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Patterns of Dental Morphology and Disparity in the Eocene Herbivore Lineage Esthonyx (Mammalia, Tillodontia)
Author(s) -
Luongo Ricki A,
Cozart Hannah K,
Ahrens Heather E
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.614.3
Subject(s) - lineage (genetic) , dentition , morphometrics , biology , clade , premolar , evolutionary biology , herbivore , morphology (biology) , extinction (optical mineralogy) , zoology , molar , phylogenetic tree , paleontology , biochemistry , gene
The extinct clade Tillodontia includes numerous species representing relatively common, specialized herbivores of the Paleogene. The Eocene (56 – 33.8 mya) fossil record of the Bighorn Basin, Wyoming contains abundant fossils of the tillodont lineage, Esthonyx . Due to the abundance of specimens and their specialized diet, Esthonyx provides a valuable case study in phenotypic variation during climatic change over an extended temporal scale. Our objective was to quantify morphological disparity along the tooth row and assess variation between species and through time. To evaluate patterns of dental variation within Esthonyx , we used landmark‐based geometric morphometrics. Twelve landmarks representing prominent cusps and additional anatomical features in occlusal view of the lower fourth premolar and three molars were digitized for analysis. Principal components analysis indicated that the majority of shape variation, though very slight, occurred within the trigonid. Along the tooth row, p4 and m3 possessed greater disparity than m1 and m2; however, those differences were not significant. When dental loci were examined by both species and temporal unit, distinct species groupings and temporal shifts were difficult to distinguish because of the well‐conserved dental morphology within the lineage. In total, these results indicate that the lower dentition of Esthonyx is relatively conservative both along the tooth row, as well as between species and through time. The lack of evidence for morphologic change during significant climatic events may indicate low capacity for evolution and could have ultimately led to the extinction of this lineage. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .