THE FIRST APPEARANCE OF TINOSAURUS FOSSIL IN THEQUATERNARY

Some Tinosaurus fossils were collected from the Quaternary caves of County, Shaanxi Province, which are well-preserved row of teeth and dentary. The dentary is stronger and has the grooves between teeth on external side of ramus caused by wear of opposing upper teeth. The teeth are reducing in size from back to front. It is the first report of Tionsaurus in the Quaternaryand made the record of this genus extended from early Tertiary to the Quaternary. The specimens from the area show the characters of Tinosaurus well, and compared with other species of the genera, they show some differences. So we record it as a new species: T. luonanensis sp. nov.1 Systematic paleontologyFamily SquamataSubfamily LacertiliaTribe Chameleontidae Gray, 1825Genus Tinosaurus Marsh, 1872Tinosaurus luonanensis sp.nov.(Fig. 1,2)Holotype NWUV 1134.1 - 2, a right maxilla with 12 teeth; a left mandible with 11 teeth.Referred specimens A pair of right maxilla and mandible, two left mandibles ( NWUV 1135- 1136, NWUV 1137,NWUV 1138).Etymology Named after Luonan County, Shaanxi Province, where the new species is discovered .Locality and age Zhangping of County, Shaanxi Province; Quaternary ( mid-late of Early Pleistocene?).Diagnosis are small size, heterodonty, acrodont anteriorly, conical; subacrodont posteriorly , tricuspid; the center main cusp is stronger than those of both sides. are reducing in size from back to front. The anterior of the upper jaw is convex highly at back-wall of the nostril and the posterior is smooth. The lower jaw is stronger and arched down or not, and there are grooves between teeth on external side of ramus caused by wear of opposing upper teeth.2 DiscriptionUpper jaw Length of upper jaw specimen is 8.13mm, highest is 2.31 mm. Its widely anterior part is the bottom of the nostril, which united with the premaxilla. The highest of the upper side is between the nosalia and prefrontal, then smooth posterior after sharply down .There are 12 teeth on the upper jaw with 7.0mm in length. The first 2 teeth are conical, 1 .06mm long; the following 10 teeth are tricuspid, 5 .87mm in length. The width of the last one on the upper tooth row is 0.68mm,0.87mm in height. The three cusps of are arranged along a line. There are two neuroforamens on anterior in external view .Lower jaw Length of lower jaw specimens is 8. 17mm, height ( under the last tooth) is 1.5mm. The anterior of mandible is small, lightly bent to internal and with five neuroforamens on external. The supraangular is difficult to distinguish since its sutural line is hard to see. But there seems a sutural line of angular and which looks narrowly long. The mackelian canal is uncovered, which is narrow along its anterior half but slightly increases in depth posteriorly.There are 11 teeth on the lower jaw, the total length of the teeth is 6.3mm. On the specimen 1137(Fig. 1 ,e,f) .the first four teeth are similar with those of upper jaw while the 4th tooth slightly larger than the first three teeth . The features of the posterior teeth are almost the same to those of the upper jaw.3 Comparison and discussionThe genus Tinosaurus was established by Marsh in 1872. Its features was given by Gilmore (1928) as: Teeth typically of small size,acrodont; tricuspid posteriorly, denticles reducing anteriorly vertical grooves between teeth on external side of ramus caused by wear of opposing upper teeth. reducing in size from back to front .After Marsh, 6 species have been reported from the northern hemisphere; two of which were from the northern America and the others from Asia.The new species T. luonanensis is distinguished from all the other species (including the Tino-saurus stenodon , T. pristinus, Gilmore, 1928; T. asiaticus , Gilmore, 1943; T. lushihensis, Dong, 1965 ; T. doumuensis , Hou, 1974 and T. yuanquensis , Li, 1991 ) in genus Tinosaurus by following: 1) T. luonanensis is distinguished from T. asiaticus , T. lushihensis and T. doumuensis by its presence of grooves between teeth on external surface