Funston, GF, dePolo, PE, Sliwinski, JT, Dumont, M, Shelley, SL, Pichevin, LE, Cayzer, NJ, Wible, JR, Williamson, TE, Rae, JWB and Brusatte, SL (2022) The origin of placental mammal life histories. Nature, 610. pp. 107-111. ISSN 0028-0836

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Abstract

After the end-Cretaceous extinction, placental mammals quickly diversified1, occupied key ecological niches2,3 and increased in size4,5, but this last was not true of other therians6. The uniquely extended gestation of placental young7 may have factored into their success and size increase8, but reproduction style in early placentals remains unknown. Here we present the earliest record of a placental life history using palaeohistology and geochemistry, in a 62 million-year-old pantodont, the clade including the first mammals to achieve truly large body sizes. We extend the application of dental trace element mapping9,10 by 60 million years, identifying chemical markers of birth and weaning, and calibrate these to a daily record of growth in the dentition. A long gestation (approximately 7 months), rapid dental development and short suckling interval (approximately 30–75 days) show that Pantolambda bathmodon was highly precocial, unlike non-placental mammals and known Mesozoic precursors. These results demonstrate that P. bathmodon reproduced like a placental and lived at a fast pace for its body size. Assuming that P. bathmodon reflects close placental relatives, our findings suggest that the ability to produce well-developed, precocial young was established early in placental evolution, and that larger neonate sizes were a possible mechanism for rapid size increase in early placentals.

Item Type:	Article
Uncontrolled Keywords:	Dentition; Animals; Mammals; Trace Elements; Body Size; Phylogeny; Weaning; Fossils; History, Ancient; Life History Traits; Animals; Body Size; Dentition; Fossils; History, Ancient; Life History Traits; Mammals; Phylogeny; Trace Elements; Weaning; Animals; Body Size; Dentition; Fossils; History, Ancient; Life History Traits; Mammals; Phylogeny; Trace Elements; Weaning; General Science & Technology
Subjects:	Q Science > QH Natural history > QH301 Biology Q Science > QL Zoology
Divisions:	Biological and Environmental Sciences (from Sep 19)
Publisher:	Nature Research
SWORD Depositor:	A Symplectic
Date Deposited:	22 Jan 2025 11:46
Last Modified:	22 Jan 2025 11:46
DOI or ID number:	10.1038/s41586-022-05150-w
URI:	https://researchonline.ljmu.ac.uk/id/eprint/25361

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