The Rise & Possible Immediate Fall of the Ornithoscelida

Last week, the world was stunned by a new paper by Baron, Norman & Barrett (2017) that challenged Seeley's 130-year-old dichotomy of the Dinosauria. No longer were Saurischia and Ornithischia neatly separated. Instead, ornithischians were the sister group of theropods in a united Ornithoscelida, and sauropodomorpha (which now included Herrerasauridae as its most basal member) were spun off on their own in a weirdly lonesome Saurischia.

I spent several days writing a very lengthy post about this subject, as I considered it interesting and important. I also haven't really found the thesis statement for my WIP article on thalattosaurs.

Here's a link to the unfortunately-paywalled Nature paper. It's not difficult to find online through various channels (or just email the authors).

The immediate response from the paleo community was encouraging. People seemed to like this idea. It was novel and based on an impressively large dataset. Darren Naish wrote a good summary of the research over at TetZoo, which I recommend reading.

Then Mickey Mortimer took a look at it and seemed okay with it at first, apart with disagreements about what taxa to use when revising group definitions.

But the next day, things took a turn.

Long story short, the dataset might not be reliable. In my original three-page-long post, I'd ended things by asking whether this New Dinosauria would withstand further testing and scrutiny. Looks like we're going to find out sooner rather than later.