Struthiomimus altus, S. sedens
Name: Struthiomimus altus, S. sedens
Name Meaning: Ostrich Mimic
First Described: 1917
Described By: Osborn
Classification: Dinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoriformes, Ornithomimosauria, Ornithomimidae, Ornithomiminae
Struthiomimus is, arguably, the best known ornithomimosaur, and the most famous. It is known from many individuals and lived primarily in the USA and Canada. S. altus is known mainly from the Dinosaur Park Formation in Alberta, Canada, dating back to the Campanian age of the Late Cretaceous, about 75 million years ago. S. sedens is known from the Lance and Hell Creek Formations in the United States, dating to the Maastrichtian age of the Late Cretaceous, about 66 million years ago. Finally, a third species which has not yet been named was found in the Horseshoe Canyon Formation in Canada, dating to 70 million years ago in the early Maastrichtian age of the Late Cretaceous. This third species differed from the other two in having more slender hands. S. sedens was the largest of the three, similar in size to Gallimimus, about 5 meters long. S. altus was about 4.3 meters long.
Struthiomimus was actually one of the first theropods imagined with a horizontal posture that we think of them in today, rather than the vertical one common to many early examples of palaeoart. It had a keratinous, toothless beak that could have been used for a variety of feeding strategies. It could have been used to selectively browse in trees, or to pick out grubs and insects, or to better grab small reptiles and animals. It also could have been a filter feeder. The modern consensus seems to be that it was an omnivore. Its hands could have functioned at hooks or clamps, sort of like the hands of sloths, to bring branches and ferns within reach. It had powerful, well structured legs, allowing it to run away from predators at speeds between 50 and 80 km/h (31 and 50 mph). And it needed this speed - it lived alongside large tyrannosaurs such as Albertosaurus and Tyrannosaurus, and dromaeosaurs like Dromaeosaurus, as well as many herbivores such as Chasmosaurus, Euoplocephalus, and Edmontosaurus.
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