276°
Posted 20 hours ago

Stenonychosaurus (North American Dinosaurs)

£3.785£7.57Clearance
ZTS2023's avatar
Shared by
ZTS2023
Joined in 2023
82
63

About this deal

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.

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] Stenonychosaurus teeth, however, are different from most other theropods. One comparative study of the feeding apparatus suggests that Stenonychosaurus could have been an omnivore. [15] 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 herbivorous or omnivorous primates and omnivorous Procyon (raccoon). The scientific paper: “Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with a Description of a Unique New Taxon: Implications for Deinonychosaur Diversity in North America” by Aaron J. van der Reest and Philip J. Currie published in the Canadian Journal of Earth Sciences. The first specimens assigned to Troodon that were not teeth were both found by Sternberg in the early 1930s 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. In 1951, Sternberg later 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. In a recent revision of the material by van der Reest & Currie, Polyodontosaurus was determined to be a nomen dubium, not fit for synonymy with other taxa. [5]Yes, some corvids [crows] and parrots are very smart (and crocodiles are much smarter than most people realise) so the *capacity* for high intelligence would appear to be there. 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). 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. Many Dinosaur Park troodontid specimens once referred to Troodon have recently been referred to Stenonychosaurus and Latenivenatrix. The specimens now referred to Stenonychosaurus include several frontals (UALVP 5282, TMP 1986.078.0040, TMP 1988.050.0088, TMP 1991.036.0690), a partial dentary (TMP 1982.019.0151), and the distal portion of a left metatarsal III (TMP 1998.068.0090). 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.

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. Eberth, D.A. (2005). "The geology". In Currie, P.J.; Koppelhus, E.B. (eds.). Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press. pp. 54–82. ISBN 978-0-253-34595-0. Freimuth, William (2021). "Mammal-bearing gastric pellets potentially attributable to Troodon formosus at the Cretaceous Egg Mountain locality, Two Medicine Formation, Montana, USA". Palaeontology. 64 (5): 699–725. doi: 10.1111/pala.12546. S2CID 237659529. Sellés, A. G.; Vila, B.; Brusatte, S.L.; Currie, P.J.; Galobart, A. (2021). "A fast-growing basal troodontid (Dinosauria: Theropoda) from the latest Cretaceous of Europe". Scientific Reports. 11 (1): 4855. Bibcode: 2021NatSR..11.4855S. doi: 10.1038/s41598-021-83745-5. PMC 7921422. PMID 33649418.Alternative Timeline Dinosaurs, the View From 2019 (Part 3): the Dinosauroid and its Chums, December 2019 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] Sternberg, C. (1945). "Pachycephalosauridae proposed for domeheaded dinosaurs, Stegoceras lambei n. sp., described". Journal of Paleontology. 19: 534–538.

Varricchio et al. also found evidence for iterative laying, where the adult might lay a pair of eggs every one or two days, and then ensured simultaneous hatching by delaying brooding until all eggs were laid. MOR 363 was found with 22 empty (hatched) eggs, and the embryos found in the eggs of MOR 246 were in very similar states of development, implying that all of the young hatched approximately simultaneously. The embryos had an advanced degree of skeletal development and empty eggs were relatively uncrushed, implying that hatchlings were precocial. The authors estimated 45 to 65 total days of adult nest attendance for laying, brooding, and hatching. [21] My research and writing (including the material that appears here) is supported by the contributions I receive via patreon. If you value what I do, please consider supporting it here.However, the concept that all Late Cretaceous North American troodontids belong to one 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) reverted to keeping the Dinosaur Park Formation fossils separate as Troodon inequalis. [11] The holotype of Stenonychosaurus inequalis, CMN 8539, is a partial skeleton consisting of six caudal vertebrae, hand bones, the distal end of the left tibia and astragalus, and a complete left foot. A couple of cranial specimens were also referred to the genus: UALVP 52611 (a nearly complete skull roof) and TMP 1986.036.0457 (a partial braincase). He goes on to envision a "dinosauroid" with a shorter muzzle and chillingly similar to contemporary popular representations of UFO pilots. 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.

That’s when everything fell together and we were able to confirm that there were in fact two different species — named Latenivenatrix mcmasterae and Stenonychosaurus inequalis— in the Dinosaur Park Formation, instead of just one,” van der Reest said. Age determination studies performed on the Two Medicine troodont using growth ring counts suggest that this dinosaur reached its adult size probably in 3–5 years. [17]Russell, D. A. 2009 Islands in the Cosmos: the Evolution of Life on Land. Indiana University Press, Bloomington & Indianapolis. A 2023 study using presumed Troodon eggshells from the Oldman Formation used clumped isotope thermometry to determine their formation and development. The study found that in contrast to the accelerated mineralization of eggs in modern birds, Troodon and likely other non-avian maniraptorans had slowed egg calcification akin to other reptiles. This would indicate that, unlike birds, Troodon and other maniraptorans had two functional ovaries that would limit the number of eggs produced. Thus, the study concluded that the large clutches of fossilized eggs present in the formation, despite the limited egg production each individual had, would indicate that Troodon had communal nesting behavior, where eggs would be laid together at a single nest by multiple females, forming large clutches. This is a strategy also used by some modern birds, such as ostriches. [17] [18] Paleoecology [ edit ] Restored skeleton of an unnamed Alaskan species, Perot Museum For most of the 19th and 20th centuries troodontid fossils from North America tended to be assigned to T. formosus. Based on this, Troodon ranged from Mexico in the south to Montana and beyond Alberta in the north and existed as a species through some fifteen million years. A contradiction indeed, when the rapid dinosaur faunal turnover of Laramidia in the Late Cretaceous is considered.

Asda Great Deal

Free UK shipping. 15 day free returns.
Community Updates
*So you can easily identify outgoing links on our site, we've marked them with an "*" symbol. Links on our site are monetised, but this never affects which deals get posted. Find more info in our FAQs and About Us page.
New Comment