峡东寒武纪第二期三管缠绕形壳Anabarites cf.tripartitus的螺旋手性

Spiral chirality of three-lobes helical tube Anabarites cf.tripartitus from Cambrian Age 2 in Three Gorges area

在现生生物和化石记录中螺旋手性十分常见,然而,其发生机制一直悬而未决,尤其是寒武纪早期小壳化石。阿纳巴管类(anabaritids)是一类广布于寒武纪纽芬兰世地层中呈明显三辐射对称的管状化石,前人对该类化石中螺旋扭转属种的研究大多仅限于形态描述,其手性机制讨论甚少。本文依托湖北宜昌寒武系纽芬兰统岩家河组中111枚右手螺旋手性的小壳化石——Anabarites cf.tripartitus,探讨该类化石右手螺旋模式生长机制,认为螺旋扭转原因并非外部环境所致(水流变化、埋藏作用、科里奥利力),而应从生物自身因素(功能形态学、分子发育生物学)出发探究其固定的右旋不对称性机制。

Helical chirality is a widespread phenomenon observed in both extant organisms and the fossil record.Despite its prevalence,this phenomenon has received comparatively little attention in scientific research,especially in the context of small shelly fossils from the Early Cambrian.Anabaritids,a group of tubular fossils exhibiting distinctive triradial symmetry,are known from the Early Cambrian strata worldwide.Previous studies on some helical anabaritid species have mostly focused on morphological descriptions,with the underlying causes for their helical chirality remaining largely unexplored.This study examines the mechanism responsible for the fixed right-handed(dextral)spiral chiralityobserved in Anabarites cf.tripartitus,based on an analysis of 111 specimensobtained from Member 5 of the Yanjiahe Formation(Cambrian Stage 2)in the Three Gorges area of Hubei Province,China.The cause of right-handed helical chirality should be inferred from the perspective of molecular genetics,considering biological factors(e.g.,functional morphology,molecular developmental biology)instead of external environmental factors(e.g.,water change,taphonomy,Coriolis force).