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Parareptilia "folded" tooth structure and other non-dino papers



From: Ben Creisler
bcreisler@gmail.com

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

Mark J. MacDougall, Aaron R. H. LeBlanc & Robert R. Reisz (2014)
Plicidentine in the Early Permian Parareptile Colobomycter pholeter,
and Its Phylogenetic and Functional Significance among Coeval Members
of the Clade.
PLoS ONE 9(5): e96559.
doi:10.1371/journal.pone.0096559
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0096559

Once thought to be an exclusively anamniote characteristic,
plicidentine, a pattern of infolding of dentine, is now known to be
found in various amniote clades, including Parareptilia. In the
absence of detailed analyses of parareptilian dentition, most
parareptiles were assumed to lack plicidentine due to the absence of
external indicators, such as plications on the tooth base. The clear
presence of this dentinal feature in the largest premaxillary and
maxillary teeth of Colobomycter pholeter, led us to the present
detailed study within the dentition of this unusual parareptile, and
those of coeval members of this clade. Our study reveals that there is
large variability in the degree of dentine infolding within C.
pholeter dentition, as well as within those of closely related
parareptiles. This variability ranges from a lack of plications, to
very complex anamniote-like plicidentine. Utilizing computed
tomography scans in conjunction with histological sections we also
demonstrate the utility of computed tomography scans in conducting
non-destructive sampling in the identification of plicidentine. Given
the variability of plicidentine in this sample of parareptiles, we
hypothesize that one function of parareptilian plicidentine is to
increase the surface area for attachment tissues, and we suggest that
the use of plicidentine as a character in phylogenetic analyses of
parareptiles may be misleading.
==

Christian A. Sidor, J. SéBastien Steyer & William R. Hammer (2014)
A new capitosauroid temnospondyl from the Middle Triassic upper
Fremouw Formation of Antarctica.
Journal of Vertebrate Paleontology 34(3): 539-548
DOI:10.1080/02724634.2013.808205
http://www.tandfonline.com/doi/full/10.1080/02724634.2013.808205#.U2lenfldXeI

We describe a new capitosauroid temnospondyl, Antarctosuchus polyodon,
gen. et sp. nov., on the basis of a large and relatively complete
skull from the upper Fremouw Formation of Antarctica. The new species
is characterized by its possession of numerous, extremely small
maxillary, palatine, and ectopterygoid teeth, a dental pattern that
suggests specialization on small prey items, possibly invertebrates.
The taxon is also characterized by a parachoanal tooth row that
extends far posterior to the choana and occipital condyles set close
to the midline. A combination of features, including a flat skull and
low occiput together with well-developed sensory canals, suggests an
aquatic lifestyle. We address the phylogenetic relationships of
Antarctosuchus by adding it to a recent cladistic analysis of
Capitosauria. The revised data set includes 27 taxa and 53 characters.
The results of this analysis place Antarctosuchus within a clade of
derived Triassic stereospondyls as the sister taxon to
Paracyclotosaurus crookshanki from the Triassic Denwai Formation of
India. To date, the upper Fremouw Formation has yielded two endemic
temnospondyl species (viz., Kryostega collinsoni and Antarctosuchus
polyodon), although indeterminate remains referred to benthosuchids
and a cranial fragment assigned to Parotosuchus sp. have also been
noted. In contrast to the broadly distributed therapsid taxa
recognized from the Middle Triassic of Antarctica (e.g., Cynognathus,
Diademodon), the temnospondyl fauna suggests more limited interchange
with other coeval southern Pangean basins (e.g., Karoo, Luangwa,
Ruhuhu, Waterberg).

==

Estevan Eltink & Max C. Langer (2014)
A new specimen of the temnospondyl Australerpeton cosgriffi from the
late Permian of Brazil (Rio do Rasto Formation, Paraná Basin):
comparative anatomy and phylogenetic relationships.
Journal of Vertebrate Paleontology 34(3): 524-538
DOI:10.1080/02724634.2013.826667
http://www.tandfonline.com/doi/full/10.1080/02724634.2013.826667#.U2lgvvldXeI

A new temnospondyl specimen from the Rio do Rasto Formation (late
Permian, Paraná Basin) of south Brazil is composed of a left mandible,
right pelvis, femur, tibia, and fibula. Preserved lower jaws are rare
for Australerpeton cosgriffi, and the weak ossification of the
temnospondyl postcranium renders their preservation generally
uncommon. A detailed comparative description of the material allowed
its assignment to Australerpeton cosgriffi, and yielded new
information about the morphology of mandible, pelvis, and hind limb of
that taxon. This long-snouted temnospondyl has uncertain affinities
and has been assigned either to stereospondyl Rhinesuchidae or to
archegosaurid Platyoposaurinae. Reassessment of the phylogenetic
placement of Australerpeton cosgriffi, with information drawn from the
new specimen, confirms a basal stereospondyl position, between
Peltobatrachus pustulatus and Rhinesuchidae. The synapomorphies shared
with other stereospondyls include tabular and exoccipital contacting
in the paroccipital process; parasphenoid articulates with corpus of
the pterygoid forming a broad contact along the lateral margins of the
parasphenoid plate; internal carotid passes through the dorsal surface
of the parasphenoid plate; and parasphenoid denticles field enlarged
to a transverse ‘belt’ extending between the pterygoid-parasphenoid
articulations. Accordingly, Australerpeton cosgriffi represents one of
the first stereospondyls, and the oldest long-snouted member of the
group. The Paraná Basin can be included within the stereospondyl
ancestral range, and dispersion and diversification of this clade
appears to have happened before the Permo-Triassic boundary.

==

Actually, this one would be a dino paper...

Daniel Moen & Hélène Morlon (2014)
>From Dinosaurs to Modern Bird Diversity: Extending the Time Scale of
Adaptive Radiation.
PLoS Biol 12(5): e1001854.
doi:10.1371/journal.pbio.1001854
http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001854;jsessionid=B4539FF41AA2083BB76245D4DD6D5B66

What explains why some groups of organisms, like birds, are so species
rich? And what explains their extraordinary ecological diversity,
ranging from large, flightless birds to small migratory species that
fly thousand of kilometers every year? These and similar questions
have spurred great interest in adaptive radiation, the diversification
of ecological traits in a rapidly speciating group of organisms.
Although the initial formulation of modern concepts of adaptive
radiation arose from consideration of the fossil record, rigorous
attempts to identify adaptive radiation in the fossil record are still
uncommon. Moreover, most studies of adaptive radiation concern groups
that are less than 50 million years old. Thus, it is unclear how
important adaptive radiation is over temporal scales that span much
larger portions of the history of life. In this issue, Benson et al.
test the idea of a “deep-time” adaptive radiation in dinosaurs,
compiling and using one of the most comprehensive phylogenetic and
body-size datasets for fossils. Using recent phylogenetic statistical
methods, they find that in most clades of dinosaurs there is a strong
signal of an “early burst” in body-size evolution, a predicted pattern
of adaptive radiation in which rapid trait evolution happens early in
a group's history and then slows down. They also find that body-size
evolution did not slow down in the lineage leading to birds, hinting
at why birds survived to the present day and diversified. This paper
represents one of the most convincing attempts at understanding
deep-time adaptive radiations.