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Showing posts from 2016

Top 10 scientifically important theropod dinosaurs of all time (off the top of my head)

I thought I'd do a fun post for once. And since list based articles are the norm for fun on the internet, I thought I'd do one on dinosaurs, but given that I know most about theropods, I've decided to restrict my list to theropods (...maybe in a future post, I'll do other clades). My ranking is based mostly on scientific importance so it may not reflect awesomeness, and it is obviously subjective as to how I rank importance to science. For instance, interesting discoveries or unique palaeobiology are ranked relatively low compared to wealth of information and data or completely revolutionising our understanding of the evolution of theropods. So here are my top 10 scientifically important theropod dinosaurs of all time (off the top of my head) 10. Megalosaurus Being the first dinosaur to be named, Megalosaurus automatically deserves a spot on this list, but given the fragmentary nature of known fossil specimens, and being mostly useless as a meaningful source

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

Hind limb proportions do not support the validity of Nanotyrannus

While it was not the main focus of their paper, Persons and Currie (2016) , in a recent paper in Scientific Reports hinted at the possibility of Nanotyrannus lancensis being a valid taxon distinct from Tyrannosaurus rex , using deviations from a regression model of lower leg length on femur length. Similar to encephalisation quotients , Persons and Currie devised a score (cursorial-limb-proportion; CLP) based on the difference between the observed lower leg length and the predicted lower leg length (from a regression model) expressed as a percentage of the observed value. The idea behind this is pretty simple in that if the observed lower leg length value is higher than that predicted for its size (femur length), then that taxon gets a high CLP score. I don't particularly like this sort of data characterisation (a straightforward regression [albeit with phylogeny, e.g. pGLS] would do the job well), but nonetheless, Persons and Currie found that when applied to Nanotyrannus , it