Selective termination of peak predators recommends a shift to more generalist diet plans.
A worldwide disaster 66 million years ago resulted in the termination of all non-avian dinosaurs, and big marine reptiles like mosasaurs and plesiosaurs. But what occurred to the sharks? According to a research study of sharks’ teeth publishing August 10th in the open-access journal PLOS Biology by Mohamad Bazzi of Uppsala University and associates, shark-tooth variety stayed reasonably consistent throughout the mass termination occasion at the end of the Cretaceous.
The scientists evaluated the morphology of 1239 fossil shark teeth, consisting of types in 8 existing orders and one now-extinct order. The teeth cover a 27-million-year duration from the late Cretaceous 83.6 million years back to the early Paleogene 56 million years ago, throughout the so-called K-Pg border that brought the age of the dinosaurs to an end.
Late Cretaceous (Campanian) shark teeth from the Kristianstad Basin, southern Sweden. Credit: Benjamin Kear, Bazzi M et. al, PLOS Biology, 2021
The researchers discovered that shark oral variety was currently decreasing prior to the K-Pg border, however stayed reasonably consistent throughout the mass-extinction occasion itself. Some groups of peak predators, especially those with triangular blade-like teeth, did suffer selective terminations throughout the duration studied, which might have been connected to the termination of their victim types.
However, other shark family trees increased in oral variety after the K-Pg border. For example, sharks in the Odontaspididae household, which have narrow, cusped teeth adjusted for eating fish, revealed boosts in variety that accompanied the fast diversity of finned fish in the early Paleogene. The authors recommend this pattern of selective terminations might show an eco-friendly shift from expert tetrapod predators to more basic bony fish diet plans.
This research study is the very first international examination of oral morphology in numerous shark groups throughout completion Cretaceous mass termination occasion, and suggests that the K-Pg border was not as remarkable for sharks, as it was most other vertebrate family trees.
Reference: “Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction” by Bazzi M, Campione NE, Ahlberg PE, Blom H, Kear BP, 10 August 2021, PLoS Biology.
DOI: 10.1371/journal.pbio.3001108
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 Foundation to P.E.A. B.P.K. likewise acknowledges financing from a Swedish Research Council Project Grant (2020-3423), and N.E.C. is moneyed by an Australian Research Council Discovery Early Career Research Grant (DE190101423). The funders had no function in research study style, information collection and analysis, choice to release, or preparation of the manuscript.
