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Bobosaurus (Triassic pistosauroid) and plesiosaur evolution



From: Ben Creisler
bcreisler@gmail.com


A new online paper:

Matteo Fabbri, Fabio M. Dalla Vecchia & Andrea Cau (2013)
New information on Bobosaurus forojuliensis (Reptilia: Sauropterygia):
implications for plesiosaurian evolution.
Historical Biology (advance online publication)
DOI:10.1080/08912963.2013.826657
http://www.tandfonline.com/doi/full/10.1080/08912963.2013.826657#.UiifDca1EYE



Preparation of the holotype specimen of Bobosaurus forojuliensis, a
large sauropterygian from the lower Carnian of northeastern Italy,
revealed new morphological data relevant in establishing its
phylogenetic affinities among pistosauroid taxa and its relationships
with plesiosaurians. Inclusion of B. forojuliensis in two phylogenetic
analyses focusing, respectively, on sauropterygians and pistosauroids
agreed in placing the Italian taxon as closer to plesiosaurians than
to other pistosauroids. The phylogenetic interpretation of Bobosaurus
was not biased by assumptions on character weighting, is consistent
with its relatively younger age compared to most pistosauroids,
extends the fossil record of the plesiosaurian basal lineage back to
the Carnian and supports the earliest diversification of the clade
during the Late Triassic in agreement with the record of several
distinct lineages of rhomaleosaurids, plesiosauroids and pliosauroids
in the lowermost Jurassic. Bobosaurus shows that the evolution of the
plesiosaurian body plan from the ancestral pistosauroid grade was a
step-wise process, and that some of the vertebral and appendicular
specialisations of Jurassic and Cretaceous plesiosaurians had already
developed in the earliest Late Triassic.