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| Dryolestes, a Late Jurassic relative of the Cretaceous therians in Janis, Martín-Serra, Theodor et Scott, 2025. Artwork by James Brown. |
Abstract
The end Cretaceous extinctions had a profound effect on mammalian diversity, especially on metatherians (marsupials and their extinct relatives). Could mammalian substrate preference have influenced differential survival patterns? The plant fossil record shows changing angiosperm leaf anatomy during the last ten million years of the Cretaceous that would have resulted in a greater richness of terrestrial understory habitats, and work by other researchers implies that terrestrial (vs arboreal) substrate preference promoted increased survival over the Cretaceous–Palaeogene boundary for both mammals and birds. Here we use fragmentary postcranial remains of Late Cretaceous mammals and show that, at least in the Western Interior of North America, therian mammals were becoming more terrestrial in their locomotor mode towards the end of the Cretaceous.
Keywords: Mesozoic mammal, postcranial anatomy, locomotor mode, Cretaceous habitat, end Cretaceous extinction
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| Dryolestes (left) and Haldanodon (right), two creatures from the Late Jurassic period, Digital reconstruction by James Brown, in consultation Pamela G. Gill. Copyright Pamela G. Gill. |
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| Dryolestes, a Late Jurassic relative of the Cretaceous therians. Artwork by James Brown. Pamela Gill |
Christine M. Janis, Alberto Martín-Serra, Jessica M. Theodor and Craig S. Scott. 2025. Down to Earth: Therian Mammals became more Terrestrial towards the End of the Cretaceous. Palaeontology. DOI: doi.org/10.1111/pala.70004 [01 April 2025]
Researchers unlock life secrets of Jurassic mammals using X-ray imaging
