A systematic revision of the genus Prognathodon (Squamata: Mosasauridae)

• Author / Creator

  Mohr, Sydney R

• Mosasaurs are an extinct group of large aquatic lizards that swam the world’s oceans during the late Cretaceous, approximately 94 to 66 million years ago. The genus Prognathodon is a diverse subgroup of medium to large-sized mosasaurs with a unique set of features that have made it difficult for researchers to classify amongst other major mosasaurs groups. Furthermore, multiple analyses attempting to classify Prognathodon typically find highly inconsistent patterns of relationship and often part of a poorly resolved clade comprising of other mosasaur genera. A critical examination of the historical conceptualization of Prognathodon finds a series of recurring issues in the diagnoses and descriptions of both the type species and referred taxa, underpinning the need for a broad systematic reassessment of the group. A detailed re-evaluation of type species, Prognathodon solvayi, recognizes several newly identified osteological characters and provided a precise diagnosis that established a well-defined and informative concept of the taxon. A comparison between the emended diagnosis and the morphological characteristics of six referred species forms hypotheses as to their validity as members within Prognathodon. A single species, Prognathodon giganteus, bears strong enough resemblance to warrant synonymizing it with the type species. All other taxa deviate from the generic diagnosis to a great enough degree that supported their exclusion from the group. A phylogenetic analysis further tests these assumptions by incorporating a set of updated and new data based on the morphological assessment of Prognathodon. The resulting trees both recover Prognathodon solvayi as the sole member of the genus Prognathodon and support the referral of Prognathodon giganteus to the type species. Informed by morphological comparisons, the remaining referred taxa that fell outside Prognathodon were assigned to different genera. Although precisely how Prognathodon fits into the larger context of other major mosasaur groups remains unclear, the integration between a comprehensive morphological review and phylogenetic analysis nevertheless provided a coherent model of the genus and improved understanding of the internal systematic relationships of the group as a whole.

• Subjects / Keywords

  • Prognathodon
  • Mosasauridae
  • Squamata
  • Mosasaurs
  • Mosasaurinae

• Graduation date

  Fall 2024

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-z4nd-8d82

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.