Year: 2020
Type: article
Abstract: 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.
Source: Nature Communications
Authors: Elis Newham, Pamela G. Gill, Philippa Brewer, Michael J. Benton, Vincent Fernandez, Neil J. Gostling, David Haberthür, Jukka Jernvall, Tuomas Kankaanpää, 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
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $5,380
OpenAlex ID: W3091992950