217-11 A new actinopterygian assemblage from the Upper Campanian Cliff House Sandstone at Tsaya Canyon, New Mexico

Session: Paleontology, Paleoecology/Taphonomy

Presenting Author:

Authors:

Abstract:

The Upper Cretaceous Cliff House Sandstone (CHS) in the structural San Juan Basin of New Mexico and southwestern Colorado offers a unique opportunity to examine marine vertebrate assemblages in the southwestern ranges of the Western Interior Seaway, providing significant data on marine ecosystems during the middle Campanian. This study presents a preliminary assessment of actinopterygian (ray-finned fish) fossils from field work conducted in the CHS of northwestern New Mexico. The actinopterygians currently make up over half of all extant vertebrate species and are cosmopolitan in their distribution, encompassing a wide range of both marine and freshwater habitats. The fossil record of actinopterygians extends as far as the late Silurian, but the group experienced rapid diversification in the Cretaceous. Fossils attributable to actinopterygians in the CHS were primarily collected from talus boulders and smaller rocks beneath an overhanging cliff face along the northeastern wall of Tsaya Canyon.

We identified two distinct actinopterygian genera in Tsaya Canyon thus far: Enchodus and Cf. Albula. These findings mark the first tentative report of the bonefish Albula from the CHS. The presence of these taxa in the CHS indicate a local environment comprising a tropical, shallow water system capable of supporting fish taxa with diverse feeding ecologies. Enchodus was an important component in Late Cretaceous marine ecosystems as an active predator of small, fast moving prey such as cephalopods and smaller fish, and it was preyed upon by larger predators including sharks and marine reptiles, both of which have been identified at Tsaya Canyon. The Cf. Albula tooth caps collected at Tsasya canyon are circular in shape with a smooth enamel surface, ideal for catching benthic and epibenthic prey. Like Enchodus, Cf. Albula was also likely prey for larger predators in the ecosystem preserved in the CHS.  

This research offers new insights into the evolutionary and ecological dynamics of the southern portion of marine ecosystems associated with the southern Western Interior Seaway during the Late Cretaceous.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11286

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