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Pterosaur diversity



From: Ben Creisler
bcreisler@gmail.com

A new online paper:

Richard J. Butler, Roger B.J. Benson & Paul M. Barrett (2012)
Pterosaur diversity: Untangling the influence of sampling biases,
Lagerstätten, and genuine biodiversity signals.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
http://dx.doi.org/10.1016/j.palaeo.2012.08.012
http://www.sciencedirect.com/science/article/pii/S0031018212004877?v=s5


Pterosaurs were a diverse and successful group of Mesozoic reptiles
with an evolutionary history that extended for approximately 145
million years. Recent attempts to understand species-richness
trajectories for pterosaurs have led to them becoming a focal group
for ongoing debate about the importance of sampling biases in
determining observed species-richness patterns in the vertebrate
fossil record. Here, we reanalyse pterosaur species-richness through
time, and make statistical comparisons to proxies for pterosaur fossil
record sampling and ‘global’ terrestrial tetrapod sampling, using
several approaches including generalised least-squares multiple
regression models. Moreover, we make quantitative comparisons between
species-richness and morphological diversity (disparity). Sampling of
the pterosaur fossil record shows substantial temporal heterogeneity,
with Cretaceous pterosaur records more commonly recovered from
terrestrial environments, and with sampling proxies for Cretaceous
pterosaurs closely tracking ‘global’ sampling proxies for terrestrial
tetrapods. The similarities between pterosaur-based and ‘global’
sampling proxies for Cretaceous data call into question the hypothesis
that observed correlations between pterosaur sampling proxies and
pterosaur species-richness result from mere ‘redundancy’. Multiple
regression modelling supports the hypothesis that much of the
variation present in pterosaur palaeobiodiversity curves results from
a combination of the presence or absence of Lagerstätten (sites of
exceptional preservation) and a ‘background’ sampling signal that may
reflect temporal variation in fossiliferous sedimentary rock. Despite
these evident strong biases in the pterosaur record, it seems
plausible that both species-richness and disparity peaked relatively
late in the evolutionary history of pterosaurs (during the Late
Jurassic–Early Cretaceous), although an absence of pterosaur-bearing
terrestrial Lagerstätten in the Late Triassic–Early Jurassic fossil
record means that caution is required. It is possible that a late peak
in diversity may reflect the ecological radiation of pterodactyloid
pterosaurs from the Late Jurassic onwards, which has been linked to
increased terrestrial locomotory abilities and ecological niche
occupancy and relaxed constraints upon body size evolution.