Protacanthopterygii - Characteristics and Origin

Characteristics and Origin

Protacanthopterygii contains a number of moderately advanced teleosts. Anatomical and other traits commonly found in this superorder are: more than 24 vertebrae, epicentral cartilages, one supraorbital bone, and a mesocoracoid, an adipose fin and (often prominent) glossohyal teeth. However, they usually lack a protrusible upper jaw, a gular plate and proximal forking of the intermuscular bones. Most members of this family are rather specialization mid-sized to larger predators of smaller animals.

As a group, they prefer temperate waters and are far more diverse in the Northern Hemisphere than in the Southern. Some are anadromous migrants and many are quite euryhaline. Thus, it is likely that they originated in nearshore or brackish waters of the N hemisphere – theoretically the original protacanthopterygian might have been a catadromous migrant inhabiting freshwater, but given that the basal Otocephala were very likely marine this seems not so likely. Given that they are widespread in the Holarctic but reached the Southern hemisphere in the Pacific region, it is more likely than not that they originated in general region of the Turgai Strait and the nearby Tethys Sea – perhaps towards the Eastern Tethys as they never seem to have settled Africa or Atlantic South America.