Fossil Friday: The Sudden Appearance of Crocs in the Triassic Fossil Record
This Fossil Friday we will look at a clade of reptiles that is called Pseudosuchia, which includes living crocodiles and their fossil relatives such as the featured Postosuchus from the Late Triassic of Texas. Like so many other groups, pseudosuchians appeared very abruptly in the Early Triassic period after the ‘Great Dying’ of the end-Permian mass extinction event about 250 million years ago.
Just a few weeks ago a new fossil poposauroid pseudosuchian was described from the Middle Triassic Favret Formation in Nevada (Smith et al. 2024). The new genus received the almost unpronounceable name Benggwigwishingasuchus. The find was very surprising, because only marine organisms (e.g., ichthyosaurs and ammonites) were previously known from these sediments, which have been produced in an open sea environment. A co-author of the study remarked that their first reaction was “What the hell is this?” (Baisas 2024). They certainly did not expect to find a terrestrial animal in these layers, but the well-preserved leg bones left no doubt that this reptile lacked any secondary aquatic adaptations and had a primarily terrestrial mode of life (Klein 2024). Because the preservation of the skeleton suggests a minimal post-mortem transport, the researchers suppose that it lived along the shores of the ancient Panthalassan Ocean. The authors concluded that the new discovery “implies a greater undiscovered diversity of poposauroids during the Early Triassic, and supports that the group, and pseudosuchians more broadly, diversified rapidly following the End-Permian mass extinction” (Smith et al. 2024). They also emphasize that more generally “recent studies have inferred a rapid diversification of archosaurs and their stem lineages, which established major clades by the end of the Early Triassic” (Smith et al. 2024).
A Kind of “Explosion”
In other words, all the subgroups of archosaurs appeared abruptly in a kind of “explosion,” similar to the sudden appearance of 15 different families of marine reptiles in the Early Triassic (Bechly 2023a), or the sudden appearance of different groups of gliding and flying reptiles during the Middle Triassic (Bechly 2023b). Also, dinosaurs appeared so suddenly in the Late Triassic that one expert commented that “it’s amazing how clear cut the change from ‘no dinosaurs’ to ‘all dinosaurs’ was” (University of Bristol 2018). And famous paleontologist Peter Ward (2006: 160) explained that “the diversity of Triassic animal plans is analogous to the diversity of marine body plans that resulted from the Cambrian Explosion.” The Triassic period proves to be a real carpet bombing of bursts of biological creativity (Bechly 2024), which does not resonate well with a Darwinian paradigm at all.
References
Baisas L 2024. Say hello to the surprising crocodile relative Benggwigwishingasuchus eremicarminis. Popular Science July 11, 2024. https://www.popsci.com/science/triassic-crocodile/
Bechly G 2023a. Fossil Friday: The Triassic Explosion of Marine Reptiles. Evolution News March 31, 2023. https://evolutionnews.org/2023/03/fossil-friday-the-triassic-explosion-of-marine-reptiles/
Bechly G 2023b. Fossil Friday: The Explosive Origin of Flying Reptiles in the Mid Triassic. Evolution News May 19, 2023. https://evolutionnews.org/2023/05/fossil-friday-the-explosive-origin-of-flying-reptiles-in-the-mid-triassic/
Bechly G 2024. Fossil Friday: Discontinuities in the Fossil Record — A Problem for Neo-Darwinism. Evolution News May 10, 2024. https://evolutionnews.org/2024/05/fossil-friday-discontinuities-in-the-fossil-record-a-problem-for-neo-darwinism/
Klein N 2024. Diverse growth rates in Triassic archosaurs—insights from a small terrestrial Middle Triassic pseudosuchian. The Science of Nature 111:38, 1–5. DOI: https://doi.org/10.1007/s00114-024-01918-4
Smith ND, Klein N, Sander PM & Schmitz L 2024. A new pseudosuchian from the Favret Formation of Nevada reveals that archosauriforms occupied coastal regions globally during the Middle Triassic. Biology Letters 20(7):20240136, 1–8. DOI: https://doi.org/10.1098/rsbl.2024.0136
University of Bristol 2018. Dinosaurs ended – and originated – with a bang! University of Bristol press release April 16, 2018. http://www.bristol.ac.uk/news/2018/april/dinosaurs-ended-and-originated-with-a-bang-.html
Ward PD 2006. Out of Thin Air. Joseph Henry Press, Washington DC, 296 pp. https://books.google.at/books?id=baJVAgAAQBAJ
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