Kaatedocus was a sauropod dinosaur that lived during the Jurassic Period in North America. It was the ancestor of the more famous Diplodocus, and one feature that makes it recognizable is its "toothy smile".
In 1934, paleontologist Barnum Brown, who also first discovered Tyrannosaurus rex on 1902, lead an expedition in the Morrison Formation in Wyoming to uncover new dinosaur fossils. This lead him to uncover over 3,000 bones of sauropod dinosau
rs. Unfortunately the expedition was cancelled the next year and many of the bones were lost in a fire at the American Museum of Natural History. Only about 10% of the bones survived, part of it in
cluding a fully-complete skull. At first they were thought to have belonged to another large sauropod called Barosaurus, but a closer analysis in 2012 by Emanuel Tschopp and Octavio Mateus revealed that it was in fact its own species. It was named Kaatedocus siberi, which means "Siber's small Diplodocus".
Kaatedocus is rather small by sauropod standards, only growing 12 to 14 m (40 to 46 ft) long and roughly 8 tons in weight, comparing that to its descendant Diplodocus, which grew to be over 27 m (90 ft) long and 20 tons in weight, and you can see how much smaller it is. It was one of the earlier sauropods, coming from the earlier Jurassic approximately 150 million years ago. It looks a lot like its descendant Diplodocus, having the same long neck, horizontal body, and whip-like tail, but unlike its relative it had a very toothy grin. Its teeth were much lar
ger than other diplodocids, and were designed to strip plants like ferns instead of chew their food. Like other diplodocids, they weren't as heavily-built as other sauropods, but were relatively very long animals. They couldn't move very fast, but its size protected it from most predators. It had four pillar-like legs that were built to support its massive size instead of sprint away quickly. Like other sauropods, Kaatedocus had a small head on a very long neck, travelled in herds, and swallowed stones called gastroliths to grind their food for them.