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Body size evolution in Mesozoic Birds

Hone, D.W.E., Dyke, G.J., Benton, M.J. and Haden, M. (2008) Body size evolution in Mesozoic Birds Journal of Evolutionary Biology, 21, (2), pp. 618-624. (doi:10.1111/j.1420-9101.2007.01483.x).

Record type: Article


The tendency for the mean body size of taxa within a clade to increase through evolution (Cope’s Rule) has been demonstrated in a number of terrestrial vertebrate groups. However, because avian body size is strongly constrained by flight, any increase in size during the evolution of this lineage should be limited – there is a maximum size that can be attained by a bird for it to be able to get off the ground. Contrary to previous interpretations of early avian evolution, we demonstrate an overall increase in body size across Jurassic and Cretaceous flying birds: taxon body size increases from the earliest Jurassic through to the end of the Cretaceous, across a time span of 70 Myr. Although evidence is limited that this change is directional, it is certainly nonrandom. Relative size increase occurred presumably as the result of an increase in variance as the avian clade diversified after the origin of flight: a progression towards larger body size is seen clearly within the clades Pygostylia and Ornithothoraces. In contrast, a decrease in body size characterizes the most crownward lineage Ornithuromorpha, the clade that includes all extant taxa, and potentially may explain the survival of these birds across the Cretaceous-Palaeogene boundary. As in all other dinosaurs, counter selection for small size is seen in some clades, whereas body size is increasing overall

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e-pub ahead of print date: 10 January 2008
Published date: March 2008
Organisations: Ocean Biochemistry & Ecosystems


Local EPrints ID: 205193
ISSN: 1010-061X
PURE UUID: 13157555-3dff-4665-9b6e-4c5ff67fd5dc

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Date deposited: 07 Dec 2011 12:23
Last modified: 18 Jul 2017 11:05

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Author: D.W.E. Hone
Author: G.J. Dyke
Author: M.J. Benton
Author: M. Haden

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