Cryolophosaurus
Cryolophosaurus | |
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Reconstructed skeleton, Field Museum of Natural History | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Eusaurischia
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Clade: | Theropoda |
Clade: | Neotheropoda |
Genus: | †Cryolophosaurus Hammer & Hickerson, 1994 |
Type species | |
†Cryolophosaurus ellioti Hammer & Hickerson, 1994
|
Cryolophosaurus (/ˌkraɪəˌloʊfəˈsɔːrəs/ or /kraɪˌɒləfəˈsɔːrəs/; KRY-ə-LOH-fə-SAWR-əs) is a genus of large theropod dinosaur known from only a single species Cryolophosaurus ellioti, from the early Jurassic of Antarctica. It was one of the largest theropods of the Early Jurassic, with the subadult being estimated to have reached 6–7 metres (20–23 ft) long and weighed 350–465 kilograms (772–1,025 lb).
Cryolophosaurus was first excavated from Antarctica's Early Jurassic,
Cryolophosaurus is known from a skull, a femur and other material, all of which have caused its classification to vary greatly. The femur possesses many primitive characteristics that have classified Cryolophosaurus as a
Discovery and naming
Cryolophosaurus originally was collected during the 1990–91 austral summer on
In 1991, both Hammer and the Ohio State University geologist David Elliot excavated separate outcrops near Beardmore Glacier, sharing logistical expenses. Elliot's team first came across the remains of Cryolophosaurus in a rock formation around the altitude of 4,000 m (13,000 ft) high and about 640 km (400 mi) from the South Pole. When the discovery was made, they soon notified Hammer. Over the next three weeks, Hammer excavated 2,300 kg (5,100 lb) of fossil-bearing rock. The team recovered over 100 fossil bones, including those of Cryolophosaurus.[4] The specimens were formally named and described in 1994 by Hammer and Hickerson, in the journal Science.[4]
During the 2003 season, a field team returned and collected more material from the original site. A second locality was discovered about 30 metres (98 ft) higher in the section on Mt. Kirkpatrick.[5]
The name Cryolophosaurus ellioti is derived from the Greek words κρυος (meaning 'cold' or 'frozen', in reference to its discovery in Antarctica), λοφος (meaning 'crest') and σαυρος (meaning 'lizard'), thus "cold crest lizard". Hammer and Hickerson named the species C. ellioti, after David Elliot, who had made the initial discovery of the fossils.[4]
Description
Cryolophosaurus was a large, well-built
The
Skull
The holotype of Cryolophosaurus consists of a high, narrow skull, which was discovered articulated with the rest of the skeleton.[6] The skull is an estimated 65 centimetres (26 in) long. It has a peculiar nasal crest that runs just over the eyes, where it rises perpendicular to the skull and fans out. It is thin and highly furrowed, giving it a unique "pompadour" appearance and earned it the nickname "Elvisaurus."[13] The crest is an extension of the skull bones, near the tear ducts, fused on either side to orbital horns which rise from the eye sockets. While other theropods like the Monolophosaurus have crests, they usually run along the skull instead of across it.[14]
An unpublished study conducted by Vernon Meidlinger-Chin in 2013 suggested that previous studies lacked focus on endocranial details. The study found that the Cryolophosaurus fossil has a nearly complete, undistorted cranial cavity which is complete enough to give an approximate shape and size of the living brain. The endocast features clarified the dissimilarity of the skull with those of
Classification
The following cladogram illustrates a synthesis of the relationships of the early theropod groups compiled by Hendrickx et al. in 2015.[22]
However, a 2020, a study conducted Adam Marsh and Timothy Rowe found Cryolophosaurus to be a basal Neotheropod. While it was still closer to Averostra than Coelophysoidea was, it was still more basal than Dilophosaurus.[23]
Neotheropoda |
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Paleobiology
Cranial ornamentation
Cranial display features, such as the one possessed by Cryolophosaurus, make sense in social, gregarious animals, where other members of the species are available to observe and interpret messages of sexual status.[24] Kevin Padian et al. (2004) challenged conventional hypotheses that the purpose of bizarre cranial structures and post-cranial armor in dinosaurs, was either for attracting mates, intimidating/fighting rivals in the group, or intimidating potential predators of other species. Padian et al. noted that based on phylogenetic, histological, and functional evidence these bizarre structures can be explained by the phenomenon of intra-species recognition, which is supported by the fossil evidence.[25][26] Thomas R. Holtz Jr. (2010) found that the bizarre crest of Cryolophosaurus was primarily for intra-species recognition, based on evidence from related species and studies of bone texture.[27] According to Thomas Rich and his colleagues, the crest would have been ineffective as a weapon and may have possibly functioned as a display feature during certain types of social behavior such as mating.[28] In 2019, a species recognition function was disputed but a socio-sexual display structure model was suggested.[29]
Diet
When the type specimen was discovered, several long cervical ribs, of a supposed prosauropod dinosaur were found in the mouth of Cryolophosaurus, which led Hammer (1998) to conclude that it was feeding on the prosauropod when it died. Hammer further noted that since the ribs were found extending all the way back to the theropod's neck region, this individual may have choked to death on these ribs.
Paleopathology
Some Cryolophosaurus bones have pathologies that show evidence of scavenging. Broken teeth from a juvenile Cryolophosaurus were found nearby.[28] These teeth have no roots and likely shed naturally while scavenging the adult Cryolophosaurus carcass.
Another possible pathology is found in the astragalus (ankle bone) of Cryolophosaurus. This bone was preserved with a small splint from the fibula located just above the ankle. The splint, however, may also be just a unique morphological feature of Cryolophosaurus.[7]
Paleoenvironment
All known specimens of Cryolophosaurus have been recovered in the Hanson Formation, which is one of only two major dinosaur-bearing rock formations found on the continent of Antarctica. Cryolophosaurus was found about 650 kilometres (400 mi) from the
This formation has produced the remains of two smaller theropods, the sauropodomorph
References
- . Retrieved 20 February 2022.
- ^ Evans, D.C.; Vavrek, M.J. (2012). Ultimate Dinosaurs: Giants from Gondwana. Toronto:Royal Ontario Museum. pp. 30–1.
- ^ Pickrell, John (2004). "Two New Dinosaurs Discovered in Antarctica". National Geographic. Archived from the original on March 11, 2004. Retrieved 20 December 2013.
- ^ S2CID 38933265.
- ^ Leslie, M (2007). "The Strange Lives of Polar Dinosaurs". Smithsonian Magazine. Archived from the original on 2012-07-02. Retrieved 2008-01-24.
- ^ a b c d Hammer, W.R.; Hickerson, W.J. (1999). Tomida, Y.; Rich, T.H.; Vickers-Rich, Y. (eds.). "Gondwana Dinosaurs from the Jurassic of Antarctica". Proceedings of the Second Gondwana Dinosaur Symposium National Science Museum Monographs. 15: 211–217.
- ^ ]
- ISBN 9781400836154.
- ^ Molina-Pérez & Larramendi (2016). Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos. Barcelona, Spain: Larousse. p. 254.
- ^ OCLC 444710202.
- ^ a b Meidlinger-Chin, V. (2013). "Braincase and Endocranial anatomy of Cryolophosaurus ellioti (Dinosauria: Theropoda) from the Early Jurassic of Antarctica". Geological Society of America Abstracts with Programs. 45 (4): 65.
- ^ Smith, N.D.; Hammer, W.R.; Makovicky, P.J. (2013). "New Dinosaurs from the Early Jurassic Hanson Formation of Antarctica, and Patterns of Diversity and Biogeography in Early Jurassic Sauropodomorphs". Geological Society of America Abstracts with Programs: 405–406. Archived from the original on 2017-12-22. Retrieved 2013-12-20.
- ^ swigodner (2017-08-02). "Antarctic Dinosaurs". Field Museum. Retrieved 2018-12-31.
- ^ S2CID 220413556.
- ^ "VERTEBRAL ANATOMY OF CRYOLOPHOSAURUS ELLIOTI, A THEROPOD DINOSAUR FROM THE EARLY JURASSIC OF ANTARCTICA". gsa.confex.com. Archived from the original on 2019-01-01. Retrieved 2018-12-31.
- ISBN 978-0-520-24209-8.
- S2CID 36090994.
- ^ .
- S2CID 8349110.
- S2CID 85354215.
- S2CID 220601744.
- ^ Hendrickx, C.; Hartman, S.A.; Mateus, O. (2015). "An Overview of Non- Avian Theropod Discoveries and Classification". PalArch's Journal of Vertebrate Palaeontology. 12 (1): 1–73.
- S2CID 220601744.
- ISBN 978-0-12-226810-6.
- ISBN 978-0-7864-2295-1.
- S2CID 220410105.
- ISBN 978-0-375-82419-7.
- ^ ISBN 978-0-12-226810-6.
- ^ Chan-gyu, Yun. (2019). "An enigmatic theropod Cryolophosaurus: Reviews and Comments on its paleobiology". Volumina Jurassica. 17: 1–8.
- ISBN 978-0-7864-0591-6.
- ISBN 978-0-12-226810-6.
- S2CID 132900754. Retrieved 7 March 2022.
- .
- ^ Smith, Nathan D.; Pol, Diego (2007). "Anatomy of a basal sauropodomorph dinosaur from the Early Jurassic Hanson Formation of Antarctica" (PDF). Acta Palaeontologica Polonica. 52 (4): 657–674.[permanent dead link]
- ^ Hammer, W.R.; Hickerson, W.J.; Slaughter, R.W. (1994). "A dinosaur assemblage from the Transantarctic Mountains" (PDF). Antarctic Journal of the United States. 29 (5): 31–32.
- ^ Smith, Nathan D. (2013). "New Dinosaurs from the Early Jurassic Hanson Formation of Antarctica, and Patters of Diversity and Biogeography in Early Jurassic Sauropodomorphs". Geological Society of America Abstracts with Programs. 45 (7): 897.
- ^ Bomfleur, B.; Schneider, J. W.; Schöner, R.; Viereck-Götte, L.; Kerp, H. (2011). "Fossil sites in the continental Victoria and Ferrar groups (Triassic-Jurassic) of north Victoria Land, Antarctica". Polarforschung. 80 (2): 88–99. Retrieved 15 November 2021.
- ^ Musumeci, G.; Pertusati, P. C.; Ribecai, C.; Meccheri, M. (2006). "Early Jurassic fossiliferous black shales in the Exposure Hill Formation, Ferrar Group of northern Victoria Land, Antarctica". Terra Antartica Reports. 12 (1): 91–98. Retrieved 17 November 2021.
- ^ S2CID 130084588.
- . Retrieved 13 February 2022.
External links
- Transantarctic Vertebrate Paleontology Project, official website for the NSF project conducting research on Cryolophosaurus and related fauna (photos, research information, publication list, geology, project members ...)
- Fryxell Geology Museum (photos, information)
- Field Museum of Natural History (video, information)