First record of Acanthocephala parasites eggs in coprolites preliminary assigned to Crocodyliformes from the Adamantina Formation (Bauru Group, Upper Cretaceous), São Paulo, Brazil

Abstract Abstract: This study presents the oldest record of Acanthocephala parasite eggs in coprolites preliminary assigned to Crocodyliformes, recovered in the region of Santo Anastácio Municipality, Southwestern São Paulo State. For this, a paleoparasitological investigation was carried out on 53 mineralized coprolites (complete or fragmented), with round shape or cylindrical shape of rounded or pointed ends, 0.2 - 3.9 cm in length x 0.1 - 2.4 cm in diameter, 3.7 grams in weight, and absence of food remains. Individual samples of the surface and internal portions of each coprolite were extracted by electric drill, dissociated with Cloridic Acid 10% solution, washed with Distilled Water, and filtered in granulometric screen Mesh / Tyler 325. After laboratory processing, the sediments retained on the granulometric screen was studied with Glycerin under optical microscopy, and the presence of four Acanthocephala eggs could be observed in sample of only one of these ichnofossils. All specimens were well preserved and showed 72.5 - 85 µm in length x 27.5 - 50 µm in width, elliptical shape, three concentric and thick shells, and embryos in their interior. This study inaugurates investigations and knowledge about Paleoparasitology in Crocodyliformes coprolites from the Bauru Group, Upper Cretaceous from the Paraná Basin.

摘要：本研究报道了采自圣保罗州西南部圣阿纳斯塔西奥市辖区、初步归属于鳄形目（Crocodyliformes）的粪化石（coprolites）中，迄今最古老的棘头动物门（Acanthocephala）寄生虫卵记录。本次研究对53枚矿化粪化石（完整或破碎）开展古寄生虫学调查（paleoparasitological investigation）：这些粪化石呈圆形或两端圆润/尖锐的圆柱形，单枚长0.2~3.9厘米、直径0.1~2.4厘米，平均重量约3.7克，且未检出食物残留。研究人员通过电动钻分别采集每枚粪化石的表面与内部样品，采用10%盐酸（Cloridic Acid）溶液进行解离处理，经蒸馏水（Distilled Water）洗涤后过325目泰勒筛（Mesh/Tyler 325）进行粒度分离。实验室处理完成后，将筛上留存的沉积物以甘油（Glycerin）封片，置于光学显微镜下观测，最终仅在其中1枚遗迹化石（ichnofossils）的样品中检出4枚棘头动物门虫卵。所有虫卵标本保存完好，尺寸为长72.5~85微米、宽27.5~50微米，呈椭圆形，具有三层厚实的同心壳结构，内部包含胚胎。本研究首次针对巴拉那盆地（Paraná Basin）上白垩统（Upper Cretaceous）鲍鲁群（Bauru Group）的鳄形目粪化石开展古寄生虫学研究，为该领域的相关认知奠定了全新基础。