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Mesozoic radiation of crocodylomorphs after Triassic-Jurassic extinction



From: Ben Creisler
bcreisler@gmail.com

A new online paper:

Olja Toljagić and Richard J. Butler (2013)
Triassic–Jurassic mass extinction as trigger for the Mesozoic
radiation of crocodylomorphs.
Biology Letters 9 (3):  20130095 (advance online publication)
doi: 10.1098/rsbl.2013.0095
http://rsbl.royalsocietypublishing.org/content/9/3/20130095.abstract


Pseudosuchia, one of the two main clades of Archosauria (Reptilia:
Diapsida), suffered a major decline in lineage diversity during the
Triassic–Jurassic (TJ) mass extinction (approx. 201 Ma).
Crocodylomorpha, including living crocodilians and their extinct
relatives, is the only group of pseudosuchians that survived into the
Jurassic. We reassess changes in pseudosuchian morphological diversity
(disparity) across this time interval, using considerably larger
sample sizes than in previous analyses. Our results show that metrics
of pseudosuchian disparity did not change significantly across the TJ
boundary, contrasting with previous work suggesting low pseudosuchian
disparity in the Early Jurassic following the TJ mass extinction.
However, a significant shift in morphospace occupation between Late
Triassic and Early Jurassic taxa is recognized, suggesting that the TJ
extinction of many pseudosuchian lineages was followed by a major and
geologically rapid adaptive radiation of crocodylomorphs. This marks
the onset of the spectacularly successful evolutionary history of
crocodylomorphs in Jurassic and Cretaceous ecosystems.