What's that machine doing in Derring Hall?

It's finding fossils!!

You have stumbled upon the screenwashing machine! This device uses a slow turning wheel to gently rock trays of sediment back and forth to separate mud particles from harder, larger, chunks of sediment and fossils. The sediment is then laid out to dry before being transported upstairs to our prep lab, where students in the Paleo Picker Pals sort through it to look for teeny tiny vertebrate fossils.

What are we finding?

We are currently screenwashing sediment from the Late Triassic of Arizona and Texas, over 200 million years old! Check out some of the microvertebrate fossils below and the animals they represent.

Phytosaurs (croc-like animals)

Phytosaurs might look like crocodiles, but they actually are much older and have their nares (nose) retracted to be way up between their eyes! We often find teeth from these animals in the sediment we wash, and bigger bones when we excavate in the field.

Small bodied reptiles

The triassic was filled with unique small reptiles like drepanosaurs, which had tails tipped with sharp claws, tanystrophieds, which had necks like giraffes, and lepidosauromorphs, which are relatives of living lizards.

Screen Shot 2025-02-04 at 12.07.51 PM.png

Fish and Sharks

The ecosystems we study (though now deserts) were once full of streams and lakes, and those bodies of water were full of fish and freshwater sharks called hybodonts! The teeth of these sharks are very common in our screenwashed sediment, as are the scales of redfieldiid fish.

and more!

aetosaur

phytosaur

metoposaur

vancleavea

raiusuchian

drepanosaur

pterosaur

coelocanth

cynodont

dinosauromorph

lunfish

shark

Mural by Victor Leshyk at the Rainbow Forest Museum at Petrified Forest National park depicting the amazing reptile communities of the Late Triassic in the southwest United States.