page_title: Hypacrosaurus
section_title: Species
hierarchical_section_title: Hypacrosaurus / Discovery and history / Species
caption_attribution_description: The holotype skull of Hypacrosaurus stebingeri, collected in Glacier County, Montana, at the Museum of the Rockies in Bozeman, Montana. A holotype is the "type specimen" -- that first specimen ever found which is used to describe the entire species. Hypacrosaurus is a duckbilled dinosaur with a hollow crest on its head. It was discovered in 1910 in Alberta, and named Hypacrosaurus altispinus. In 1994, Hypacrosaurus stebingeri was discovered in Montana. Scientists quickly realized that many H. altispinus juveniles were rally H. stebingeri instead. Shortly thereafter, a vast amount of Hypacrosaurus stebingeri baby, juvenile, and egg were discovered in Glacier County -- the largest collection of baby skeletal material of any hadrosaur yet discovered. Once obscure, Hypacrosaurus stebingeri is now a star, baby!
context_page_description: Hypacrosaurus was a genus of duckbill dinosaur similar in appearance to Corythosaurus. Like Corythosaurus, it had a tall, hollow rounded crest, although not as large and straight. It is known from the remains of two species that spanned 75 to 67 million years ago, in the Late Cretaceous of Alberta, Canada, and Montana, United States, and is the latest hollow-crested duckbill known from good remains in North America. It was an obscure genus until the discovery in the 1990s of nests, eggs, and hatchlings belonging to H. stebingeri.
context_section_description: H. altispinus, the type species, is known from 5 to 10 articulated skulls with some associated skeletal remains, from juvenile to adult individuals found in the Horseshoe Canyon Formation. H. stebingeri is known from an unknown but substantial number of individuals, with an age range of embryos to adults. The hypothesis that H. altispinus and H. stebingeri form a natural group excluding other known hadrosaur species may be incorrect, as noted in Suzuki et al.'s 2004 redescription of Nipponosaurus; their phylogenetic analysis found that Nipposaurus was more closely related to H. altispinus than H. stebingeri was to H. altispinus. This was rejected by Evans and Reisz (2007), though.
  The new species Hypacrosaurus stebingeri was named for a variety of remains, including hatchlings with associated eggs and nests, found near the top of the late Campanian (Upper Cretaceous) Two Medicine Formation in Glacier County, Montana, and across the border in Alberta. These represent "the largest collection of baby skeletal material of any single species of hadrosaur known".
caption: H. stebingeri holotype skull
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