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Turtle draft genomes support sister-group to archosauria (free pdf)

From: Ben Creisler

A new online open-access paper:

Zhuo Wang, Juan Pascual-Anaya, Amonida Zadissa, et al.
The draft genomes of soft-shell turtle and green sea turtle yield
insights into the development and evolution of the turtle-specific
body plan.
Nature Genetics (advance online publication)

The unique anatomical features of turtles have raised unanswered
questions about the origin of their unique body plan. We generated and
analyzed draft genomes of the soft-shell turtle (Pelodiscus sinensis)
and the green sea turtle (Chelonia mydas); our results indicated the
close relationship of the turtles to the bird-crocodilian lineage,
from which they split ~267.9–248.3 million years ago (Upper Permian to
Triassic). We also found extensive expansion of olfactory receptor
genes in these turtles. Embryonic gene expression analysis identified
an hourglass-like divergence of turtle and chicken embryogenesis, with
maximal conservation around the vertebrate phylotypic period, rather
than at later stages that show the amniote-common pattern. Wnt5a
expression was found in the growth zone of the dorsal shell,
supporting the possible co-option of limb-associated Wnt signaling in
the acquisition of this turtle-specific novelty. Our results suggest
that turtle evolution was accompanied by an unexpectedly conservative
vertebrate phylotypic period, followed by turtle-specific repatterning
of development to yield the novel structure of the shell.