First vertebrate assemblage from the middle member of the Fremouw Formation (Lower Triassic) of Antarctica

Antarctic Science
By: , and 

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Abstract

The Fremouw Formation of the Central Transantarctic Mountains preserves the southernmost record of Early to Middle Triassic terrestrial ecosystems that developed in the aftermath of the end-Permian mass extinction. Although the well-studied vertebrate fossil assemblage in the lower member of the Fremouw Formation provides a detailed snapshot of subpolar ecosystems immediately following the end-Permian mass extinction, the nature of how long these earliest Triassic communities persisted at the southern extremes of Pangaea is virtually unknown. Importantly, the timing and extent of the major faunal turnover between the lower and upper members of the Fremouw Formation have been obscured by the paucity of fossil specimens historically recovered from the middle member. Here, we describe the first vertebrate assemblage from the middle member of the Fremouw Formation, including occurrences of procolophonids (including Procolophon trigoniceps) and archosauromorphs (including Prolacerta broomi), as well as infilled vertebrate burrow casts referrable to the ichnogenus Reniformichnus. We also summarize and expand on lithostratigraphic shifts between the lower, middle and upper members of the Fremouw Formation. Although the sample size of vertebrate body fossils is small compared to the lower and upper members of the Fremouw Formation, we discuss the evidence for a taphonomic shift between the lower and middle members of the Fremouw Formation that favours preservation of smaller-bodied taxa and individuals in the latter. Together, these preliminary data add crucial context to the persistence of subpolar vertebrate communities in the earliest Mesozoic.

Suggested Citation

Woolley, C.H., McIntosh, J.A., Smith, R.M., and Sidor, C.A., 2026, First vertebrate assemblage from the middle member of the Fremouw Formation (Lower Triassic) of Antarctica: Antarctic Science, v. 38, no. 3, p. 278-297, https://doi.org/10.1017/S0954102026100613.

ISSN: 1365-2079 (online)

Study Area

Publication type Article
Publication Subtype Journal Article
Title First vertebrate assemblage from the middle member of the Fremouw Formation (Lower Triassic) of Antarctica
Series title Antarctic Science
DOI 10.1017/S0954102026100613
Volume 38
Issue 3
Publication Date April 06, 2026
Year Published 2026
Language English
Publisher Cambridge University Press
Contributing office(s) Geology, Geophysics, and Geochemistry Science Center
Description 20 p.
First page 278
Last page 297
Other Geospatial Antarctica
Additional publication details