Anchisaurus
Anchisaurus | |
---|---|
Life restoration | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | †Sauropodomorpha |
Clade: | † Sauropodiformes
|
Clade: | †Anchisauria |
Genus: | †Anchisaurus Marsh, 1885 |
Species: | †A. polyzelus
|
Binomial name | |
†Anchisaurus polyzelus (Hitchcock, 1865)
| |
Synonyms | |
|
Anchisaurus is a genus of
Discovery and naming
Sauropodomorph remains were first documented in North America in 1818, when some bones nearly 1.8 m (6 ft) in length were uncovered by Mr. Solomon Ellsworth Jr. while excavating a well with gunpowder in East Windsor, Connecticut. At the time of their discovery it was thought that the bones might be those of a human,[3] but the presence of tail vertebrae falsified that idea. They are now recognized as those of an indeterminate sauropodomorph, possibly more closely related to the plateosaurian prosauropods.[4][5]
In 1855, the original
In 1863, the son of the ichnologist Edward Hitchcock, Edward Hitchcock Jr, described the Springfield remains in a supplement to his father's work on fossil footprints, suggesting they could explain a certain mysterious kind of reptile tracks.[6][7] He then contacted the British paleontologist Richard Owen. Owen advised him to name the finds as a new genus. Owen suggested the name Megadactylus, "large finger" in Greek, in reference to the enormous thumb of the animal. Hitchcock Jr himself then chose the specific name polyzelus, "much sought for" in Greek, referring to the fact that his father had for many years vainly sought to discover the identity of the track-maker.[8]
In 1877, Professor Othniel Charles Marsh had noted that the name Megadactylus had been preoccupied by Megadactylus Fitzinger 1843, a subgenus of the lizard genus Stellio. In 1882, he replaced the name with Amphisaurus, "near saurian", probably referring to Marsh's interpretation of it as intermediate between primitive dinosaurs—at the time the British Palaeosaurus was an example of what was thought to be a primitive dinosaur—and more derived dinosaurs.[9] In 1885, Marsh had discovered that this name also had been preoccupied, by the anthracosaurian Amphisaurus Barkas 1870, and again replaced it by Anchisaurus, with the same meaning.[10]
Meanwhile, nearly complete specimens had been found in Manchester, Connecticut. In 1884, a series of bridges was built over the Hop Creek. Sandstone blocks were sawed out of Wolcott's Quarry north of Buckland Station. On 20 October, an amateur paleontologist, Charles H. Owen, observed that a block had been removed containing the hind part of a skeleton. He warned Marsh who, using T. A. Bostwick as an intermediary, acquired the piece from the quarry owner, Charles O. Wolcott. Marsh tried to secure the front half of the skeleton but it had already been used in a bridge abutment. The specimen, YPM 208, was named Anchisaurus major, "the larger one", by Marsh in 1889.[11] Eventually, when the bridge was demolished in August 1969, John Ostrom would save the front block. Subsequently, two other dinosaur fossils were located in the quarry. Six metres south of the original find a second skeleton was visible in the quarry face. It was removed as a single block and given the inventory number YPM 1883. In Yale, the part containing the skull was split off and became specimen YPM 40313. In 1891, Marsh made Anchisaurus major a separate genus, Ammosaurus, the "sand saurian". In the same publication he named YPM 1883/YPM 40313 as a new species of Anchisaurus, Anchisaurus colurus, "the mangled one".[12] They served as the templates from which O. C. Marsh in 1893 restored the skeleton.[13] The Manchester specimens are now considered conspecific with Anchisaurus polyzelus.[14] The East Windsor and Manchester specimens are housed at the Peabody Museum of Natural History at Yale University.
The
Broom named Gyposaurus capensis in 1911, from bones discovered in South Africa but Peter Galton renamed these Anchisaurus capensis in 1976. This species has since been reclassified again and is probably a juvenile of Massospondylus carinatus. G. sinensis was also referred here, but appears to be a distinct animal.
The
In the eastern
Description
Anchisaurus was a rather small dinosaur, with a length of just over 2 meters (6.6 ft), which helps explain why it was once mistaken for human bones.[20] It probably weighed around 27 kilograms (60 lb). However, Marsh's species A. major (also known as Ammosaurus) was larger, from 2.5 to 4 meters (8 ft 2 in to 13 ft 1 in) and some estimates give it a weight of up to 32 kilograms (70 lb). Gregory S. Paul estimated its length at 2.2 meters (7.2 ft) and its weight at 20 kilograms (44 lb) in 2010.[21]
According to the presence of cf. Otozoum tracks on the Connecticut Valley, Anchisaurus could reach even greater sizes.[22] Otozoum tracks were made by a semibipedal to quadrupedal sauropodomorph close to or on the line leading toward eusauropods. Anchisaurus is one of the two sauropodomorphs recognized in the zone. Based on the four known specimens of Anchisaurus, Yates estimated that the animal measured up to 4.9 meters (16 ft) in length.[14] This matches well with the estimated average size of the adult Eubrontes track-maker in the Hartford and Deerfield basins. Based on the largest known Eubrontes footprint, exceptionally large individuals of Anchisaurus probably measured up to 6 meters (20 ft) in length.[22]
Classification
This section needs additional citations for verification. (December 2016) |
Due to its primitive appearance, Anchisaurus was previously classified as a prosauropod, a member of a group of animals related to or ancestral to the sauropods. Recent investigations show that a group of traditional prosauropods form a monophyletic sister-group to Sauropoda, and that Anchisaurus is instead closer to sauropods.[14]
The family Anchisauridae was first proposed by Othniel Charles Marsh in 1885 and later defined as a clade consisting of Anchisaurus and its nearest relatives. However, it is not clear which other genera are included in the family; many of the dinosaurs once included have since been moved elsewhere, and the group is not used in most current taxonomies.[14]
Paleobiology
This section needs additional citations for verification. (December 2016) |
Digesting plant matter is a much more intensive biochemical process than digesting meat. This herbivore swallowed
As a
References
- ^ ISBN 1-57765-488-9.
- ^ a b Olsen, P.E. (2002). STRATIGRAPHY AND AGE OF THE EARLY JURASSIC PORTLAND FORMATION OF CONNECTICUT AND MASSACHUSETTS: A CONTRIBUTION TO THE TIME SCALE OF THE EARLY JURASSIC Archived 2018-11-28 at the Wayback Machine. Session No. 26 Studies of Depositional Systems and Sedimentary Rocks: In Honor of Edward Scudder Belt. 37th Annual Meeting (March 25–27, 2002).
- ^ Smith, Nathan (1820). "Fossil bones found in red sandstones". American Journal of Science. 2: 146–147.
- ^ Galton, Peter (1976). "Prosauropod dinosaurs (Reptilia: Saurischia) of North America". Postilla. 169: 1–98.
- ^ Yates, Adam (2004). "Anchisaurus polyzelus (Hitchcock): The smallest known sauropod dinosaur and the evolution of gigantism among sauropodomorph dinosaurs". Postilla. 230: 1–57.
- ^ a b Hitchcock, Edward (1858). Ichnology of New England. Boston: William White.
- ^ Hitchcock, Edward (1841). Final Report on the Geology of Massachusetts. Volume 2. Containing III Scientific Geology. IV Elementary Geology. Amherst and Northampton: J. S. & C. Adams, J. H. Butler.
- ^ E. Hitchcock. 1865. Appendix [A]. Bones of Megadactylus polyzelus. Supplement to the Ichnology of New England. A Report to the Government of Massachusetts in 1863. Wright and Potter, Boston 39–40
- ^ Marsh, O. C. 1882. "Classification of the Dinosauria". American Journal of Science, Series 3, 23: 81–86
- ^ O. C. Marsh. 1885. "Names of extinct reptiles". American Journal of Science 29: 169
- S2CID 131729220.
- ^ O. C. Marsh. 1891. "Notice of new vertebrate fossils". The American Journal of Science, series 3 42: 265–269
- S2CID 130187840.
- ^ S2CID 140535438.
- ^ ICZN, 2015, "Opinion 2361 (Case 3561): Anchisaurus Marsh, 1885 (Dinosauria, Sauropodomorpha): usage conserved by designation of a neotype for its type species Megadactylus polyzelus Hitchcock, 1865", Bulletin of Zoological Nomenclature 72(2): 176–177
- ^ Galton, P.M. (1971).
- ^ Galton, P. M., Upchurch, P. (2004).
- ^ Shubin, N. H. et al. (1994).
- ^ Fedak, T. J. (2007).
- ^ ISBN 0-7853-0443-6.
- ^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 163
- ^ ISSN 1042-0940.
- ISBN 1-84028-152-9.