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Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction.
PLoS Biol. 2021 08; 19(8):e3001108.PB

Abstract

Sharks (Selachimorpha) are iconic marine predators that have survived multiple mass extinctions over geologic time. Their prolific fossil record is represented mainly by isolated shed teeth, which provide the basis for reconstructing deep time diversity changes affecting different selachimorph clades. By contrast, corresponding shifts in shark ecology, as measured through morphological disparity, have received comparatively limited analytical attention. Here, we use a geometric morphometric approach to comprehensively examine tooth morphologies in multiple shark lineages traversing the catastrophic end-Cretaceous mass extinction-this event terminated the Mesozoic Era 66 million years ago. Our results show that selachimorphs maintained virtually static levels of dental disparity in most of their constituent clades across the Cretaceous-Paleogene interval. Nevertheless, selective extinctions did impact apex predator species characterized by triangular blade-like teeth. This is particularly evident among lamniforms, which included the dominant Cretaceous anacoracids. Conversely, other groups, such as carcharhiniforms and orectolobiforms, experienced disparity modifications, while heterodontiforms, hexanchiforms, squaliforms, squatiniforms, and †synechodontiforms were not overtly affected. Finally, while some lamniform lineages disappeared, others underwent postextinction disparity increases, especially odontaspidids, which are typified by narrow-cusped teeth adapted for feeding on fishes. Notably, this increase coincides with the early Paleogene radiation of teleosts as a possible prey source, and the geographic relocation of disparity sampling "hotspots," perhaps indicating a regionally disjunct extinction recovery. Ultimately, our study reveals a complex morphological response to the end-Cretaceous mass extinction and highlights an event that influenced the evolution of modern sharks.

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Authors+Show Affiliations

Bazzi M
Subdepartment of Evolution and Development, Department of Organismal Biology, Uppsala University, Uppsala, Sweden.
Campione NE
Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia.
Ahlberg PE
Subdepartment of Evolution and Development, Department of Organismal Biology, Uppsala University, Uppsala, Sweden.
Blom H
Subdepartment of Evolution and Development, Department of Organismal Biology, Uppsala University, Uppsala, Sweden.
Kear BP
Museum of Evolution, Uppsala University, Uppsala, Sweden.

MeSH

AnimalsBiological EvolutionEcosystemExtinction, BiologicalFossilsSharksTooth

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

34375335

Citation

Bazzi, Mohamad, et al. "Tooth Morphology Elucidates Shark Evolution Across the end-Cretaceous Mass Extinction." PLoS Biology, vol. 19, no. 8, 2021, pp. e3001108.
Bazzi M, Campione NE, Ahlberg PE, et al. Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction. PLoS Biol. 2021;19(8):e3001108.
Bazzi, M., Campione, N. E., Ahlberg, P. E., Blom, H., & Kear, B. P. (2021). Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction. PLoS Biology, 19(8), e3001108. https://doi.org/10.1371/journal.pbio.3001108
Bazzi M, et al. Tooth Morphology Elucidates Shark Evolution Across the end-Cretaceous Mass Extinction. PLoS Biol. 2021;19(8):e3001108. PubMed PMID: 34375335.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction. AU - Bazzi,Mohamad, AU - Campione,Nicolás E, AU - Ahlberg,Per E, AU - Blom,Henning, AU - Kear,Benjamin P, Y1 - 2021/08/10/ PY - 2021/01/07/received PY - 2021/07/05/accepted PY - 2021/8/10/entrez PY - 2021/8/11/pubmed PY - 2021/11/19/medline SP - e3001108 EP - e3001108 JF - PLoS biology JO - PLoS Biol VL - 19 IS - 8 N2 - Sharks (Selachimorpha) are iconic marine predators that have survived multiple mass extinctions over geologic time. Their prolific fossil record is represented mainly by isolated shed teeth, which provide the basis for reconstructing deep time diversity changes affecting different selachimorph clades. By contrast, corresponding shifts in shark ecology, as measured through morphological disparity, have received comparatively limited analytical attention. Here, we use a geometric morphometric approach to comprehensively examine tooth morphologies in multiple shark lineages traversing the catastrophic end-Cretaceous mass extinction-this event terminated the Mesozoic Era 66 million years ago. Our results show that selachimorphs maintained virtually static levels of dental disparity in most of their constituent clades across the Cretaceous-Paleogene interval. Nevertheless, selective extinctions did impact apex predator species characterized by triangular blade-like teeth. This is particularly evident among lamniforms, which included the dominant Cretaceous anacoracids. Conversely, other groups, such as carcharhiniforms and orectolobiforms, experienced disparity modifications, while heterodontiforms, hexanchiforms, squaliforms, squatiniforms, and †synechodontiforms were not overtly affected. Finally, while some lamniform lineages disappeared, others underwent postextinction disparity increases, especially odontaspidids, which are typified by narrow-cusped teeth adapted for feeding on fishes. Notably, this increase coincides with the early Paleogene radiation of teleosts as a possible prey source, and the geographic relocation of disparity sampling "hotspots," perhaps indicating a regionally disjunct extinction recovery. Ultimately, our study reveals a complex morphological response to the end-Cretaceous mass extinction and highlights an event that influenced the evolution of modern sharks. SN - 1545-7885 UR - https://www.unboundmedicine.com/medline/citation/34375335/Tooth_morphology_elucidates_shark_evolution_across_the_end_Cretaceous_mass_extinction_ DB - PRIME DP - Unbound Medicine ER -