292-5 Bivalve Fossils of the Earliest Triassic in Central Saudi Arabia: Systematic Paleontology and Paleobiological Analysis

Session: Life and Environments Through Time and Space: Multi-Record Approaches to Stratigraphic Paleobiology, Part II

Presenting Author:

Jood Al Aswad

Authors:

Al Aswad, Jood¹, Hautmann, Michael², Singh, Pulkit³, Lehrmann, Daniel James⁴, Morsilli, Michele Domenico⁵, Koeshidayatullah, Ardiansyah⁶, Payne, Jonathan L.⁷

(1) Stanford University, Stanford, CA, USA, (2) Paleontological Institute & Museum, University Zurich, Zurich, Switzerland, (3) Stanford University, Stanford, CA, USA, (4) Trinity University, San Antonio, TX, USA, (5) Università degli Studi di Ferrara, Ferrara, Italy, (6) King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia, (7) Stanford University, Stanford, CA, USA,

Abstract:

The end-Permian mass extinction (~252 Ma) resulted in the taxonomic and ecological upheaval in benthic marine communities worldwide. To understand how these communities recovered from this extinction event, we require a record of taxonomically identified fossils for the succeeding Early Triassic epoch. However, these attempts are hampered due to the sparseness of the Early Triassic marine fossil record, which is in large part a result of the severe taxonomic loss of the extinction event along with sampling and taphonomic biases or barriers (Erwin, 1998; Foote, 1998; Smith, 2007). In central Saudi Arabia, accessible outcrops exist bearing nearshore benthic macrofauna that have yet to be systematically studied. The Permo-Triassic transition is presumed to be recorded somewhere within the Khartam Member of the Khuff Formation in Saudi Arabia, but the absence of the Hindeodus parvus index fossil makes the exact position of the biostratigraphic boundary poorly constrained. Here, we provide initial descriptions of 6 bivalve species representing 6 genera from the Khartam Member of Saudi Arabia that indicate an earliest Triassic age and illustrate a warm, shallow tidal flat ecosystem over a barred shelf. Our analysis provides context on the approximate stratigraphic position of the Permo-Triassic position in Saudi Arabia and on local variations of the taxonomic composition and depositional environment from which these specimens were sampled. Additionally, we compare the taxonomic and ecological diversity of the Saudi bivalve community with other Early Triassic bivalve communities across the globe to gain a better understanding of the recovery of these communities from the end-Permian mass extinction.

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

doi: 10.1130/abs/2025AM-6846

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.