Lagosuchus (Wikimedia Commons).


Lagosuchus (Greek for "rabbit crocodile"); pronounced LAY-go-SOO-cuss


Woodlands of South America

Historical Period:

Middle Triassic (230 million years ago)

Size and Weight:

About a foot long and one pound



Distinguishing Characteristics:

Tiny size; bipedal posture; long hind legs

About Lagosuchus

Although it wasn't a true dinosaur, many paleontologists believe Lagosuchus may have been the genus of archosaur from which all dinosaurs subsequently evolved. This tiny reptile certainly had plenty of dinosaur-like characteristics, including long legs, large feet, a flexible tail, and (at least some of the time) a bipedal posture, giving it an uncanny similarity to the first theropods of the middle to late Triassic period.

If you doubt that a mighty race of dinosaurs could have evolved from a tiny creature that weighed about a pound, keep in mind that all of today's mammals--including whales, hippopotamuses, and elephants--can trace their lineage back to comparably tiny, shrew-like mammals that scurried under the feet of huge dinosaurs a hundred million years ago! (By the way, among paleontologists, the genus Marasuchus is often used interchangeably with Lagosuchus, since it's represented by more complete fossil remains.)