The porolepiforms, like the onychodontids (above), were rhipidistians that existed only during the Devonian period. But, unlike their contemporaries, the porolepiformes had developed the muscular, lobed fins typical of the sarcopterygians. They also had the unique jointed skull, as described for Strunius.
name: Gyroptychius time: Middle Devonian locality: Europe (Scotland) size: 1 ft/30 cm long
Qyroptychius was a fast-moving, long-bodied predator in Devonian rivers, with small eyes and a keen sense of smell. Like other porolepiforms, it had short jaws. This actually enhanced the bite-power of the jaws.
Qyroptychius had fleshy, muscular fins, all of which, except for the pectorals, were concentrated at the rear of the body. This increased the propulsive force of the arrow-shaped tail.
name: Holoptychius time: Late Devonian locality: Worldwide size: 20 in/50 cm long
Holoptychius was a deep-bodied, streamlined fish, with a lightweight covering of thin, rounded scales. It was a voracious predator of other bony fishes. Like all its rhipidistian relatives, it had fanglike teeth arranged around the margin of its palate, and numerous smaller, pointed teeth lined both jaws. Prey would have been held fast between the teeth, then swallowed whole.
Holoptychius had an asymmetrical tail. The powerful thrust produced by its upper lobe would have tended to drive Holoptychius down in the water. To compensate for this, the muscular pectoral fins were extra-long and mounted high on the flanks. They acted as hydrofoils; their slightest movement out to the sides would have elevated the front of the body, and counteracted the down-thrust produced by the tail. They also stabilized the fish and steered a course by their concerted movements.
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