The origin of placental mammal life histories
Abstract
After the end-Cretaceous extinction, placental mammals quickly diversified , occupied key ecological niches and increased in size , but this last was not true of other therians. The uniquely extended gestation of placental young may have factored into their success and size increase, 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 mapping 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.
Citation
Funston , G F , dePolo , P E , Sliwinski , J T , Dumont , M , Shelley , S L , Pichevin , L E , Cayzer , N J , Wible , J R , Williamson , T E , Rae , J W B & Brusatte , S L 2022 , ' The origin of placental mammal life histories ' , Nature , vol. 610 , pp. 107-111 . https://doi.org/10.1038/s41586-022-05150-w
Publication
Nature
Status
Peer reviewed
ISSN
0028-0836Type
Journal article
Rights
Copyright © The Author(s), under exclusive licence to Springer Nature Limited 2022. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1038/s41586-022-05150-w
Description
Funding was provided by the University of Edinburgh, the Royal Society (grant NIF\R1\191527), National Science Foundation (grants DEB 1654949 and EAR 1654952), European Research Council (ERC) starting grants (nos. 756226 and 805246) under the European Union’s Horizon 2020 Research and Innovation Programme, a Philip Leverhulme Prize and a SNSF Mobility Fellowship (grant P2EZP2_199923).Collections
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