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"Thecodont" teeth in diadectids and other new non-dino papers



From: Ben Creisler
bcreisler@gmail.com

 A number of new non-dino papers that may be of interest to some:

Aaron R. H. LeBlanc  & Robert R. Reisz (2013)
Periodontal Ligament, Cementum, and Alveolar Bone in the Oldest
Herbivorous Tetrapods, and Their Evolutionary Significance.
PLoS ONE 8(9): e74697.
doi:10.1371/journal.pone.0074697
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0074697


Tooth implantation provides important phylogenetic and functional
information about the dentitions of amniotes. Traditionally, only
mammals and crocodilians have been considered truly thecodont, because
their tooth roots are coated in layers of cementum for anchorage of
the periodontal ligament, which is in turn attached to the bone lining
the alveolus, the alveolar bone. The histological properties and
developmental origins of these three periodontal tissues have been
studied extensively in mammals and crocodilians, but the identities of
the periodontal tissues in other amniotes remain poorly studied. Early
work on dental histology of basal amniotes concluded that most possess
a simplified tooth attachment in which the tooth root is ankylosed to
a pedestal composed of “bone of attachment”, which is in turn fused to
the jaw. More recent studies have concluded that stereotypically
thecodont tissues are also present in non-mammalian, non-crocodilian
amniotes, but these studies were limited to crown groups or
secondarily aquatic reptiles. As the sister group to Amniota, and the
first tetrapods to exhibit dental occlusion, diadectids are the ideal
candidates for studies of dental evolution among terrestrial
vertebrates because they can be used to test hypotheses of development
and homology in deep time. Our study of Permo-Carboniferous diadectid
tetrapod teeth and dental tissues reveal the presence of two types of
cementum, periodontal ligament, and alveolar bone, and therefore the
earliest record of true thecodonty in a tetrapod. These discoveries in
a stem amniote allow us to hypothesize that the ability to produce the
tissues that characterize thecodonty in mammals and crocodilians is
very ancient and plesiomorphic for Amniota. Consequently, all other
forms of tooth implantation in crown amniotes are derived arrangements
of one or more of these periodontal tissues and not simply ankylosis
of teeth to the jaw by plesiomorphically retaining “bone of
attachment”, as previously suggested.

===

Haiyan Tong, Lu Li and Hui Ouyang (2013)
A revision of Sinaspideretes wimani Young & Chow, 1953 (Testudines:
Cryptodira: Trionychoidae) from the Jurassic of the Sichuan Basin,
China.
Geological Magazine (advance online publication)
DOI: http://dx.doi.org/10.1017/S0016756813000575
http://128.232.233.5/action/displayAbstract?fromPage=online&aid=9000138&fulltextType=RA&fileId=S0016756813000575


Sinaspideretes wimani Young & Chow, 1953 was based on a single shell
from the Jurassic red beds of the Sichuan Basin. Originally referred
to Trionychidae but later tentatively assigned to Carettochelyidae, it
was long thought to be the oldest representative of those families.
The re-examination of the carapace and further preparation of the
plastron of the holotype of S. wimani revealed a number of important
characters which clearly exclude this taxon from both Trionychidae and
Carettochelyidae, but unite it with the primitive trionychoid Yehguia
tatsuensis (Ye, 1963). S. wimani is therefore considered as the
basalmost member of Trionychoidae. Our study adds to the evidence from
the fossil record for the antiquity of Trionychoidae, thus is in
agreement with the early split of Trionychia (Trionychidae and
Carettochelyidae) among the crown Testudines suggested by the
molecular phylogeny of turtles.

==

Hans-Dieter Sues & Rainer R. Schoch (2013)
Anatomy and phylogenetic relationships of Calamops paludosus
(Temnospondyli, Stereospondyli) from the Triassic of the Newark Basin,
Pennsylvania.
Journal of Vertebrate Paleontology 33(5):  1061-1070
DOI:10.1080/02724634.2013.759120
http://www.tandfonline.com/doi/full/10.1080/02724634.2013.759120#.UiejFMa1EYE

The holotype of the large temnospondyl Calamops paludosus is the
oldest known tetrapod fossil from the Triassic of the Newark basin in
Pennsylvania. Although it is usually placed in Metoposauridae, its
affinities have remained unknown since its original description
because the unique specimen had never been prepared. Preparation and
casting of the specimen, which comprises three pieces of a left
mandibular ramus, now permits detailed anatomical description of the
jaw and assessment of its affinities. Calamops paludosus is a valid
taxon of trematosauroid temnospondyls that can be diagnosed by several
autapomorphies. It represents one of the geologically youngest known
records of long-snouted trematosaurs and the first record of these
temnospondyls from the Late Triassic of North America.

SUPPLEMENTAL DATA—Supplemental materials are available for this
article for free at www.tandfonline.com/UJVP


==

Dorota Konietzko-Meier & P. Martin Sander (2013)
Long bone histology of Metoposaurus diagnosticus (Temnospondyli) from
the Late Triassic of Krasiejów (Poland) and its paleobiological
implications.
Journal of Vertebrate Paleontology 33(5):  1003-1018
DOI:10.1080/02724634.2013.765886
http://www.tandfonline.com/doi/full/10.1080/02724634.2013.765886#.Uiektsa1EYE



Long bones of the temnospondyl Metoposaurus diagnosticus
krasiejowensis from the Late Triassic of Krasiejów, Poland, were
studied using histological analysis. Six femora, three humeri, a
radius, and an ulna were prepared for thin-sectioning. In all bones,
the dominant type of primary bone matrix is parallel-fibered bone with
secondary, or rarely primary, deposition of lamellar bone inside
vascular canals. Two small humeri and the smallest femur showed
incipient fibrolamellar bone, which may be a character typical for
juvenile individuals. The medullary region is filled with
well-developed trabecular bone. The growth marks in all bones are
organized as thick layers of highly vascularized zones and thick
compact annuli with numerous rest lines, which may correspond with
favorably wet and long, unfavorably dry seasons. The thickness of the
annuli is similar to the thickness of zones for reasons still unknown.
Based on the highest estimated number of growth cycles in the femora,
the long bones from Krasiejów all belong to juvenile animals. High
amounts of Sharpey's fibers are very characteristic in all described
bones. A new interpretation of mode of life is proposed based on these
findings: the extremely flat skull, the relatively short and wide
humerus, large manus, and limbs with strong muscles suggest that this
species might have been able to burrow underground during the long
unfavorable part of the year.


SUPPLEMENTAL DATA—Supplemental materials are available for this
article for free at www.tandfonline.com/UJVP


==

Catactegenys, Apsgnathus,

Randall L. Nydam, Timothy B. Rowe & Richard L. Cifelli (2013)
Lizards and snakes of the Terlingua Local Fauna (late Campanian),
Aguja Formation, Texas, with comments on the distribution of
paracontemporaneous squamates throughout the Western Interior of North
America.
Journal of Vertebrate Paleontology 33(5): 1081-1099
DOI:10.1080/02724634.2013.760467
http://www.tandfonline.com/doi/full/10.1080/02724634.2013.760467#.UiejW8a1EYE

The late Campanian–aged (= Judithian) squamates from the Terlingua
Local Fauna of the Aguja Formation, southern Texas, includes four
scincomorphans: a new taxon (Catactegenys solaster, gen. et sp. nov.),
referable to Xantusiidae, that has massive teeth and tooth crown
morphology similar to that of contogeniid lizards; an indeterminate
scincomorphan (Apsgnathus triptodon, gen et sp. nov.) with robust
teeth; and two unnamed scincomorphan morphotypes. Anguimorphans in the
fauna include Odaxosaurus piger, cf. Parasaniwa wyomingensis, and a
likely xenosaur. Ophidian jaw fragments confirm the presence of a
snake in the fauna. The Aguja squamate assemblage is one of the most
southerly of a series of paracontemporaneous squamate faunas extending
from central Alberta to northern Mexico. Comparison of these faunas
reveals that, although two taxa are endemic to the Aguja Formation,
others show some latitudinal trends. Odaxosaurus and Parasaniwa are
present in all well-sampled faunas from Alberta to Texas. The
mammal-like Peneteius and snakes are found only in faunas from
southern Utah to Mexico. Chamopsiids are only present from Alberta to
New Mexico. The sole representatives of Contogeniidae and Xantusiidae
are restricted to southern Utah and southern Texas, respectively.
These hypotheses of distributional patterns must continue to be tested
through ongoing investigations of all of the relevant faunas from the
late Campanian of the Western Interior.

SUPPLEMENTAL DATA—Supplemental materials are available for this
article for free at www.tandfonline.com/UJVP

===

Nidophis

Stefan Vasile, Zoltán Csiki-Sava & Márton Venczel (2013)
A new madtsoiid snake from the Upper Cretaceous of the Hateg Basin,
western Romania.
Journal of Vertebrate Paleontology 33(5): 1100-1119
DOI:10.1080/02724634.2013.764882
http://www.tandfonline.com/doi/full/10.1080/02724634.2013.764882#.Uieke8a1EYE


Madtsoiidae are a group of archaic snakes, widely distributed in the
Upper Cretaceous of Gondwanan landmasses (South America, Madagascar,
India, Africa), but otherwise reported outside Gondwana based only on
scarce material from a few southern European localities. Here, we
describe associated snake remains from uppermost Cretaceous
(Maastrichtian) beds of the Hateg Basin, Romania, as a new
small-madtsoiid taxon, Nidophis insularis, gen. et sp. nov. Nidophis,
represented by a large number of well-preserved vertebrae and ribs
that apparently belonged to one individual, is one of the best-known
Cretaceous madtsoiids, and the most completely documented member of
the family from Europe. Phylogenetic analyses place the new taxon
within a moderately supported Madtsoiidae, closely related to
Herensugea from the Upper Cretaceous of Spain. The two European taxa,
together with other small madtsoiids, are recovered as the sister
taxon to a second madtsoiid clade including large-to-gigantic forms
such as Madtsoia, Wonambi, and Yurlunggur. The presence of these small
madtsoiids, together with that of Menarana, in the uppermost
Cretaceous of Europe, suggests that early widespread distribution of
madtsoiids, extending over the southern part of Europe, instead of
late northward immigration from Gondwanan landmasses, as proposed
previously, might account for the paleobiogeographic distribution of
Cretaceous Madstoiidae.

SUPPLEMENTAL DATA—Supplemental materials are available for this
article for free at www.tandfonline.com/UJVP