Deltasuchus motherali

While formally trained as a paleontologist, at heart I am an evolutionary ecologist concerned with how organisms function and interact with their environment, with special focus on the Mesozoic. My primary research interests lie in reconstructing the ecology of extinct vertebrates that lack modern analogs and understanding how the ancient ecosystems in which these organisms lived were structured and functioned. Such work provides insight to how life evolved and responded to changing conditions through geologic time. Such paleoecological questions require a synthetic approach. I have utilized a wide variety of methods, including taphonomy, functional morphology, and paleobiogeography. I address my research questions through a combination of field work, modeling, and experimentation. Below are some of my current research projects:

Preservation and description of the Arlington Archosaur Site (AAS).

Exposing a croc frontal.

The Arlington Archosaur Site (AAS) is an important, productive fossil locality that preserves a previously unknown fauna from North America. Located in a suburban enclave between Dallas and Forth Worth, the rocks here contain a rare record of ecosystem transition, when major groups of dinosaurs and other animals were changing significantly. The AAS preserves a nearly complete coastal ecosystem, providing an unparalleled glimpse into the life that existed here over 95 million years ago. Over 3000 specimens have been recovered including previously unknown dinosaurs, crocodiles, turtles, mammals, amphibians, fish, invertebrates, and plants. I have spent the past nine years overseeing field work to recover and preserve the remains, document the fossils and their geologic context, and describing the morphology and phylogenetic relationships of the fossils. I have helped describe this unusual fauna, including two new species of crocodyliform and the first postcranial remains and ontogenetic series of the dinosaur Protohadros, and predatory relationships between these taxa. Numerous specimens, many likely representing new taxa, remain to be described.

Functional morphology of tetrapod unguals

X-ray of an osprey ungual

Theropods demonstrate a wide diversity of body sizes, limb proportions, and claw morphologies similar to living avian raptors, which show strong correlations between claw shape and predatory behavior. This work employs both traditional and geometric morphometric methods on photographs and X-ray images from a wide range of extant avian taxa. A variety of projects have developed from this work, including studying patterns of ungual change as a proxy for a shift to herbivory in certain theropod lineages, using morphometrics to identify isolated unguals, and quantifying morphological relationships between the hard and soft tissue components of bird claws to better understand the structure and function of theropod unguals. The latter work is part of an ongoing collaboration with Dr. Lindsay Zanno (North Carolina Museum of Natural Sciences) and Dr. Brandon Hedrick (University of Oxford, UK). One of the most significant applications of this work to date is the reconstruction of the claws of the theropod dinosaur Therizinosaurus from Mongolia, an animal with some of the largest unguals ever known in tetrapod evolution, reaching up to over 1 meter in total length.