Portal:Mesozoic

Edmontosaurus is a genus of crestless duck-billed dinosaur. The fossils of this animal have been found in rocks of western North America that date from the late Campanian stage to the end of the Maastrichtian stage of the Cretaceous Period, between 73 and 65.5 million years ago. It was one of the last non-avian dinosaurs, and lived shortly before the Cretaceous–Paleogene extinction event. Edmontosaurus was one of the largest hadrosaurids, measuring up to 13 meters (43 ft) long and weighing around 4.0 metric tons (4.4 short tons). It is known from several well-preserved specimens that include not only bones, but in some cases extensive skin impressions and possible gut contents.

Edmontosaurus has a lengthy and complicated taxonomic history dating to the late 19th century. The type species, E. regalis, was named by Lawrence Lambe in 1917, although several other species that are now classified in Edmontosaurus were named earlier. The best known of these is E. annectens, originally named by Othniel Charles Marsh in 1892.

Edmontosaurus was widely distributed across western North America. The distribution of Edmontosaurus fossils suggests that it preferred coasts and coastal plains. It was an herbivore that could move on both two legs and four. Because it is known from several bone beds, Edmontosaurus is thought to have lived in groups, and may have been migratory as well. (see more...)

There have been a number of potential species assigned to the carnosaurian dinosaur genus Allosaurus since its description in 1877 by Othniel Charles Marsh, but only a handful are still regarded as valid. Allosaurus was originally described from material from the Upper Jurassic Morrison Formation of the western United States of America; the type species A. fragilis became one of the best-known species of dinosaur.

The genus Allosaurus was part of the Marsh/Cope "Bone Wars" of the late 19th century, and its taxonomy became increasingly confused due to the competition, with several genera and species named by Cope and Marsh now regarded as synonyms of Allosaurus or A. fragilis. Since the description of Allosaurus, scientists have proposed additional species from such far-flung locales as Portugal, Siberia, Switzerland, and Tanzania, and unnamed remains from Australia and China have also been assigned to the genus at one time or another. (see more...)

• ... that the Late Cretaceous madtsoiid snake Sanajeh preyed on hatchling sauropod dinosaurs at nesting sites in India?
• ... that Nanoraphidia electroburmica, known from a fossil in amber, is the smallest known snakefly species, living or extinct?
• ... that Ororaphidia and Styporaphidia are the oldest snakeflies known from China, dating from the Middle Jurassic?
• ... that fossils of the temnospondyl amphibian Kourerpeton were notoriously discovered in the window of a barber's shop in Arizona?
• ... that the extinct snakefly genus Proraphidia is known from fossils found in Spain, England, and Kazakhstan?

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