A late Permian ichthyofauna from the Zechstein Basin, Lithuania-Latvia Region

Abstract

The late Permian is a transformative time, which ended in one of the most significant extinction events in Earth's history. Fish assemblages are a major component of marine foods webs. The macroevolution and biogeographic patterns of late Permian fish are currently insufficiently known. In this contribution, the late Permian fish fauna from Kūmas quarry (southern Latvia) is described for the first time. As a result, the studied late Permian Latvian assemblage consisted of isolated chondrichthyan teeth of Helodus sp., ?Acrodus sp., ?Omanoselache sp. and euselachian type dermal denticles as well as many osteichthyan scales of the Haplolepidae and Elonichthydae; numerous teeth of Palaeoniscus, rare teeth findings of ?Platysomus sp. and many indeterminate microremains. This ichthyofaunal assemblage is very similar to the contemporaneous Lopingian complex of the carbonate formation from the Karpėnai quarry (northern Lithuania), despite the fact that Kūmas samples include higher diversity and abundance in fossil remains. The differences in abundance of microremains could possibly be explained by a fresh water influx in the northeastern Zechstein Basin margin, which probably reduced the salinity of the sea water. The new data enable a better understanding of the poorly known late Permian fish diversity from the Lithuania-Latvia Region.