广东三水盆地的哺乳动物化石

在广东三水盆地新村水库附近的第三系中发现了一哺乳动物的下颌骨和上臼齿。其形态特征很象叉齿兽（Hypsilolambda），但尺寸比已知的种大很多。它可能代表叉齿兽的一新种，或新属。现暂将其归入叉齿兽属。其产出地层心群一组的时代可能为古新世。

MAMMALIAN FOSSILS FROM SANSHUI BASIN,GUANGDONG, CHINA

A left upper molar (IVPP Vlll97) and a fragment of lowe jaw, tWo vertebrae and some ribs (V12180) wer collected from Formation Ⅰof the Buxin Grop in Sanshui Basin, Guangdong Province, China.The lower jaw is more sindlar to that of Bemalambdidae than to other mammals as evidenced by its robust body, deep mandible symphysis with rather smp anterior border, presence of three pairs of indsors, a large c and espedally a long diastema between c and p2, Which is one of the dishnctive features of Bemlambdidae. The upper molar is also sindlar to that of the Bemalambdidae in being proportionally wide and short, with a wide stylar shelf, developed parastyle and metastyle,and a V-shaped protocone. The specimens from Sanshui are more Similar to those of Hypsilolambda than to Bemalambda in lacking a distinct antero-extemal border on the lowe jaw and having a forked and V-shaped parastyle on the upper molar. Hypsilolambda is known to indude two species H chalingensis and H impensa. The Sanshui specimens are much larger and robuster than both of them. The molar is also much wider in proportion. They may represent a new species of Hypsilolambda, or even a new genus. At present we tentahvely assign it to Hypsiloambda as ? Hypsilolambda sp.The deposits bearing the mammal fossils was named as Formation I of the Buxin Group. Recently it was suggested to be transferred to midddle Eocene Baoyue Formation. The Bemalambdidae are only known from early-midddle Paleocen. Hypsilolambda is only known from midddle Paleocene. Therefore, the age of the fossil -bearing deposits is unlikely Eocene, but Paleocene. As for the tritigraphic terminology of the deposits, it seems better to keep the original one, Formation I of the Buxin Group.