Newly discovered / described fossil species 2022

Harenaichthys lui • A New Species of Osteoglossomorpha (Actinopterygii: Teleostei) from the Upper Cretaceous Nemegt Formation of Mongolia

Species New to Science: [PaleoIchthyology • 2022] Harenaichthys lui • A New Species of Osteoglossomorpha (Actinopterygii: Teleostei) from the Upper Cretaceous Nemegt Formation of Mongolia: Paleobiological and Paleobiogeographic Implications

A new species of Osteoglossomorpha (Actinopterygii: Teleostei) from the Upper Cretaceous Nemegt Formation of Mongolia: paleobiological and paleobiogeographic implications - ScienceDirect

 

Miophyseter chitaensis • A New Physeteroid (Cetacea, Physeteroidea) from the Lower Miocene of Japan

Abstract

We describe a new specimen of physeteroid from the lower Miocene (Burdigalian) of Japan. This specimen was recovered from the Toyohama Formation, Chita County, Aichi Prefecture, Japan in 1984 and includes a finely preserved cranium with detached teeth and ear bones (periotic, tympanic bulla, and malleus). Here we refer this specimen to a new genus and species of the Physeteroidea, Miophyseter chitaensis gen. et sp. nov. Our phylogenetic analysis suggests that Miophyseter is a physeteroid more closely related to the crown Physeteroidea (Physeteridae and Kogiidae) than the macroraptorial physeteroids that flourished in middle and late Miocene times. A deep and large excavation on the ventral surface of the palatine and pterygoid in Miophyster suggests an adaptation for deep dives and/or the development of robust pterygoid muscles for active biting.

Species New to Science: [PaleoMammalogy • 2022] Miophyseter chitaensis • A New Physeteroid (Cetacea, Physeteroidea) from the Lower Miocene of Japan

 

Yelaphomte praderioi & Pachagnathus benitoi • The Dawn of the Flying Reptiles: First Triassic Record in the Southern Hemisphere

Abstract

Pterosaurs were the first vertebrates to evolve powered flight. The timing of their origin is still debated, and hypotheses range from the end of the Permian Period, to the lower Mesozoic Era, and through to the Middle–Late Triassic epochs. Regardless of when they originated, the oldest records are restricted to the Upper Triassic Norian Stage in the northern hemisphere (Europe, USA and Greenland). We report two new raeticodactylid pterosaurs, Yelaphomte praderioi gen. et sp. nov. and Pachagnathus benitoi gen. et sp. nov. from the upper Norian to Rhaetian Quebrada del Barro Formation in north-western Argentina. The new specimens (an isolated dentary symphysis, partial rostrum, and distal half of ulna) are the first unequivocal Triassic records of pterosaurs in the southern hemisphere, confirming that the absence of pterosaurs outside north-western Pangaea during the Late Triassic was the result of poor sampling rather than true absence. These new discoveries provide evidence of a greater diversity of pterosaurs living in terrestrial habitats and a wider global distribution of pterosaurs from the beginning of their evolution on Earth.

Species New to Science: [Paleontology • 2022] Yelaphomte praderioi & Pachagnathus benitoi • The Dawn of the Flying Reptiles: First Triassic Record in the Southern Hemisphere

 

Hutchemys walkerorum • A Softshell Turtle (Testudines: Trionychidae: Plastomeninae) from the uppermost Cretaceous (Maastrichtian) Hell Creek Formation, North Dakota, USA, with Implications for the Evolutionary Relationships of Plastomenines and Other Trionychids

Abstract

Plastomeninae, a clade of fossil turtles that has recently undergone significant revision, are currently known from the Late Cretaceous to the Eocene, with some genera known to survive the end-Cretaceous mass extinction (e.g., Hutchemys). Only one taxon survives past the Paleocene into the Eocene (Plastomenus thomasii). Despite the majority of Hutchemys being known from the Paleocene, only a single species is known from the Cretaceous. Here we describe Hutchemys walkerorum sp. nov. from the Upper Cretaceous of North Dakota. This new species can be assigned to Hutchemys by fading surface sculpturing of the carapace and distally split costals and distinguished from other Hutchemys species by several features, including aspects of the nuchal, costals, and placement of a carapacial constriction. The new species represents the second species of Hutchemys known from the Cretaceous, and potentially provides a direct anagenetic evolutionary lineage to H. tetanetron. It represents a third plastomenine evolutionary lineage present in the Hell Creek fauna of North Dakota, with Gilmoremeys lancensis and Helopanoplia distincta. A phylogenetic analysis recovers H. walkerorum among other Hutchemys species in a monophyletic group of derived plastomenines (Plastomenini clade nov.) and recovers a basal clade of trionychids (Kuhnemydinae subfam. nov.), along with Chitrainae subfam. nov., Cyclanorbinae, and Trionychinae. Trionychids likely originated in Asia during the middle-late Early Cretaceous, while plastomenines, an exclusively North American clade, evolved in, or prior to, the Campanian. Plastomenines were at their peak diversity in the Maastrichtian through the Paleocene, with complete extinction of the clade occurring by the Lutetian (Eocene).

Species New to Science: [Paleontology • 2022] Hutchemys walkerorum • A Softshell Turtle (Testudines: Trionychidae: Plastomeninae) from the uppermost Cretaceous (Maastrichtian) Hell Creek Formation, North Dakota, USA, with Implications for the Evolutionary Relationships of Plastomenines and Other Trionychids

 

Rododelphis stamatiadisi • The Origins of the Killer Whale Ecomorph: A New False Killer Whale (Odontoceti: Delphinidae) from the Pleistocene of Rhodes (Greece)

Highlights:
• New fossil false killer whale, Rododelphis stamatiadisi, found on island of Rhodes
• Discovered with fish remains as its last meal and unlikely that it fed on other dolphins
• Killer whales are the sole survivors of a clade that flourished 4 million years ago
• Tooth wear in fossil killer whales suggest preying on dolphins evolved recently

Summary

The killer whale (Orcinus orca) and false killer whale (Pseudorca crassidens) are the only extant cetaceans that hunt other marine mammals, with pods of the former routinely preying on baleen whales >10 m in length and the latter being known to take other delphinids. Fossil evidence for the origins of this feeding behavior is wanting, although molecular phylogenies indicate that it evolved independently in the two lineages. We describe a new extinct representative of the killer whale ecomorph, Rododelphis stamatiadisi, based on a partial skeleton from the Pleistocene of Rhodes (Greece). Five otoliths of the bathypelagic blue whiting Micromesistius poutassou are associated with the holotype, providing unexpected evidence of its last meal. The evolutionary relationships of R. stamatiadisi and the convergent evolution of killer whale-like features were explored through a broad-ranging phylogenetic analysis that recovered R. stamatiadisi as the closest relative of P. crassidens and O. orca as the only living representative of a once diverse clade. Within the clade of Orca and kin, key features implicated in extant killer whale feeding, such as body size, tooth size, and tooth count, evolved in a stepwise manner. The tooth wear in Rododelphis and an extinct species of Orcinus (O. citoniensis) are consistent with a fish-based diet, supporting an exaptative Pleistocene origin for marine mammal hunting in both lineages. If correct, predation by the ancestors of Pseudorca and Orca did not play a significant role in the evolution of baleen whale gigantism.

Species New to Science: [PaleoMammalogy • 2022] Rododelphis stamatiadisi • The Origins of the Killer Whale Ecomorph: A New False Killer Whale (Odontoceti: Delphinidae) from the Pleistocene of Rhodes (Greece)

 

Miotadorna catrionae • A New Species of Large Duck (Aves: Anatidae) from the Miocene of New Zealand

Abstract

We describe a new species of extinct duck, Miotadorna catrionae sp. nov. (Anatidae, Tadornini, Tadorninae), based on a right humerus from the Miocene lacustrine deposits of St Bathans, Otago, New Zealand. Principal component analysis reveals that the new taxon is distinguished by its large size and relative proportions. This is the eighth and largest species of duck described from the St Bathans fossil assemblage and further underscores the global importance of this site for understanding anatid evolution.

Species New to Science: [PaleoOrnithology • 2022] Miotadorna catrionae • A New Species of Large Duck (Aves: Anatidae) from the Miocene of New Zealand

 

Rare fossil of ancient dog species discovered by San Diego paleontologists

San Diego Natural History Museum scientists say they roamed the San Diego region up to 28 million years ago

Sometime around 14,000 years ago, the first humans crossed the Bering Strait to North America with canines, domesticated dogs they used for hunting, by their side.

But long before the canines arrived here, there were predatory doglike canid species who hunted the grasslands and forests of the Americas. A rare and nearly complete fossilized skeleton of one of these long-extinct species was recently discovered by paleontologists at the San Diego Natural History Museum.

This fossil belongs to a group of animals called Archeocyons, which means “ancient dog.” It was embedded in two large chunks of sandstone and mudstone unearthed in 2019 from a construction project in the Otay Ranch area of San Diego County. The fossil dates to the late Oligocene epoch and is believed to be 24 million to 28 million years old.

https://www-sandiegouniontribune-co...-rare-fossil-of-ancient-dog-species?_amp=true

 

Description of a crown-group cnidarian from the Ediacaran of Charnwood Forest, UK, Auroralumina attenboroughii (genus et species nova).

The fossil represents the earlier known animal predator.

A crown-group cnidarian from the Ediacaran of Charnwood Forest, UK | Nature Ecology & Evolution

Ancient fossil is earliest known animal predator
Fossil of ‘earliest animal predator’ is named after David Attenborough

 

A new istiodactylid pterosaur, Lingyuanopterus camposi gen. et sp. nov., from the Jiufotang Formation of western Liaoning, China

The Istiodactylidae is a group of pterodactyloids characterised by large nasoantorbital fenestrae and labiolingually compressed teeth, with several records reported from the Early Cretaceous of northeastern China and western Europe. Here we report a new istiodactylid, Lingyuanopterus camposi gen. et sp. nov. from the Jiufotang Formation of Lingyuan, Liaoning, northeastern China. The holotype is represented by a near-complete skull, mandible and atlas-axis complex. It is distinguished from other istiodactylids by several characters, including two autapomorphies: short triangular tooth crowns with sharp mesial and distal carinae limited to the distal teeth, mandibular symphysis occupying approximately a quarter the mandible length. We also report the presence of helical jaw joints in istiodactylids, and provide a revised diagnosis of the clade Istiodactylidae, which includes five genera: Istiodactylus, Liaoxipterus, Nurhachius, Luchibang and Lingyuanopterus. Four pellets containing fish fragments were observed and are tentatively interpreted as bromalites of Lingyuanopterus. Although members of this clade possess similar skull morphologies, istiodactylids vary in terms of their dentition, with at least three forms from the Jiufotang Formation alone. This may represent different feeding strategies, and also indicate a similarity between the pterosaur assemblages of northeastern China and Britain during the Early Cretaceous.

A new istiodactylid pterosaur, Lingyuanopterus camposi gen. et sp. nov., from the Jiufotang Formation of western Liaoning, China

 

Agriarctos nikolovi • A late Turolian Giant Panda (Carnivora: Ursidae: Ailuropodinae) from Bulgaria and the early Evolution and dispersal of the Panda Lineage

With advances in molecular phylogeny, the Ursidae affinity of Ailuropoda is no longer controversial. However, the early evolution of Ailuropoda and its close relatives (the tribe Ailuropodini) is still unclear. In this study, we describe a new fossil discovery from Bulgaria, which represents a new taxon of Ailuropodini, ?Agriarctos nikolovi. The materials of Ailurarctos are restudied and the evolution and dispersal of Ailuropodini are discussed. Early Ailuropodini split into two lineages, one in Europe as Agriarctos (three species, whose assignment to the same genus is not certain), and one in southeastern Asia as Ailurarctos and later Ailuropoda. Ailurarctos is a paraphyletic group, with both known species as successive direct ancestors to Ailuropoda. Subtribe Ailuropodina is proposed here to include Ailurarctos and Ailuropoda. Turolian European Agriarctos paralleled with Ailuropodina in many aspects, which reflects similar adaptation towards a specific herbivorous diet.

Species New to Science: [PaleoMammalogy • 2022] ?Agriarctos nikolovi • A late Turolian Giant Panda (Carnivora: Ursidae: Ailuropodinae) from Bulgaria and the early Evolution and dispersal of the Panda Lineage

https://www.tandfonline.com/doi/full/10.1080/02724634.2021.2054718

 

Plesiosaurs from the Fluvial Kem Kem Group (mid-Cretaceous) of eastern Morocco and A Review of Non-marine Plesiosaurs

Plesiosaurs were a long-lived and widespread group of marine reptiles, with a worldwide distribution and a temporal range from the Late Triassic to the Late Cretaceous. Most occur in marine deposits, but some occur in low-salinity, brackish to freshwater environments. We report plesiosaurs from the freshwater fluvial deposits of the mid-Cretaceous (?Albian-Cenomanian) Kem Kem Group of Morocco. Remains include numerous shed teeth, vertebrae, and a humerus. The humerus represents a young juvenile; vertebrae likely belong to sub-adults. Teeth show heavy wear, similar to teeth of co-occurring spinosaurids. While coeval plesiosaurs from the Bahariya Formation of Egypt are members of Polycotylidae, the Kem Kem fossils show features of Leptocleididae, small-bodied plesiosaurs that were widely distributed in nearshore and non-marine settings in the Early Cretaceous. These fossils are the first freshwater plesiosaurs from Morocco, and are among the youngest representatives of Leptocleididae. The Kem Kem leptocleidids could have been infrequent visitors from the sea, freshwater-tolerant, or even freshwater-adapted, as in modern river dolphins. The abundance of shed teeth in the Kem Kem Group supports the hypothesis that they had some degree of freshwater tolerance. Furthermore, leptocleidids occur almost exclusively in shallow nearshore, brackish, or freshwater environments, suggesting adaptation to shallow, low-salinity environments. Other plesiosaur groups and other Mesozoic marine reptiles, including teleosaurids and mosasaurids, also occur in freshwater settings, suggesting plesiosaurs and other marine reptiles frequently exploited non-marine environments.

Species New to Science: [Paleontology • 2022] Plesiosaurs from the Fluvial Kem Kem Group (mid-Cretaceous) of eastern Morocco and A Review of Non-marine Plesiosaurs

Plesiosaurs from the fluvial Kem Kem Group (mid-Cretaceous) of eastern Morocco and a review of non-marine plesiosaurs - ScienceDirect

 

Qikiqtania wakei • A New Elpistostegalian (Sarcopterygii: Tetrapodomorpha) from the Late Devonian of the Canadian Arctic

A fundamental gap in the study of the origin of limbed vertebrates lies in understanding the morphological and functional diversity of their closest relatives. Whereas analyses of the elpistostegalians Panderichthys rhombolepis, Tiktaalik roseae and Elpistostege watsoni have revealed a sequence of changes in locomotor, feeding and respiratory structures during the transition, an isolated bone, a putative humerus, has controversially hinted at a wider range in form and function than now recognized. Here we report the discovery of a new elpistostegalian from the Late Devonian period of the Canadian Arctic that shows surprising disparity in the group. The specimen includes partial upper and lower jaws, pharyngeal elements, a pectoral fin and scalation. This new genus is phylogenetically proximate to T. roseae and E. watsoni but evinces notable differences from both taxa and, indeed, other described tetrapodomorphs. Lacking processes, joint orientations and muscle scars indicative of appendage-based support on a hard substrate, its pectoral fin shows specializations for swimming that are unlike those known from other sarcopterygians. This unexpected morphological and functional diversity represents a previously hidden ecological expansion, a secondary return to open water, near the origin of limbed vertebrates.

Species New to Science: [Paleontology • 2022] Qikiqtania wakei • A New Elpistostegalian (Sarcopterygii: Tetrapodomorpha) from the Late Devonian of the Canadian Arctic

A new elpistostegalian from the Late Devonian of the Canadian Arctic | Nature

 

More Bones of Leptoptilos robustus from Flores reveal New Insights into Giant Marabou Stork Paleobiology and Biogeography

Liang Bua (Flores, Indonesia) has yielded remains of a faunal community that included small-bodied and small-brained hominins, dwarf proboscideans, Komodo dragons, vultures and giant marabou storks (Leptoptilos robustus). Previous research suggested that L. robustus evolved from a smaller Leptoptilos dubius-like Middle Pleistocene ancestor and may have been flightless. However, analyses of this species' considerably expanded hypodigm (n = 43, MNI = 5), which includes 21 newly discovered bones described here for the first time, reveals that the wing bones of L. robustus were well-developed and this species was almost certainly capable of active flight. Moreover, L. robustus bones are broadly similar to Leptoptilos falconeri remains from sites in Africa and Eurasia, and its overall size range is comparable to fossils attributed to L. falconeri and similar specimens, as well as those of Leptoptilos lüi (China) and Leptoptilos titan (Java). This suggests that a Pleistocene dispersal of L. falconeri into Island Southeast Asia may have given rise to populations of giant marabou storks in this region. As L. robustus and L. titan are the most recent known representatives of these once plentiful giant marabou storks, Island Southeast Asia likely acted as a refugium for the last surviving members of this lineage.

Species New to Science: [PaleoOrnithology • 2022] More Bones of Leptoptilos robustus from Flores reveal New Insights into Giant Marabou Stork Paleobiology and Biogeography

https://royalsocietypublishing.org/doi/10.1098/rsos.220435

 

Marmorerpeton wakei • Middle Jurassic Fossils (Caudata: Karauridae) document An early Stage in Salamander Evolution

Little is known about stem-lineage salamanders, limiting understanding of their early evolution and of the origins of modern amphibian diversity. We report new, three-dimensionally preserved skeletons of the stem-salamander Marmorerpeton, from 166 million-year-old rocks in Scotland, documenting many phylogenetically informative anatomical traits. High resolution computed tomography (CT) scans reveal unprecedented three-dimensional anatomical detail, illuminating anatomical changes during early salamander evolution. Phylogenetic analysis provides evidence for an anatomically diverse radiation of early stem salamanders distributed across Eurasia during the Middle Jurassic and Early Cretaceous. Our findings highlight the morphological variety of stem-salamanders, undermining the use of single exemplars (e.g., Karaurus; the “Archaeopteryx” of salamanders) to represent early evolutionary transitions.

Species New to Science: [Paleontology • 2022] Marmorerpeton wakei • Middle Jurassic Fossils (Caudata: Karauridae) document An early Stage in Salamander Evolution

 

Solitudo sicula • The Last of the Large-sized Tortoises of the Mediterranean Islands

Archaeological investigations carried out in the cave Zubbio di Cozzo San Pietro, Bagheria, Sicily, revealed the presence of a few skeletal elements of a large-sized tortoise in a funerary area dating to the Copper/Bronze Age. The tortoise has been AMS-dated revealing an age of 12.5 ± 0.5 kyr BP and therefore it pre-dates the funerary activities. The morphology of the retrieved skeletal elements differs from that of the only native tortoise currently living in Sicily, Testudo hermanni. The tortoise’s size significantly exceeds the size range of extant Te. hermanni and all Testudo spp., as well as that of their known fossils, and suggests a shell length of 50–60 cm. Repeated efforts to obtain DNA sequences from the tortoise of Zubbio di Cozzo San Pietro failed, but the morphology of the femur is distinct enough to allow us to erect a new taxon, Solitudo sicula gen. et sp. nov., based on a parsimony analysis. It belongs to a hitherto unrecognized clade that includes other large-sized tortoises from Mediterranean islands, like Malta and Menorca. A review of the pertinent taxa indicates that the remains here described represent the geologically youngest large-sized tortoise of the Mediterranean area.

Species New to Science: [Paleontology • 2022] Solitudo sicula • The Last of the Large-sized Tortoises of the Mediterranean Islands

last of the large-sized tortoises of the Mediterranean islands

 

Thalassotitan atrox • A Giant Predatory Mosasaurid (Squamata: Mosasauridae) from the Upper Maastrichtian Phosphates of Morocco

Abstract

The Cretaceous-Paleogene (K-Pg) transition saw mass extinctions in terrestrial and marine ecosystems. Terrestrial vertebrate diversity patterns across the K-Pg boundary have seen extensive study, but less is known about marine vertebrates. We describe a new mosasaurid from the latest Maastrichtian phosphatic beds of Morocco, showing how mosasaurids evolved to become apex predators in the latest Cretaceous. Thalassotitan atrox n. gen. et sp., from the Oulad Abdoun Basin of Khouribga Province, Morocco is characterized by large size, a broad skull, massive jaws, and reduced cranial kinesis, suggesting it was highly adapted for carnivory. Teeth resemble those of killer whales in their robust, conical shape, and show heavy wear and damage. Phylogenetic analysis recovers Thalassotitan as a close relative of Prognathodon currii and P. saturator within the Prognathodontini. Among the associated fauna, three genera of mosasaurids, elasmosaurid plesiosaur, chelonioid turtle, and enchodontid fish show acid damage, and could be prey ingested by mosasaurids, likely Thalassotitan. Thalassotitan shows mosasaurids evolved to fill the marine apex predator niche, a niche occupied by orcas and white sharks today. Mosasaurs continued to diversify and fill new niches until their extinction at the end of the Cretaceous.

Species New to Science: [Paleontology • 2022] Thalassotitan atrox • A Giant Predatory Mosasaurid (Squamata: Mosasauridae) from the Upper Maastrichtian Phosphates of Morocco

Thalassotitan atrox, a giant predatory mosasaurid (Squamata) from the Upper Maastrichtian Phosphates of Morocco - ScienceDirect

 

Appalachemys ebersolei • A Large non-marine Turtle from the Upper Cretaceous of Alabama and A Review of North American “Macrobaenids”

Abstract

The abundant record of marine turtles from the Late Cretaceous of Appalachia contrasts with the relatively poor record of contemporaneous terrestrial and freshwater species. A new taxon from the Santonian-Campanian of Alabama, Appalachemys ebersolei gen. et sp. nov., is described here and assigned to a grade of freshwater turtles known as “macrobaenids.” Appalachemys can be differentiated from other “macrobaenids” by the presence of a nearly round carapace, deep nuchal emargination, and nine pairs of costals. With a carapace more than 80 cm in length, Appalachemys is among the largest freshwater turtles to ever inhabit North America. The absence of pre-Campanian “macrobaenids” from Laramidia indicates that the North American distribution of this grade may have been restricted to Appalachia prior to the recession of the Western Interior Seaway. Phylogenetic analysis places Appalachemys as the sister taxon to all post-Santonian “macrobaenids.” Although the phylogeny lacks statistical support, it demonstrates morphological similarities between the K/Pg boundary species Osteopygis emarginatus and Maastrichtian-Danian species referred to Judithemys. We, therefore, refer all but the Campanian type species of Judithemys to the genus Osteopygis. A review of all North American “macrobaenid” occurrences reveals that despite originating in Asia, the record of the grade (as defined here) is predominantly North American. Future studies can test whether late Paleocene records in Asia and Europe resulted from dispersal from North America.

Species New to Science: [Paleontology • 2022] Appalachemys ebersolei • A Large non-marine Turtle from the Upper Cretaceous of Alabama and A Review of North American “Macrobaenids”

https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25054

 

Kaykay lafken • A New Pachycormiformes (Actinopterygii) from the Upper Jurassic of Gondwana sheds light on the Evolutionary History of the Group

Abstract

As part of the transition from Holostei to Teleostei, †Pachycormiformes represent a key group of fishes. However, the anatomy and phylogenetic relationships of the group in the context of the neopterygians are far from being understood. In this contribution we describe a new pachycormiform, †Kaykay lafken gen. et sp. nov., from the Upper Jurassic of Argentina. We made an exhaustive review of morphological characters of holostean and teleostean fishes and explore through a cladistic analysis the phylogenetic relationships of the new species. †Kaykay gen. nov. is retrieved among †Pachycormiformes as being the sister taxon of the macrocarnivorous clade composed of †Orthocormus and †Hypsocormus. Among †Pachycormiformes the pattern of relationships mostly agrees with previous hypotheses, although our study highlights the still poor knowledge of the anatomy of this group. According to our results †Saurostomus is the sister taxon of other toothed pachycormids. †Orthocormus species are recovered as a monophyletic group. The unsolved position of †Pachycormus and †Sauropsis might be a consequence of poor preservation, revealing a lack of understanding of their anatomy. Our phylogenetic analysis also confirms the rapid radiation of holosteans and teleosteomorphs in the Early Triassic and the radiation of pholidophoriforms in the Middle Triassic. †Aspidorhynchoidei radiate in the Early Jurassic. The large ghost ranges (e.g. between †Aspidorhynchoidei and Teleosteomorpha) evidence biases in the fossil record.

Species New to Science: [PaleoIchthyology • 2022] Kaykay lafken • A New Pachycormiformes (Actinopterygii) from the Upper Jurassic of Gondwana sheds light on the Evolutionary History of the Group

https://www.tandfonline.com/doi/abs/10.1080/14772019.2022.2049382?journalCode=tjsp20

 

Nevadadromeus schmitti (gen. et sp. nov.), a New Basal Neornithischian with Affinities to the Thescelosaurinae, from the Upper Cretaceous (Cenomanian) Willow Tank Formation of Southern Nevada

Abstract

In 2008, and subsequent collecting trips, the remains of a partial basal neornithischian were recovered from the Cenomanian Willow Tank Formation of southern Nevada. Bones identified include the proximal femora, a series of vertebrae missing neural arches, several pedal phalanges, fragments of ossified tendons, and some as yet unidentified elements. Size and shape of the femora are consistent with other known basal neornithischians of both orodromine- and thescelosaurine-grade. The round femoral head exhibits a convex anterior side but a concave posterior surface. The neck beneath the head projects proximodorsally at an obtuse angle (∼100°) from the femoral shaft. The greater trochanter sits slightly posterior to and offset from the neck of the femoral head. Anterior and lateral to the greater trochanter is a pointed lesser trochanter. The three-sided lesser trochanter bows slightly posterior toward the greater trochanter. A prominent and deep notch separates the lesser from the greater trochanter and is characteristic of thescelosaurine-grade ornithischians. This deep intertrochanteric notch is absent in the femora of orodromines. A raised but taphonomically truncated base on the posterior femoral diaphysis likely represents the remnants of a pendant fourth trochanter. The vertebrae of the Nevada basal neornithischian are similar to both thescelosaurine- and orodromine-grade morphology. The laterally biconcave vertebrae are asymmetrical in having a boss on the posteroventral end of the centrum. The centra are nearly twice as long as they are tall with the oval articular surfaces, taller than they are wide. Due to the very fragmentary nature of this specimen, parsimonious phylogenetic analysis yields statistically insignificant results. Nevertheless, a few taxonomically important characters, particularly those of the femur, support the hypothesis that this is a thescelosaurine, and a new genus and species, herein referred to as

Nevadadromeus schmitti gen. et sp. nov. This would represent the earliest occurrence of thescelosaurines in the fossil record of North America as all other thescelosaurines from the continent date to the Maastrichtian. The geographic position of the Willow Tank Formation depocenter, very proximal to the Sevier highlands of the time, likely experienced some biogeographic insularity from other areas represented by contemporaneous units of western North America, e.g., Mussentuchit Member of the Cedar Mountain Formation of Utah, the Wayan Formation of Idaho, and the Blackleaf Formation of Montana.

Nevadadromeus schmitti (gen. et sp. nov.), a New Basal Neornithischian with Affinities to the Thescelosaurinae, from the Upper Cretaceous (Cenomanian) Willow Tank Formation of Southern Nevada

A dinosaur like no other: 'Dino Diggers' discover new fossils at Nevada's Valley of Fire

In the age of dinosaurs, Schmitti wasn’t the most imposing.

Standing only about knee height, Schmitti was the size of a large dog, or a turkey with feathers on display.

Reaching speeds of up to 30 mph, the dinosaur spent much of its time running toward food or running away from predators.

But roughly 100 million years later, Schmitti’s diminutive stature hasn't prevented it from being one of the coolest finds in the Nevada desert.

The fossils of Schmitti — also known as Nevadadromeus Schmitti — were found in 2008 near Las Vegas by Nevada paleontologists. After more than a decade of sorting through bone fragments, they have finally reassembled portions of his skeleton.

What they found excited them.

Paleontologists discover fossils of Nevada's very own dinosaur