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Parareptilia paleobiology papers



From: Ben Creisler
bcreisler@gmail.com

It's holiday in the United States so there might be an excuse to post
some non-dino items. A couple of recent papers about the paleobiology
of parareptiles:


Flávio A. Pretto, Sérgio F. Cabreira and Cesar L. Schultz (2012)
Tooth microstructure of the Early Permian aquatic predator
Stereosternum tumidum and paleobiological implications.
Acta Palaeontologica Polonica (in press)
doi: http://dx.doi.org/10.4202/app.2011.0121
http://app.pan.pl/article/item/app20110121.html



A histological investigation of the feeding apparatus of a
Stereosternum specimen revealed a great number of adaptations in the
structure and insertion of teeth, to deal with breakage risks. The
tooth wall is composed of different layers of dentine, varying in
orientation and composition. This mixed arrangement may have increased
tooth resistance to lateral tension. The tooth insertion also involves
more than one mechanism. The teeth are located inside shallow tooth
sockets and are held in place by a tripartite periodontium (composed
of alveolar bone, cementum and possibly soft periodontal tissue) and
accessory structures, here termed anchorage trabeculae (mainly
composed of cementum). Fully grown teeth are ankylosed to the bottom
of the tooth socket. The recognition of alveolar bone and cementum
(and the possible presence of a soft periodontal ligament) reinforces
the idea that these tissues were widespread among Amniota, not being
exclusive to mammals and archosaurs. The adaptations identified here
reinforce the hypothesis that Stereosternum was an active aquatic
predator.

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Jennifer Botha-Brink & Roger Malcolm Harris Smith (2012)
Palaeobiology of Triassic procolophonids, inferred from bone microstructure.
Comptes Rendus Palevol (advance online publication)
doi: http://dx.doi.org/10.1016/j.crpv.2012.03.002
http://www.sciencedirect.com/science/article/pii/S1631068312000735


Procolophonoidea represent the most successful radiation of
Parareptilia that lived during the Permo-Triassic. They are one of the
few vertebrate groups that survived the end-Permian extinction and are
thus important for studying the recovery of the post-extinction
terrestrial ecosystem. Here, we investigate the palaeobiology of three
Triassic procolophonid parareptiles, namely Sauropareion anoplus,
Procolophon trigoniceps and Teratophon spinigenis, from the Karoo
Basin of South Africa, inferred from histological analyses of their
limb bones. Results reveal that all three taxa exhibit
parallel-fibered bone tissue. Growth rings are absent in the Early
Triassic Sauropareion and Procolophon whereas annuli are present in
the Middle Triassic Teratophon, even during early ontogeny, suggesting
a difference in life histories. Morphology and bone histology imply
fossorial lifestyles for all three taxa, suggesting that burrowing may
have played an important role in their survival during the harsh
post-extinction Triassic environment.