Skip to main content
Dryad

Systematics and biostratigraphy of non-mammalian vertebrates across the K/Pg transition, southern Wyoming, USA

Wroblewski, Anton1

Published Apr 08, 2026 on Dryad. https://doi.org/10.5061/dryad.tqjq2bwc7

Data files

Apr 08, 2026 version files 35.89 MB

Click names to download individual files

Abstract

Non-mammalian vertebrate fossils from the Ferris Formation in southern Wyoming span the Cretaceous/Paleogene boundary and add to the growing paleontological data set for testing models of biostratigraphic and paleobiogeographic change in Laramidia during this interval. The collection comprises over 6500 skeletal, dental, and epidermal elements from 56 fossil sites and has not previously been described. New stratigraphic and paleontological data suggest that the local K/Pg boundary is 50 m stratigraphically above its previously proposed location, but its precise location remains uncertain because an iridium layer has not yet been located. Prior claims that dinosaurian diversity remained high and non-mammalian vertebrate diversity was unchanged through the Maastrichtian part of the formation are not supported by the fossil data. Euselachian numerical abundance and taxonomic richness increase through the Maastrichtian section, are at their highest ca. 94-26 ky before the K/Pg event and then decline towards the boundary. Dinosaurian taxonomic richness decreases through the Maastrichtian section, but low numerical abundance of fossils makes the cause of this decrease uncertain. The decrease in dinosaur fossils towards the K/Pg boundary corresponds to a change in lithology of the formation and may not signal a true ecological trend.