An enigmatic ‘conchostracan’ fauna in the eastern Dead Sea region of Jordan: First records of Rossolimnadiopsis Novozhilov from the Early Triassic Ma'in Formation

The Late Permian–Early Triassic sedimentary succession in the eastern Dead Sea Region of Jordan was surveyed for conchostracans (Crustacea: Branchiopoda). Whereas their occurrence in the Middle–Late Permian Umm Irna Formation could not be confirmed, the overlying Ma'in Formation contained a fauna comprising Rossolimnadiopsis Novozhilov and other, thus far, taxonomically undetermined conchostracans. Here, a new species, Rossolimnadiopsis hanskerpi nov. sp., is described and figured. It shows a very distinctive concavely curved dorsal margin and an elevated, outwardly curved semi-circular flange. Rossolimnadiopsis hanskerpi nov. sp. occurs in dark gray, laminated, lacustrine, siltstones of the Ma'in Formation (Nimra Member), which is considered to be of Early Triassic age. Based on literature data, Rossolimnadiopsis was previously recorded only from two localities in the Moscow syncline in Central Russia. In addition to Jordan, the genus has been identified in India and possibly in Germany. All these occurrences seem to be restricted to a narrow stratigraphic interval ranging from the Late Permian to the Early Triassic. [Display omitted] •Our study describes and figures Early Triassic conchostracans from Jordan.•Among them we define the new species Rossolimnadiopsis hanskerpi nov. sp.•Rossolimnadiopsis hanskerpi nov. sp. was collected from the Ma'in Formation.•The occurrences were interpreted as pond deposits on a coastal plain.•Diverse invertebrate traces and a marine bivalve from the Ma'in Formation are figured.