18 Apr (GEOL) Thesis Defense: Hoppe, Ceteotherid

David Hoppe, Earth System Science MS Thesis Defense

A large Cetotherid (Cetacea, Mysticeti) from the Late Miocene of Calvert Cliffs, Maryland, USA

Fri, 18 Apr, 10:30am, Exploratory Hall 1309

Advisor: Mark Uhen

Cetotheriidae is a family of baleen whales (Cetacea, Mysticeti) that was prolific in the Miocene Epoch. Previously considered a “wastebasket taxon” consisting of many unrelated species, the family has undergone a massive phylogenetic revision in recent years. Most cetotheriids were relatively small, especially compared to the enormous mysticetes of today, though some species evidently attained larger sizes in the Late Miocene. This thesis describes a new genus and species of large cetotheriid, Invictocetus nancei, from the Late Miocene (Tortonian) St. Marys Formation of Calvert Cliffs, Maryland, USA. The holotype skeleton (CMM-V-3988) is nearly complete and exhibits several conspicuous postcranial pathologies, including healed compression fractures in the ribs which suggest the whale was impacted by a large predator but survived. Fossil shark teeth found in association with the skeleton indicate the whale’s carcass was extensively scavenged. A phylogenetic analysis recovered I. nancei within Cetotheriidae sensu stricto, as closely related to European species such as Herentalia nigra. Using published equations and direct measurements of the holotype, the total body length of I. nancei was estimated to be approximately 7.82 meters, with upper estimates reaching 8.32 meters, making it one of the largest known species in Cetotheriidae. I. nancei represents the largest and most complete fossil mysticete specimen ever discovered from the Calvert Cliffs and the first new mysticete taxon to be described from the locality in over half a century. The discovery of an additional “large-bodied” cetotheriid in the Late Miocene adds to our understanding of the taxonomic and ecological scope of the family and provides additional insight into trophic interactions during this time of peak mysticete diversity. This thesis serves as an initial description of the new taxon, but further research is needed to fully understand the paleopathology of this extraordinary fossil whale.