Grace Pizzini
Pronouns: She/They
Research Mentor(s): Lucas Weaver
Co-Presenter:
Research Mentor School/College/Department: Ecology and Evolutionary Biology / LSA
Presentation Date: April 20
Presentation Type: Poster
Session: Session 3 – 1:40pm – 2:30 pm
Room: League Ballroom
Authors: Lucas Weaver, Grace Pizzini, Jake Downey, Benny Cho
Presenter: 57
Abstract
The Cretaceous-Paleogene (K-Pg) mass extinction was followed by the rapid diversification of mammals, and the early Paleocene portion of the Denver Formation in the Denver Basin offers one of the best records of mammalian evolution in this crucial period. The Denver Formation’s proximity to the Rocky Mountain front range additionally provides a unique contrast between more typical Cretaceous and Paleogene deposits in western North America from paleo-lowlands and can also allow for comparison between patterns of fossil preservation and taxonomic composition of mountain distal and proximal sites. In this study we examine the taphonomy of vertebrate microfossil bonebeds (VMBs) in areas proximal to the Rocky Mountain front range outside of Colorado Springs, CO (El Paso County) in the early Paleocene (ca. 66–65 million years ago [Ma]) aspect of the Denver Formation, D1 sequence. Microfossils (majority < 5 cm) were collected from samples taken from four different localities: DMNH 3875, DMNH 6284, DMNH 7383, and DB 1759. Size shape, element, and taxon were documented for each vertebrate fossil and the total mass was taken for the sedimentary matrix processes and the plant and vertebrate fossils. We found that locality DMNH 7383 was the most prolific, characterized by high frequencies of small elongate and equidimensional miscellaneous vertebrate fossils, large plate-like dermal bone material including turtle shells, crocodile scutes, and fish scales, and conical crocodile and fish teeth. Locality DB 1759 was the least prolific, producing few identifiable fossils and a shorter range of sizes. Previous studies on the taphonomy of vertebrate microfossil bonebeds focused primarily on the Judith River Formation (middle–late Campanian, ca. 78–75 million years ago) of northcentral Montana, which was deposited along a topographically uniform coastal plain very near to the Western Interior Seaway. Our results are dissimilar in size and taxonomic makeup; the Judith River Formation VMBs contained a larger percentage of smaller vertebrate microfossils, particularly gar, dinosaur, lizard, and amphibian, which suggests taphonomic differences between mountain proximal and mountain distal localities. Studying the taphonomy of these mountain-proximal localities allows us to better understand the biases that exist in our interpretations of the fossil record and to more accurately draw conclusions from the VMBs from the Denver Basin which are integral to our understanding of early Paleocene evolution of mammals in the shadow of the rising Rocky Mountains. Presentation link
Interdisciplinary, Natural/Life Sciences
