[dinosaur] Early Jurassic stem-mammals had reptile-like physiology (free pdf)

Ben Creisler
[email protected]

A new preprint:


Elis Newham, Pamela G Gill, Philippa Brewer, Michael J Benton, Vincent
Fernandez, Neil J Gostling, David Haberthür, Tuomas Kankaanpaa, Aki
Kallonen, Charles Navarro, Alexandra Pacureanu, Berit Zeller-Plumhoff,
Kelly Richards, Kate Robson-Brown, Philipp Schneider, Heikki Suhonen, Paul
Tafforeau, Katherine Williams & Ian J Corfe (2019)
Reptile-like physiology in Early Jurassic stem-mammals.
bioRxiv (preprint)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1101_785360&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nMMQpmqB5mKFSBtndJUhv4hAs7-gowymJLLrCs8NMTs&s=TQwiDn4LN_V-3Y1MgMOMwTIAWQP0-mT5Ra9ZwhxJsWo&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.biorxiv.org_content_10.1101_785360v1.abstract&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nMMQpmqB5mKFSBtndJUhv4hAs7-gowymJLLrCs8NMTs&s=IjNNEJpfrAoqafqpFMnJqhGpilUaGK3LaosGhzKCSoo&e= 
Free pdf:
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.biorxiv.org_content_biorxiv_early_2019_09_30_785360.full.pdf&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nMMQpmqB5mKFSBtndJUhv4hAs7-gowymJLLrCs8NMTs&s=vuu9diqkfMI3hI8QCoGc6oHZ-Jv8eBx0tMFHftoGQcE&e= 

There is uncertainty regarding the timing and fossil species in which
mammalian endothermy arose, with few studies of stem-mammals on key aspects
of endothermy such as basal or maximum metabolic rates, or placing them in
the context of living vertebrate metabolic ranges. Synchrotron X-ray
imaging of incremental tooth cementum shows two Early Jurassic
stem-mammals, Morganucodon and Kuehneotherium, had lifespans (a basal
metabolic rate proxy) considerably longer than comparably sized living
mammals, but similar to reptiles, and that Morganucodon had femoral blood
flow rates (a maximum metabolic rate proxy) intermediate between living
mammals and reptiles. This shows maximum metabolic rates increased
evolutionarily before basal rates, and that contrary to previous
suggestions of a Triassic origin, Early Jurassic stem-mammals lacked the
endothermic metabolism of living mammals.

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