Tawa, Postosuchus and Late Triassic Wildfires

New Mexico - Chinle Formation, Late Triassic Period

Recent research shows that the Late Triassic tropics (including modern day New Mexico) experienced frequent wildfires and fluctuating climate extremes, which may have prevented large-bodied herbivorous dinosaurs from dominating and diversifying in the low latitudes. Small theropod dinosaurs like Tawa (pictured here, lower right) existed alongside other types of archosaurs such as the large, carnivorous Postosuchus (pictured here, upper left) in the Triassic tropics, but dinosaurs were relatively rare and less diverse at low latitudes until the more stable climate of the Jurassic Period, 15 million years after relatively large dinosaurs were fairly common in the higher latitudes.

I made this illustration for Earth Archives. Follow Earth Archives here on Tumblr!

[Please don’t use or reproduce without permission, and thanks for viewing!]

Anonymous request (sort of): a Fasolasuchus and some large theropods.

Now, what they actually wanted was said Fasolasuchus (biggest rauisuchid discovered, estimated at 33 feet long max) showing the theropods that they aren’t the only big land predators.

However, I wasn’t exactly able to think of how it’d be accomplishing this, and, well, since it isn’t exactly such a big guy compared to the largest theropods… I sorta came up with this instead.

So here we have Spinosaurus, Tyrannosaurus, and Giganotosaurus all heckling the Fasolasuchus. Please don’t try to use this as a reference for scale, because I’m pretty sure I got it wrong. The frontward view doesn’t help either.

Anyways, to the requestee, sorry for not drawing exactly what you wanted.


Once you Poposaurus, You Can’t Stoposaurus!


Poposaurus is one of those prehistoric reptiles that no one is exactly sure how to classify, and it has been shifted around to a few different groups. It seems like the general consensus now is that this bipedal archosaur is most likely a Rauisuchian, along with awesome creatures like Postosuchus and Polonosuchus.

Unlike most other prehistoric archosaurs (a big ass possibly polyphyletic group of reptiles that includes crocodylomorpha), this creature was bipedal. There were a few other bipedal early archosaurs (here’s a good article by Brian Switek).

They’re known from fossils found throughout the American West, and they were up to 4 m long. As you might assume to look at them, they were swift predators, probably capable of taking down larger and fast moving prey.

Find out more about their relatives here:

illustrations by Smokeybjb and Jeff Martz/National Park Service