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Crocodyliform extinction across Jurassic/Cretaceous transition



Ben Creisler
bcreisler@gmail.com

A new paper in open access:

Jonathan P. Tennant, Philip D. Mannion & Paul Upchurch (2016)
Environmental drivers of .
Proceedings of the Royal Society B 283: 20152840.
doi: http: // dx.doi.org/10.1098/rspb.2015.2840
http: // rspb.royalsocietypublishing.org/content/283/1826/20152840
http: // 
rspb.royalsocietypublishing.org/content/royprsb/283/1826/20152840.full.pdf



Crocodyliforms have a much richer evolutionary history than
represented by their extant descendants, including several independent
marine and terrestrial radiations during the Mesozoic. However,
heterogeneous sampling of their fossil record has obscured their
macroevolutionary dynamics, and obfuscated attempts to reconcile
external drivers of these patterns. Here, we present a comprehensive
analysis of crocodyliform biodiversity through the Jurassic/Cretaceous
(J/K) transition using subsampling and phylogenetic approaches and
apply maximum-likelihood methods to fit models of extrinsic variables
to assess what mediated these patterns. A combination of fluctuations
in sea-level and episodic perturbations to the carbon and sulfur
cycles was primarily responsible for both a marine and non-marine
crocodyliform biodiversity decline through the J/K boundary, primarily
documented in Europe. This was tracked by high extinction rates at the
boundary and suppressed origination rates throughout the Early
Cretaceous. The diversification of Eusuchia and Notosuchia likely
emanated from the easing of ecological pressure resulting from the
biodiversity decline, which also culminated in the extinction of the
marine thalattosuchians in the late Early Cretaceous. Through
application of rigorous techniques for estimating biodiversity, our
results demonstrate that it is possible to tease apart the complex
array of controls on diversification patterns in major archosaur
clades.

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