奇虾类前附肢化石在河北唐山地区寒武系馒头组的发现

A NEW ANOMALOCARIDID FRONTAL APPENDAGE FROM THE MIDDLE CAMBRIAN MANTOU FORMATION OF THE TANGSHAN AREA , HEBEI

奇虾类是寒武纪海洋中的大型捕食动物,广泛发现于世界各地的寒武纪地层,但是多为前附肢或口器的标本。我国扬子地台云南、贵州一带的寒武纪特异埋藏动物群中都发现了奇虾化石,如澄江动物群、牛蹄塘动物群、关山动物群、凯里动物群等。但在华北地台,寒武纪特异埋藏动物化石目前为止只有零星报道,包括一些大型双瓣壳节肢动物、古蠕虫类等。本文描述一枚发现于河北省唐山市丰润区左家坞一带馒头组(毛庄期)紫红色页岩中的奇虾类前附肢化石,可能代表了一个新类型。这枚化石的发现丰富了奇虾类的古地理分布,也为在华北地台边缘地区寻找特异埋藏动物化石提供了线索。

Anomalocaridids are a group of large preda- tors that world-widely lived in the Cambrian ma- rine ecosystem. Most of them are preserved as iso- lated frontal appendages and mouthparts. Anoma- locaridid fossils are common in the Cambrian fau- nas of the Yangtze Platform, such as Chengjiang, Niutitang, Guanshan, and Kaili faunas in Yunnan and Guizhou provinces. However, soft-bodied ani- mal fossils including anomalocaridids have been poorly reported from the North China Platform. Here we describe such an anomalocaridid specimen from the purple reddish shale of the Mantou For- mation （Luaspides huoshanensis Zone） at Zuo- jiawu, Fengrun District of Tangshan City, Hebei. The specimen is a frontal appendage, 2.3 cm long, with 12 podomeres visible; its basal sections missing and the terminal sections incomplete; it is rather straight but curved after the middle section. The length of each podomere being reduces back- wards, bears a pair of ventral spines, the proximalventral spine invisible. The ventral spines are arranged alternately in length on successive podo- meres, auxiliary spines not clearly visible they are distally directed and inclined to the margin of the podomere at an angle of 100-80 at least one terminal spine is clearly visible a pair of conical shaped dorsal spines armed on the reciprocal second podomere.