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Triassic odd couple (therapsid and temnospondyl) in same burrow from Karoo



From: Ben Creisler
bcreisler@gmail.com

New in PLoS ONE:

Vincent Fernandez, Fernando Abdala, Kristian J. Carlson, Della Collins
Cook, Bruce S. Rubidge, Adam Yates & Paul Tafforeau (2013)
Synchrotron Reveals Early Triassic Odd Couple: Injured Amphibian and
Aestivating Therapsid Share Burrow.
PLoS ONE 8(6): e64978.
doi:10.1371/journal.pone.0064978
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0064978


Fossorialism is a beneficial adaptation for brooding, predator
avoidance and protection from extreme climate. The abundance of
fossilised burrow casts from the Early Triassic of southern Africa is
viewed as a behavioural response by many tetrapods to the harsh
conditions following the Permo-Triassic mass-extinction event.
However, scarcity of vertebrate remains associated with these burrows
leaves many ecological questions unanswered. Synchrotron scanning of a
lithified burrow cast from the Early Triassic of the Karoo unveiled a
unique mixed-species association: an injured temnospondyl amphibian
(Broomistega) that sheltered in a burrow occupied by an aestivating
therapsid (Thrinaxodon). The discovery of this rare rhinesuchid
represents the first occurrence in the fossil record of a temnospondyl
in a burrow. The amphibian skeleton shows signs of a crushing trauma
with partially healed fractures on several consecutive ribs. The
presence of a relatively large intruder in what is interpreted to be a
Thrinaxodon burrow implies that the therapsid tolerated the
amphibian’s presence. Among possible explanations for such unlikely
cohabitation, Thrinaxodon aestivation is most plausible, an
interpretation supported by the numerous Thrinaxodon specimens
fossilised in curled-up postures. Recent advances in synchrotron
imaging have enabled visualization of the contents of burrow casts,
thus providing a novel tool to elucidate not only anatomy but also
ecology and biology of ancient tetrapods.


Also a news release:

http://phys.org/news/2013-06-oddest-couple-amphibian-mammal-forerunner.html