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Showing posts from April, 2016

Putting dinosaur decline into context

It is probably safe to say that to many, the idea that dinosaurs were slowly in decline , or that they weren't 'evolving' as fast as they should have been, is an uncomfortable thought. I thought some context will make this idea easier to appreciate. Palaeontologists are generally happy to say that Velociraptor is a very close relative of birds. It is morphologically very similar to birds, and there is even strong evidence that it possessed secondary feathers on its forearms ( Turner et al., 2007. Science 317 : 1721 ). Velociraptor lived during the Campanian Stage of the Late Cretaceous, 83.6 - 72.1 million years ago (Ma). Velociraptor from Wikimedia Commons On the other hand, the oldest bird known to date, Archaeopteryx , is known from the Tithonian Stage of the Late Jurassic, 152.1 - 147.7 Ma. Archaropteryx as a Blue Jay Archaeopteryx with red plumage So that's on average about 72 million years (Myr) between these two dinosaurs, with a

Dinosaurs in decline tens of millions of years before their final extinction - new paper in PNAS

There is no dispute that non-avian dinosaurs went extinct at the Cretaceous-Paleogene (K-Pg) boundary, most likely owing to a large asteroid hitting the Earth, but what has been debated for decades is whether dinosaurs were reigning strong up to the end of the Cretaceous, or whether they were already in decline and were on their way out only to be killed off by the asteroid impact 66 million years ago (Ma). That is the question that Mike Benton, Chris Venditti and I hopefully helped resolve with our new paper that came out electronically Monday in PNAS. The paper is pretty straightforward, and we provided lots of details in the supplementary information, so it shouldn't be a difficult read. Please do have a read . Below I provide a brief summary. 1. Previous studies The majority of previous studies dealt with counting the number of dinosaur species in geologically defined time bins (such as geological stages), charting the resulting diversity curve through time, and making