Chilantaisaurus

''Chilantaisaurus'' (" lizard") is a genus of large theropod dinosaur, possibly a neovenatorid or a primitive coelurosaur, from the Late Cretaceous Ulansuhai Formation of China (Turonian age, about 92 million years ago). The type species, ''C. tashuikouensis'', was described by Hu in 1964.

Description

''Chilantaisaurus'' was a large theropod, measuring long and weighing . While Brusatte ''et al.'' (2010) estimated that ''Chilantaisaurus'' might have weighed about based on femur length similar to that of ''Tyrannosaurus'', Persons ''et al.'' (2020) argued that greater femoral circumference indicates the greater capacity to withstand greater locomotor loads, not greater body mass.

Classification

Hu considered ''Chilantaisaurus'' to be a carnosaur related to ''Allosaurus'', though some subsequent studies suggested that it may be a spinosauroid, possibly a primitive member of the spinosaurid family (Sereno, 1998; Chure, 2000; Rauhut, 2001) because it had large claws on the forelimbs thought to be unique to that group. Other studies suggested that it could be a member of an alternate offshoot of neotetanuran theropods, with some similarities to allosauroids, spinosauroids, and coelurosaurians.

A 2009 study noted that it was difficult to rule out the possibility that ''Chilantaisaurus'' was the same animal as the carnosaur ''Shaochilong'', which was thought to be from the same geological formation (a later study indicated that the latter genus actually derives from the Early Cretaceous Miaogou Formation). However, they did note an enormous size difference between the two. Further study by Benson, Carrano and Brusatte found that it was not as closely related to ''Shaochilong'' as first thought, but that it was a carnosaur (of the family Neovenatoridae), closely related to ''Allosaurus'' as Hu had initially thought. Phylogenetic analysis published by Porfiri et al. in 2018 recovered ''Chilantaisaurus'' as a primitive coelurosaurian.

Several species have been described based on very poor remains. The species ''"Chilantaisaurus" sibiricus'' (previously informally known as either ''Allosaurus? sibiricus'' or ''Antrodemus? sibiricus'') is based on a single distal metatarsal discovered in 1915 in the Turginskaya Svita of the Buryat Autonomous Soviet Socialist Republic, Russia, dating to the Early Cretaceous period (Berriasian to Hauterivian stages). It is poorly described, so its relationships cannot be accurately determined (Chure, 2000) and its placement as a species of ''Chilantaisaurus'' is highly questionable. "Chilantaisaurus" ''maortuensis'' was reclassified as ''Shaochilong maortuensis'' in 2009.Brusatte, S., Benson, R., Chure, D., Xu, X., Sullivan, C., and Hone, D. (2009). "The first definitive carcharodontosaurid (Dinosauria: Theropoda) from Asia and the delayed ascent of tyrannosaurids." ''Naturwissenschaften'',

An additional species named in 1979, "Chilantaisaurus" ''zheziangensis'', based on bones from the foot and a partial tibia, is actually a therizinosaur taxon.

The cladogram below follows a 2016 analysis by Sebastián Apesteguía, Nathan D. Smith, Rubén Juarez Valieri, and Peter J. Makovicky based on the dataset of Carrano et al. (2012).

References

External links

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{{Taxonbar, from=Q134633

Tetanurae
Dinosaur genera
Turonian dinosaurs
Fossil taxa described in 1964
Dinosaurs of China