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A new high-latitude Tylosaurus (Squamata, Mosasauridae) from Canada with unique dentition

Garvey, Samuel T
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1584001060097071

Abstract Details

2020, MS, University of Cincinnati, Arts and Sciences: Biological Sciences.
Mosasaurs were large aquatic lizards, typically 5 m or more in length, that lived during the Late Cretaceous (ca. 100–66 Ma). Of the six subfamilies and more than 70 species recognized today, most were hydropedal (flipper-bearing). Mosasaurs were cosmopolitan apex predators, and their remains occur on every continent, including Antarctica. In North America, mosasaurs flourished in the Western Interior Seaway, an inland sea that covered a large swath of the continent between the Gulf of Mexico and the Arctic Ocean during much of the Late Cretaceous. The challenges of paleontological fieldwork in high latitudes in the Northern Hemisphere have biased mosasaur collections such that most mosasaur fossils are found within 0°–60°N paleolatitude, and in North America plioplatecarpine mosasaurs are the only mosasaurs yet confirmed to have existed in paleolatitudes higher than 60°N. However, this does not mean mosasaur fossils are necessarily lacking at such latitudes. Herein, I report on the northernmost occurrence of a tylosaurine mosasaur from near Grande Prairie in Alberta, Canada (ca. 86.6–79.6 Ma). Recovered from about 62°N paleolatitude, this material (TMP 2014.011.0001) is assignable to the subfamily Tylosaurinae by exhibiting a cylindrical rostrum, broadly parallel-sided premaxillo-maxillary sutures, and overall homodonty. I further refer this material to Tylosaurus based on the lack of a dorsal midsagittal ridge on the premaxilla. Unexpectedly, TMP 2014.011.0001 exhibits widely spaced, high-aspect-ratio marginal tooth crowns and low-profile maxillae, similar to the typical juvenile condition of Tylosaurus, despite its likely adult age based on an estimated body length of at least 6.5 m. The specimen also exhibits anterior maxillary tooth roots covered by downward extensions of the maxillary cortical bone, a feature previously unknown in Tylosaurinae. TMP 2014.011.0001 hints at an undiscovered, temporally more stable Tylosaurus diversity in the northern latitudes of the seaway throughout the Late Cretaceous, possibly even into the latest Cretaceous and inclusive of the Arctic Circle. Analogous dental morphologies in other non-mosasaurid taxa, as well as a standard model of tooth function based on tooth morphology, indicate TMP 2014.011.0001 may have been specially adapted for piscivory. This study suggests the possible presence of a Cretaceous boreal marine community that was distinct from those across the more southern stretches of the Western Interior Seaway, in the western and southern United States.
Bruce Jayne, Ph.D. (Committee Chair)
Takuya Konishi (Committee Member)
Eric Tepe, Ph.D. (Committee Member)
135 p.
Biology
mosasaur; Tylosaurus; Western Interior Seaway; dentition; paleobiogeography; piscivory

Recommended Citations

Citations

  • Garvey, S. T. (2020). A new high-latitude Tylosaurus (Squamata, Mosasauridae) from Canada with unique dentition [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1584001060097071

    APA Style (7th edition)

  • Garvey, Samuel. A new high-latitude Tylosaurus (Squamata, Mosasauridae) from Canada with unique dentition. 2020. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1584001060097071.

    MLA Style (8th edition)

  • Garvey, Samuel. "A new high-latitude Tylosaurus (Squamata, Mosasauridae) from Canada with unique dentition." Master's thesis, University of Cincinnati, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1584001060097071

    Chicago Manual of Style (17th edition)

ucin1584001060097071
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This open access ETD is published by University of Cincinnati and OhioLINK.