贵州松桃寒武系清虚洞组Mongolitubulus squamifer壳体显微结构初步研究

本文主要对贵州松桃寒武系清虚洞组灰岩中酸泡获得的管状化石Mongolitubulus squamifer壳体显微及亚显微结构进行研究。研究结果显示, M. squamifer不仅内层广泛发育纵向纤维结构,具鳞片的外层外壁也发育有微弱的纵向纤维结构,可能解释了管体外壁广泛发育的纵向开裂现象。在一枚保存有圆卵形鳞片以下部位的标本中发现,鳞片排列形式是由基部密集的小瘤点状颗粒然后过渡为不规则的圆卵形鳞片,到管体中上部逐渐形成规则排列的三角形鳞片。通过测量部分已报道的M.squamifer管体宽度与鳞片宽度发现正常发育的棘刺,鳞片大小与管体宽度有一定相关性。贵州松桃的M.squamifer壳层原始结构为2层,包括致密的具鳞片的外层和具明显纵向纤维结构的内层,管体内外层之间发育空隙导致管体容易破损。一些标本近基部断口处的层间空隙容易被次生矿物充填,导致内层增厚致密纤维结构消失或产生中间填充层。该研究揭示了M.squamifer的鳞片排列特征和壳体微观结构,为解释其亲缘关系提供新的形态学证据。

Microstructure of Mongolitubulus squamifer from the Cambrian Tsinghsu-tung Formation of Songtao, Guizhou

Microstructures of the small shelly fossils of Mongolitubulus squamifer from the Cambrian Tsinghsutung Formation in Songtao, Guizhou province, were studied. Our results show that M. squamifer has extensive longitudinal fiber structure on both inner walls and outer walls, which may explain the tube''s outer wall''s widespread longitudinal cracking. In a specimen with well-preserved part below the round oval scales, we found that the exterior wall scales transform from punctate grains to irregular scales at the lower part of the base. They gradually form regular triangular scales at the upper part of the tube body. By measuring some of the reported tube width and scale width of M. squamifer, we found normal spines, and the scale size increased with the increase of tube width. The M. Squamifer in Songtao was usually observed with two major layers, in-cluding a dense with scales with outer and inner longitudinal fiberstructure. The development gap between the tubular body results in the outer tube is easily damaged. In some specimens, the interlaminar voids near the base fracture are quickly filled by secondary minerals, resulting in the loss of the thickened and dense fiber structure of the inner layer or forming an inter-mediate filling layer. The study revealed the scale arrangement characteristics and shell microstructure of M. squamifer, providing new information to explore the species'' phylogenetic affinities further.