An Eocene shallow water isselicrinid sea lilies from the Northern Hemisphere.

Stalked crinoids are uncommon fossils in the Cenozoic. This is particularly due to their continuous decline starting from the Late Cretaceous and gradual restriction to the deep-sea environment, which bears a fossil record bias. On the other hand, in recent times, new data have emerged documenting some relict populations of sea lilies in the shallow marine facies from the Cenozoic. Here, we report shallow-water occurrences of Eocene crinoids from Romania that are classified as Isselicrinus. The representatives of Isselicrinus reached their greatest palaeogeographic distribution during the Eocene in offshore environments, and the only find of these crinoids from shallow-water facies was from the Southern Hemisphere. Thus, our discovery documents the first Eocene shallow-water occurrence of this taxon from the Northern Hemisphere. This finding shows that isocrinids locally might have remained in shallow environments after the initiation of the so-called Mesozoic marine revolution (MMR).