Gabbert, Sherri L.2005-10-062005-10-061998http://hdl.handle.net/2246/324413 p. : ill. ; 26 cm.Includes bibliographical references (p. 11-13)."Cranial anatomy of early Tertiary Herpetotherium is described, with an emphasis on the auditory region. The preserved anatomy presents a suite of characters indicating a conservative morphological trend in the ear region. The tympanic cavity floor has a large alisphenoid contribution that resembles the condition seen in Caluromys. No other bony structures from the petrosal or surrounding bones contribute to closure of the tympanic floor, and it is not known how much was contributed by the ectotympanic. The exit for mandibular nerve (V3) through a rostral incisure of the piriform fenestra is most similar to the condition observed in Marmosa and Monodelphis. In general, the anatomy of the ear region observed in Herpetotherium resembles that observed in extant didelphids; however, changes in spatial morphology appear to distinguish taxonomic groups"--P. [1].2357509 bytesapplication/pdfen-USQL1 .A436 no.3235, 1998Herpetotherium.Skull.Opossums, Fossil.Middle ear -- Evolution.Mammals, Fossil -- Wyoming.Paleontology -- Eocene -- Wyoming.Paleontology -- Wyoming.text