Hoffman, Devin;
Miller-Camp, Jess;
Heckert, Andrew;
(2021)
Tooth enamel microstructure in North American Phytosauria (Diapsida:Archosauriformes): Implications for biogeography and ecology of a Late Triassic clade of crocodylian-like predators.
Palaeontologia Electronica
, 24
(3)
, Article 24.3.a32. 10.26879/1162.
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Abstract
Teeth can provide important insight into diet and evolution of extinct vertebrates. Tooth enamel microstructure records functional and phylogenetic signals beyond the gross morphology of the dentition. Here, we provide the first systematic sampling of phytosaur tooth enamel to address questions of intra- and interspecific variation, and thus taxonomic identification, biogeographic connectivity, and heterodonty. We sampled 23 phytosaur teeth from five localities throughout the American Southwest and one locality from the Newark Supergroup of North Carolina. These teeth probably represent five heterodont genera and are tentatively assigned to Angistorhinus, Smilosuchus, Machaeroprosopus, Redondasaurus, and “Rutiodon”. We used scanning electron microscopy to examine their enamel microstructure from transverse, longitudinal, and tangential cross-sections. All sampled teeth are composed of columnar enamel ranging in thickness from 20 to 150 µm, typically 50–100 µm, across all genera. In phytosaurs from the western US, lines of incremental growth (LIGs) are rare, whereas in the Newark Supergroup phytosaur “Rutiodon”, LIGs are abundant and welldeveloped. Although phytosaur tooth enamel microstructure is not useful for the taxonomic assignment of isolated teeth, it can be used to differentiate phytosaurs from different basins and lends support to the hypothesis that western and eastern North American phytosaurs are taxonomically distinct. The posterior blade-like teeth of heterodont phytosaurs are consistently composed of proportionately thicker enamel (10– 14 µm thicker than anterior teeth of comparable size in heterodont phytosaurs), implying a greater degree of force on these teeth during food processing. Combined with independent measures of diet, enamel microstructure can help refine dietary hypotheses during the Triassic archosauriform radiation.
| Type: | Article |
|---|---|
| Title: | Tooth enamel microstructure in North American Phytosauria (Diapsida:Archosauriformes): Implications for biogeography and ecology of a Late Triassic clade of crocodylian-like predators |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.26879/1162 |
| Publisher version: | https://doi.org/10.26879/1162 |
| Language: | English |
| Additional information: | Copyright: October 2021 Society of Vertebrate Paleontology. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. creativecommons.org/licenses/by/4.0 |
| Keywords: | archosauriform; phytosaur; Triassic; tooth enamel; microstructure |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10178422 |
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