Hesperornis
Hesperornis | |
---|---|
Restored skeleton of H. regalis in diving posture at the American Museum of Natural History | |
Life reconstruction of H. regalis in diving posture | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | Avialae |
Clade: | †Hesperornithes |
Family: | † Hesperornithidae
|
Genus: | †Hesperornis Marsh, 1872 |
Type species | |
†Hesperornis regalis Marsh, 1872
| |
Species | |
†H. regalis Marsh, 1872 | |
Synonyms | |
Lestornis Marsh, 1876 |
Hesperornis (meaning "western bird") is a genus of cormorant-like Ornithuran that spanned throughout the Campanian age, and possibly even up to the early Maastrichtian age, of the Late Cretaceous period.[1][2] One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an early find in the history of avian paleontology. Locations for Hesperornis fossils include the Late Cretaceous marine limestones from Kansas and the marine shales from Canada. Nine species are recognised, eight of which have been recovered from rocks in North America and one from Russia.
Description
Hesperornis was a large bird, reaching up to 1.8 metres (5.9 ft) in length.[3] It had virtually no wings, and swam with its powerful hind legs. Studies on the feet initially indicated that Hesperornis and kin had lobed toes similar to modern-day grebes, as opposed to webbed toes as seen in most aquatic birds such as loons.[4] More recent work looking at the morphometrics of the feet in hesperornithiformes and modern sea birds has thrown this interpretation into question, making webbed toes equally as likely as lobed toes for this group.[5]
Like many other
History
The first Hesperornis specimen was discovered in 1871 by Othniel Charles Marsh. Marsh was undertaking his second western expedition, accompanied by ten students.[10] The team headed to Kansas where Marsh had dug before. Aside from finding more bones belonging to the flying reptile Pteranodon, Marsh discovered the skeleton of a "large fossil bird, at least five feet in height". The specimen was large, wingless, and had strong legs—Marsh considered it a diving species. Unfortunately, the specimen lacked a head.[11] Marsh named the find Hesperornis regalis, or "regal western bird".[12]
Marsh headed back west with a smaller party the following year. In western Kansas, one of Marsh's four students, Thomas H. Russell, discovered a "nearly perfect skeleton" of Hesperornis.
Classification and Species
Many
The first species to be described, the
Hesperornis crassipes was named in 1876 by Marsh, who initially classified it in a different genus as Lestornis crassipes. H. crassipes was larger than H. regalis, had five ribs as opposed to four in the first species, and differed in aspects of the bone sculpturing on the breastbone and lower leg. H. crassipes is known from the same time and place as H. regalis. One incomplete skeleton is known, including teeth and parts of the skull.[19]
Marsh explicitly named his second species of Hesperornis in 1876 for an incomplete
The first species recognized from outside the Niobrara chalk, Hesperornis altus, lived about 78 million years ago in Montana, and is known from a partial lower leg from the base of the freshwater Judith River Formation (or, possibly, the top of the underlying, marine Claggett Shale formation). While initially placed in the new genus Coniornis by Marsh, this was due mostly to his belief that Hesperornis existed only in Kansas, so any species from Montana should be placed in a different genus. Most later researchers disagreed with this, and have placed Coniornis altus in the same genus as Hesperornis as H. altus.[22][23] A second species from Montana has also been described from the Claggett Shale. H. montana was named by Shufeldt in 1915, and while its known material (a single dorsal vertebra) cannot be directly compared to H. altus, Shufeldt and others have considered it distinct due to its apparently smaller size.[24]
In 1993, the first Hesperornis remains from outside of North America were recognized as a new species by Nessov and Yarkov. They named Hesperornis rossicus for a fragmentary skeleton from the early Campanian of Russia near Volgograd. Several other specimens from contemporary deposits have since been referred to this species. At about 1.4 metres (4.6 ft) long, H. rossicus was the largest species of Hesperornis and among the largest hesperornithines, slightly smaller than the large Canadian genus Canadaga.[12] Aside from its large size and different geographic location, H. rossicus differs from other Hesperornis in several features of the lower leg and foot, including a highly flattened metatarsus.[25]
In 2002, Martin and Lim formally recognized several new species for remains that had previously been unstudied or referred without consideration to previously named North American hesperornithines. These include the very small H. mengeli and H. macdonaldi, the slightly larger H. bairdi, and the very large H. chowi, all from the Sharon Springs member of the Pierre Shale Formation in South Dakota and Alberta, 80.5 million years ago.[26]
In addition, there are some unassigned remains, such as SGU 3442 Ve02 and LO 9067t and bones of an undetermined species from Tzimlyanskoe Reservoir near Rostov. The former two bones are probably H. rossicus; some remains assigned to that species in turn seem to belong to the latter undetermined taxon.[27] It is also suggested that Hesperornis likely lived throughout the Campanian age based on remains found on middle to late Campanian age rocks,[1] and possibly even up to the early Maastrichtian age.[2]
Paleobiology
Hesperornis was primarily marine, and lived in the waters of such contemporary shallow
Traditionally, Hesperornis is depicted with a mode of locomotion similar to modern loons or grebes, and study of their limb proportions and hip structure has borne out this comparison. In terms of limb length, shape of the hip bones, and position of the hip socket, Hesperornis is particularly similar to the common loon (Gavia immer), probably exhibiting a very similar manner of locomotion on land and in water. Like loons, Hesperornis were probably excellent foot-propelled divers, but might have been ungainly on land.[29] Like loons, the legs were probably encased inside the body wall up to the ankle, causing the feet to jut out to the sides near the tail. This would have prevented them from bringing the legs underneath the body to stand, or under the center of gravity to walk. Instead, they likely moved on land by pushing themselves along on their bellies, like modern seals.[30] However, more recent studies on hesperornithean hindlimbs suggest they were more functionally similar to those of the still upright walking cormorants.[31]
Young Hesperornis grew fairly quickly and continuously to adulthood, as is the case in modern birds, but not Enantiornithes.[32]
Pathology
A Hesperornis leg bone uncovered in the 1960s was examined by David Burnham, Bruce Rothschild et al. and was found to bear bite marks from a young
References
- ^ S2CID 83921936.
- ^ doi:10.1139/e99-060. Archived from the originalon 2007-03-11.
- ^ ISBN 0895770652.
- S2CID 11147804.
- S2CID 133964417.
- ^ Marsh, Othniel Charles (1880): Odontornithes, a Monograph on the Extinct Toothed Birds of North America. Government Printing Office, Washington DC.
- JSTOR 1364594.
- S2CID 18430834. Archived from the original(PDF) on 2015-09-24. Retrieved 2013-03-25.
- ^ Elzanowski, A. (1991). "New observations on the skull of Hesperornis with reconstructions of the bony palate and otic region". Postilla. 207: 1–20.
- ^ Thomson, 191.
- ^ Thomson, 193.
- ^ a b Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.
- ^ Charles Schuchert and Clara Mae LeVene, O.C. Marsh: Pioneer in Paleontology, p. 427. New York: Arno Press, 1978. Later, Russell assisted Marsh while attending medical school; he became a surgeon, professor of Clinical Surgery in the Yale School of Medicine, and Marsh's personal physician until Marsh's death in 1899. See Proceedings of the Connecticut State Medical Society (Google eBook) and Genealogical and Family History of the State of Connecticut: A Record of the Achievements of Her People in the Making of a Commonwealth and the Founding of a Nation. Editorial staff: William Richard Cutter, Edward Henry Clement, Samuel Hart, Mary Kingsbury Talcott, Frederick Bostwick, Ezra Scollay Stearns. Volume I (of 4). New York: Lewis Historical Publishing Company, 1911.
- ^ a b Wallace, 86.
- ^ Thomson, 226.
- ^ Wallace, 87.
- ^ Wallace, 132.
- ISBN 978-1-4020-1443-7.
- S2CID 131496417.
- S2CID 86083098.
- ^ Mortimer, Michael (2004): The Theropod Database: Phylogeny of taxa Archived 2013-05-16 at the Wayback Machine.
- ^ Shufeldt, R.W. (1915). "Fossil birds in the Marsh Collection of Yale University". Transactions of the Connecticut Academy of Arts and Sciences. 19: 1–110.
- JSTOR 3627850.
- JSTOR 4072679.
- Kurochkin, (2000). "Mesozoic birds of Mongolia and the former USSR." Pp. 533–559 in Benton, Shishkin, Unwin and Kurochkin (eds.). The Age of Dinosaurs in Russia and Mongolia.
- ^ Martin, L. and Lim, (2002). "New information on the hesperornithiform radiation." pp. 113–124 in Zhou and Zhang (eds.), Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing.
- ^ doi:10.1111/j.1475-4983.2005.00507.x.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - doi:10.1139/e74-127.
- S2CID 220413406.
- .
- S2CID 133964417.
- doi:10.1006/cres.1997.0102.)
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: CS1 maint: multiple names: authors list (link - ^ "BBC Earth | Home".
Sources
- Thomson, Keith Stewart (2008). The Legacy of the Mastodon: The Golden Age of Fossils in America. Yale University Press. ISBN 978-0-300-11704-2.
- Wallace, David Rains (1999). The Bonehunters' Revenge: Dinosaurs, Greed, and the Greatest Scientific Feud of the Gilded Age. Houghton Mifflin Books. ISBN 0-618-08240-9.
Further reading
- Everhart, M.J. (2012): Oceans of Kansas: Hesperornis regalis Marsh 1872 – Toothed marine birds of the Late Cretaceous seas Archived 2007-09-29 at the Wayback Machine. Version of 2012-September-19.
- Everhart, M.J. 2011. Rediscovery of the Hesperornis regalis Marsh 1871 holotype locality indicates an earlier stratigraphic occurrence. Kansas Academy of Science, Transactions 114(1-2):59-68.
External links
- Eastern Kentucky University: Closeup of Hesperornis skull. Retrieved 2007-NOV-04.
- savageancientseas.com: Forward view of H. regalis skeleton in diving pose. Note realistic position of legs and toe rotation. Retrieved 2007-NOV-04.
- . Digitized from KUVP PU17193. Requires Java, IFC or 3DC plugin. Retrieved 2007-NOV-04.