晚三叠世泡孔类苔藓动物Casianopora及其种系发生关系

THE CYSTOPORATE BRYOZOAN CASSIANOPORA FROM THE EARLY NORIAN (LATE TRIASSIC) AND ITS PHYLOGENETIC RELATIONS

本文描述了窄唇纲苔藓动物的一个新种Ｃａｓｉａｎｏｐｏｒａｈｅｉｓｐ．ｎｏｖ．，此新种发现于我国滇西北宁蒗彝族自治县松桂组１５层（菊石Ｍａｌａｙｉｔｅｓ－Ｐｓｅｕｄｏｃａｒｄｉｏｃｅｒａｓ带），是迄今已知的全球三叠纪泡孔类的一个最新代表。重新确定了Ｃａｓｉａｎｏｐｏｒａ属（卡尼中期－诺利早期）的分类位置，它和Ｃｙｓｔｉｔｒｙｐａ属（卡尼早期）都归入Ｆｉｓｔｕｌｉｐｏｒｉｄａｅ科。这两个三叠纪的属，与古生代和古生代后的一些泡孔类的种系发生关系的初步探讨表明，所有古生代后的窄唇纲的各个目（除环口目外），可能都是从同一演化根系上发展而来的。

The last representative of the cystoporates is a new stenolaemate bryozoan species, Cassianopora hei, which is described from the Late Triassic (late early Norian). It occurs in Bed 15 (ammonoid Malayites Pseudocardioceras Zone) of the Songgui Formation in Ninglang Yizu Zizhixian, northwestern Yunnan, China. In this paper, the genus Cassianopora Bizzarini et Braga(1978) is formally assigned to the family Fistuliporidae. Cassianopora (middle Carnian early Norian) and Cystitrypa (early Carnian), which was established and placed tentatively in the family Fistuliporidae by Schfer and Fois(1987), have close phylogenetic affinities. These two Late Triassic cystoporate genera appear to have phylogenetic connection with some early Paleozoic cystoporate genera, such as Revalotrypa, Profistulipora (early Arenig-Llanvir), as well as with the latest Paleozoic cystoporate subspecies Dybowskiella sinensis regularis Lu(late Changxingian). These taxa share a most important characteristic extrazooidal vesicular structure. Only a few cystoporate taxa have been discovered from Jurassic and Cretaceous strata in Canada, Chile and China. A preliminary probe into the phylogenetic relations of all orders of the post Paleozoic and Paleozoic Stenolaemata suggests that all orders of the post Paleozoic Stenolaemata, exclusive of Cyclostomida, could develop independently from the same evolutionary root stock, though a big gap exists in stenolaemate fossil records from Paleozoic to Mesozoic.