Post by Derdadort on Oct 30, 2013 19:02:16 GMT 5
Fossils (left dentary and left maxilla) of Kelmayisaurus petrolicus
by Stephen L. Brusatte, Roger B.J. Benson, and Xing Xu under Creative Commons Attribution 2.0 Generic license
Classification:
Dinosauria
Saurischia
Theropoda
Carnosauria
Allosauroidea
Carcharodontosauridae
Kelmayisaurus
K. petrolicus (Dong 1978, Brusatte et al. 2012)
Fossilsite: Karamay (China)
Age: ca. 136,4 to 112 mya (Valanginian(?) to Albian, Lower Cretaceous)
Holotype: IVPP V 4022
Description:
Kelmayisaurus was a genus of big theropods from the lower Cretaceous of China. Only valid species is K.petrolicus. It was first described by Dong Zhiming in 1978, a second description was made by Brusatte et al. in 2012.
Due to the meagre material a size estimate of K.petrolicus is very difficult, however Brusatte et al. concluded by its dentary that its size was comparable to Allosaurus. According to this they estimate a length of about 10 to 11m and a mass of 1600kg.
The holotype consists of the fragmentary left maxilla and a nearly complete left dentary. The maxilla is similar to other allosauroids like Allosaurus, Monolophosaurus or Neovenator, the rough surface like in carcharodontosaurids and abelisaurids is missing. The dentary is well preserved and 525mm long. It shows a concave groove on its anteriorly lateral surface, Brusatte et al. evaluate it as an autapomorphy.
Systematics:
The attribution of the genus was uncertain for a long time. In his first description Dong classified Kelmayisaurus as a megalosaurid, Carroll (1988) declared it as a carnosaur, Molnar et al. (1990) as a tetanur. Dong classified it a second time in 1992 as an allosaurid. Rauhut and Xu (2005) finally made it a nomen dubium, because of its lacking fossils.
However a cladistic analysis of Brusatte et al. contradicts Rauhut and Xu's decision. Furthermore it shows that Kelmayisaurus was a basal carcharodontosaurid, which faces togehter with Eocarcharia the clade of Acrocanthosaurus and other derived carcharodontosaurids.
after Brusatte et al. (2012)
Therefore K.petrolicus would be the second known Asian carcharodontosaurid after Shaochilong, which corroborates the thesis of a successful currency of the carcharodontosaurids during the early and middle Cretaceous.
Nevertheless Brusatte et al. admitted that an alternative classification of K.petrolicus is possible, e.g. a relation to Megalosaurus or Guanlong. But a detailed analysis of the fossils and comparison with other species still supports Carcharodontosauridae.
Sometimes K.gigantus is mentioned as a second species. It supposedly reached a length of about 22m. If this is true, it would be the largest known ground dwelling predator of earth histroy. However the existence of a that big theropod can't be confirmed.
Sources:
1) Stephen L. Brusatte, Roger B.J. Benson, Xing Xu: A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous of China, 2012. Acta Palaeontologica Polonica 57 (1), 2012: app.pan.pl/archive/published/app57/app20100125.pdf
2) Z. Dong. 1973. [Dinosaurs from Wuerho]. Reports of Paleontological Expedition to Sinkiang (II): Pterosaurian Fauna from Wuerho, Sinkiang. Memoirs of the Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica 11:45-52
3) R. L. Carroll. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York 1-698
4) R. E. Molnar, S. M. Kurzanov, and Z. Dong. 1990. Carnosauria. In D. B. Weishampel, H. Osmólska, and P. Dodson (eds.), The Dinosauria. University of California Press, Berkeley
5) Z. Dong. 1992. Dinosaurian Faunas of China. China Ocean Press, Beijing 1-188
6) O. W. M. Rauhut and X. Xu. 2005. The small theropod dinosaurs Tugulusaurus and Phaedrolosaurus from the Early Cretaceous of Xinjiang, China. Journal of Vertebrate Paleontology 25(1):107-118
by Stephen L. Brusatte, Roger B.J. Benson, and Xing Xu under Creative Commons Attribution 2.0 Generic license
Classification:
Dinosauria
Saurischia
Theropoda
Carnosauria
Allosauroidea
Carcharodontosauridae
Kelmayisaurus
K. petrolicus (Dong 1978, Brusatte et al. 2012)
Fossilsite: Karamay (China)
Age: ca. 136,4 to 112 mya (Valanginian(?) to Albian, Lower Cretaceous)
Holotype: IVPP V 4022
Description:
Kelmayisaurus was a genus of big theropods from the lower Cretaceous of China. Only valid species is K.petrolicus. It was first described by Dong Zhiming in 1978, a second description was made by Brusatte et al. in 2012.
Due to the meagre material a size estimate of K.petrolicus is very difficult, however Brusatte et al. concluded by its dentary that its size was comparable to Allosaurus. According to this they estimate a length of about 10 to 11m and a mass of 1600kg.
The holotype consists of the fragmentary left maxilla and a nearly complete left dentary. The maxilla is similar to other allosauroids like Allosaurus, Monolophosaurus or Neovenator, the rough surface like in carcharodontosaurids and abelisaurids is missing. The dentary is well preserved and 525mm long. It shows a concave groove on its anteriorly lateral surface, Brusatte et al. evaluate it as an autapomorphy.
Systematics:
The attribution of the genus was uncertain for a long time. In his first description Dong classified Kelmayisaurus as a megalosaurid, Carroll (1988) declared it as a carnosaur, Molnar et al. (1990) as a tetanur. Dong classified it a second time in 1992 as an allosaurid. Rauhut and Xu (2005) finally made it a nomen dubium, because of its lacking fossils.
However a cladistic analysis of Brusatte et al. contradicts Rauhut and Xu's decision. Furthermore it shows that Kelmayisaurus was a basal carcharodontosaurid, which faces togehter with Eocarcharia the clade of Acrocanthosaurus and other derived carcharodontosaurids.
after Brusatte et al. (2012)
Therefore K.petrolicus would be the second known Asian carcharodontosaurid after Shaochilong, which corroborates the thesis of a successful currency of the carcharodontosaurids during the early and middle Cretaceous.
Nevertheless Brusatte et al. admitted that an alternative classification of K.petrolicus is possible, e.g. a relation to Megalosaurus or Guanlong. But a detailed analysis of the fossils and comparison with other species still supports Carcharodontosauridae.
Sometimes K.gigantus is mentioned as a second species. It supposedly reached a length of about 22m. If this is true, it would be the largest known ground dwelling predator of earth histroy. However the existence of a that big theropod can't be confirmed.
Sources:
1) Stephen L. Brusatte, Roger B.J. Benson, Xing Xu: A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous of China, 2012. Acta Palaeontologica Polonica 57 (1), 2012: app.pan.pl/archive/published/app57/app20100125.pdf
2) Z. Dong. 1973. [Dinosaurs from Wuerho]. Reports of Paleontological Expedition to Sinkiang (II): Pterosaurian Fauna from Wuerho, Sinkiang. Memoirs of the Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica 11:45-52
3) R. L. Carroll. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York 1-698
4) R. E. Molnar, S. M. Kurzanov, and Z. Dong. 1990. Carnosauria. In D. B. Weishampel, H. Osmólska, and P. Dodson (eds.), The Dinosauria. University of California Press, Berkeley
5) Z. Dong. 1992. Dinosaurian Faunas of China. China Ocean Press, Beijing 1-188
6) O. W. M. Rauhut and X. Xu. 2005. The small theropod dinosaurs Tugulusaurus and Phaedrolosaurus from the Early Cretaceous of Xinjiang, China. Journal of Vertebrate Paleontology 25(1):107-118