HypacrosaurusHypacrosaurus (meaning "near the highest lizard" [Greek υπο-, hypo- = less + ακρος, akros, high], because it was almost but not quite as large as Tyrannosaurus) 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.
Timeline of hadrosaur researchThis timeline of hadrosaur research is a chronological listing of events in the history of paleontology focused on the hadrosauroids, a group of herbivorous ornithopod dinosaurs popularly known as the duck-billed dinosaurs. Scientific research on hadrosaurs began in the , when Joseph Leidy described the genera Thespesius and Trachodon based on scrappy fossils discovered in the western United States. Just two years later he published a description of the much better-preserved remains of an animal from New Jersey that he named Hadrosaurus.
ParasaurolophusParasaurolophus (ˌpærəsɔːˈrɒləfəs,_-ˌsɔːrəˈloʊfəs; meaning "near crested lizard" in reference to Saurolophus) is a genus of hadrosaurid "duck-billed" dinosaur that lived in what is now western North America and possibly Asia during the Late Cretaceous period, about 76.5–73 million years ago. It was a herbivore that could move as both as a biped and as a quadruped. Three species are universally recognized: P. walkeri (the type species), P. tubicen, and the short-crested P. cyrtocristatus. Additionally, a fourth species, P.
CorythosaurusCorythosaurus (kəˌrɪθəˈsɔːrəs; helmeted lizard) is a genus of hadrosaurid "duck-billed" dinosaur from the Late Cretaceous period, about 77–75.7 million years ago, in what is now western North America. Its name is derived from the Greek word κόρυς, meaning "helmet", named and described in 1914 by Barnum Brown. Corythosaurus is now thought to be a lambeosaurine, thus related to Lambeosaurus, Nipponosaurus, Velafrons, Hypacrosaurus, and Olorotitan. Corythosaurus has an estimated length of and has a skull, including the crest, that is tall.
TrachodonTrachodon (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S. It is a historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists. Despite being used for decades as the iconic duckbill dinosaur, the material it is based on is composed of teeth from both duckbills and ceratopsids (their teeth have a distinctive double root), and its describer, Joseph Leidy, came to recognize the difference and suggested limiting the genus to what would now be seen as ceratopsid teeth.
AmurosaurusAmurosaurus (əˌmʊərəˈsɔːrəs; "Amur lizard") is a genus of lambeosaurine hadrosaurid dinosaur found in the latest Cretaceous period (66 million years ago) of eastern Asia. Fossil bones of adults are rare, but an adult would most likely have been at least long. According to Gregory S. Paul, it was about long and weighed about . Russian paleontologists Yuri Bolotsky and Sergei Kurzanov first described and named this dinosaur in 1991. The generic name is derived from the Amur River and the Greek word sauros ("lizard").
StyracosaurusStyracosaurus (stɪˌrækəˈsɔːrəs ; meaning "spiked lizard" from the Ancient Greek styrax/στύραξ "spike at the butt-end of a spear-shaft" and sauros/σαῦρος "lizard") is a genus of herbivorous ceratopsian dinosaur from the Cretaceous Period (Campanian stage), about 75.5 to 74.5 million years ago. It had four to six long parietal spikes extending from its neck frill, a smaller jugal horn on each of its cheeks, and a single horn protruding from its nose, which may have been up to long and wide.
BlasisaurusBlasisaurus is a genus of lambeosaurine hadrosaurid dinosaur from the Late Cretaceous. It is known from a partial skull and skeleton found in late Maastrichtian-age rocks of Spain. The type species is Blasisaurus canudoi, described in 2010 by Penélope Cruzado-Caballero, Xabier Pereda-Suberbiola and José Ignacio Ruiz-Omeñaca, a group of researchers from Spain. The generic name refers to the Blasi 1 site where the fossil was found. The specific epithet honours paleontologist José Ignacio Canudo.
PararhabdodonPararhabdodon (meaning "near fluted tooth" in reference to Rhabdodon) is a genus of tsintaosaurin hadrosaurid dinosaur, from the Maastrichtian-age Upper Cretaceous Tremp Group of Spain. The first remains were discovered from the Sant Romà d’Abella fossil locality and assigned to the genus Rhabdodon, and later named as the distinct species Pararhabdodon isonensis in 1993. Known material includes assorted postcranial remains, mostly vertebrae, as well as from the skull.
NipponosaurusNipponosaurus (meaning "Japanese lizard") is a lambeosaurine hadrosaur from sediments of the Yezo Group, in Sinegorsk on the island of Sakhalin, which was part of Japan at the time of the species' classification. The type and only species is N. sachalinensis, known only from a single juvenile specimen discovered in 1934 and named in 1936, by Takumi Nagao, with further material of the same individual found in 1937. Since then, the taxon has been largely ignored, and its validity has been doubted, with synonymy with other Asian hadrosaurs or status as a nomen dubium being suggested.
