Panderichthys is a genus of extinct sarcopterygian (lobe-finned fish) from the late Devonian period, about 380 Mya.

Panderichthys, which was recovered from Frasnian (early Late Devonian) deposits in Latvia, is represented by two species.

The intracranial joint, which is characteristic of most lobe-fin fishes, has been lost from the external elements of the skull, but is still present in the braincase.

The body form of Panderichthys and Tiktaalik represents a major step in the transition from fish to tetrapods and they were even able to haul out on land.

During the transition from fish to tetrapods the limbs began to move and became located at a right angle to the body rather than being oriented toward the posterior end.

The humerus of Panderichthys is more derived than that of Tiktaalik because of the presence of a more preaxially oriented radial facet as well as a more slender shaft.

[8] Due to the orientation of the fin towards the posterior end, the attitude of the limb is more horizontal than vertical and the operational space in which it acts is level to the shoulder joint, which causes the muscles to pull at a right angle to the body.

However, a reexamination[10] of existing Panderichthys fossils using a CT scanner shows at least four very clearly differentiated distal radial bones at the end of the fin skeletal structure.

The CT scan displayed an ulnare, a blocky carpal (wrist bone) that articulates with the ulna and two terminal radials.

This is due to the humerus of Panderichthys being a shape that is more of an intermediate, while the femur is more primitive because of the length ratio to the fibula and that it lacks an adductor blade and crest.

In general, Panderichthys demonstrates that the braincase structure evolved much more slowly than the external skull morphology that created the tetrapod-like appearance of the head.

[3] In January 2010, Nature reported well-preserved and "securely dated" tetrapod tracks from Polish marine tidal flat sediments approximately 397 million years old.

The tracks "force a radical reassessment of the timing, ecology and environmental setting of the fish–tetrapod transition, as well as the completeness of the body fossil record.

Lode is known to be a marginal marine environment and it has been hypothesized that Panderichthys was adapted for movement in shallow and debris filled waters.

[3] Panderichthys was collected in deposits that were formerly believed to be from a calm freshwater basin, but have proven to be from shallow tidal flats or an estuary.

Most of the specimens are well preserved due to anaerobic substrate conditions as well as rapid burial in depressions on the submarine delta slopes.

Within this environment it has been hypothesized that P. rhombolepis was a large predator and fed upon dipterids, small and juvenile sarcopterygians, and Latvius.

[15] Associated vertebrates found in the same deposits include an armored jawless fish (Psammolepis), two placoderms (Asterolepis and Plourdosteus), an unidentified acanthodid acanthodian, a porolepiform lobe-fin (Laccognathus), a lungfish (Dipterus), and another elpistostegalian (Livoniana).

The enlargement of the spiracular chamber itself as well as its opening to the outside suggests that Panderichthys was part of a transition to an increased capacity for air breathing that was completed in tetrapods.