Abstract

On the basis of new extensive collections, made by the present authors, a group of unsegmented three-dimensional fossil remains from the Late Precambrian of Namibia and the southeastern White Sea area, including such genera as Protechiurus, Vendoglossa, and Vendoconularia, were restudied. It is established that the fossils belong to two morphologically close genera (Protechiurus and Vendoconularia), composing the new family Protechiuridae. It is possible that they represent the same genus or even species, but the incompleteness of the preservation of the Namibian member of the group prevents their integration. The fossils initially represented conical hollow elastic objects, hexagonal in the cross-section, which were open at the wide end and closed at the pointed end. The sculpture of their surface consisted of longitudinal ridges, both single and double, bounding the rows of the short transverse ridges, scalloped along one margin. Vendoconularia had wide plates which were attached to the cone outwardly along the longitudinal unpaired ridges. In general morphology and several details the fossils resemble the thecae of conulariids and anabaritids, known from Late Precambrian and Paleozoic and classified as the scyphozoan cnidarians. The main difference lays in the theca mineralization, which consists of phosphate in conulariids, carbonate in anabaritids, and is absent in the case of protechiurids. It is proposed that the protechiurids, which appeared in the fossil record first, may belong to the basal group of ancient scyphozoans, ancestral to the conulariids on the one hand, and to the anabaritids on the other.

中文翻译：

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前寒武纪大生物的圆锥形鞘

摘要

在新的广泛收集的基础上，由本作者提出，一组非分割三维化石遗骸纳米比亚晚前寒武纪和东南部的白海区域，包括这些属为Protechiurus，Vendoglossa和Vendoconularia，进行重新研究。它建立在化石属于两个形态接近属（Protechiurus和Vendoconularia），组成新的家庭Protechiuridae。它们有可能代表相同的属，甚至是物种，但纳米比亚成员的保存不完整会阻止它们的融合。这些化石最初代表的是圆锥形的空心弹性物体，其横截面为六边形，在宽端敞开，在尖端敞开。它们表面的雕塑由纵向和横向的山脊组成，这些山脊既有单根的也有双重的，沿着短的横向山脊排成一排，沿着一个边缘呈扇形。Vendoconularia具有宽板，这些宽板沿着不成对的纵向脊向外连接到锥。从形态学和细节上讲，这些化石类似于前寒武纪晚期和古生代已知的并归类为子生孢子的刺孢子虫的卵壳和拟南芥的卵鞘。主要区别在于卵泡膜的矿化作用，其由针孢菌中的磷酸盐，Anabaritids中的碳酸盐组成，而在protechiurids中则不存在。有人提出，最早出现在化石记录中的protechiurids可能属于古代裂殖体的基群，一方面是卵圆con的祖先，另一方面是伞形目的。