RT Journal Article
SR Electronic
T1 Reptile-like physiology in Early Jurassic stem-mammals
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 785360
DO 10.1101/785360
A1 Elis Newham
A1 Pamela G. Gill
A1 Philippa Brewer
A1 Michael J. Benton
A1 Vincent Fernandez
A1 Neil J. Gostling
A1 David Haberthür
A1 Jukka Jernvall
A1 Tuomas Kankanpää
A1 Aki Kallonen
A1 Charles Navarro
A1 Alexandra Pacureanu
A1 Berit Zeller-Plumhoff
A1 Kelly Richards
A1 Kate Robson-Brown
A1 Philipp Schneider
A1 Heikki Suhonen
A1 Paul Tafforeau
A1 Katherine Williams
A1 Ian J. Corfe
YR 2019
UL http://biorxiv.org/content/early/2019/10/10/785360.abstract
AB 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. Morganucodon also 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.One Sentence Summary Surprisingly long lifespans and low femoral blood flow suggest reptile-like physiology in key Early Jurassic stem-mammals.