This extinction at the Cretaceous–Paleogene (K-Pg) was complicated than straight away wipe out of dinosaurs. A recent study published in Proceedings of the National Academy of Sciences by Manabu Sakamoto (post doctoral fellow, University of Reading) Michael J. Bentonb (University of Bristol), and Chris Vendittia (University of Reading) challenges the existing theory. With their novel approach to statistically analyze the speciation and extinction, the researchers resorted to Bayesian phylogenetic approach to study the dynamics model for three subclades of dinosaurs: Ornithischia (beaked herbivores), Sauropodomorpha (long-necked plant-eaters), and Theropoda (flesh-eaters).
The reason of the decline is suspected to be the transformation of Earth due to deadly tectonic shifts during the Cretaceous period (145.5 million-65.5 million years ago), though the researchers are not sure of it.
In a drastic geological change, Earth’s two supercontinents was falling apart, climate was cooling down, sea level was fluctuating and persistent volcanic activity prevailed. Simultaneously, India’s Deccan Traps saw eruption of megavolcanoes that might have driven the dinosaurs extinctions, as suggested by Gerta Keller (Professor of Geoscience, Princeton University). These events, consequently, lead to the attenuation of the habitat of dinosaurs. According to Sakamoto and Venditti, “Any combination of these processes could have affected dinosaur speciation”. The authors believe that the dinosaurs were probably under stress for a prolonged period.
Disagreeing to this latest finding, Stephen Brusatte (Palaeontologist, University of Edinburgh) says the decline was “very, very plausible” but that doesn’t mean dinosaurs were “wasting away” towards the extinction, as reported by The Guardian. He believes, however, that they could have bounced back.
As said by Stephen “It may be that the effects of the asteroid were a bit worse because you had dinosaurs that maybe weren’t as strong in an evolutionary sense as they once had been,” he said. “But I think if there was no asteroid you would still have dinosaurs around today.”
The above post is reprinted from materials provided by National Academy of Sciences written By Swati Shikha.