Theropoda Teeth Of Early Cretaceous From Quantou Formation In Gongzhuling, Jilin Province

Theropoda is one of the main groups in dinosaurs. The number of their fossils is small,but they were very diverse. The classification and evolution of Theropoda have always beenthe focus to paleontologists. From early 1970s, some paleontologists found the value ofisolated teeth in dinosaurian study. Based on the tooth size,shape,denticles andcross-section, we can classify some dinosaurs, at least it is creditable over genus.This paper summarized the identification characteristics and evolutionary trends of thisgroup. And , summarized the teeth characteristics of basal groups in Dinosauria.Also, introduced the situation in the field of Theropoda teeth study. This paper originallydescribed Theropoda fossils found in Jilin province, and identified two families and twogenuses, which are Chilantaisaurus (Allosauridae) and Aublysodon(Tyrannosauridae).The fauna of Allosauridae/Tyrannosauridae probably represented the transitional type fromLate Jurassic to Late Cretaceous!Among the fossils found in Gongzhuling area, there were five teeth (Ya01-05), whichpossessed the typical large Theropoda characteristics: the crown was compressed laterally,curved backwards; there were chisel-like denticles on both edges. Carnosauria andTyrannosauroids were the most popular large theropods during Cretaceous. The teeth ofTyrannosauroids were large and robust; the denticles were very coarse, about 10 per 5mm;there were blood-grooves between denticles. As to the specimen of Gongzhuling area, therewere no blood-groove, and 18 per 5mm, which were different from Tyrannosauroids'.Carnosauria referred to Allosauridea and the groups which were more close to it than toothers, mainly included Sinraptoridae ,Allosauridae and Carcharodontosauridae.Carcharodontosauridae teeth were similar to sharks', the crown were not curve; thedenticles were sinuate to the apex along both two edges. Whereas the specimen'teeth werecurved backwards; the denticles were chisel-like, not curve to the apex. Which weredifferent from Carcharodontosauridae. The denticles of Sinraptoridae were totally differentfrom the specimen': as to the former, the anterior were distinct than the posterior. While thelatter was just on the contrary. Allosauridae teeth were the most similar to the specimen':they were all compressed laterally, curved backwards; the anterior denticles were faint, theposterior developed well; the cross-section was oval. So the specimen were belong toAllosauridae without any doubt. Allosauridae was consist of Allosaurus andChilantaisaurus. They were mostly the same in teeth, except the denticle coarseness: there...