Mosasaurs have become all the rage lately with the release (and immense popularity) of Jurassic World. Purely by coincidence I had a commission for a mosasaur, Tylosaurus pembinensis. I hadn't done a mosasaur before (or any lizards), but I'm reasonably familiar with squamate osteology so I figured it wouldn't be nearly as far "out there" as say doing a skeletal of an actinopterygian fish. But it turns out that when it comes to their tail fins, science is still in the middle of telling the mosasaurs' tale...Read More
As most of you reading this will know, I've written two posts on Spinosaurus - the first one questioned the proportions of the composite skeleton that recently gained fame through a paper in Science, the second one discussing a photo that has been used for and against those proportions. In the comments section on the second post Nizar Ibrahim wrote a length response, which (with his kind permission) I would like to elevate to a full post. As is often true in these debates there are parts I agree with and others I disagree with, but I will address those at a future date. For now I think it's only fair to give their comments the floor...Read More
In my previous post on the proportions of the new Spinosaurus material I argued that the pelvis and legs are not nearly as reduced in size as the composite skeletal in Ibrahim, et al., (2014) implies. Theropod-worker extraordinaire and all-around swell guy Thomas Holtz mentioned a photo (seen at left) that could serve as a sort of independent visual line of evidence that the pelvis and legs of the new Spinosaurus specimen are shorter than other theropods, and potentially shorter than I calculated from the supplementary data. I think it's worth taking a closer look...Read More
Today, after weeks of rampant internet speculation the new-look Spinosaurus was revealed. And it certainly didn't disappoint: the paper by Ibrahim et al. musters a range of evidence from bone density, bone isotope data, facial innervation, osteology, etc., to suggest that Spinosaurus not only was a fish-eater (i.e. piscivorous) but was adaptive to that lifestyle to a greater degree than other known spinosaurids. Not only do they claim that Spinosaurus spent most of its life swimming in the water with adaptations that would rival early whales, but Ibrahim et al. specifically claim that the altered limb proportions would require Spinosaurus to have been an obligate quadruped on land, a first for a theropod.
Unfortunately, there seems to be something fishy with those new proportions...Read More