108-6 Preliminary Examination of the Dynamics of the Marine Vertebrate Extinction and Recovery from the Latest Cretaceous through the Early Paleocene in Eastern Texas (USA)

Session: The Cretaceous-Paleogene (K-Pg) Boundary Interval: From Large-Scale Geological Events to Mass Extinction Mechanisms (Posters)

Presenting Author:

Authors:

Abstract:

Eastern Texas marine vertebrate assemblages recovered by screen-washing from the latest Cretaceous Corsicana Formation, the earliest Paleocene Kincaid Formation, and overlying Wills Point Formation help to detail the magnitude of local extinction and pace of recovery and diversification in the earliest Cenozoic. A taxonomically and ecologically diverse chondrichthyan fauna with more than 20 species in the latest Cretaceous suggests that there was not a continued decline after the mid-Campanian extinction, but instead a significant level of extinction loss at the end of the Cretaceous. Area post-Cretaceous Midway Group chondrichthyan assemblages reveal a much more limited and diminutive sized shark and ray fauna not exceeding five species per collection. The batoid chondrichthyans of the Kincaid Formation are dominated by species and specimens of Dasyatidae (Myliobatiformes), consistent with hypotheses of their dominance in the benthic durophagous role after the extinction. The bony fish Enchodus and Albula are known extinction survivors with records in the Kincaid Formation indicating a continuation of their ecological roles into the dawn of the Paleocene. The fish otolith assemblages collected from horizons from the base and the near the top of the early Paleocene Wills Point Formation document a diverse osteichthyan fauna. The otolith assemblages include many lineages that are part of the Percomorpha which is the dominate clade of extant osteichthyans and diversified greatly following the mass extinction. This diversity within the earliest Paleocene supports the hypothesis of a rapid radiation following the extinction. These fossil fish records (of relatively small-sized fish) add data to the so-called Patterson Gap. When considered along with the diminutive chondrichthyan record, the small-sized assemblages suggest the possibility of a lingering lilliput effect among the eastern Texas marine vertebrate taxa during the early Paleocene. The Wills Point Formation otoliths share some faunal links with other Gulf Coast localities, but also record previously undocumented groupings pointing to potential regional variation (and overall greater diversity) along the Paleocene coastline. These Paleocene collections comprise lineages that survived the K-T mass extinction and “new” taxa that likely represent either immigrants to the western Gulf Coast in Texas after the extinction or are taxa that evolved in the extinction aftermath.

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

doi: 10.1130/abs/2025AM-8804

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