Selective extinction of apex predators suggests a shift to extra generalist diets.
A world disaster 66 million years in the past led to the extinction of all non-avian dinosaurs, and enormous marine reptiles like mosasaurs and plesiosaurs. However what occurred to the sharks? In line with a research of sharks’ tooth publishing August 10th in the open-access journal PLOS Biology by Mohamad Bazzi of Uppsala College and colleagues, shark-tooth range remained comparatively fixed throughout the mass extinction occasion at the finish of the Cretaceous.
The researchers analyzed the morphology of 1239 fossil shark tooth, together with species in eight present orders and one now-extinct order. The tooth span a 27-million-year interval from the late Cretaceous 83.6 million years in the past to the early Paleogene 56 million years in the past, throughout the so-called Okay-Pg boundary that introduced the age of the dinosaurs to an finish.
The scientists discovered that shark dental range was already declining previous to the Okay-Pg boundary, however remained comparatively fixed throughout the mass-extinction occasion itself. Some teams of apex predators, notably these with triangular blade-like tooth, did undergo selective extinctions throughout the interval studied, which can have been linked to the extinction of their prey species.
Nevertheless, different shark lineages elevated in dental range after the Okay-Pg boundary. For instance, sharks in the Odontaspididae household, which have slender, cusped tooth tailored for feeding on fish, confirmed will increase in range that coincided with the speedy diversification of finned fish in the early Paleogene. The authors recommend this sample of selective extinctions might mirror an ecological shift from specialist tetrapod predators to extra common bony fish diets.
This research is the first world investigation of dental morphology in a number of shark teams throughout the finish Cretaceous mass extinction occasion, and signifies that the Okay-Pg boundary was not as dramatic for sharks, because it was most different vertebrate lineages.
Reference: “Tooth morphology elucidates shark evolution throughout the end-Cretaceous mass extinction” by Mohamad Bazzi, Nicolás E. Campione, Per E. Ahlberg, Henning Blom and Benjamin P. Kear, 10 August 2021, PLoS Biology.
Funding: This work was supported by the Royal Swedish Academy of Sciences (GS2017-0018) to M.B., and a Wallenberg Scholarship from the Knut and Alice Wallenberg Basis to P.E.A. B.P.Okay. additionally acknowledges funding from a Swedish Analysis Council Undertaking Grant (2020-3423), and N.E.C. is funded by an Australian Analysis Council Discovery Early Profession Analysis Grant (DE190101423). The funders had no position in research design, knowledge assortment and evaluation, determination to publish, or preparation of the manuscript.