[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

[dinosaur] Morganucodon & Kuehneotherium (mammaliaforms) had more reptile-like physiology (free pdf)




Ben Creisler
bcreisler@gmail.com

A new paper with free pdf:

Free pdf:

Elis Newham, Pamela G. Gill, Philippa Brewer, Michael J. Benton, Vincent Fernandez, Neil J. Gostling, David HaberthÃr, Jukka Jernvall, Tuomas KankaanpÃÃ, Aki Kallonen, Charles Navarro, Alexandra Pacureanu, Kelly Richards, Kate Robson Brown, Philipp Schneider, Heikki Suhonen, Paul Tafforeau, Katherine A. Williams, Berit Zeller-Plumhoff & Ian J. Corfe (2020)
Nature Communications 11, Article number: 5121
Reptile-like physiology in Early Jurassic stem-mammals
DOI: https://doi.org/10.1038/s41467-020-18898-4
https://www.nature.com/articles/s41467-020-18898-4



Despite considerable advances in knowledge of the anatomy, ecology and evolution of early mammals, far less is known about their physiology. Evidence is contradictory concerning the timing and fossil groups in which mammalian endothermy arose. To determine the state of metabolic evolution in two of the earliest stem-mammals, the Early Jurassic Morganucodon and Kuehneotherium, we use separate proxies for basal and maximum metabolic rate. Here we report, using synchrotron X-ray tomographic imaging of incremental tooth cementum, that they had maximum lifespans considerably longer than comparably sized living mammals, but similar to those of reptiles, and so they likely had reptilian-level basal metabolic rates. Measurements of femoral nutrient foramina show Morganucodon had blood flow rates intermediate between living mammals and reptiles, suggesting maximum metabolic rates increased evolutionarily before basal metabolic rates. Stem mammals lacked the elevated endothermic metabolism of living mammals, highlighting the mosaic nature of mammalian physiological evolution.

==

News

https://www.bristol.ac.uk/news/2020/october/ancient-tiny-teeth.html

https://phys.org/news/2020-10-ancient-tiny-teeth-reveal-mammals.html

https://www.sciencetimes.com/articles/27672/20201012/200-million-year-old-first-mammals-lived-reptiles.htm

==

Virus-free. www.avg.com