Skip to main content
Kent Academic Repository

Completeness of the eutherian mammal fossil record and implications for reconstructing mammal evolution through the Cretaceous/Paleogene mass extinction

Davies, Thomas W., Bell, Mark A., Goswami, Anjali, Halliday, Thomas J. D. (2017) Completeness of the eutherian mammal fossil record and implications for reconstructing mammal evolution through the Cretaceous/Paleogene mass extinction. Paleobiology, 43 (4). pp. 521-536. ISSN 0094-8373. (doi:10.1017/pab.2017.20) (KAR id:98299)


There is a well-established discrepancy between paleontological and molecular data regarding the timing of the origin and diversification of placental mammals. Molecular estimates place interordinal diversification dates in the Cretaceous, while no unambiguous crown placental fossils have been found prior to the end-Cretaceous mass extinction. Here, the completeness of the eutherian fossil record through geological time is evaluated to assess the suggestion that a poor fossil record is largely responsible for the difference in estimates of placental origins. The completeness of fossil specimens was measured using the character completeness metric, which quantifies the completeness of fossil taxa as the percentage of phylogenetic characters available to be scored for any given taxon. Our data set comprised 33 published cladistic matrices representing 445 genera, of which 333 were coded at the species level.There was no significant difference in eutherian completeness across the Cretaceous/Paleogene (K/Pg) boundary. This suggests that the lack of placental mammal fossils in the Cretaceous is not due to a poor fossil record but more likely represents a genuine absence of placental mammals in the Cretaceous. This result supports the "explosive model" of early placental evolution, whereby placental mammals originated around the time of the K/Pg boundary and diversified soon after.No correlation was found between the completeness pattern observed in this study and those of previous completeness studies on birds and sauropodomorph dinosaurs, suggesting that different factors affect the preservation of these groups. No correlations were found with various isotope proxy measures, but Akaike information criterion analysis found that eutherian character completeness metric scores were best explained by models involving the marine-carbonate strontium-isotope ratios (87Sr/86Sr), suggesting that tectonic activity might play a role in controlling the completeness of the eutherian fossil record.

Item Type: Article
DOI/Identification number: 10.1017/pab.2017.20
Additional information: Unmapped bibliographic data: ET - 2017/08/22 [Field not mapped to EPrints] DB - Cambridge Core [Field not mapped to EPrints] DP - Cambridge University Press [Field not mapped to EPrints]
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Funders: Natural Environment Research Council (
Depositing User: Tom Davies
Date Deposited: 24 Nov 2022 10:37 UTC
Last Modified: 04 Mar 2024 18:20 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

  • Depositors only (login required):

Total unique views for this document in KAR since July 2020. For more details click on the image.