Poposaurus, Postosuchus, and the Dinosaur Mimic Croc Walk

by Brian Switek

Poposaurus walked like a dinosaur. That’s weird, because the Triassic critter wasn’t a dinosaur at all, but a peculiar archosaur more closely related to crocodiles. Even though paleontologists traditionally thought that dinosaurs had an immediate edge over all over forms of Triassic life thanks to muscular legs held close together right beneath their bodies, rather than sprawled out to the sides, there were also croc copycats that cramped dinosaurian style.

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 Poposaurus belonged to, called poposauroids, which included bipedal herbivores and sail-backed carnivores such as Arizonasaurus in their ranks…

(read more: National Geo - Laelaps)

(images: T - Smokey bjb | Wikipedia; M - Jonathan Weinbaum; B - Dallas Krentzel | Wikipedia)

  1. abbysambles reblogged this from rhamphotheca
  2. jurassicturtle reblogged this from rhamphotheca
  3. shadowboy378 reblogged this from rhamphotheca
  4. pestobutterfoot-fallen-angel reblogged this from rhamphotheca
  5. migratingmeanders reblogged this from rhamphotheca
  6. man-is-the-measure reblogged this from peakedmuscle
  7. mollisaurus reblogged this from tyrannosaurslair
  8. aurusallos reblogged this from tyrannosaurslair
  9. tyrannosaurslair reblogged this from pseudosuchia
  10. mythicalskeletons reblogged this from pseudosuchia
  11. cabooscarytops reblogged this from pseudosuchia
  12. peakedmuscle reblogged this from pseudosuchia
  13. noxtheox reblogged this from pseudosuchia
  14. pseudosuchia reblogged this from rhamphotheca
  15. sinovenator-archive reblogged this from rhamphotheca
  16. hymmnal reblogged this from funguszone and added:
    hehe Poposaurus
  17. funguszone reblogged this from skeleton-magnus
  18. skeleton-magnus reblogged this from rhamphotheca
  19. elementaleternal reblogged this from mawoffenris
  20. mawoffenris reblogged this from ayatollahofrockandrollah
  21. ayatollahofrockandrollah reblogged this from rhamphotheca
  22. pleasedonthitmemommy reblogged this from darthpod
  23. thecuttlefishblues reblogged this from scientificillustration