Stenonychosaurus (North American Dinosaurs)

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Troodontids are known from both Asia and North America, the most complete specimens come from Upper Jurassic Strata of China, Lower Cretaceous strata of China (western Liaoning Province) and the Cretaceous of Mongolia. In contrast, troodontids from the western hemisphere, specifically Mexico, USA and Canada are very poorly known with a very fragmentary fossil record. Previously unassigned fossils from the lower part of the Dinosaur Park Formation have now been assigned to the resurrected troodontid species Stenonychosaurus inequalis. It’s about 50% larger than any other troodontids previously known, making it one of the largest deinonychosaurs (raptor-like dinosaurs) we currently recognize.” It’s not an essential or inevitable effect of evolution: elephants, dolphins, pigs and crows – those airborne descendants of the dinosaurs – are all impressively intelligent creatures that have never needed to make the leap to using technology. There has been a lot of debate about which specimens, all very incomplete, should be called Troodon. The genus now includes specimens previously classified as Stenonychosaurus.

Their eyes were very large (perhaps suggesting a partially nocturnal lifestyle), and slightly forward facing, giving Stenonychosaurus some degree of depth perception. [12] Brain and inner ear [ edit ] Restoration

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They were probably carnivorous, but details of their teeth are a bit unusual. Some experts suggest they may have included plant material in their diet, but this is not a majority view. Holtz, Thomas R., Brinkman, Daniel L., Chandler, Christine L. (1998) Denticle Morphometrics and a Possibly Omnivorous Feeding Habit for the Theropod Dinosaur Troodon. Gaia number 15. December 1998. pp. 159-166. Russell, D. A. 2009 Islands in the Cosmos: the Evolution of Life on Land. Indiana University Press, Bloomington & Indianapolis. 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 Russell, D. A. (1987). "Models and paintings of North American dinosaurs." In: Czerkas, S. J. & Olson, E. C. (eds) Dinosaurs Past and Present, Volume I. Natural History Museum of Los Angeles County/University of Washington Press (Seattle and Washington), pp.114–131.

Stenonychosaurus (meaning "narrow claw lizard") is a genus of troodontid dinosaur from the Late Cretaceous Dinosaur Park Formation of Alberta, Canada, as well as possibly the Two Medicine Formation. The type and only species, S. inequalis, was named by Charles Mortram Sternberg in 1932, based on a foot, fragments of a hand, and some caudal vertebrae from the Late Cretaceous of Alberta. S. inequalis was reassigned in 1987 by Phil Currie to the genus Troodon, which was reverted by the recognition of Stenonychosaurus as a separate genus from the possibly dubious Troodon in 2017 by Evans et al. and also later in the same year by Van der Reest and Currie.In 2011, another derived troodontid, Linhevenator, was described from Inner Mongolia. It was noted by the authors as having relatively short and robust forelimbs, along with an enlarged second pedal ungual akin to that of the dromaeosaurids compared to more basal troodontids. It was proposed that derived troodontids had convergently evolved dromaeosaurid-style large second pedal unguals, likely as an adaptation relating to predation. The authors noted that it is plausible that this may be applicable to other derived troodontids, including Troodon, although this is currently uncertain due to a paucity of sufficient remains of the latter genus. [16] Communal nesting [ edit ] SPECULATION: Some scientists believe dinosaurs would eventually have achieved full sentience (Image: Canadian Museum of Nature / Getty) In 2014, University of Alberta paleontology student Aaron J. van der Reest discovered an intact troodontid pelvis in Dinosaur Provincial Park, leading him to take a closer look at previously collected troodontid cranial bones from southern Alberta. Troodons size ranged widely. In general, individuals that lived further north were larger than those that lived in more southern areas. Troodons in Alaska were especially large, up to 12 feet long, 5 feet tall, and weighing up to 175 pounds. Meanwhile, Troodons that lived in more southern locations were only around 7 feet long, 3 feet tall, and weighed up to 50 pounds, about the size of a Velociraptor. Very likely Troodon had feathers, but no fossil evidence for feathers has yet been found.

Currie, P. J. (1987). "Bird-like characteristics of the jaws and teeth of troodontid theropods (Dinosauria, Saurischia)". Journal of Vertebrate Paleontology. 7: 72–81. doi: 10.1080/02724634.1987.10011638. Russell, D. A. 1989. An Odyssey in Time: the Dinosaurs of North America. University of Toronto Press, Toronto. 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. He goes on to envision a "dinosauroid" with a shorter muzzle and chillingly similar to contemporary popular representations of UFO pilots.

Troodontids had semi-manipulative fingers, able to grasp and hold objects to a certain degree, and binocular vision. [8] Russell proposed that his "Dinosauroid", like members of the troodontid family, would have had large eyes and three fingers on each hand, one of which would have been partially opposed. Russell also speculated that the "Dinosauroid" would have had a toothless beak. As with most modern reptiles (and birds), he conceived of its genitalia as internal. Russell speculated that it would have required a navel, as a placenta aids the development of a large brain case. However, it would not have possessed mammary glands, and would have fed its young, as some birds do, on regurgitated food. He speculated that its language would have sounded somewhat like bird song. [8][15]

At Kidadl we pride ourselves on offering families original ideas to make the most of time spent together at home or out and about, wherever you are in the world. We strive to recommend the very best things that are suggested by our community and are things we would do ourselves - our aim is to be the trusted friend to parents.a b c d Russell, D. A.; Séguin, R. (1982). "Reconstruction of the small Cretaceous theropod Stenonychosaurus inequalis and a hypothetical dinosauroid". Syllogeus. 37: 1–43. Latenivenatrix was suggested to be distinguishable from Stenonychosaurus due to the structure of its frontals and metatarsal III, [2] although later analyses found these characters to be individually variable, and also present in specimens of Stenonychosaurus. [1] Description [ edit ] Life restoration with human to scale 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?