Bathynectes muelleri

Bathynectes muelleri is an extinct species of polybiid crab and the oldest known species of the genus "Bathynectes". It lived in the Central Paratethys of modern-day Ukraine during the Badenian age(Langhian, middle Miocene ). While extant species of "Bathynectes" live mainly in deep water habitats, "B. muelleri" fossils were found in sediments indicative of shallow water habitats, suggesting the earliest "Bathynectes" originated in shallow waters, and descendent species migrated to deep-water habitats.