First occurrence of fossil shrimps (crustacea, decapoda) in the Ipubi Formation (Lower cretaceous, Araripe Basin)

The Ipubi Formation of the Araripe Basin is an important gypsum cretaceous reserve whose environment had resulted in the deposition of evaporites with narrow black shale lenses. In this work, we present the first occurrence of caridean for the dark shale levels of the Ipubi Formation. The analyzed specimen, although not achieving a detailed taxonomic determination, is a very important one because it is the first decapod crustacean found in this formation. We believe the specimen LPU-0918/A and B, is a caridean because of its second abdominal somite having a strongly rounded pleura in the base and it apparently overlaps the first and the third. The knowledge about fossil shrimps is still sparse, and the information presented here can be valuable to the understanding of the evolutive history of the carideans.阿拉里皮盆地（Araripe Basin）的伊普比组（Ipubi Formation）是一处重要的白垩纪石膏矿床，其沉积环境形成了夹有小型黑色页岩透镜体的蒸发岩沉积序列。本研究首次报道了伊普比组黑色页岩层位中的真虾下目（Caridea）生物化石。本次分析的标本虽未能完成详细的分类学鉴定，但仍具有极高研究价值——这是该地层中首次发现的十足目甲壳动物（decapod crustacean）化石。我们将标本LPU-0918/A与B归为真虾类，依据是其第二腹体节基部的侧突呈显著圆形，且该侧突明显覆盖了第一与第三腹体节的侧突。目前学界对化石虾类的研究仍较为匮乏，本次披露的研究信息对阐明真虾类的演化历史具有重要参考价值。