Tanycolagreus
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Tanycolagreus Temporal range: Late Jurassic, 153–150 Ma |
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| Tanycolagreus holotype, North American Museum of Ancient Life. | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Order: | Saurischia |
| Suborder: | Theropoda |
| Genus: |
†Tanycolagreus Carpenter et al., 2005 |
| Species: | †T. topwilsoni |
| Binomial name | |
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Tanycolagreus topwilsoni Carpenter et al., 2005 |
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Tanycolagreus is a genus of coelurosaurian theropod from the Late Jurassic of North America.
Carpenter et al. (2005, pp. 43–44) determined that the holotype of Tanycolagreus represents a subadult individual which measured approximately 3.3 meters (11 ft) long in life. However, one of the referred fossils, the premaxilla from the Cleveland-Lloyd Quarry, would have belonged to a larger individual, measuring 4 meters (13 ft) long. In 2010 Gregory S. Paul estimated the weight of a four metres long animal at hundred twenty kilogrammes. It cannot be determined whether or not the Cleveland-Lloyd specimen represents a fully mature adult, so the upper size limit for the taxon remains unknown.
The head of Tanycolagreus is large, elongated and rectangular in profile due to a blunt snout. The leg is rather long and lightly built.
Carpenter et al. (2005; pp. 27 & 29) diagnosed Tanycolagreus topwilsoni as follows: "Medium-sized tetanuran having short, deep-bodied premaxilla pierced by narial foramen at base of nasal process, orbital process on postorbital, T-shaped quadratojugal, centrodiapophyseal lamina on dorsals. Differs from Coelurus in the absence of pleurocoel on anterior dorsals; posterior caudal prezygapophyses elongated to one-third centrum length, rather than short; straight, rather than sigmoidal, humeral shaft; bowed, rather than straight, radius; flat-bottomed rather than arced pubic foot; straight rather than sigmoidal femoral shaft; metatarsal length subequal to humeral length, rather than 1.75 times humeral length. Differs from Ornitholestes in straight anterior margin of premaxilla, rather than rounded; T-shaped rather than L-shaped quadratojugal; elongate neural spine; posterior caudal prezygapophyses only one-third centrum length, rather than one-half centrum length; bowed, slender radius, rather than straight, robust radius".
The single premaxillary tooth preserved with the holotype is badly damaged, but does exhibit the asymmetrical cross-section typical in theropod teeth; the cheek teeth are too poorly preserved to show any detail. In the foot the second toe is slightly hyperextendable but does not carry an enlarged claw.
In 1995 Western Paleontological Laboratories, Inc. uncovered the partial skeleton of a small theropod at the Bone Cabin Quarry West locality, Albany County, Wyoming, from the Salt Wash Member of the Morrison Formation, dating to the Oxfordian-Tithonian. At first the find was considered to be a specimen of Coelurus but subsequent study indicated it represented a species new to science, that in 2001 was announced to be named Tanycolagreus topwilsoni. It was actually named and described by Kenneth Carpenter, Clifford Miles and Karen Cloward in 2005. The etymology of the generic name Tanycolagreus, suggested by Ben Creisler, is based upon the greater length of its forelimbs and hindlimbs compared to Coelurus. It is derived from the Greek prefix τανυ~, tany~: 'long, stretched out', κῶλον, kolon: 'limb' and ἀγρεύς, agreus: 'hunter'. The specific name honours George Eugene "Top" Wilson, the father of a benefactor financially supporting the scientific research.
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