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Constraint and adaptation in the evolution of carnivoran skull shape

Published online by Cambridge University Press:  08 April 2016

Borja Figueirido ,
Norman MacLeod ,
Jonathan Krieger ,
Miquel De Renzi ,
Juan Antonio Pérez-Claros  and
Paul Palmqvist
Borja Figueirido
Affiliation:
Departamento de Ecología y Geología, Facultad de Ciencias, Universidad de Málaga, Málaga 29071, Spain. E-mail: [email protected]
Norman MacLeod
Affiliation:
Paleontology Department, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom. E-mail: [email protected]
Jonathan Krieger
Affiliation:
Paleontology Department, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom. E-mail: [email protected]
Miquel De Renzi
Affiliation:
Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Área de Paleontología, Universidad de Valencia, Apartado 22085, Valencia 46071, Spain. E-mail: [email protected]
Juan Antonio Pérez-Claros
Affiliation:
Departamento de Ecología y Geología, Facultad de Ciencias, Universidad de Málaga, Málaga 29071, Spain. E-mail: [email protected]
Paul Palmqvist
Affiliation:
Departamento de Ecología y Geología, Facultad de Ciencias, Universidad de Málaga, Málaga 29071, Spain. E-mail: [email protected]
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Abstract

The evolutionary history of the Order Carnivora is marked by episodes of iterative evolution. Although this pattern is widely reported in different carnivoran families, the mechanisms driving the evolution of carnivoran skull morphology remain largely unexplored. In this study we use coordinate-point extended eigenshape analysis (CP-EES) to summarize aspects of skull shape in large fissiped carnivores. Results of these comparisons enable the evaluation of the role of different factors constraining the evolution of carnivoran skull design. Empirical morphospaces derived from mandible anatomy show that all hypercarnivores (i.e., those species with a diet that consists almost entirely of vertebrate flesh) share a set of traits involved in a functional compromise between bite force and gape angle, which is reflected in a strong pattern of morphological convergence. Although the paths followed by different taxa to reach this “hypercarnivore shape-space” differ because of phylogenetic constraints, the morphological signature of hypercarnivory in the mandible is remarkably narrow and well constrained. In contrast, CP-EES of cranial morphology does not reveal a similar pattern of shape convergence among hypercarnivores. This suggests a lesser degree of morphological plasticity in the cranium compared to the mandible, which probably results from a compromise between different functional demands in the cranium (e.g., feeding, vision, olfactory sense, and brain processing) whereas the mandible is only involved in food acquisition and processing. Combined analysis of theoretical and empirical morphospaces for these skull data also show the lower anatomical disparity of felids and hyaenids compared to canids and ursids. This indicates that increasing specialization within the hypercarnivorous niche may constrain subsequent morphological and ecological flexibility. During the Cenozoic, similar skull traits appeared in different carnivoran lineages, generated by similar selection pressures (e.g., toward hypercarnivory) and shared developmental pathways. These pathways were likely the proximate source of constraints on the degree of variation associated with carnivoran skull evolution and on its direction.

Type
Articles
Information
Paleobiology , Volume 37 , Issue 3 , Summer 2011 , pp. 490 - 518
Copyright
Copyright © The Paleontological Society 

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