Paleontology Commons^™

An Exceptionally Small New Polycotylid Plesiosaur (Reptilia: Sauropterygia) With Raptorial Eyes From The Western Interior Seaway Of North America, Robert O’Brien Clark

Theses, Dissertations and Capstones

Polycotylidae is a family of plesiosaurian marine reptiles that evolved during the Early Cretaceous and radiated into multiple genera during the Late Cretaceous, achieving a worldwide distribution. Derived polycotylids of the subclade Polycotylinae have a gracile and elongated rostrum, homodont dentition, an extended mandibular symphysis, and foreshortened temporal fenestrae. In this thesis, I describe a small and highly derived new polycotylid taxon based on three specimens from the Campanian of the Western Interior Seaway in North America. A high number of maxillary teeth, fused neural arches, propodials with well-defined facets, and heavily remodeled cortical bone indicate the specimens are adults, …

Revision Of The Genus Styxosaurus And Relationships Of The Late Cretaceous Elasmosaurids (Sauropterygia: Plesiosauria) Of The Western Interior Seaway, Elliott Armour Smith

Theses, Dissertations and Capstones

Growing evidence indicates that elasmosaurid plesiosaurs from the Late Cretaceous Western Interior Seaway are members of a single clade, the Styxosaurinae. The styxosaurines are reported to be mostly Campanian in age, and taxa within the clade obtain the longest necks, by number of cervical vertebrae, of any known vertebrate. The styxosaurines are morphologically diverse and include taxa that exhibit a secondary reduction in neck length. Given the evolutionary plasticity of postcranial characters in plesiosaurs in general, and neck length in elasmosaurs, scrutiny of cranial osteology is pertinent to advancing understanding of Western Interior Seaway elasmosaurids. This study finds that an …

Revision Of Polycotylid Plesioaur Systematics (Sauropterygia Plesiosauria) And Description Of The Axial Osteology Of A Juvenile Polycotylid, Donald Joseph Morgan Iii

Theses, Dissertations and Capstones

The polycotylids were a clade of plesiosaurs that proliferated during the Cretaceous period. Despite recent research efforts, evolutionary relationships among polycotylid species remain unresolved. In this study, a phylogenetic analysis incorporating a large taxon sampling from the Polycotylidae was used to parse out the evolutionary relationships among the taxa. The main focus was to assign two polycotylid specimens from the Wallace Ranch to a formal species. A study on the axial osteology of the juvenile Wallace Ranch polycotylid was also performed, as the development of the axial column of a polycotylid plesiosaur has been poorly understood and may have phylogenetic …

Analyzing Pterosaur Ontogeny And Sexual Dimorphism With Multivariate Allometry, Erick Charles Anderson

Theses, Dissertations and Capstones

The relationships of pterosaurs have been previously inferred from observed traits, depositional environments, and phylogenetic associations. A great deal of research has begun to analyze pterosaur ontogeny, mass estimates, wing dynamics, and sexual dimorphism in the last two decades. The latter has received the least attention because of the large data set required for statistical analyses. Analyzing pterosaurs using osteological measurements will reveal different aspects of size and shape variation in Pterosauria (in place of character states) and sexual dimorphism when present. Some of these variations, not easily recognized visually, will be observed using multivariate allometry methods including Principle Component …

Shape Evolution And Sexual Dimorphism In The Mandible Of The Dire Wolf, Canis Dirus, At Rancho La Brea, Alexandria L. Brannick

Theses, Dissertations and Capstones

The Rancho La Brea tar pits are a classic fossil lagerstätten, famous for the deposition of episodic accumulations of large numbers of fossils over short intervals in the late Pleistocene. I analyzed 157 Canis dirus (dire wolf) hemi-mandibles from Rancho La Brea through a 2D landmark-based morphometric analysis to test for size and shape changes through time. I scored 16 landmarks on each mandible gathered from four pits of different ages: 61/67 (~13-14 thousand years ago [ka]), 13 (~17-18 ka), 2051 (~26 ka), and 91 (~28 ka). Analyses indicate size does change through time, and shares a broad correlation with …

Tooth Chipping Can Reveal The Diet And Bite Forces Of Fossil Hominins, Paul J. Constantino, James Jin-Wu Lee, Herzl Chai, Bernhard Zipfel, Charles Ziscovici, Brian R. Lawn, Peter W. Lucas

Biological Sciences Faculty Research

Mammalian tooth enamel is often chipped, providing clear evidence for localized contacts with large hard food objects. Here, we apply a simple fracture equation to estimate peak bite forces directly from chip size. Many fossil hominins exhibit antemortem chips on their posterior teeth, indicating their use of high bite forces. The inference that these species must have consumed large hard foods such as seeds is supported by the occurrence of similar chips among known modern-day seed predators such as orangutans and peccaries. The existence of tooth chip signatures also provides a way of identifying the consumption of rarely eaten foods …

The Influence Of Fallback Foods On Great Ape Tooth Enamel, Paul J. Constantino, Peter W. Lucas, James J.-W. Lee, Brian R. Lawn

Biological Sciences Faculty Research

Lucas and colleagues recently proposed a model based on fracture and deformation concepts to describe how mammalian tooth enamel may be adapted to the mechanical demands of diet (Lucas et al.: Bioessays 30[2008] 374-385). Here we review the applicability of that model by examining existing data on the food mechanical properties and enamel morphology of great apes (Pan, Pongo, and Gorilla). Particular attention is paid to whether the consumption of fallback foods is likely to play a key role in influencing great ape enamel morphology. Our results suggest that this is indeed the case. We also consider the implications of …

Mechanical Properties Of Plant Underground Storage Organs And Implications For Dietary Models Of Early Hominins, Nathaniel J. Dominy, Erin R. Vogel, Justin D. Yeakel, Paul J. Constantino, Peter W. Lucas

Biological Sciences Faculty Research

The diet of early human ancestors has received renewed theoretical interest since the discovery of elevated d13C values in the enamel of Australopithecus africanus and Paranthropus robustus. As a result, the hominin diet is hypothesized to have included C4 grass or the tissues of animals which themselves consumed C4 grass. On mechanical grounds, such a diet is incompatible with the dental morphology and dental microwear of early hominins. Most inferences, particularly for Paranthropus, favor a diet of hard or mechanically resistant foods. This discrepancy has invigorated the longstanding hypothesis that hominins consumed plant underground storage organs (USOs). Plant USOs are …

The Evolution Of Zinjanthropus Boisei, Paul J. Constantino, Bernard A. Wood

Biological Sciences Faculty Research

Many people assume that OH 5, the type specimen of Paranthropus boisei, collected in 1959, was the first evidence of that taxon to be found, but OH 3, recovered in 1955, predated the discovery of OH 5 by four years. Thus, Paranthropus boisei recently celebrated the equivalent of its fiftieth birthday. This review marks that milestone by examining the way our understanding of this taxon has changed during its fifty, or so, year history.

Paranthropus Paleobiology, Paul J. Constantino, Bernard A. Wood

Biological Sciences Faculty Research

No abstract provided.

The Paleontology And Paleoenvironments Of The Kanawha Black Flint Member And Related Facies, Kanawha Formation (Middle Pennsylvanian), Northwest Boone County And Vicinity, West Virginia, Matthew B. Watson

Theses, Dissertations and Capstones

The Kanawha Black Flint member of the Kanawha Formation was deposited in a shallow marine coastal setting with low sand supply and low wave energy. The Kanawha Black Flint member and adjacent coal zones are divisible into five sedimentary facies based on lithology, body and trace fossils and sedimentary structures. Coastal swamps and lakes are represented by thinly laminated carbonaceous shales and coals containing rooted seat rocks and crevasse sandstones with root traces and vertical Calamites trunks.

The offshore facies consists of a gray laminated sideritic shale. Phosphatic and calcareous brachiopods and shallow burrowing bivalves predominate in the offshore assemblage. …