Science, Tech, Math › Animals & Nature Hypacrosaurus Share Flipboard Email Print Hypacrosaurus surrounding a Rubeosaurus (Sergey Krasovskiy). Animals & Nature Dinosaurs Basics Paleontologists Carnivores Dinosaurs & Birds Herbivores Marine Reptiles Prehistoric Mammals Amphibians Birds Habitat Profiles Mammals Reptiles Wildlife Conservation Insects Marine Life Forestry Evolution View More By Bob Strauss Science Writer B.S., Cornell University Bob Strauss is a science writer and the author of several books, including "The Big Book of What, How and Why" and "A Field Guide to the Dinosaurs of North America." our editorial process Bob Strauss Updated March 30, 2017 Name: Hypacrosaurus (Greek for "almost the highest lizard"); pronounced hi-PACK-roe-SORE-us Habitat: Woodlands of North America Historical Period: Late Cretaceous (70-65 million years ago) Size and Weight: About 30 feet long and 4 tons Diet: Plants Distinguishing Characteristics: Pointed crest; spines growing out from backbone About Hypacrosaurus Hypacrosaurus received its odd name ("almost the highest lizard") because, when it was discovered in 1910, this duck-billed dinosaur was considered second only to Tyrannosaurus Rex in size. Needless to say, it has since been outclassed by numerous other dinosaurs, both herbivorous and carnivorous, but the name has stuck. What sets Hypacrosaurus apart from most other hadrosaurs is the discovery of a complete nesting ground, complete with fossilized eggs and hatchlings (similar evidence has been found for another North American duck-billed dinosaur, Maiasaura). This has allowed paleontologists to piece together a fair amount of information about Hypacrosaurus' growth patterns and family life: for instance, we know that Hypacrosaurus hatchlings attained adult size in 10 or 12 years, far sooner than the 20 or 30 years of the typical tyrannosaur. Like most other hadrosaurs, Hypacrosaurus was distinguished by the prominent crest on its snout (which didn't quite attain the baroque shape and size of, say, the crest of Parasaurolophus). The current thinking is that this crest was a resonating device for funneling blasts of air, allowing males to signal females (or vice-versa) about their sexual availability, or to warn the herd about approaching predators.