Paleontology Commons^™

Assessing Unstable Fossils For Long-Term Storage, Carson Cope, Alex Landwehr, Kale Link, Israel Rivera-Molina, Laura E. Wilson

SACAD: John Heinrichs Scholarly and Creative Activity Days

In 2022, Fort Hays State University’s Sternberg Museum of Natural History (FHSM) began a project to address the long-term preservation of a Late Miocene mammal collection. Many of the fossils from the collection were poorly consolidated, uncurated, and improperly stored, leaving them unstable and prone to significant degradation. To organize our stabilization efforts, we developed a new assessment workflow consisting of two evaluation tools. These tools have helped us categorize the risk factors for specimens, the priority in which they should be addressed, and how to store the fossils long-term. With these newly developed workflows, we are in a better …

The Anatomy And Phylogeny Of A New Large Plioplatecarpine Mosasaur From The Campanian Bearpaw Shale Of Montana (Usa), Richard A. Carr

Master's Theses

In 2018, a large and associated plioplatecarpine mosasaur skull, pectoral girdle, and rib cage, whose total body length may have exceeded five meters, was uncovered in the Late Campanian Bearpaw Shale of Northeast Montana (USA). Phylogenetic analysis of this specimen, MOR 10855, recovers this individual as a basal member of the genus Plioplatecarpus. This specimen, is unique in that it is estimated to be nearly twice the size of any of the other species of Plioplatecarpus found in the Western Interior Seaway during this part of the Cretaceous. While the included phylogenetic study suggests MOR 10855 represents a new …

Rapid Growth In Late Cretaceous Sea Turtles Reveals Life History Strategies Similar To Extant Leatherbacks, Laura E. Wilson

Geosciences Faculty Publications

Modern sea turtle long bone osteohistology has been surprisingly well-studied, as it is used to understand sea turtle growth and the timing of life history events, thus informing conservation decisions. Previous histologic studies reveal two distinct bone growth patterns in extant sea turtle taxa, with Dermochelys (leatherbacks) growing faster than the cheloniids (all other living sea turtles). Dermochelys also has a unique life history compared to other sea turtles (large size, elevated metabolism, broad biogeographic distribution, etc.) that is likely linked to bone growth strategies. Despite the abundance of data on modern sea turtle bone growth, extinct sea turtle osteohistology …

Timing Of Diversification, Dispersal, And Biogeography Of Parrots In The Genus Amazona (Psittaciformes: Psittacidae) Throughout The Caribbean, Visualized In Gis, Christopher Kingwill

Master's Theses

Avian fossil records from across the Caribbean (Greater and Lesser Antilles) demonstrate higher avian diversity prior to extinction events due to climate change at the end of the Pleistocene and human impact across the Caribbean throughout the Holocene. Amazon parrots (Amazona) are a diverse genus of New World parrots found throughout Central and South America, as well as the Caribbean. Their phylogeny and evolutionary history, specifically for Caribbean species, has been debated in terms of source areas in Central and South America and the timing of and number of colonization events to different islands that preceded diversification into …

Stable Isotope Analysis Of A Platecarpus Tympaniticus (Squamata, Mosasauridae) With Actinocamax Sternbergi (Mollsuca, Belemnoidea) Reveals Possible Endothermic Thermoregulation, Mitchell Lukens

Master's Theses

Mosasaurs, ancient marine reptiles, dominated the late Cretaceous oceans. However, their ecological success is a contentious topic. Were they ectothermic, like their modern relatives the varanid lizards? Or endothermic like extant marine mammals? Stable isotopes can reveal temperature and physiological variances within skeletons, but do not differentiate between body temperature and ambient environmental temperature. A rare mosasaur specimen from the Smoky Hill Chalk of a partial, articulated Platecarpus tympaniticus with stomach contents of belemnites provides a possible direct temperature contrast between predator and prey. The belemnites, related to modern coleoids, are identified as Actinocamax sternbergi. These animals possessed body …

Ecological Controls On The Campanian Distribution Of Hesperornis (Aves: Hesperornithiformes) In The Western Interior Seaway, Blake Chapman

Master's Theses

The epicontinental Western Interior Seaway (WIS) of Late Cretaceous North America provided a unique marine habitat for cephalopods, fish, marine reptiles, and the foot-propelled diving seabird Hesperornis. While several predator-prey relationships among Hesperornis or other hesperornithiforms and other WIS animals have been hypothesized based on gut contents, bite marks, and coprolites/colonites, ecological relationships have not been quantitatively tested. Paleontological species distribution modeling (SDM) studies have focused on extinct non-marine taxa and marine invertebrates, with only two marine vertebrate studies of extant taxa. Here, two SDM methods were used to test the influence of vertebrate faunas, sedimentary rock type, paleogeography, …

An Assessment Of Convergence In The Feeding Morphology Of Xiphactinus Audax And Megalops Atlanticus Using Landmark-Based Geometric Morphometrics, Edward Chase Shelburne

Master's Theses

Convergence is an evolutionary phenomenon wherein distantly related organisms independently develop features or functional adaptations to overcome similar environmental constraints. Historically, convergence among organisms has been speculated or asserted with little rigorous or quantitative investigation. More recent advancements in systematics has allowed for the detection and study of convergence in a phylogenetic context, but this does little to elucidate convergent anatomical features in extinct taxa with poorly understood evolutionary histories. The purpose of this study is to investigate one potentially convergent system—the feeding structure of Xiphactinus audax (Teleostei: Ichthyodectiformes) and Megalops atlanticus (Teleostei: Elopiformes)—using a comparative anatomical approach to assess …

Osteohistology And Skeletochronology Of An Ontogenetic Series Of Clidastes (Squamata: Mosasauridae): Growth And Metabolism In Basal Mosasaurids, Cyrus C. Green

Master's Theses

Clidastes was a large marine reptile from the Late Cretaceous Western Interior Seaway of North America. Though the remains of Clidastes have been found in the Cretaceous chalks and shales for over 150 years, little is known about their growth rates.

Osteohistology is a well-documented technique used to investigate growth in extinct animals. Previous histological studies of Clidastes have hypothesized higher growth rates in basal mosasaurids than varanids due to higher vascularity. These studies focused on adult specimens but did not look at ontogenetic changes in growth rates. Isotopic studies of Clidastes indicate high metabolic temperatures, leading to speculation these …

Revised Vertebral Count In The "Longest-Necked Vertebrate" Elasmosaurus Platyurus Cope 1868, And Clarification Of The Cervical-Dorsal Transition In Plesiosauria, Sven Sachs, Benjamin P. Kear, Michael J. Everhart

Sternberg Museum of Natural History Faculty Publications

Elasmosaurid plesiosaurians are renowned for their immensely long necks, and indeed, possessed the highest number of cervical vertebrae for any known vertebrate. Historically, the largest count has been attributed to the iconic Elasmosaurus platyurus from the Late Cretaceous of Kansas, but estimates for the total neck series in this taxon have varied between published reports. Accurately determining the number of vertebral centra vis-à-vis the maximum length of the neck in plesiosaurians has significant implications for phylogenetic character designations, as well as the inconsistent terminology applied to some osteological structures. With these issues in mind, we reassessed the holotype of E. …

Three-Dimensionally Preserved Integument Reveals Hydrodynamic Adaptations In The Extinct Marine Lizard Ectenosaurus (Reptilia, Mosasauridae), Johan Lindgren, Michael J. Everhart, Michael W. Caldwell

Sternberg Museum of Natural History Faculty Publications

The physical properties of water and the environment it presents to its inhabitants provide stringent constraints and selection pressures affecting aquatic adaptation and evolution. Mosasaurs (a group of secondarily aquatic reptiles that occupied a broad array of predatory niches in the Cretaceous marine ecosystems about 98-65 million years ago) have traditionally been considered as anguilliform locomotors capable only of generating short bursts of speed during brief ambush pursuits. Here we report on an exceptionally preserved, long-snouted mosasaur (Ectenosaurus clidastoides) from the Santonian (Upper Cretaceous) part of the Smoky Hill Chalk Member of the Niobrara Formation in western Kansas, USA, that …

Tylosaurus Kansasensis, A New Species Of Tylosaurine (Squamata, Mosasauridae) From The Niobrara Chalk Of Western Kansas, Usa, M. J. Everhart

Sternberg Museum of Natural History Faculty Publications

Tylosaurus kansasensis sp. nov. is described herein on the basis of thirteen specimens collected from the Smoky Hill Chalk (upper Coniacian) of western Kansas, USA. The new species, originally designated Tylosaurus n. sp., co-occurred with T. nepaeolicus and exhibits a number of primitive characters that place it in a basal position in the mosasaur phylogeny. Among the key differences separating this species from other tylosaurines are a shortened, more rounded pre-dental process of the premaxilla, a distinctive quadrate lacking an infrastapedial process, and a parietal foramen located adjacent to the frontal-parietal suture.