猛洞河虫(Mengdongella)是仅发现于湘西寒武系芙蓉统排碧阶的微体双瓣壳节肢动物。由于缺少不同发育阶段的标本, 前人的研究仅限于双瓣壳的形态描述和壳刺的功能分析, 对生长过程缺乏关注。本文研究了产自湘西王村剖面芙蓉统排碧阶比条组上部的猛洞河虫标本, 标本数共计229枚。不同大小的标本代表着不同的生长阶段。通过对它们的壳长、壳高、壳刺长和壳刺起始宽度的测量和分析, 发现这些参数之间存在线性相关关系, 猛洞河虫双瓣壳各部分是异速生长的。通过对壳长—壳高分析, 可能存在至少7个龄期。猛洞河虫最小的个体壳长在320 μm左右, 属于小型(meiofaunal)节肢动物, 可能生活在海底沙粒缝隙之中或营浮游生活; 而较大个体的壳长可以达到2.6 mm以上, 属于大型(macrofaunal)节肢动物, 营底栖爬行或游泳生活。

Mengdongella is a microscopic bivalved arthropod found exclusively from the Paibian Stage (Furongian Series, upper Cambrian) of western Hunan, China. Due to the lack of specimens in different growth stages, previous studies are limited to morphological description of bivalved carapaces and functional analysis of valve spines, without investigating their growth process. In this paper, we present our in-depth study of the growth process of Mengdongella based on 229 specimens from the Bitiao Formation (Furongian) at the Wangcun section, Yongshun County, western Hunan. Specimens with different carapace sizes represent different growth stages. Detailed meas-urements and analyses reveal that there is a positive linear correlation between two of the following variables: valve length, valve height, valve spine length, and basal valve spine width. Thus, we propose that the carapace of Mengdongella shows allometry. Moreover, analysis on the valve length and valve height reveals discontinuous growth, indicating that Mengdongella has at least seven instars during its life span. The smallest individuals of Mengdongella are about 320 μm in length, belonging to meiofauna and possibly living in the space among sand grains or being pelagic, whereas larger individuals can reach at least 2.6 mm in length, belonging to macrofauna and living by creeping on the sea floor or swimming in the waters.

本研究由国家自然科学基金项目(42172020)支持