Translator Disclaimer
27 September 2018 First Paleoichnological Evidence for Baby–Riding in Early Mammals
Author Affiliations +
Abstract

It is not yet known how old parental care in mammals is. One fossil trackway ascribed to Ameghinichnus patagonicus of a mouse-sized primitive mammal from the Middle Jurassic of Patagonia, Argentina, of almost 170 Ma, shows deviation from the usual bilateral symmetry of posture and motion: the left forelimb digits were dragging in the swing phase, and the tail was bent to the right and dragged over the right footprints. However, the footprints are evenly spaced, indicating that the animal was not limping. The opposition of the tail and the forelimb dragging marks could possibly be explained by a heavy load carried on the left side. This hypothesis is supported by experiments on laboratory rats. A plausible load for Ameghinichnus track-maker could be babies riding on a milk-producing mother, as they do in extant opossums and many other mammals. Baby-riding is a missed possible feature of basal mammals, which potentially integrates evolutionary acquisition of profound mammalian features, such as milk-feeding, endothermy, hairs, and limb parasagittalism.

Alexander N. Kuznetsov and Aleksandra A. Panyutina "First Paleoichnological Evidence for Baby–Riding in Early Mammals," Ameghiniana 55(6), 668-676, (27 September 2018). https://doi.org/10.5710/AMGH.03.02.2018.3184
Received: 3 February 2018; Accepted: 19 September 2018; Published: 27 September 2018
JOURNAL ARTICLE
9 PAGES


SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top