17 Paleoceanography and paleoclimate of the Gulf of California and how they resonate with the evolution of other marginal seas

This session features studies on the climatic and marine history of the Gulf of California and its connections to the global climate and ocean system, utilizing multidisciplinary geological, micropaleontological, geochemical, and numerical modeling proxies.

Thursday, 23 April 2026
9:30 AM - 12:00 PM
LMH, Deli

The Pliocene-Holocene shark and ray fauna of the Baja California Peninsula and its paleoceanographic and paleoclimatic implications for the history of the Gulf of California

Paper number: 17-8
Program: Technical Sessions
Time: 11:20 AM – 11:35 AM

Authors

Abstract

A diverse, yet poorly documented chondrichthyan fauna is represented among several locations of Pliocene through Holocene age on the Baja California Peninsula. These include San Francisquito in southeastern Baja California (Pliocene), Santa Rosalía and Punta Chivato in northeastern Baja California Sur (Pliocene and Pleistocene), Carmen and San José Islands (Pliocene), Cueva del León southeast of La Paz (Pliocene), and San José del Cabo Basin (Pliocene). Finally, the archaeozoological record of the El Conchalito site in the bay of La Paz provides a Holocene snapshot of chondrichthyans in the Gulf of California.

The Gloria (Pliocene) and Infierno (Pleistocene) formations of Santa Rosalía Basin represent the most diverse, abundant, and most studied shark fauna in the region. This is followed by the Refugio Formation (Pliocene) of the San Jose del Cabo Basin. The faunas of the other locations are generally poorer in diversity and abundance, although the presence of Carcharodon carcharias, the great white shark, stands out in most. This species has recent records in the Gulf and is indicative of more temperate conditions, perhaps associated with upwelling. However, species such as Carcharhinus leucas, the bull shark, and Galeocerdo cuvier, the tiger shark, still present in the Cabo Pulmo area, were very abundant in the faunas of the islands and near Santa Rosalía, indicating more tropical climatic conditions. The species Otodus megalodon and Hemipristis serra, present in many of the locations, are extinct species, with last occurring in rocks of late Pliocene age, although the genus Hemipristis survives in the Indian Ocean today.

The most common ray records correspond to the genera Myliobatis, Rhinoptera, Aetobatus, and Hypanus (Dasyatis). In general, they represent a mixture of tropical and temperate conditions, demonstrating that the paleoceanography of the Gulf has been variable in both space and time since the Pliocene.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3

doi: 10.1130/abs/2026CD-411064

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