A scale drawing of a typical member of the Troodontidae dinosaur family. Picture credit: Everything Dinosaur. The first specimens currently assigned to Troodon that were not teeth were both found by Sternberg in 1928, in the Dinosaur Park Formation of Alberta. The first was named Stenonychosaurus inequalis by Sternberg in 1932, based on a foot, fragments of a hand, and some tail vertebrae. A remarkable feature of these remains was the enlarged claw on the second toe, which is now recognized as characteristic of early paravians. Sternberg initially classified Stenonychosaurus as a member of the family Coeluridae. The second, a partial lower jaw bone, was described by Gilmore (1932) as a new species of lizard which he named Polyodontosaurus grandis. Later, in 1951, Sternberg recognized P. grandis as a possible synonym of Troodon, and speculated that since Stenonychosaurus had a "very peculiar pes" and Troodon "equally unusual teeth", they may be closely related. No comparable specimens were available at that time to test the idea. Evans, D. C.; Cullen, T.M.; Larson, D.W.; Rego, A. (2017). "A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada". Canadian Journal of Earth Sciences. 54 (8): 813–826. Bibcode: 2017CaJES..54..813E. doi: 10.1139/cjes-2017-0034. He told us: “We have no good reliable ways to saying how smart dinosaurs were, only really some rough estimates.

Paul, G.S. (1988). Predatory Dinosaurs of the World. New York: Simon and Schuster. pp. 398–399. ISBN 978-0-671-61946-6. Two things make our paper different from previous contributions on the dinosauroid. One is that – thanks to kind co-operation from Jordan Mallon at the Canadian Museum of Nature – we had full access to Dale Russell’s correspondence. And two is that we corresponded extensively with Ron Séguin. Ron was extremely generous with his time and the material he owns, and provided us with a large amount of information not shared before. I should add that, some years in the past, I corresponded with Dr Russell too, albeit never on the dinosauroid. Russell, D. A. 1989. An Odyssey in Time: the Dinosaurs of North America. University of Toronto Press, Toronto. The first specimens currently assigned to Troodon that were not teeth were both found by Sternberg in 1928, in the Dinosaur Park Formation of Alberta. The first was named Stenonychosaurus inequalis by Sternberg in 1932, based on a foot, fragments of a hand, and some tail vertebrae. A remarkable feature of these remains was the enlarged claw on the second toe, which is now recognized as characteristic of early paravians. Sternberg initially classified Stenonychosaurus as a member of the family Coeluridae. The second, a partial lower jaw bone, was described by Gilmore (1932) as a new species of lizard which he named Polyodontosaurus grandis. Later, in 1951, Sternberg recognized P. grandis as a possible synonym of Troodon, and speculated that since Stenonychosaurus had a "very peculiar pes" and Troodon "equally unusual teeth", they may be closely related. Unfortunately, no comparable specimens were available at that time to test the idea.

But it’s an enticing thought. Douglas Dixon’s book The New Dinosaurs explores how dinosaurs might have adapted to exploit current evolutionary niches. He anticipates dino whales, dino giraffes…but could there be dino humans? A few dinosaurs had relatively big brains for their body size, which implies intelligence but putting that factor alone against modern animals is obviously limiting. Alternative Timeline Dinosaurs, the View From 2019 (Part 3): the Dinosauroid and its Chums, December 2019

a b Sternberg, C.M. (1951). "The lizard Chamops from the Wapiti Formation of Northern Alberta: Polyodontosaurus grandis is not a lizard". Annual Report of the National Museum of Canada Bulletin. 123: 256–258. A more complete skeleton of Stenonychosaurus was described by Dale Russell in 1969 from the Dinosaur Park Formation, which eventually formed the scientific foundation for a famous life-sized sculpture of Stenonychosaurus accompanied by its fictional, humanoid descendant, the "dinosauroid". [1] Stenonychosaurus inequalis is known from the Dinosaur Park Formation of southern Alberta, Canada, which at the time was a warm coastal floodplain covered by temperate forests. Apex predators included tyrannosaurids such as Daspletosaurus and Gorgosaurus. Herbivores included hadrosaurids such as Lambeosaurus, Corythosaurus, and Prosaurolophus; ceratopsids such as Styracosaurus, Centrosaurus, and Chasmosaurus; ankylosaurs such as Scolosaurus, Euoplocephalus, and Edmontonia; and pachycephalosaurs such as Stegoceras and Foraminacephale. Stenonychosaurus teeth, however, are different from most other theropods. One comparative study of the feeding apparatus suggests that Stenonychosaurus could have been an omnivore. [16] The jaws met in a broad, U-shaped symphysis similar to that of an iguana, a lizard species adapted to a plant-eating lifestyle. Additionally, the teeth of Stenonychosaurus bore large serrations, each of which is called a denticle. There are pits at the intersections of the denticles, and the points of the denticles point towards the tip, or apex, of each tooth. The teeth show wear facets on their sides. Holtz (1998) also noted that characteristics used to support a predatory habit for Stenonychosaurus – the grasping hands, large brain and stereoscopic vision, are all characteristics shared with the herbivorous/omnivorous primates and omnivorous Procyon (raccoon).Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs 2nd Edition. Princeton University Press. p.160. ISBN 978-0-691-16766-4. Troodon ( / ˈ t r oʊ . ə d ɒ n/ TROH-ə-don; Troödon in older sources) is a former wastebasket taxon and a potentially dubious genus of relatively small, bird-like theropod dinosaurs definitively known from the Campanian age of the Late Cretaceous period (about 77 mya). It includes at least one species, Troodon formosus, known from Montana. Discovered in October 1855, T. formosus was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877. Several well-known troodontid specimens from the Dinosaur Park Formation in Alberta were once believed to be members of this genus. However, recent analyses in 2017 have found this genus to be undiagnostic and referred some of these specimens to the genus Stenonychosaurus (long believed to be synonymous with Troodon) some to the genus Latenivenatrix, and some to the genus Pectinodon. The genus name is Ancient Greek for "wounding tooth", referring to the teeth, which were different from those of most other theropods known at the time of their discovery. The teeth bear prominent, apically oriented serrations. These "wounding" serrations, however, are morphometrically more similar to those of herbivorous reptiles, and suggest a possibly omnivorous diet. [1] History of discovery [ edit ] Early research [ edit ] 1860 illustration of the T. formosus holotype tooth Currie, P. (2005). "Theropods, including birds." in Currie and Koppelhus (eds). Dinosaur Provincial Park, a spectacular ecosystem revealed, Part Two, Flora and Fauna from the park. Indiana University Press, Bloomington. Pp 367–397. If that unwelcome intruder from outer space hadn’t slammed into our planet 65 million years ago might Russell’s "dinosaurids" have used all this millennia to develop a civilisation far in advance of our own?

In 2011, Zanno and colleagues reviewed the convoluted history of troodontid classification in Late Cretaceous North America. They followed Longrich (2008) in treating Pectinodon bakkeri as a valid genus and noted that it is likely the numerous Late Cretaceous specimens currently assigned to Troodon formosus, but that a more thorough review of the specimens is required. Because the holotype of T. formosus is a single tooth, this renders Troodon a nomen dubium. [3]However, the concept that all Late Cretaceous North American troodontids belong to one single species began to be questioned soon after Currie's 1987 paper was published, including by Currie himself. Currie and colleagues (1990) noted that, while they believed the Judith River troodontids were all T. formosus, troodontid fossils from other formations, such as the Hell Creek Formation and Lance Formation, might belong to different species. In 1991, George Olshevsky assigned the Lance formation fossils, which had first been named Pectinodon bakkeri, but later synonymized with Troodon formosus, to the species Troodon bakkeri, and several other researchers (including Currie) have reverted to keeping the Dinosaur Park Formation fossils separate as Troodon inequalis (now Stenonychosaurus inequalis). [9] Would huge animals such as Tyrannosaurus rex and Triceratops have given rise to an intelligent, technological society like ours? Additional specimens currently referred to Troodon come from the upper Two Medicine Formation of Montana. Troodon-like teeth have been found in the lower Javelina Formation of Texas and the Naashoibito Member of the Ojo Alamo Formation in New Mexico. [25] [26] See also [ edit ]

Did Dinosaurs and Pterosaurs 'Glow'? Extinct Archosaurs and the Capacity for Photoluminescent Visual Displays a b van der Reest, A. J.; Currie, P. J. (2017). "Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with a description of a unique new taxon: implications for deinonychosaur diversity in North America". Canadian Journal of Earth Sciences. 54 (9): 919–935. Bibcode: 2017CaJES..54..919V. doi: 10.1139/cjes-2017-0031. hdl: 1807/78296. In 2021, a more comprehensive re-analysis of the morphology and stratigraphic positions of known skeletal material assigned to Stenonychosaurus and Latenivenatrix determined that several characters described as diagnostic of Latenivenatrix are in fact individually variable, that both taxa overlap stratigraphically, and that Latenivenatrix mcmasterae is a junior synonym of Stenonychosaurus inequalis. [8] This leaves S. inequalis as the only valid troodontid taxon currently identified from the Dinosaur Park Formation.

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Evans, D. C.; Cullen, T. M.; Larson, D. W.; Rego, A. (2017). "A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada". Canadian Journal of Earth Sciences. 54 (8): 813–826. Bibcode: 2017CaJES..54..813E. doi: 10.1139/cjes-2017-0034. Discovered in central Montana in 1855, it was among the first dinosaurs found in North America. Its species ranged widely, with fossil remains recovered from as far north as Alaska, and the Judith River formation of Alberta, and as far south as Wyoming and even possibly Texas and New Mexico. [2] Varricchio et al.(1997) were able to extract enough evidence from the nests to infer several characteristics of troodont reproductive biology. The results are that they appear to have had a type of reproduction that is intermediate between crocodiles and birds, as phylogeny would predict. The eggs are statistically grouped in pairs, which suggests that the animal had two functional oviducts, like crocodiles, rather than one, as in birds. Crocodiles lay many eggs that are small proportional to adult body size. Birds lay fewer, larger, eggs. The Two Medicine troodont was intermediate, laying an egg of about 0.5 kg for a 50 kg adult. This is 10 times larger than reptiles of the same mass, but two troodont eggs are roughly equivalent to the 1.1 kg egg predicted for a 50 kg bird. According to van der Reest and his co-author, University of Alberta Professor Philip Currie, Latenivenatrix mcmasterae and Stenonychosaurus inequalis roamed the Earth around 72 million years ago during the Campanian, the fifth of six ages of the Upper Cretaceous epoch. Varricchio et al. (1997) described the exact structure of the nests. They were built from sediments, they were dish shaped, about 100 cm in internal diameter, and with a pronounced raised rim encircling the eggs. The more complete nests had between 16 (minimum number in MOR 246) and 24 (MOR 963) eggs. The eggs are shaped like elongated teardrops, with the more tapered ends pointed downwards and imbedded about halfway in the sediment. The eggs are pitched at an angle so that, on average, the upper half is closer to the center of the nest. There is no evidence that plant matter was present in the nest.