Two years ago, I wrote a short ScienceNOW piece about Poposaurus and a monograph describing the creature’s postcranial skeleton. Even though the 225 million year old archosaur was named almost a century ago, it has only been recently that more complete individuals have shown how strange Poposaurus truly was.

In the big picture of archosaur evolution, Poposaurus was a pseudosuchian – a group solely represented by alligators, crocodiles, and gharials today, but encompassed a surprising and frightening array of related lineages in the deep past. Roughly, the pseudosuchians are “croc-line archosaurs.” The group not only includes scattered modern species, but totally extinct groups such as the “armadillodile” aetosaurs, terrifying rauisuchians, and the strange lineage of animals that