232 D29. Recent Developments in Phylogeny and Morphological Patterns (Posters)

Wednesday, 18 October 2023
8:00 AM - 5:30 PM
Hall B

DIETARY MODIFICATIONS OF THE TEETH IN THE EARLY MIOCENE STENOMYLINE CAMELS (CAMELIDAE: ARTIODACTYLA)

Paper number: 232-7
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

The stenomylines were a small group of early Miocene gazelle-like camels that developed extremely hypsodont, or high-crowned teeth. Previous authors measured the tooth crown height and mesowear of Stenomylus itself, but did not include a study of the even more hypsodont genera Rakomylus and particularly Blickomylus. We measured the height index (HI = total tooth height of unworn m3/transverse width of m3) and estimated the mesowear of early camelids such as Poebrotherium, plus the basal stenomyline Pseudolabis, which had brachydont teeth (HI < 2) and relatively high cusp relief. As previously reported, Stenomylus has a HI as high as 4 and slightly more mesowear (levels 3-4). Similarly, Rakomylus has a HI = 4 and mesowear values around 5. But, Blickomylus was dramatically more hypsodont, with a HI as high as 6.5 on the least-worn teeth (the same as the most hypsodont horses of the later Miocene), and a mesowear index of 6 (completely flat tooth-crowns with no cusp relief). This suggests that Blickomylus had an extremely abrasive diet, like the most hypsodont horses and ruminants of the Miocene. In fact, it is the most hypsodont animal of the early Miocene, at a time when horses like Parahippus had low-crowned teeth. It is unclear why such high-crowned teeth were selected for in Blickomylus in the early Miocene, as they would have been high-crowned before the extensive savanna grasslands had appeared. However, it is striking that this only occurs in the Zia Sand of New Mexico and in central Utah, but is unknown in High Plains deposits of Nebraska, Colorado, and South Dakota, which yields the greatest diversity of Hemingfordian mammals, including many other camel groups. Possibly, Blickomylus lived on a diet of plants covered with abrasive materials in New Mexico and Utah, but not in the northern High Plains.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-395956

© Copyright 2023 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.