Raptor's Nest

Extinct horses to scale illustrating differences in size: Left to right: Mesohippus , Neohipparion , Eohippus , Equus scotti and Hypohippus  . (Heinrich Harder, 1914; Public Domain) The evolution of body size has been the focus of countless studies, not only in palaeontology but also in evolutionary biology using data from extant animals (or neontology as palaeontologists would say). While some colleagues have argued recently that body size is not necessarily a good trait to study, nonetheless, it still stands that body size is an important factor of fundamental biological phenomena, including metabolism, physiology, biomechanics, and ecology. For instance, the largest source of variance in biomechanical performance measures like bite force is body size - a lion's bite force is an order or two higher in magnitude than that of a domestic cat just purely out of simple scaling. Similarly, prey size categories, such as large, medium/mixed and small, are highly affected by p...

From Wikimedia Commons (CC BY-SA 3.0) This blog post is way overdue, being mostly written months ago in late Oct. Anyway, it's a bit technical - but it relates to how palaeontologists quantify biodiversity through time (like the famous Sepkoski curve shown above). I have a newish paper ( ‘Residual diversity estimates’ do not correct for sampling bias in palaeodiversity data ) in Methods in Ecology and Evolution,  with Chris Venditti and Mike Benton, that became available in  Early View version  in Oct last year (24 Oct 2016). The paper is very simple and straightforward. In it we assess a popular method that has been used numerous times to 'correct' for sampling bias in palaeobiodiversity data. It is safe to say that most palaeontologists would agree that the fossil record is far from complete and that any kind of tallying of the numbers of species that were present in any given time period would suffer from this incompleteness - biodiversity curves (such as the ...

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 ...

Despite phylogenetic comparative methods being around for a few decades now (see Harvey and Pagel, 1991 for a good introduction), there is still a very strong tendency in comparative studies to report both the phylogenetic and non-phylogenetic comparative analyses. My take on this phenomenon is that researchers are interpreting these two statistical procedures as equally valid alternative approaches , similar to a case where you don't know if one phylogeny is correct over another so you report both sets of results. However, these two examples are not directly comparable, and reporting results from non-phylogenetic comparative analyses alongside results from phylogenetic comparative analyses is wrong. This is simply because non-phylogenetic analyses violate statistical non-independence when data show strong phylogenetic non-independence, while phylogenetic comparative analyses account for this non-independence. It's exactly the same issue with analysing temporally corre...