Ceratodus

Ceratodus (C. latissimus "horn tooth"), is an extinct genus of sarcopterygians of the lungfish group that lived during the Middle Triassic Ladinian to the Late Cretaceous Campanian.
Possibly omnivorous in diet, it reached a size of about 60 cm in length and would have had a long, narrowly shaped body with a severely reduced caudal tail; this shows that Ceratodus was not a particularly strong or fast swimmer.
It was one of the most widely distributed fish to ever live on the planet and being a lungfish, Ceratodus would have had the ability to breathe air when out of water, although it would eventually have to return to the water to prevent it from drying out. he thinks that was the adaptation that hundreds of millions of years earlier allowed early tetrapods to leave the water for long periods so they could colonize land.
The pose represents a school of Ceratodus latissimus developing in the riverbed.

Approximate measurements of one of the Ceratodus:

Scale 1:35 - 50 mm Length