Tarrasiiformes

• Scotland
• Montana

The Tarrasiidae are an extinct bony fish family of the subclass of Knorpelganoiden ( Chondrostei ). The group lived in the Lower Carboniferous.

Features

The Tarrasiidae were ten to 13 inches long. Her body was elongated and resembled that of a fish larva or the bichirs ( Polypterus ). Your short skull resembled that of Palaeonisciformes. Directly behind the head began a long dorsal fin, which formed a long, uninterrupted Flossensaum with the diphycerken tail fin and the beginning roughly in the middle of the body anal fin. Under each fin ray of the dorsal fin were two rows of fins carrier ( radials ) in the anal fin, it was just a number. The small pectoral fins had eight radials that sat right on the shoulder belt. Pelvic fins were not available. All fin rays were not divided, but divided. The notochord has not regressed throughout life. Only the back and ventral arches ossified.

System

The Tarrasiidae be assigned by Joseph S. Nelson, author of the standard work on fish systematics, the subclass of Knorpelganoiden ( Chondrostei ), which also includes the recent sturgeon. A cladistic study came to the conclusion that they are the sister group of all ray-finned fishes with the exception of Flössler ( Polypteridae ). The exact systematic position shows the following cladogram.

Meat -finned fishes ( Sarcopterygii )

Flössler ( Polypteridae )

Tarrasiidae

Cheirolepis

Other ray-finned

Genera

Two genera have been described in numerous ways:

• Paratarrasius Traquair, 1881 ( 69 species )
• Tarrasius Lund & Melton, 1982 ( ten species)

Tarrasius had a scaleless front and rear scaly body while Paratarrasius was complete with scales.