Testing a developmental model in the fossil record: Molar proportions in South American ungulates
Abstract
A developmental model, based upon murine rodents, has been proposed by Kavanagh et
al. (2007) to explain lower molar proportions in mammals. We produce a clade-wide
macroevolutionary test of the model using the dental evolutionary trends in a unique
radiation of extinct mammals endemic to South America ("Meridiungulata") that comprise
a diverse array of molar morphologies. All of the South American ungulate groups examined
follow the inhibitory cascade model with the exception of two groups: Interatheriidae
(Notoungulata) and Astrapotheria. For most taxa studied, ratios between lower molar
areas are greater than 1.0, indicating a weak inhibition by m1 on the subsequent molars
in the tooth row, and a trend to greater absolute size of the posterior molars. Comparisons
of mean ratios between clades indicate that a significant phylogenetic signal can
be detected, particularly between the two groups within Notoungulata Typotheria and
Toxodontia. Body mass estimates were found to be significantly correlated with both
m3/m1 and m2/m1 ratios, suggesting that the larger body size achieved the weaker inhibition
between the lower molars. Molar ratio patterns are examined and discussed in relation
to the independent and numerous acquisitions of hypsodonty that are characteristic
of dental evolution in "Meridiungulata. © 2012 The Paleontological Society. All rights
reserved.
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https://hdl.handle.net/10161/10792Published Version (Please cite this version)
10.1666/11001.1Publication Info
Wilson, LAB; Madden, RH; Kay, RF; & Sánchez-Villagra, MR (2012). Testing a developmental model in the fossil record: Molar proportions in South American
ungulates. Paleobiology, 38(2). pp. 308-321. 10.1666/11001.1. Retrieved from https://hdl.handle.net/10161/10792.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Richard Frederick Kay
Professor of Evolutionary Anthropology
I have two areas of research:1) the evolution of primates in South America; and 2)
the use of primate anatomy to reconstruct the phylogenetic history and adapations
of living and extinct primates, especially Anthropoidea. 1) Evolution of primates
and mammalian faunal evolution, especially in South America. For the past 30 years,
I have been engaged in research in Argentina, Bolivia The Dominican Republic, Peru,
and Colombia with three objectives:a) to reconstruct the evol

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