, Upper Jurassic) is studied here. The material is constituted by a group of bones from the head and shoulder girdle of a considerably large individual (estimated length ca. 1.5 m), including the left angular, left dentary, left prearticular, left palatoquadrate complex, both ceratohyals and right cleithrum. Characters such as the coarse external ornamentation of the angular, and the robustness of the quadrate and the cleithrum allow classification of the individual as a member of the Mawsoniidae; whereas the configuration of external bones of the lower jaw (ornamentation of the angular constituted mainly by longitudinal ridges, the presence of a lateral swelling in the dentary) indicates stronger Gondwanan affinities than previously expected (i.e., with the genus Mawsonia, up to now only recorded in South America by the end of the Jurassic). Considering the above, two alternative evolutionary, paleobiogeographic, and taxonomic scenarios are discussed: (1) the new individual can be referred to the European mawsoniid genus Trachymetopon (Lower–Middle Jurassic), in which case it should be assumed this genus reached the Upper Jurassic, and with a morphological variability higher than previously suspected (including some characters previously assumed as diagnostic for Mawsonia). Or (2) an unknown Mawsonia-like form was present in the Upper Jurassic of Europe. The last scenario puts the identification of isolated elements of European Jurassic giant mawsoniids in a new complex taxonomic and paleobiogeographic context, which will deserve further research. [ABSTRACT FROM AUTHOR]

A new fossil lanternfish of the extant genus Stenobrachius, †S. sangsunii sp. nov., is described from the Middle Miocene deposits of the Duho Formation, South Korea. This is the second fossil species of the genus after the Miocene †S. salnikovi from Karaginsky Island in the Bering Sea. The new species differs from its congeners by the presence of six photophores in ventral series, presence of only one, long supracaudal gland, lesser numbers of the caudal and total vertebrae, greater prepelvic distance, and shorter anal fin base. The presence of a representative of this boreal genus in the Duho Formation fossil assemblage hints at climatic conditions comparable with the modern era during the time of deposition of this formation. This new finding indicates a wide distribution range and substantial morphological diversity of the genus in the North-west Pacific during the Neogene. [ABSTRACT FROM AUTHOR]

Proganochelys quenstedtii represents the best-known stem turtle from the Late Triassic, with gross anatomical and internal descriptions of the shell, postcranial bones and skull based on several well-preserved specimens from Central European fossil locations. We here report on the first specimen of P. quenstedtii from the Late Triassic (Klettgau Formation) Frickberg near the town of Frick, Canton Aargau, Switzerland. Similar to other Late Triassic ‘Plateosaurus-bearing bonebeds’, Proganochelys is considered to be a rare faunal element in the Swiss locality of Frick as well. The specimen, which is largely complete but was found only partially articulated and mixed with large Plateosaurus bones, overall resembles the morphology of the classical specimens from Germany. Despite being disarticulated, most skull bones could be identified and micro-computed tomography (CT) scanning of the posterior skull region reveals new insights into the braincase and neurovascular anatomy, as well as the inner ear region. These include the presence of a fenestra perilymphatica, potentially elongated cochlear ducts, and intense vascularization of small tubercles on the posterior end of the skull roof, which we interpret as horn cores. Other aspects of the skull in the braincase region, such as the presence or absence of a supratemporal remain ambiguous due to the fusion of individual bones and thus lack of visible sutures (externally and internally). Based on the size of the shell and fusion of individual elements, the specimen is interpreted as a skeletally mature animal. [ABSTRACT FROM AUTHOR]

The Anablepidae are a family of mostly livebearing cyprinodontiform fishes with few living representatives, but an increasingly diverse fossil record. According to recent contributions, an important part of their evolution can be traced back to Miocene remains in Central and Northwestern Argentina. In this article we describe the oldest known fossil species of Jenynsia, the most diverse genus of the family, from upper Miocene lacustrine deposits in Catamarca, Argentina. The new taxon is herein described based on many specimens of both females and sexually dimorphic males and a phylogenetic hypothesis is provided. The new species was recovered as the sister group of the remaining taxa of the nominal subgenus Jenynsia in our final hypothesis. However, it was also recovered as forming a clade with the extinct †Sachajenynsia pacha, and this clade as sister group of the subgenus Jenynsia, under one of the explored analytical conditions. The evolutionary history of Jenynsia was related in the literature to marine transgressions and the species radiation was dated through evolutionary model-based methods. Our findings and interpretations challenge the mostly marine-driven diversification of Jenynsia and the new taxon is older than predicted by the published estimations. This study reinforces the hypothesis that sexual reproduction by means of internal fertilization was already well-established in the Miocene for anablepids. [ABSTRACT FROM AUTHOR]

The Smoky Hill Chalk Member of the Upper Cretaceous Niobrara Formation is a sedimentary deposit formed in the Western Interior Seaway of North America. Here, we examined a fossiliferous bonebed from an uncertain horizon within the Smoky Hill Chalk in Gove County, Kansas, U.S.A. Over 40,450 taxonomically identifiable specimens were collected, consisting of at least four chondrichthyans, 24 actinopterygians, and two tetrapods, including taxa such as Nanocorax, Squalicorax, Rhinobatos, pycnodontids, Lepisosteidae, Protosphyraena, Pachyrhizodus, ichthyodectiforms, plethodids, Albulidae, Apateodus, Cimolichthys, Enchodus, Acanthomorpha, Platecarpus, and Hesperornithiformes. The diversity of these vertebrates suggests the presence of a very complex ecosystem when the bonebed formed, which is determined to be mid- or late Santonian in age based on biostratigraphic, geographic, and geologic evidence. Based on published literature and this new study, at least 117 vertebrate taxa are now known from the Smoky Hill Chalk of Kansas, comprising 18 chondrichthyans, 63 actinopterygians, and 36 tetrapods. Comparisons of faunal data from the bonebed with databases on vertebrate fossils from the Niobrara Formation of Kansas in seven major museum collections indicate that the Niobrara fossil record based on museum collections is biased towards large reptilian remains compared with fish fossils. In particular, this study indicates that Enchodus spp. were especially common when the bonebed formed. A major corollary from this study is that a more accurate reconstruction of the paleoecology of the Western Interior Seaway requires the need for more analyses on smaller vertebrate taxa. [ABSTRACT FROM AUTHOR]

The porolepiform Holoptychius Agassiz, 1839 from the Upper Devonian is one of the most widely found vertebrates in the Palaeozoic fossil record. Holoptychius is considered to display a more ubiquitous mode of life and a greater potential of dispersion than any other sarcopterygian taxon, consistent with its cosmopolitan distribution and profuse fossil record, mainly represented by scales. Previous studies on the squamation of Holoptychius have discussed the variable ornamentation of the superficial layer; however, the basal plate has been less explored. Here we furnish new histological data on the scales of Holoptychius, focusing on the mineralisation rate and organisation of the lamellar bone. Ground sections show that the basal plate is made of a stacking of thick collagenous layers with a plywood-like structure. Collagenous fibres are parallel within layers, with two successive layers orthogonally arranged and with every second layer rotated by an angle of 36º. This condition, known as a double-twisted plywood-like organisation, is similar to that of other sarcopterygians like Eusthenopteron and extant coelacanths and dipnoans. The new palaeohistological data provide insights into the morphofunctional, palaeoecological and phylogenetical implications of the microstructural characteristics of the scales, adding to our knowledge of the histological diversity of osteichthyans. [ABSTRACT FROM AUTHOR]

We here describe a fossil catfish from freshwater deposits of the Jbel Qatrani Formation of the Fayum Depression, Egypt, as a new species of an extant genus, †Clarotes eocenicus, sp. nov., in the family Claroteidae. We base this placement on several cranial osteological features, including robust, laterally oriented anterior cornua of the mesethmoid, cranial fontanelle formed in mesethmoid and frontals but not extending into the parieto-supraoccipital, dermal ornamentation of small bumps concentrated on the posterior part of the skull, and supraoccipital crest short and broadly triangular. The material comes from the upper Eocene L-41 locality, which represents deposition in an oxbow lake environment. The new taxon, along with a previously described catfish from Tanzania, indicate that claroteid catfishes were established in both North and East Africa in the Eocene, and, unlike North America, Europe and Asia in which modern genera of catfishes were not present in the Eocene, at least two extant catfish genera had already evolved in the fresh waters of Africa by 45–35 million years ago. [ABSTRACT FROM AUTHOR]

The diversity of fishes represented in upper Paleocene microfossil localities in the Ravenscrag Formation near Roche Percée, Saskatchewan, is documented. Thirteen kinds of fishes are recognized. Two chondrosteans are present, a sturgeon and a paddlefish, both represented by small, irregularly shaped, ornamented bony plates. Four kinds of basal neopterygians are identified. Two of these, Atractosteus and Cyclurus, are widely distributed in both Paleocene and Upper Cretaceous localities. The remaining two are unnamed taxa designated Holostean A and Holostean B that were known previously from Upper Cretaceous localities but have not been reported from the Paleocene prior to this report. The presence of these taxa in the late Paleocene further supports the conclusion that basal neopterygians were little affected by the K/Pg mass extinction event. Seven teleosts are present in the assemblage. This assemblage of teleosts is similar to assemblages of upper Paleocene fishes from the Paskapoo Formation of Alberta in the presence of osteoglossomorphs, a gonorhynchiform, the esocid Esox, a percopsiform, and at least one other acanthomorph. It differs in the presence of a generically indeterminate protacanthopterygian designated here as morphotype ES-1 and a teleost of uncertain relationships designated morphotype PT-1. Neither of these taxa is present in the Late Cretaceous, suggesting that they first appeared in the area during the early or middle Paleocene. Comparison of the fish assemblages of the late Paleocene and early Eocene suggests that a major faunal transition occurred at the Paleocene/Eocene boundary, and that this involved a decrease in diversity of basal neopterygians. [ABSTRACT FROM AUTHOR]

The historical clade "Protorosauria" represents an important group of archosauromorph reptiles that had a wide geographic distribution between the Late Permian and Late Triassic. "Protorosaurs" are characterized by their long necks, which are epitomized in the genus Tanystropheus and in Dinocephalosaurus orientalis. Recent phylogenetic analyses have indicated that "Protorosauria" is a polyphyletic clade, but the exact relationships of the various "protorosaur" taxa within the archosauromorph lineage is currently uncertain. Several taxa, although represented by relatively complete material, have previously not been assessed phylogenetically. We present a new phylogenetic hypothesis that comprises a wide range of archosauromorphs, including the most exhaustive sample of "protorosaurs" to date and several "protorosaur" taxa from the eastern Tethys margin that have not been included in any previous analysis. The polyphyly of "Protorosauria" is confirmed and therefore we suggest the usage of this term should be abandoned. Tanystropheidae is recovered as a monophyletic group and the Chinese taxa Dinocephalosaurus orientalis and Pectodens zhenyuensis form a new archosauromorph clade, Dinocephalosauridae, which is closely related to Tanystropheidae. The well-known crocopod and former "protorosaur" Prolacerta broomi is considerably less closely related to Archosauriformes than was previously considered. [ABSTRACT FROM AUTHOR]

Coelacanths are represented today by a single genus, Latimeria. They are known to be 'living fossils', because their evolutionary history dates back into the Devonian. Through the Upper Triassic, coelacanths are represented by two families, the Latimeriidae and Mawsoniidae. While latimeriids represent their marine lineage, mawsoniids were, until recently (Deesri et al., 2018), thought to be exclusively freshwater inhabitants. Through the Late Triassic, mawsoniids originated in freshwater environments of America, and only little is known about their evolution in Europe during this time period. Here we report on two morphotypes of mawsoniid basisphenoids from the marine Rhaetian (Upper Triassic) Bonenburg locality (Kreis Höxter, North Rhine-Westphalia, Germany) showing that (1) Late Triassic coelacanths from Germany can be assigned to the family level, specifically to Mawsoniidae, (2) mawsoniid coelacanths were already present in Europe in the Late Triassic, and (3) these inhabited marine environments at the end of the Triassic, supporting the affinities of habitat preference of previous finds from France (Deesri et al., 2018). The results strengthen the hypothesis an intermediate marine phase between the origin of Mawsoniidae in freshwater environments of nowadays North America during the Late Triassic and their final occurrence in continental deposits of Western Gondwana (Africa and South America) and nowadays Europe in the Late Cretaceous (Cavin et al., 2019). [ABSTRACT FROM AUTHOR]

The Early Carboniferous stem tetrapod Whatcheeria deltae is among the earliest-branching limbed tetrapods represented by multiple near-complete specimens, making it an important taxon in understanding the vertebrate water-to-land transition. However, all preserved skulls of Whatcheeria suffer from post-mortem crushing and lateral compression, which has made cranial reconstruction problematic. In this study, computed tomography data of three Whatcheeria specimens were segmented using visualization software to digitally separate each individual skull bone from matrix. Digital methods were used to repair and retrodeform the bones and produce the first complete three-dimensional skull reconstruction of Whatcheeria. We provide a revised description of the cranial and lower jaw anatomy of Whatcheeria based on CT data, focusing on sutural morphology and previously unknown anatomical details. Our findings suggest that Whatcheeria had one of the narrowest skulls of any known early tetrapod, a gap between the nasals, and significant overlap of the lacrimal onto the nasal and prefrontal. Sutural morphology is used to infer loading regime in the skull during feeding and suggests the skull of Whatcheeria was well adapted to resist stresses induced by biting large prey with its enlarged anterior fangs. [ABSTRACT FROM AUTHOR]

The African Cichlidae Oreochromis (Alcolapia) and Oreochromis amphimelas can survive in extremely alkaline environments and represent the only known modern alkaliphilic cichlid fish found in Africa. The presence of fossil cichlids from the Miocene of central Kenya (Tugen Hills) that are morphologically similar to Oreochromis (Alcolapia) has been noted in previous works, but the conclusions remained tentative. The purpose of this study is to examine newly discovered fossil cichlids from the Tugen Hills and to compare their osteology with that of extant Oreochromis (Alcolapia). This is performed based on a comprehensive collection of comparative material, using microscopy and computed microtomography (μCT). We provide a revised diagnosis for the genus †Rebekkachromis, and revise its systematic relationships by assigning it to the Oreochromini (rather than to the Etiini). Two new species of †Rebekkachromis are described, i.e., †R. valyricus, sp. nov., and †R. vancouveringae, sp. nov., and a morphologically diverse assemblage of co-occurring †Rebekkachromis specimens is documented. Moreover, we found that †Rebekkachromis had three sensory canal pores (instead of four) on the lower arm of the preopercle, a feature that distinguishes both the modern Oreochromis (Alcolapia) and our fossil specimens from almost all other modern African cichlid fish. Our new data indicate that alkaliphile cichlids similar to Oreochromis (Alcolapia) were present in Central Kenya about 10–13 Ma ago and that the ability of African cichlid fishes to thrive in highly alkaline waters had already developed by that time. [ABSTRACT FROM AUTHOR]

The lungfishes, or Dipnoi, form a depauperate clade of sarcopterygian fishes living today in the freshwater systems of eastern Australia, Africa, and South America. It is reminiscent of the equivalent bone in I F. martini i , except that in the latter species the anterior portion of the ossification corresponds to the widest part of the bone, whereas in I F. annekempae i sp. nov. the anterior portion is significantly narrower than the posterior portion. In this model of I F. jurassicus i , the bone shows no anteroventral extension and it is unclear how the mandible articulates with the skull (in I Neoceratodus i , the quadrate is cartilaginous and occurs as an outgrowth from the process of the posterior bone of the lateral series, and the situation was likely similar in most extinct post-Devonian lungfishes; Kemp, [9]). Abbreviations: a.m.b, anterior bone of the medial series; a.ml.b, anterior bone of the mediolateral series; p.l.b, posterior bone of the lateral series; p.m.b, posterior bone of the medial series; p.ml.b, posterior bone of the mediolateral series; x, X bone. [Extracted from the article]