Post by creature386 on Feb 13, 2013 0:40:40 GMT 5
Chuandongocoelurus primtivus
Temporal range: 165 Ma Middle Jurassic
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Sauropsida
Superorder:Dinosauria
Order:Saurischia
Suborder:Theropoda
(unranked):Tetanurae
Superfamily:Megalosauroidea
Genus:Chuandongocoelurus
Species: Chuandongocoelurus primtivus
Location: Chuandong, Sichuan, China; Xiashaximiao
Formation; Middle Jurassic (He Xinlu 1984).[1]
Description:
Chuandongocoelurus primitivus ("primitive hollow-tail from Chuandong") has been largely ignored in literature, even tough it is known for quite a long time. It has been described by He Xinlu in 1984. The Holotype (CCG 20010) is a subadult (it has unfused structures in the dorsal vertebra, which are commonly found in not full grown animals) known from parts of the postcranial skeleton , including third cervical vertebra (61 mm), tenth cervical vertebra (69 mm), third dorsal centrum (65 mm), fourth dorsal vertebra (58 mm), proximal caudal vertebra (60 mm), partial scapula (282 mm), partial ilium, proximal pubis, proximal ischium, femur (201 mm), tibia (231 mm, so it is 15% longer than the femur, that's not very common in theropods), astragalus, calcaneum, incomplete metatarsal II, phalanx II-1 (30 mm), metatarsal III (122 mm, 61% of the femoral legth), metatarsal IV (114 mm), phalanx IV-1 (16.5 mm), phalanx IV-2 (9 mm), phalanx IV-3 (10 mm), phalanx IV-4 (12 mm) and pedal ungual IV (18 mm)[2]. Scaling from Elaphrosaurus' femur legth, the Holotype can be estimated at 2,4m and scaling from Paul's (1988)[3] estimated mass for Elaphrosaurus, we get 12 kg in mass[2]. Brusatte et al. (2010) estimated it at 13-14 kg[4]:
He Xinlu described a much larger second specimen (CCG 20011; vertebrae), but it shows little similarities with the Holotype, it seems to be more closely related to Elaphrosaurus (they have quite similar cervical centra and pleurocoelous fossa)[1].
Classification:
There are authors who believe Chuandongocoelurus primtivus to be an Ornithopod[2], but that's very unlikely, because the Tibia shape doesn't match with those of Ornithopods (Rauhut 2003)[5]. Also, the illum shape too rahter belongs to a member of the Tetanurae clade. However, the femoral head shape (~45◦ anteromedially shaped and inclined ventrally) is not a common feature of the Tetanurae clade[1]. Chuandongocoelurus primtivus also has a crest shape, what is believed to be a non-tetanuran feature (Holtz 2000)[6], but in 2010, Zhao et al. found evidence in Monolophosaurus, to have a similar crest shape[7]. In the same year, Benson et al. classified if as a sister taxon of Monolophosaurus[8]. He Xinlu classified this theropod as a relative of Coelurus. Holtz (1994) classified it as a relative of Elaphrosaurus, both were classified by him as Abelisaurids[2].
Footnotes:
[1] M. T. Carrano, R. B. J. Benson, S. D. Sampson: The phylogeny of Tetanurae (Dinosauria: Theropoda). In: Journal of Systematic Palaeontology. 10, Nr. 2, 2012, S. 233
[2] Details on Chuandongocoelurus
[3] Paul, Gregory S. (1988). Predatory Dinosaurs of the World.
[4] Brusatte, S., Benson, R. B. J. & Xu, X. 2010. The evolution of large-bodied theropod dinosaurs during the Mesozoic in Asia. Journal of Iberian Geology, 36, 275–296
[5] Rauhut, O. W. M. 2003. The interrelationships and evolution of basal theropod dinosaurs. Special Papers in Palaeontology, 69, 1–213.
[6] Holtz, T. R., Jr 2000. A new phylogeny of the carnivorous dinosaurs. GAIA, 15, 5–61.(LINK)
[7] Zhao, X.-J., Benson, R. B. J., Brusatte, S. L. & Currie, P. J. 2010. The postcranial skeleton of Monolophosaurus jiangi (Dinosauria: Theropoda) from the Middle Jurassic of Xinjiang, China, and a review of Middle Jurassic Chinese theropods. Geological Magazine, 147, 13–27.
[8] Benson, 2010. A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods. Zoological Journal of the Linnean Society (LINK)
Temporal range: 165 Ma Middle Jurassic
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Sauropsida
Superorder:Dinosauria
Order:Saurischia
Suborder:Theropoda
(unranked):Tetanurae
Superfamily:Megalosauroidea
Genus:Chuandongocoelurus
Species: Chuandongocoelurus primtivus
Location: Chuandong, Sichuan, China; Xiashaximiao
Formation; Middle Jurassic (He Xinlu 1984).[1]
Description:
Chuandongocoelurus primitivus ("primitive hollow-tail from Chuandong") has been largely ignored in literature, even tough it is known for quite a long time. It has been described by He Xinlu in 1984. The Holotype (CCG 20010) is a subadult (it has unfused structures in the dorsal vertebra, which are commonly found in not full grown animals) known from parts of the postcranial skeleton , including third cervical vertebra (61 mm), tenth cervical vertebra (69 mm), third dorsal centrum (65 mm), fourth dorsal vertebra (58 mm), proximal caudal vertebra (60 mm), partial scapula (282 mm), partial ilium, proximal pubis, proximal ischium, femur (201 mm), tibia (231 mm, so it is 15% longer than the femur, that's not very common in theropods), astragalus, calcaneum, incomplete metatarsal II, phalanx II-1 (30 mm), metatarsal III (122 mm, 61% of the femoral legth), metatarsal IV (114 mm), phalanx IV-1 (16.5 mm), phalanx IV-2 (9 mm), phalanx IV-3 (10 mm), phalanx IV-4 (12 mm) and pedal ungual IV (18 mm)[2]. Scaling from Elaphrosaurus' femur legth, the Holotype can be estimated at 2,4m and scaling from Paul's (1988)[3] estimated mass for Elaphrosaurus, we get 12 kg in mass[2]. Brusatte et al. (2010) estimated it at 13-14 kg[4]:
He Xinlu described a much larger second specimen (CCG 20011; vertebrae), but it shows little similarities with the Holotype, it seems to be more closely related to Elaphrosaurus (they have quite similar cervical centra and pleurocoelous fossa)[1].
Classification:
There are authors who believe Chuandongocoelurus primtivus to be an Ornithopod[2], but that's very unlikely, because the Tibia shape doesn't match with those of Ornithopods (Rauhut 2003)[5]. Also, the illum shape too rahter belongs to a member of the Tetanurae clade. However, the femoral head shape (~45◦ anteromedially shaped and inclined ventrally) is not a common feature of the Tetanurae clade[1]. Chuandongocoelurus primtivus also has a crest shape, what is believed to be a non-tetanuran feature (Holtz 2000)[6], but in 2010, Zhao et al. found evidence in Monolophosaurus, to have a similar crest shape[7]. In the same year, Benson et al. classified if as a sister taxon of Monolophosaurus[8]. He Xinlu classified this theropod as a relative of Coelurus. Holtz (1994) classified it as a relative of Elaphrosaurus, both were classified by him as Abelisaurids[2].
Footnotes:
[1] M. T. Carrano, R. B. J. Benson, S. D. Sampson: The phylogeny of Tetanurae (Dinosauria: Theropoda). In: Journal of Systematic Palaeontology. 10, Nr. 2, 2012, S. 233
[2] Details on Chuandongocoelurus
[3] Paul, Gregory S. (1988). Predatory Dinosaurs of the World.
[4] Brusatte, S., Benson, R. B. J. & Xu, X. 2010. The evolution of large-bodied theropod dinosaurs during the Mesozoic in Asia. Journal of Iberian Geology, 36, 275–296
[5] Rauhut, O. W. M. 2003. The interrelationships and evolution of basal theropod dinosaurs. Special Papers in Palaeontology, 69, 1–213.
[6] Holtz, T. R., Jr 2000. A new phylogeny of the carnivorous dinosaurs. GAIA, 15, 5–61.(LINK)
[7] Zhao, X.-J., Benson, R. B. J., Brusatte, S. L. & Currie, P. J. 2010. The postcranial skeleton of Monolophosaurus jiangi (Dinosauria: Theropoda) from the Middle Jurassic of Xinjiang, China, and a review of Middle Jurassic Chinese theropods. Geological Magazine, 147, 13–27.
[8] Benson, 2010. A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods. Zoological Journal of the Linnean Society (LINK)