Enigmatic fish taxa

species of fish

Psarolepis (; psārolepis, from Greek ψαρός 'speckled' and λεπίς 'scale') is a genus of extinct bony fish which lived around 397 to 418 million years ago (Pridoli to Lochkovian stages). Fossils of Psarolepis have been found mainly in South China and described by paleontologist Xiaobo Yu in 1998. It is not known certainly in which group Psarolepis belongs, but paleontologists agree that it probably is a basal genus and seems to be close to the common ancestor of lobe-finned and ray-finned fishes. In 2001, paleontologist John A. Long compared Psarolepis with onychodontiform fishes and refer to th

Cretalamna is a genus of extinct otodontid shark that lived from the latest Early Cretaceous to Eocene epoch (about 103 to 46 million years ago). It is considered by many to be the ancestor of the largest sharks to have ever lived, such as Otodus angustidens, Otodus chubutensis, and Otodus megalodon.

Megamastax (meaning "big mouth") is a genus of lobe-finned fish which lived during the late Silurian period, about 423 million years ago, in China. Before the discovery of Megamastax, it was thought that jawed vertebrates (gnathostomes) were limited in size and variation before the Devonian period. Megamastax is known only from jaw bones and it is estimated that it reached about long.

Janusiscus schultzei is an extinct gnathostome vertebrate dating from the Early Devonian period in Siberia, approximately 415 million years ago. It may be the sister group of the last common ancestor of Chondrichthyes (cartilaginous fish) or Osteichthyes (bony fish). This makes J. schultzei a sister species to all living jawed vertebrates. The species name is in honor of Hans-Peter Schultze; the genus named after Janus, the Roman god of duality.