Petrosal Anatomy of the Paleocene Eutherian Mammal (Cope, 1881).

J Mamm Evol

New Mexico Museum of Natural History and Science, Albuquerque, New Mexico United States of America.

Published: August 2021

AI Article Synopsis

  • The paper examines the ear anatomy of a mysterious Paleocene mammal from New Mexico, providing a detailed, illustrated analysis using modern anatomical terms.
  • The species exhibits dental and cranial features similar to both 'condylarth' and 'cimolestan' mammals, leading to ongoing uncertainty about its evolutionary relationships.
  • Key findings include unique anatomical characteristics, contributing new insights that may clarify the evolutionary history of Paleocene eutherians and their connections to modern mammals.

Article Abstract

Unlabelled: We describe the tympanic anatomy of the petrosal of an enigmatic Paleocene mammal based on cranial specimens recovered from New Mexico, U.S.A. Although the ear region of has previously been described, there has not been a comprehensive, well-illustrated contribution using current anatomical terminology. The dental and cranial anatomy of is a chimera, with morphological similarities to both 'condylarth' and 'cimolestan' taxa. As such, the phylogenetic relationships of this taxon have remained elusive since its discovery, and it has variably been associated with Arctocyonidae, Pantodonta and Tillodontia. The petrosal of is anteriorly bordered by an open space comprising a contiguous carotid opening and pyriform fenestra. The promontorium features both a small rostral tympanic process and small epitympanic wing but lacks well-marked sulci. A large ventral facing external aperture of the canaliculus cochleae is present and bordered posteriorly by a well-developed caudal tympanic process. The hiatus Fallopii opens on the ventral surface of the petrosal. The tegmen tympani is mediolaterally broad and anteriorly expanded, and its anterior margin is perforated by a foramen for the ramus superior of the stapedial artery. The tympanohyal is small but approximates the caudal tympanic process to nearly enclose the stylomastoid notch. The mastoid is widely exposed on the basicranium and bears an enlarged mastoid process, separate from the paraoccipital process. These new observations provide novel anatomical data corroborating previous hypotheses regarding the plesiomorphic eutherian condition but also reveal subtle differences among Paleocene eutherians that have the potential to help inform the phylogeny of

Supplementary Information: The online version contains supplementary material available at 10.1007/s10914-021-09568-3.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8406390PMC
http://dx.doi.org/10.1007/s10914-021-09568-3DOI Listing

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