Eusthenopteron is a genus of prehistoric sarcopterygian fishes known from several species that lived during the Late Devonian period, about 385 million years ago. It has attained an iconic status from its close relationship to tetrapods. Early depictions of animals of this genus show them emerging onto land, but paleontologists now widely agree that eusthenopteron species were strictly aquatic animals.
Eusthenopteron
Eusthenopteron foordi
Reconstruction of Eusthenopteron
Head of Eusthenopteron (model)
Sarcopterygii — sometimes considered synonymous with Crossopterygii — is a clade including both a group of bony fish commonly referred to as lobe-finned fish, and tetrapods. They are characterised by prominent muscular limb buds (lobes) within their fins, which are supported by articulated appendicular skeletons. This is in contrast to the other clade of bony fish, the Actinopterygii, which have only skin-covered bony spines supporting the fins.
Guiyu oneiros, the earliest-known bony fish, lived during the Late Silurian, 419 million years ago). It has the combination of both ray-finned and lobe-finned features, although analysis of the totality of its features places it closer to lobe-finned fish.
Tooth from the sarcopterygian Onychodus from the Devonian of Wisconsin
Image: Latimeria Paris
Life restoration of Sparalepis tingi and other fauna from the Silurian of Yunnan