Saurornitholestes
Saurornitholestes | |
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Skeletal reconstruction of S. langstoni | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Family: | †Dromaeosauridae |
Clade: | †Eudromaeosauria |
Subfamily: | †Saurornitholestinae |
Genus: | †Saurornitholestes Sues, 1978 |
Type species | |
†Saurornitholestes langstoni Sues, 1978
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Other species | |
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Synonyms | |
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Saurornitholestes ("lizard-bird thief") is a
Two species have been named: Saurornitholestes langstoni in 1978 and Saurornitholestes sullivani in 2015. Saurornitholestes was a small bipedal meat-eating dinosaur, equipped with a sickle-claw on the foot.
Discovery and naming
In 1974, Canadian amateur paleontologist Irene Vanderloh discovered the skeleton of a small theropod near
The holotype specimen, TMP 1974.10.5, was uncovered in a layer of the Dinosaur Park Formation dating to the late Campanian. It consists of a very fragmentary skeleton including teeth, skull elements, two vertebrae, ribs, tail elements and a part of the hand. Also three paratypes were assigned: CMN 12343, CMN 12354, and UA 5283, all frontals.[1]
Additional specimens
Two more complete and larger partial skeletons (RTMP 88.121.39 and MOR 660), dozens of isolated bones, and scores of teeth are known from the badlands of Dinosaur Provincial Park in Alberta; most of these are housed at the Royal Tyrrell Museum of Palaeontology, in Drumheller, Alberta and remain undescribed. The Alberta and Montana remains are usually attributed to the single species Saurornitholestes langstoni, though they come from a variety of rock formations indicating a wide span of time; for example, the Oldman Formation (dated to about 77 million years ago[2]) and the upper Two Medicine Formation (about 72 million years ago). Similar teeth are found in younger deposits, dated to around 70 to 69 million years ago,[3] but whether they represent S. langstoni or a different, related species is unknown. Neonate-sized Saurornitholestes fossils have been reported in the scientific literature.[4]
Fragmentary fossils of Saurornitholestes have also been found from the eastern half of North America. A tooth found in the
Saurornitholestes sullivani is known from the Hunter Wash fauna of the Kirtland Formation in New Mexico, based on the frontal SMP VP-1270. It differs from S. langstoni in the characters of the frontal.[6]
A well-preserved skeleton of Saurornitholestes (specimen UALVP 55700) discovered in 2014 is currently under preparation by University of Alberta paleontologists working in Japan.[7] After examining the skull of that specimen, Currie and Evans announced in 2019 that the Zapsalis teeth from the Dinosaur Park Formation represented the second premaxillary tooth of S. langstoni.[8]
Formerly assigned species
In 2006, Robert Sullivan named and described a second nominal species, Saurornitholestes robustus, based on holotype SMP VP-1955, a left frontal. The specific name refers to the great thickness of this bone, the only trait in which the species is known to differ from S. langstoni. The holotype was found in the Willow Wash fauna of the Kirtland Formation in New Mexico, dated to about 73 million years ago.[9] However, a subsequent overview of dromaeosaurid phylogeny asserted that S. robustus lacked dromaeosaurid characters and should be considered an indeterminate theropod,[10] and a study published in 2014 took the conclusion a step further by demonstrating that S. robustus was assignable to Troodontidae based on similarities with troodontids.[11]
Possible indeterminate fossils are known from the Hell Creek Formation in Montana, North Dakota, and South Dakota, dated to about 66 million years ago.[12]
Description
Saurornitholestes was a small dromaeosaur, with the type species S. langstoni measuring about 1.3–1.8 m (4 ft 3 in – 5 ft 11 in) long and weighing approximately between 5 and 22.5 kg (11 and 50 lb).
Classification
In 1978, Sues assigned Saurornitholestes to the
The cladogram below is the result of a 2019 analysis by Philip J. Currie and David C. Evans. Currie and Evans recovered Saurornitholestes as the sister taxon of Atrociraptor.[8]
Eudromaeosauria |
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Paleobiology
Senses
Saurornitholestes sullivani is thought to have had a keen sense of smell, due to its skull suggesting an unusually large olfactory bulb.[6]
Teeth function
The second premaxillary teeth of (at least) Saurornitholestes, Velociraptor, and Bambiraptor may have been structurally specialized for preening feathers. This may also have been the function of the unusual premaxillary teeth of the oviraptorosaurs Protarchaeopteryx and Incisivosaurus.[8]
Feeding habits
Saurornitholestes' feeding habits were discovered to be typical of coelurosaurian theropods, with a characteristic "puncture and pull" feeding method. Studies of wear patterns on the teeth of this animal by Angelica Torices et al. in a study regarding theropod feeding habits indicate that dromaeosaurid teeth share similar wear patterns to those seen in the tyrannosauridae and troodontidae, respectively. However, micro-wear on the teeth indicated that Saurornitholestes likely preferred larger prey items than the troodontids it shared their environment with. Such differentiations in its diet likely allowed the theropod to inhabit the same environment as its more distant maniraptoran relations. The same study also indicated that both Saurornitholestes and the related Dromaeosaurus (also analyzed in the study) likely included bone in their diet and were better adapted to handle the stresses associated with attacking struggling prey while troodontids, equipped with weaker jaws, preyed on softer animals and prey items such as invertebrates and carrion. This feeding strategy and ability to handle struggling prey was also a feature that the dromaeosaurid also shared with tyrannosaurids such as Gorgosaurus, which was also analyzed in said study alongside these smaller theropods.[17][18]
A tooth of Saurornitholestes has been found embedded in the wing bone of a large pterosaur, probably a juvenile Quetzalcoatlus.[19] Because the pterosaur was so much larger than Saurornitholestes, Currie and Jacobsen suggest that the theropod was probably scavenging the remains of an already dead animal.[19]
Paleopathology
In 2001,
Aase Roland Jacobsen published a description of a Saurornitholestes
The shape of the preserved serrations are too different from those of Saurornitholestes for the marks to be the result of injuries incurred during
Paleoenvironment
Saurornitholestes was found on both sides of the
See also
Footnotes
- ^ a b H.-D. Sues, 1978, "A new small theropod dinosaur from the Judith River Formation (Campanian) of Alberta Canada", Zoological Journal of the Linnean Society 62: 381-400
- ^ Arbour, et al. (2009).
- ^ "3.33 Alaska, United States; 3. Prince Creek Formation," in Weishampel et al. (2004). Page 587.
- ^ "Abstract," Tanke and Brett-Surman (2001). Page 207.
- ^ ISSN 1094-8074.
- ^ a b Steven E. Jasinski (2015) A new dromaeosaurid (Theropoda: Dromaeosauridae) from the Late Cretaceous of New Mexico. in Sullivan, R.M. and Lucas, S.G., eds. Fossil Record 4. New Mexico Museum of Natural History and Science Bulletin 67: 79-88
- ^ "Small but vicious Alberta dinosaur to be discussed in Red Deer - Red Deer Advocate". Red Deer Advocate. 2018-03-09. Retrieved 2018-03-11.
- ^ S2CID 202002676.
- ^ Sullivan and Lucas (2006).
- ^ Turner, A.H., Makovicky, P.J. and Norell, M.A., 2012, A review of dromaeosaurid systematics and paravian phylogeny: Bulletin of the American Museum of Natural History, v. 371, p. 1–206.
- ^ Evans, D.C., Larson, D.W., Cullen, T.M. and Sullivan, R.M., 2014. "Saurornitholestes" robustus is a troodontid (Dinosauria: Theropoda): Canadian Journal of Earth Sciences, v. 51, p. 730–734.
- ^ Dinosaur distribution (Late Cretaceous; North America; North Dakota). Weishampel, et al. (2004). Page 585
- ^ Currie and Koppelhus (2005). Pages 372–373.
- ^ Longrich and Currie (2009).
- OCLC 985402380.
- S2CID 84322349.
- ^ "Dinosaurs' tooth wear sheds light on their predatory lives". ScienceDaily. April 2018. Retrieved 14 February 2019.
- ^ "Scratches on dinosaur teeth reveal their fierce, efficient eating habits - The Washington Post". The Washington Post.
- ^ a b Currie and Jacobsen (1995).
- ^ "Table 23.1," in Rothschild, et al. (2001); page 333.
- ^ "Abstract," Jacobsen (2001). Page 58.
- ^ a b c "Description," Jacobsen (2001). Page 59.
- ^ "Description," Jacobsen (2001). Page 60.
- ^ a b "Discussion," Jacobsen (2001). Page 60.
- ^ "Discussion," Jacobsen (2001). Page 61.
- ^ Strauss, Bob. "Meet the Raptor Dinosaurs of the Mesozoic Era". ThoughtCo. Retrieved 14 February 2019.
- ^ Norell and Makovicky.
References
- S2CID 85665879.
- doi:10.1139/e95-077. Archived from the original(PDF) on 2006-05-28.
- Currie P.J. & Koppelhus E.B., Dinosaur Provincial Park: a spectacular ancient ecosystem revealed, Vol. 1 (Indiana University Press, 2005), p. 372–373.
- Jacobsen, A.R. 2001. Tooth-marked small theropod bone: An extremely rare trace. p. 58-63. In: Mesozoic Vertebrate Life. Ed.s Tanke, D. H., Carpenter, K., Skrepnick, M. W. Indiana University Press.
- Longrich N.R. & Currie P.J. (2009), "A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America", PNAS 106(13): p. 5002-5007.
- Norell, Mark A. and Makovicky, Peter J. "Dromaeosauridae." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 208. ISBN 0-520-24209-2
- Saurornitholestes - Dinosaur Saurornitholestes Characteristics, Behavior and Habitat Archived 2014-12-02 at the Wayback Machine; Subheadings: Habitat, Historical Period, Size and Weight
- Sullivan, R.M. (2006). "Saurornitholestes robustus, n. sp. (Theropoda:Dromaeosauridae) from the Upper Cretaceous Kirtland Formation (De-Na-Zin member_), San Juan Basin, New Mexico." NMMNH Bulletin 35: 253–256.
- Sullivan, R.M. and Lucas, S.G. (2006). "The Kirtlandian land-vertebrate "age" – faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America[permanent dead link]." New Mexico Museum of Natural History and Science, 35: 7-29.
- Tanke, D.H. and Brett-Surman, M.K. 2001. Evidence of Hatchling and Nestling-Size Hadrosaurs (Reptilia:Ornithischia) from Dinosaur Provincial Park (Dinosaur Park Formation: Campanian), Alberta, Canada. pp. 206–218. In: Mesozoic Vertebrate Life—New Research Inspired by the Paleontology of Philip J. Currie. Edited by D.H. Tanke and K. Carpenter. Indiana University Press: Bloomington. xviii + 577 pp.