肯尼亚早三叠世叶肢介一新属—Kenyaestheria(英文)

KENYAESTHERIA, A NEW GENUS OF CONCHOSTRACA FROM THE LOWER TRIASSIC OF KENYA

报道的叶肢介新属(Kenyaestheriagen.nov.)采自肯尼亚MajiyaChumvi地区的一钻孔,属下三叠统上马几牙楚姆维组(UpperMajiyaChumviFormation),其特征为壳瓣后背缘最后几条生长线靠近背缘处形成一个凹缘构造,但生长线在背缘并不反转弯曲,同时具有放射线纹饰,据此将其归于凹缘叶肢介科(Ulugkemiidae)。该科是一个灭绝的类群,分布于中泥盆统至上三叠统,古生代的类型都发现于欧亚大陆,晚三叠世的Triasulugkemia见于阿根廷,新属首见于早三叠世,也是在南大陆出现的第二例凹缘叶肢介类。孢粉Lunatisporitespellucidus和叶肢介AquilonoglyptaCorniaPalaeolimnadiaFalsisca组合指示含化石的地层时代为早三叠世早期。

The new genus Kenyaestheria assigned to the family Ulugkemiidae was collected from the Upper Maji ya Chumvi Formation in the Scott Borehole, Maji ya Chumvi of Kenya. It is characterized by possessing a carapace, the last few growth lines of which forming an incurvature at the postero-dorsal margin and with radial linear sculpture. The ulugkemiids are an extinct group ranging from the Middle Devonian to the Upper Triassic. The Paleozoic forms were lived in Eurasia. The Late Triassic Triasulugkernia was reported from Argentina. The new genus is the first record from the Early Triassic and the second record in the southern continents for this group. Both spore-pollen Lunatisporites pellucidus and conchostracan Aquilonoglypta-Cornia-Palaeolirnnadia-Falsisca assemblages indicate that the conchostracan-bearing beds are of early Early Triassic in age.