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Philydrosaurus (Choristodera) from Liaoning, China and other non-dino papers



From: Ben Creisler
bcreisler@gmail.com

A number of recent non-dino papers that may be of interest:

Ke-Qin Gao, Chang-Fu Zhou, Lianhai Hou & Richard C. Fox (2013)
Osteology and ontogeny of Early Cretaceous Philydrosaurus (Diapsida:
Choristodera) based on new specimens from Liaoning Province, China.
Cretaceous Research 45: 91–102
doi: http://dx.doi.org/10.1016/j.cretres.2013.08.003
http://www.sciencedirect.com/science/article/pii/S0195667113001213


Choristoderes are a group of extinct diapsid reptiles that once
occupied the freshwater systems in the Northern Hemisphere from the
Middle Jurassic through the Miocene. The Early Cretaceous
monjurosuchid Philydrosaurus from western Liaoning, China, represents
a transitional morphotype between a broad-snouted (crocodile-like) and
a narrow-snouted (gavial-like) skull during the evolution of
Choristodera. New specimens of the taxon from the Early Cretaceous
Jiufotang Formation include an incomplete braincase and a nearly
complete juvenile skeleton; the study of these specimens provides new
information on the braincase and ontogenetic change of the skeleton of
this transitional monjurosuchid. In the braincase floor, the foramen
internus canalis caroticus externus opens in a groove lateral to the
constricted lateral aspect of the parasphenoid, and ventral exposure
of this foramen differs from Champsosaurus, in which
parasphenoid/pterygoid fusion completely encloses the canal. On the
occiput, the vagus nerve foramen penetrates the basioccipital, while
the two foramina for the hypoglossal nerve open at the
exoccipital/basioccipital suture. Comparative study of the new
juvenile specimen with adult Philydrosaurus reveals previously unknown
developmental changes of the cranial and postcranial skeleton of this
monjurosuchid. Ontogenetically, Philydrosaurus underwent a dramatic
change of skull proportions, including elongation of the antorbital
and postorbital regions, and elongation of the jaws, with a great
increase of the number of marginal teeth. The lower temporal fenestra
is entirely closed in early ontogeny, as in large, fully-grown adults.

==

Juliana Sterli, Marcelo S. de la Fuente & Aldo M. Umazano (2013)
New remains and new insights on the Gondwanan meiolaniform turtle
Chubutemys copelloi from the Lower Cretaceous of Patagonia, Argentina.
Gondwana Research (advance online publication)
doi: http://dx.doi.org/10.1016/j.gr.2013.08.016
http://www.sciencedirect.com/science/article/pii/S1342937X13002931



New cranial and postcranial remains of the Gondwanan meiolaniform
turtle Chubutemys copelloi Gaffney, Rich, Vickers-Rich, Constantine,
Vacca and Kool 2007 from the Lower Cretaceous Puesto La Paloma Member
of the Cerro Barcino Formation (Chubut province, Patagonia, Argentina)
are presented, described, and compared in this contribution. Carapace
and plastral remains, pectoral and pelvic girdle, cervical and
thoracic vertebrae, and the left maxilla and jugal are the new
recovered elements from Ch. copelloi. These new remains were found in
2008 in Turtle Town locality, the same site where the holotype and
referred specimens of Ch. copelloi had been found in 1997. The facies
analysis of the sedimentary succession in Turtle Town and surrounding
areas suggests a paleoenvironment constituted by a broad alluvial
plain with influx of volcanic ash-falls, whose deposits were disturbed
by pedogenesis or reworked by current flows that supplied water and
sediment in ponded areas. The presence of a very thin shell, broad
vertebrals (broader than pleurals), the presence of a shallow nuchal
notch with the vertebral 1 almost reaching the anterior border of the
carapace, the presence of costo-peripheral fontanelles, and the
presence of an ectepicondylar canal in the humerus, are the most
notable features provided by the new remains. A cladistic analysis has
been performed to test the phylogenetic position of Ch. copelloi. This
phylogeny corroborates the basal position of Ch. copelloi among
Meiolaniformes. The plausible phylogenetic relationships of the clade
Meiolaniidae with other Gondwanan (e.g., Otwayemys cunicularius
Gaffney, Kool, Brinkman, Rich, and Vickers-Rich 1998) or Laurasian
Lower Cretaceous taxa (e.g., sinochelyids) are also discussed in this
contribution. Taxa included in Meiolaniformes have been mainly found
in Gondwana and as the most basal taxon was found in Patagonia,
paleobiogeographic studies suggest this clade originated in South
America. Due to the basal position of Ch. copelloi among
Meiolaniformes the discovery of more and previously unknown remains of
this species shed light on the origin and early evolution of this
curious clade.

==

Broiliellus reiszi


Robert Holmes, David S. Berman & Jason S. Anderson (2013)
A new dissorophid (Temnospondyli, Dissorophoidea) from the Early
Permian of New Mexico (United States).
Comptes Rendus Palevol (advance online publication)
doi: http://dx.doi.org/10.1016/j.crpv.2013.07.002
http://www.sciencedirect.com/science/article/pii/S1631068313001085


An amphibian skull and partial skeleton found from the El Cobre Canyon
Formation of New Mexico, USA, is identified as a new species of the
dissorophoid temnospondyl genus Broiliellus. Significant anatomical
features include: a relatively long, narrow preorbital region, with
both nasals and vomers no more than half as wide anteriorly than
posteriorly; extended ventral projection of the postorbital; a
unilaterally retained lateral exposure of the ectopterygoid (in
addition to the normally present lateral exposure of the palatine);
supratemporal lacking a semilunar flange; highly vaulted vomers
forming a median internasal septum; and an angular with a swollen
posteroventral keel. Phylogenetic analysis strongly supports a sister
group relationship with Broiliellus brevis and clearly distinguishes
it from another dissorophoid, ‘B.’ novomexicanus from New Mexico. The
medially restricted supraneural osteoderms are more similar to those
seen in Cacops than Broiliellus, which reinforces the importance of
avoiding using single ‘key features’ to discriminate taxa.


===


Huaichun Wu, Shihong Zhang, Linda A. Hinnov,  Ganqing Jiang,  Qinglai
Feng, Haiyan Li   & Tianshui Yang (2013)
Time-calibrated Milankovitch cycles for the late Permian.
Nature Communications 4, Article number: 2452
doi:10.1038/ncomms3452
Open access:
http://www.nature.com/ncomms/2013/130913/ncomms3452/full/ncomms3452.html



An important innovation in the geosciences is the astronomical time
scale. The astronomical time scale is based on the Milankovitch-forced
stratigraphy that has been calibrated to astronomical models of
paleoclimate forcing; it is defined for much of Cenozoic–Mesozoic. For
the Palaeozoic era, however, astronomical forcing has not been widely
explored because of lack of high-precision geochronology or
astronomical modelling. Here we report Milankovitch cycles from late
Permian (Lopingian) strata at Meishan and Shangsi, South China, time
calibrated by recent high-precision U–Pb dating. The evidence extends
empirical knowledge of Earth’s astronomical parameters before 250
million years ago. Observed obliquity and precession terms support a
22-h length-of-day. The reconstructed astronomical time scale
indicates a 7.793-million year duration for the Lopingian epoch, when
strong 405-kyr cycles constrain astronomical modelling. This is the
first significant advance in defining the Palaeozoic astronomical time
scale, anchored to absolute time, bridging the Palaeozoic–Mesozoic
transition.

==

Adrian Mitchell Currie (2013)
Venomous Dinosaurs and Rear-Fanged Snakes: Homology and Homoplasy Characterized.
Erkenntnis (advance online publication)
DOI: 10.1007/s10670-013-9533-5
http://link.springer.com/article/10.1007/s10670-013-9533-5



I develop an account of homology and homoplasy drawing on their use in
biological inference and explanation. Biologists call on homology and
homoplasy to infer character states, support adaptationist
explanations, identify evolutionary novelties and hypothesize
phylogenetic relationships. In these contexts, the concepts must be
understood phylogenetically and kept separate: as they play divergent
roles, overlap between the two ought to be avoided. I use these
considerations to criticize an otherwise attractive view defended by
Gould, Hall, and Ramsey & Peterson. By this view, homology and
homoplasy can only be delineated qua some level of description, and
some homoplasies (parallelisms) are counted as homologous. I develop
an account which retains the first, but rejects the second, aspect of
that view. I then characterize parallelisms and convergences in terms
of their causal role. By the Strict Continuity account, homology and
homoplasy are defined phylogenetically and without overlaps, meeting
my restriction. Convergence and parallelisms are defined as two types
of homoplasy: convergent homoplasies are largely constrained by
external factors, while parallelisms are due to internal constraints.