Date

2017

Major

Geology (B.S.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Dr. Katy Smith

Abstract

Mosasaurs (Reptilia: Squamata) are apex marine predators from the Late Cretaceous (Turonian to Maastrichtian) epicontinental seas of North America, Africa, Europe, and Asia. From previous studies, it has been suggested that this group trends towards increased rib compactness, lengthening and increased posterior inclination of neural spines of intermediate and terminal caudal vertebrae to support a caudal fluke, and a transition from anguilliform to carangiform locomotion, closer to thunniform in pelagic adapted species. This study examined multiple Tylosaurus specimens using centrum length/width (CL/CW) and width/height (CW/CH) ratios along with neural spine height and angle of posterior inclination to (1) describe the vertebral column of GSM-1, a previously undescribed Tylosaurus proriger and (2) asses the viability that Tylosaurus used carangiform locomotion and had a hypocercal caudal fluke. CW/CH and CL/CW showed that Tylosaurus had a neck with an increased range of motion relative to pelagic mosasaurs like Plotosaurus bennisoni, a mostly restricted dorsal region, and that pygals and caudals allow for increased ranged of motion relative to the dorsals and cervicals with the exception of those interpreted to be supporting the fluke. These trends are consistent with known fluked and/or carangiform swimmers and suggest that Tylosaurus also employed this mode of locomotion. A single juvenile specimen suggested that younger T. proriger had more restricted cervicals and dorsals with greater mobility in the tail, possibly similar to the locomotion of pelagic mosasaurs, though more research will need to be conducted.

GSM-1 (Tylosaurus proriger) vertebrae measurments.xlsx (53 kB)
One sheet of raw data from GSM-1 at the Georgia Southern Museum

All Tuscaloosa specimens - vertebrae measurments.xlsx (56 kB)
Two sheets of raw data collected from University of Alabama specimens

All Birmingham specimens - vertebrae measurments.xlsx (43 kB)
Two sheets of raw data collected from the McWane Science Center specimens

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