Struthiomimus

File:Struthiomimus ROM.jpg

In 1901, Lawrence Lambe found some incomplete remains, holotype CMN 930, and named them Ornithomimus altus, placing them in the same genus as material earlier described by Othniel Charles Marsh in 1890. The specific name altus is from Latin, meaning "lofty" or "noble". However, in 1914, a nearly complete skeleton (AMNH 5339) was discovered by Barnum Brown at the Red Deer River site in Alberta, prompting O. altus to be described as the type genus of a new subgenus, Struthiomimus, by Henry Fairfield Osborn in 1917. Dale Russell made Struthiomimus a full genus in 1972, at the same time referring several other specimens to it: AMNH 5375, AMNH 5385, AMNH 5421, CMN 8897, CMN 8902 and ROM 1790, all partial skeletons. The type species, S. altus, is known from several skeletons and skulls,{{cite book |last=Currie |first=Philip J. |author-link=Philip J. Currie |editor=Currie, Phillip J. |editor2=Koppelhus, Eva |title=Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed |chapter=Theropods, Including Birds |year=2005 |publisher=Indiana University Press |location=Bloomington |pages=[https://archive.org/details/dinosaurprovinci0000unse/page/367 367–397] |isbn=978-0-253-34595-0 |chapter-url=https://archive.org/details/dinosaurprovinci0000unse/page/367 }} In 1916 Osborn also renamed Ornithomimus tenuis Marsh 1890 into Struthiomimus tenuis. This is today considered a nomen dubium. In 2016, ROM 1790 was made the holotype of a new genus and species, Rativates evadens.{{cite journal | last1 = McFeeters | first1 = Bradley | last2 = Ryan | first2 = Michael J. | last3 = Schröder-Adams | first3 = Claudia | last4 = Cullen | first4 = Thomas M. | year = 2016 | title = A new ornithomimid theropod from the Dinosaur Park Formation of Alberta, Canada | journal = Journal of Vertebrate Paleontology | volume = 36| issue = 6| pages = e1221415| doi = 10.1080/02724634.2016.1221415 | bibcode = 2016JVPal..36E1415M | s2cid = 89242374 }}

File:Struthiomimus altus skeletal.png

In subsequent years William Arthur Parks named four other species of Struthiomimus: Struthiomimus brevetertius Parks 1926,{{cite journal | last1 = Parks | first1 = W.A. | year = 1926 | title = Struthiomimus brevetertius - A new species of dinosaur from the Edmonton Formation of Alberta |journal=Transactions of the Royal Society of Canada | series =Series 3 | volume = 20 | issue = 4| pages = 65–70 }} Struthiomimus samueli Parks 1928,{{cite journal | last1 = Parks | first1 = W.A. | year = 1928 | title = Struthiomimus samueli, a new species of Ornithomimidae from the Belly River Formation of Alberta | journal = University of Toronto Studies, Geology Series | volume = 26 | pages = 1–24 }} Struthiomimus currellii Parks 1933 and Struthiomimus ingens Parks 1933.{{cite journal | last1 = Parks | first1 = W.A. | year = 1933 | title = New species of dinosaurs and turtles from the Upper Cretaceous formations of Alberta | journal = University of Toronto Studies, Geological Series | volume = 34 | pages = 1–33 }} These are today seen as either belonging to Dromiceiomimus or to Ornithomimus.

File:Struthiomimus altus.JPG

In 1997 Donald Glut mentioned the name Struthiomimus lonzeensis.Glut, D., 1997, Dinosaurs - The Encyclopedia. McFarland Press, Jefferson, NC. 1076 pp This was probably a lapsus calami, a mistake for Ornithomimus lonzeensis (Dollo 1903) Kuhn 1965. Struthiomimus altus comes from the Late Campanian (Judithian age) Oldman Formation.

A possible second species of Struthiomimus is known from the early Maastrichtian (Edmontonian age) Horseshoe Canyon Formation. Because dinosaur fauna show rapid turnover, it is likely that these younger Struthiomimus specimens represent a species distinct from S. altus, though no new name has been given to them.

Additional Struthiomimus specimens from the lower Lance Formation and equivalents are larger (similar to Gallimimus in size) and tend to have straighter and more elongate hand claws, similar to those seen in Ornithomimus. One relatively complete Lance Formation specimen, BHI 1266, was originally referred to Ornithomimus sedens (named by Marsh in 1892{{cite journal | last1 = Marsh | first1 = O.C. | year = 1892 | title = Notice of new reptiles from the Laramie Formation | url = https://zenodo.org/record/2238442| journal = American Journal of Science |series=Series 3 | volume = 43 | issue = 257| pages = 449–453 | doi = 10.2475/ajs.s3-43.257.449| bibcode = 1892AmJS...43..449M | s2cid = 131291138 }}) and later classified as Struthiomimus sedens.Farlow, J.O., 2001, "Acrocanthosaurus and the maker of Comanchean large-theropod footprints", In: Tanke, Carpenter, Skrepnick and Currie (eds). Mesozoic Vertebrate Life: New Research Inspired by the Paleontology of Philip J. Currie. pp. 408-427 One 2015 paper by van der Reest et al. listed BHI 1266 as Ornithomimus sp.,{{cite journal | last1 = Aaron | first1 = J. | last2 = van der Reest | first2 = Alexander P. Wolfe | last3 = Currie | first3 = Philip J. | year = 2016 | title = [2015] A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada | journal = Cretaceous Research | volume = 58 | pages = 108–117 | doi = 10.1016/j.cretres.2015.10.004 | bibcode = 2016CrRes..58..108V }} while another paper the same year considered the specimen Struthiomimus sp. pending a re-evaluation of both genera.

File:Struthiomimus BW.jpg

The size of S. altus is estimated as about {{convert|4.3|m|ftin}} long and {{cvt|1.4|m|ftin}} tall at the hips, with a weight of around {{convert|150|kg}}.{{cite book |last=Paul |first=Gregory S. |title=Predatory Dinosaurs of the World |year=1988 |publisher=Simon & Schuster |location=New York |isbn=978-0-671-61946-6 |chapter=Ornithomimus altus |pages=[https://archive.org/details/predatorydinosau00paul/page/387 387–389] |chapter-url=https://archive.org/details/predatorydinosau00paul |url=https://archive.org/details/predatorydinosau00paul/page/387 }} A larger specimen of S. altus is estimated to weigh about {{convert|233.8|kg|lb}}.{{Cite journal |last1=Chinzorig |first1=Tsogtbaatar |last2=Cullen |first2=Thomas |last3=Phillips |first3=George |last4=Rolke |first4=Richard |last5=Zanno |first5=Lindsay E. |date=2022-10-19 |title=Large-bodied ornithomimosaurs inhabited Appalachia during the Late Cretaceous of North America |journal=PLOS ONE |volume=17 |issue=10 |at=e0266648 |doi=10.1371/journal.pone.0266648 |doi-access=free |pmid=36260601 |pmc=9581415 |bibcode=2022PLoSO..1766648T }} The specimens belonging to "S." sedens measured {{convert|4.8|m|ft}} long and weighed {{convert|350|kg|lb}}.{{cite book |last=Paul |first=Gregory S. |year=2010 |title=The Princeton Field Guide to Dinosaurs |url=https://archive.org/details/princetonfieldgu0000paul |url-access=registration |publisher=Princeton University Press |location=Princeton, NJ |page=[https://archive.org/details/princetonfieldgu0000paul/page/117 117] |isbn=978-0-691-13720-9}} Struthiomimus had a build and skeletal structure typical of ornithomimids, differing from closely related genera like Ornithomimus and Gallimimus in proportions and anatomical details.{{cite book |last=Paul |first=Gregory S. |title=Predatory Dinosaurs of the World |year=1988 |publisher=Simon & Schuster |location=New York |isbn=978-0-671-61946-6 |chapter=Genus Ornithomimus |pages=[https://archive.org/details/predatorydinosau00paul/page/384 384–394] |chapter-url=https://archive.org/details/predatorydinosau00paul |url=https://archive.org/details/predatorydinosau00paul/page/384 }}

File:Struthiomimus Scale.svg

As with other ornithomimids, they had small slender heads on long necks (which made up about 40% of the length of the body in front of the hips). Their eyes were large and their jaws were toothless. Their vertebral columns consisted of ten neck vertebrae, thirteen back vertebrae, six hip vertebrae, and about thirty-five tail vertebrae.{{cite book |last=Makovicky |first=Peter J. |author2=Kobayashi, Yoshitsugu |author3= Currie, Philip J. |year=2004 |chapter=Ornithomimosauria |editor=Weishampel, David B. |editor2=Dodson, Peter |editor3=Osmólska, Halszka|title=The Dinosauria |edition=2nd |publisher=University of California Press |location=Berkeley |isbn=978-0-520-24209-8 |pages=137–150}} Their tails were relatively stiff and probably used for balance.{{cite journal |last=Osborn |first=Henry Fairfield |author-link=Henry Fairfield Osborn |title=Skeletal adaptations of Ornitholestes, Struthiomimus, Tyrannosaurus |journal=Bulletin of the American Museum of Natural History |volume=35 |pages=733–771 |year=1917 |url=http://digitallibrary.amnh.org/dspace/bitstream/2246/1334/1/B035a43.pdf }} They had long slender arms and hands, with immobile forearm bones and limited opposability between the first finger and the other two.{{cite journal |last=Nicholls |first=Elizabeth L. |author2=Russell, Anthony P. |year=1985 |title=Structure and function of the pectoral girdle and forelimb of Struthiomimus altus (Theropoda: Ornithomimidae) |journal=Palaeontology |volume=28 |pages=643–677}} As in other ornithomimids but unusually among theropods, the three fingers were roughly the same length, and the claws were only slightly curved; Henry Fairfield Osborn, describing a skeleton of S. altus in 1917, compared the arm to that of a sloth. These might have been adaptations to support wing feathers.{{Cite journal | last1 = Zelenitsky | first1 = D. K. | last2 = Therrien | first2 = F. | last3 = Erickson | first3 = G. M. | last4 = Debuhr | first4 = C. L. | last5 = Kobayashi | first5 = Y. | last6 = Eberth | first6 = D. A. | last7 = Hadfield | first7 = F. | doi = 10.1126/science.1225376 | title = Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins | journal = Science | volume = 338 | issue = 6106 | pages = 510–514 | year = 2012 | pmid = 23112330| bibcode = 2012Sci...338..510Z | s2cid = 2057698 }} It is likely it had feathers all over its body. Struthiomimus differed from close relatives only in subtle aspects of anatomy. The edge of the upper beak was concave in Struthiomimus, unlike Ornithomimus, which had straight beak edges. Struthiomimus had longer hands relative to the humerus than other ornithomimids, with particularly long claws. Their forelimbs were more robust than Ornithomimus.{{cite journal | last1 = Longrich | first1 = N | year = 2008 | title = A new, large ornithomimid from the Cretaceous Dinosaur Park Formation of Alberta, Canada: Implications for the study of dissociated dinosaur remains | journal = Palaeontology | volume = 51 | issue = 4| pages = 983–997 | doi=10.1111/j.1475-4983.2008.00791.x| doi-access = | bibcode = 2008Palgy..51..983L }}

File:Struthiomimus skull reconstruction.png

Struthiomimus is a member of the family Ornithomimidae, a group which also includes Anserimimus, Archaeornithomimus, Dromiceiomimus, Gallimimus, Ornithomimus, and Sinornithomimus.

Just as the fossil remains of Struthiomimus were incorrectly assigned to Ornithomimus, the larger group that Struthiomimus belongs to, the Ornithomimosauria, also underwent many changes over the years. For example, O.C. Marsh initially included Struthiomimus in the Ornithopoda, a large clade of dinosaurs not closely related to theropods.{{cite journal | last1 = Marsh | first1 = O. C. | year = 1890 | title = Additional characters of the Ceratopsidae, with notice of new Cretaceous dinosaurs | url = https://zenodo.org/record/2513377| journal = American Journal of Science | volume = 39 | issue = 233| pages = 418–426 | bibcode = 1890AmJS...39..418M | doi = 10.2475/ajs.s3-39.233.418 | s2cid = 130812960 }} Five years later, Marsh classified Struthiomimus in the Ceratosauria.{{cite journal|last=Marsh|first=O. C.|date=1895|title=On the affinities and classification of the dinosaurian reptiles|journal=American Journal of Science|volume=50|issue=300|pages=483–498|doi=10.2475/ajs.s3-50.300.483|bibcode=1895AmJS...50..483M|s2cid=130517438 |url=https://zenodo.org/record/2522963}}O. C. Marsh. 1896. The dinosaurs of North America. United States Geological Survey, 16th Annual Report, 1894-95 55:133-244 In 1891, Baur placed the genus within Iguanodontia.{{cite journal|last=Baur|first=G.|date=1891|title=Remarks on the reptiles generally called Dinosauria|journal=The American Naturalist|volume=25|issue=293|pages=434–454|doi=10.1086/275329|bibcode=1891ANat...25..434B |s2cid=84575190 }} As late as 1993, Struthiomimus was referred to Oviraptorosauria.{{cite journal|last1=Russell|first1=D. A.|last2=Dong|first2=Z.-M.|date=1993|title=The affinities of a new Theropod from the Alxa Desert, Inner Mongolia, People's Republic of China|journal=Canadian Journal of Earth Sciences|volume=30|issue=10–11|pages=2107–2127|doi=10.1139/e93-183|bibcode=1993CaJES..30.2107R}} However, by the 1990s, there were numerous studies that placed Struthiomimus within Coelurosauria.J. A. Gauthier and K. Padian. 1985. Phylogenetic, functional, and aerodynamic analyses of the origin of birds and their flight. In M. K. Hecht, J. H. Ostrom, G. Viohl, and P. Wellnhofer (eds.), The Beginnings of Birds: Proceedings of the International Conference Archaeopteryx, Eichstätt 1984. Freunde des Jura-Museums Eichstätt, Eichstätt 185-197F. E. Novas. 1992. The evolution of carnivorous dinosaurs. In J. L. Sanz and A. D. Buscalioni (eds.), The Dinosaurs and Their Environment Biotic: Proceedings of the Second Year of Paleontology in Cuenca. Institute "Juan Valdez", Cuenca, Argentina 126-163{{cite journal | last1 = Sereno | first1 = P. C. | last2 = Wilson | first2 = J. A. | last3 = Larsson | first3 = H. C. E. | last4 = Dutheil | first4 = D. B. | last5 = Sues | first5 = H.-D. | year = 1994 | title = Early Cretaceous dinosaurs from the Sahara | journal = Science | volume = 266 | issue = 5183| pages = 267–271 | doi=10.1126/science.266.5183.267 | pmid=17771449| bibcode = 1994Sci...266..267S | s2cid = 36090994 }}{{cite book|last1=Makovicky|first1=P. J.|last2=Kobayashi|first2=Y.|last3=Currie|first3=P. J.|date=2004|chapter=Ornithomimosauria|editor-last1=Weishampel|editor-first1=D. B.|editor-last2=Dodson|editor-first2=P.|editor-last3=Osmólska|editor-first3=H.|title=The Dinosauria|edition=2nd|publisher=University of California Press|location=Berkeley|pages=137–150|doi=10.1525/california/9780520242098.003.0008|isbn=9780520242098}}

Recognizing the difference between ornithomimids and other theropods, Rinchen Barsbold placed ornithomimids within their own infraorder, Ornithomimosauria, in 1976.R. Barsbold. 1976. K evolyutsii i sistematike pozdnemezozoyskikh khishchnykh dinozavrov [The evolution and systematics of late Mesozoic carnivorous dinosaurs]. In N. N. Kramarenko, B. Luvsandansan, Y. I. Voronin, R. Barsbold, A. K. Rozhdestvensky, B. A. Trofimov & V. Y. Reshetov (eds.), Paleontology and Biostratigraphy of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition, 3:68-75 Transactions The constituency of Ornithomimidae and Ornithomimosauria varied with different authors. Paul Sereno, for example, used Ornithomimidae to include all ornithomimosaurians in 1998, but subsequently changed to a more exclusive definition (advanced ornithomimosaurs) within Ornithomimosauria,{{cite journal|last=Sereno|first=P.C.|date=1998|title=A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria|journal=Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen|volume=210|issue=1|pages=41–83|doi=10.1127/njgpa/210/1998/41}} a classification scheme that was adopted by other authors at the beginning of the current century.

The cladogram follows the 2011 analysis by Xu et al.:{{Cite journal|author=Li Xu, Yoshitsugu Kobayashi, Junchang Lü, Yuong-Nam Lee, Yongqing Liu, Kohei Tanaka, Xingliao Zhang, Songhai Jia and Jiming Zhang |year=2011 |title=A new ornithomimid dinosaur with North American affinities from the Late Cretaceous Qiupa Formation in Henan Province of China |journal=Cretaceous Research |volume=32 |issue=2 |pages=213–222 | doi=10.1016/j.cretres.2010.12.004|bibcode=2011CrRes..32..213X }}{{dead link|date=March 2019|bot=medic}}{{cbignore|bot=medic}}

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In a 2001 study conducted by Bruce Rothschild and other paleontologists, fifty foot bones referred to Struthiomimus were examined for signs of stress fracture, but none were found.Rothschild, B., Tanke, D. H., and Ford, T. L., 2001, Theropod stress fractures and tendon avulsions as a clue to activity: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 331-336.

Struthiomimus was one of the first theropods envisioned from the outset as having a horizontal posture. Osborn in 1916 let the animal intentionally be depicted with an elevated tail. This newer view created an image much more reminiscent of modern flightless birds, such as the ostrich to which this dinosaur's name refers, but would only much later be accepted for all theropods.

File:Struthiomimus skull.JPG

There has been much discussion about the feeding habits of Struthiomimus. Because of its straight-edged beak, Struthiomimus may have been an omnivore. Some theories suggest that it may have been a shore-dweller and may have been a filter feeder. Some paleontologists noted that it was more likely to be a carnivore because it is classified within the otherwise carnivorous theropod group.{{cite journal|author=Russell D|year=1972|title=Ostrich dinosaurs from the Late Cretaceous of Western Canada|journal=Canadian Journal of Earth Sciences|volume=9|pages=375–402|doi=10.1139/e72-031|issue=4|bibcode=1972CaJES...9..375R|title-link=Cretaceous}}{{cite journal|author1=Osmólska H, Roniewicz E |author2=Barsbold R |name-list-style=amp |year=1972|title=A new dinosaur, Gallimimus bullatus n. gen.,n. sp. (Ornithomimidae) from the Upper Cretaceous of Mongolia|journal=Paleontol. Polonica|volume=27|pages=103–143|title-link=Cretaceous }} This theory has never been discounted, but Osborn, who described and named the dinosaur, proposed that it probably ate buds and shoots from trees, shrubs and other plants, using its forelimbs to grasp branches and its long neck to enable it accurately to select particular items. This herbivorous diet is further supported by the unusual structure of its hands. The second and third fingers were of equal length, could not function independently, and were probably bound together by skin as a single unit. The structure of the shoulder girdle did not allow a high elevation of the arm nor was optimised for a low reach. The hand could not be fully flexed for a grasping motion or spread for raking. This indicates that the hand was used as a "hook" or "clamp", for bringing branches or fern fronds at shoulder height within reach. However, these adaptations might have been used for wing feather support instead.

File:Struthiomimus sp. and Dakotaraptor steini DinoScience 2024.jpg]]

The legs (hind limbs) of Struthiomimus were long, powerful and seemingly well-suited to rapid running, much like an ostrich. The supposed speed of Struthiomimus was, in fact, its main defense from predators (although it may also have been able to lash out with its hind claws when cornered), such as the dromaeosaurids (e.g. Saurornitholestes and Dromaeosaurus) and tyrannosaurs (e.g. Daspletosaurus and Gorgosaurus), which lived at the same time. It is estimated to have been able to run at speeds between {{cvt|50|and|80|km/h|1}}.Paul, regarding his comparative speed estimates, notes that "... just how swift is swift? In hard, precise measure, this can be a real can of worms; for just how fast living animals run is not well known." (Paul, G.S. 1988. Predatory Dinosaurs of the World. New York: Simon & Schuster.)

File:Albertosaurus hunting Saurolophus.jpg hunting Saurolophus with Struthiomimus in the foreground]]

Fossil remains of S. altus are only known definitively from the Oldman Formation, dated to between 78 and 77 million years ago during the Campanian stage of the late Cretaceous period.{{cite journal | last1 = Claessens | first1 = L. | last2 = Loewen | first2 = Mark A. | year = 2015 | title = A redescription of Ornithomimus velox Marsh, 1890 (Dinosauria, Theropoda) | journal = Journal of Vertebrate Paleontology | volume = 36| pages = e1034593| doi = 10.1080/02724634.2015.1034593 | s2cid = 85861590 }} A younger species (which has not yet been named), which apparently differed from S. altus in having longer, more slender hands, is known from several specimens found in the Horseshoe Canyon Formation and lower Lance Formation, between 69 and 67.5 million years ago (early Maastrichtian).

• Timeline of ornithomimosaur research

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{{Reflist|2}}

• {{cite journal | last1 = Russell | first1 = D. A. | year = 1969 | title = A new specimen of Stenonychosaurus from the Oldman Formation (Cretaceous) of Alberta | journal = Canadian Journal of Earth Sciences | volume = 6 | issue = 4| pages = 595–612 | doi=10.1139/e69-059| bibcode = 1969CaJES...6..595R}}
• Cranfield, I. (2004). The Illustrated Directory of Dinosaurs and other Prehistoric Creatures (pp. 30–33). Greenwich Editions. {{ISBN|0-86288-662-7}}.
• {{cite journal | last1 = Reisdorf | first1 = A.G. | last2 = Wuttke | first2 = M. | year = 2012 | title = Re-evaluating Moodie's Opisthotonic-Posture Hypothesis in fossil vertebrates. Part I: Reptiles - The taphonomy of the bipedal dinosaurs Compsognathus longipes and Juravenator starki from the Solnhofen Archipelago (Jurassic, Germany) | journal = Palaeobiodiversity and Palaeoenvironments | volume = 92| issue = 1 | pages = 119–168| doi = 10.1007/s12549-011-0068-y | bibcode = 2012PdPe...92..119R | s2cid = 129785393 }}

• {{Commons category-inline|Struthiomimus|Struthiomimus}}

{{Theropoda|O.}}

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Category:Ornithomimidae

Category:Dinosaur genera

Category:Campanian dinosaurs

Category:Oldman Formation

Category:Taxa named by Henry Fairfield Osborn

Category:Taxa named by Lawrence Lambe

Category:Fossil taxa described in 1902

Category:Fossil taxa described in 1917

Category:Dinosaurs of Canada