[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Reptilian and synapsid stuff (resend)

From: Ben Creisler

Apologies is this posting looks like a dupe. I tried to send it before and
it showed up empty for me.
Not dinosaur stuff, but maybe of interest to the DML:

Susan E. Evansa & Yuan Wang (2011)
New material of the Early Cretaceous lizard Yabeinosaurus from China.
Cretaceous Research (advance online publication)

The Early Cretaceous lizard Yabeinosaurus was one of the first taxa
described from the now famous Jehol Biota of northeast China.
Misinterpreted for more than 60 years and misclassified as a gekkotan based
on juvenile specimens, it is now recognised to be a large, well-ossified
lizard with an extended period of skeletal maturation. Here we describe two
additional complete specimens of Yabeinosaurus that provide new information
on skeletal morphology, most notably of the skull, pectoral girdle, and
tail. Both specimens also preserve gut contents, showing that large
individuals took vertebrate prey, including fish. A more complete
understanding of Yabeinosaurus permits a review of the type specimen of
Yabeinosaurus youngi. Skull traits used to distinguish Y. youngi from Y.
tenuis are invalid but, as noted by Hoffstetter, the two species differ
markedly in limb proportions. Attribution of Young?s specimen to
Yabeinosaurus is equivocal, but could potentially extend the temporal range
of the lineage into the Jurassic. A new phylogenetic analysis based on a
morphological data set places Yabeinosaurus on the stem of Scleroglossa, as
the sister taxon of the contemporaneous Japanese lizard Sakurasaurus.


Athanasia C Tzika, Raphaël Helaers, Gerrit Schramm and Michel C
Milinkovitch (2011)
Reptilian-transcriptome v1.0, a glimpse in the brain transcriptome of five
divergent Sauropsida lineages and the phylogenetic position of turtles.
EvoDevo  2(1):19 
DOI: 10.1186/2041-9139-2-19
NOTE: pdf is free

Reptiles are largely under-represented in comparative genomics despite the
fact that they are substantially more diverse in many respects than
mammals. Given the high divergence of reptiles from classical model
species, next-generation sequencing of their transcriptomes is an approach
of choice for gene identification and annotation. 
Here, we use 454 technology to sequence the brain transcriptome of four
divergent reptilian and one reference avian species: the Nile crocodile,
the corn snake, the bearded dragon, the red-eared turtle, and the chicken.
Using an in-house pipeline for recursive similarity searches of >3,000,000
reads against multiple databases from 7 reference vertebrates, we compile a
reptilian comparative transcriptomics dataset, with homology assignment for
20,000 to 31,000 transcripts per species and a cumulated non-redundant
sequence length of 248.6 Mbases. Our approach identifies the majority (87%)
of chicken brain transcripts and about 50% of de novo assembled reptilian
transcripts. In addition to 57,502 microsatellite loci, we identify
thousands of SNP and indel polymorphisms for population genetic and linkage
analyses. We also build very large multiple alignments for Sauropsida and
mammals (two million residues per species) and perform extensive
phylogenetic analyses suggesting that turtles are not basal living reptiles
but are rather associated with Archosaurians, hence, potentially answering
a long-standing question in the phylogeny of Amniotes. 
The reptilian transcriptome (freely available at
http://www.reptilian-transcriptomes.org) should prove a useful new resource
as reptiles are becoming important new models for comparative genomics,
ecology, and evolutionary developmental genetics.

Sean P. Modesto, Roger M. H. Smith, Nicolás E. Campione and Robert R. Reisz
The last ?pelycosaur?: a varanopid synapsid from the Pristerognathus
Assemblage Zone, Middle Permian of South Africa. 
Naturwissenschaften (advance publication)
DOI: 10.1007/s00114-011-0856-2

We report on a partial varanopid skull and mandible from the
Pristerognathus Assemblage Zone of the Beaufort Group, in the South African
Karoo Basin, which is probably latest Middle Permian (Capitanian) in age.
This mycterosaurine is not only the youngest known varanopid from the
Southern Hemisphere, but it is also the youngest known ?pelycosaur? (i.e.,
non-therapsid synapsid). Like all other members of this clade of
hypercarnivores, the teeth are strongly flattened, recurved, and have
finely serrated cutting edges. The anterior dentary teeth form a caniniform
region, and the splenial features a foramen intermandibularis oralis, the
first ever to be described in a ?pelycosaur.? The last varanopids were the
smallest carnivores of latest Middle Permian continental faunas. Occupation
of the small carnivore guild appears to have allowed varanopids to achieve
a nearly cosmopolitan distribution throughout the Middle Permian, between
the great Early Permian radiation of basal synapsids and the spectacular
diversification of therapsid synapsids in the Late Permian and Early

mail2web.com ? Enhanced email for the mobile individual based on Microsoft®
Exchange - http://link.mail2web.com/Personal/EnhancedEmail