A new caimanine alligatorid from the Middle Eocene of Southwest Texas and implications for spatial and temporal shifts in Paleogene crocodyliform diversity
| dc.contributor.author | Stocker, Michelle R. | en |
| dc.contributor.author | Brochu, Christopher A. | en |
| dc.contributor.author | Kirk, E. Christopher | en |
| dc.contributor.department | Geosciences | en |
| dc.date.accessioned | 2021-01-19T14:05:19Z | en |
| dc.date.available | 2021-01-19T14:05:19Z | en |
| dc.date.issued | 2021-01-15 | en |
| dc.description.abstract | Dramatic early Cenozoic climatic shifts resulted in faunal reorganization on a global scale. Among vertebrates, multiple groups of mammals (e.g., adapiform and omomyiform primates, mesonychids, taeniodonts, dichobunid artiodactyls) are well known from the Western Interior of North America in the warm, greenhouse conditions of the early Eocene, but a dramatic drop in the diversity of these groups, along with the introduction of more dry-tolerant taxa, occurred near the Eocene–Oligocene boundary. Crocodyliforms underwent a striking loss of diversity at this time as well. Pre-Uintan crocodyliform assemblages in the central Western Interior are characterized by multiple taxa, whereas Chadronian assemblages are depauperate with only Alligator prenasalis previously known. Crocodyliform diversity through the intervening Uintan and Duchesnean is not well understood. The middle Eocene Devil’s Graveyard Formation (DGF) of southwest Texas provides new data from southern latitudes during that crucial period. A new specimen from the middle member of the DGF (late Uintan–Duchesnean) is the most complete cranial material of an alligatorid known from Paleogene deposits outside the Western Interior. We identify this specimen as a caimanine based on notched descending laminae of the pterygoids posterior to the choanae and long descending processes of the exoccipitals that are in contact with the basioccipital tubera. Unlike Eocaiman cavernensis, the anterior palatine process is rounded rather than quadrangular. The relationships and age of this new taxon support the hypothesis that the modern distribution of caimanines represents a contraction of a more expansive early Cenozoic distribution. We hypothesize that the range of caimanines tracked shifting warm, humid climatic conditions that contracted latitudinally toward the hothouse-icehouse transition later in the Eocene. | en |
| dc.description.sponsorship | The Jackson School of Geosciences, The University of Texas at Austin (William Powers, Jr. Presidential Graduate Fellowship to Michelle R. Stocker), the UT College of Liberal Arts, the Society of Vertebrate Paleontology (Jackson School of Geosciences Student Member Travel Grant to Michelle R. Stocker), and the Department of Geosciences at Virginia Tech provided funding for this research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. | en |
| dc.format.mimetype | application/pdf | en |
| dc.identifier.doi | https://doi.org/10.7717/peerj.10665 | en |
| dc.identifier.uri | http://hdl.handle.net/10919/101953 | en |
| dc.identifier.volume | 9 | en |
| dc.language.iso | en | en |
| dc.publisher | PeerJ | en |
| dc.rights | Attribution 4.0 International | en |
| dc.rights.uri | http://creativecommons.org/licenses/by/4.0/ | en |
| dc.subject | Biodiversity | en |
| dc.subject | Paleontology | en |
| dc.subject | Taxonomy | en |
| dc.subject | Zoology | en |
| dc.subject | Cenozoic | en |
| dc.subject | Caimaninae | en |
| dc.subject | Diversity | en |
| dc.subject | Climate change | en |
| dc.subject | Fossils | en |
| dc.subject | Devil’s Graveyard Formation | en |
| dc.subject | Species distribution | en |
| dc.title | A new caimanine alligatorid from the Middle Eocene of Southwest Texas and implications for spatial and temporal shifts in Paleogene crocodyliform diversity | en |
| dc.title.serial | PeerJ | en |
| dc.type | Article - Refereed | en |