Phaulostephanus is an extinct genus from the ammonoid family Stephanoceratidae

Stephanoceratidae

Sephanoceratidae is a family of planulate and coronate ammonites within the Stephanocerataceae. Shells are evolute so that all whorls are exposed and have strong ribbing that bifurcates, that is splits in two, on the flanks. Many have tubercles at the point of bifurcation...

, which is part of the ammonitid

Ammonitida

The Ammonitida is an order of more highly evolved ammonoid cephalopods from the Jurassic and Cretaceous time periods, commonly with intricate ammonitic sutures....

 superfamily Stephanocerataceae

Stephanocerataceae

Stephanocerataceae is a superfamily of middle Jurassic ammonoid cephalopods within the order Ammonitida containing diverse forms, generally with sharp ribbing and complex suture lines...

, that lived during the early Middle Jurassic.

Phaulostephanus is a small serptenticone with a generally subcircular to subquadrate whorl section, slightly sinuous ribbing, and tubercles that if present are weakly developed. Primary ribs are sharp, divide about mid flank into prominent and moderately sharp secondary ribs. The aperture of the macroconch has a broad ventral collar preceded by a constriction. That of the microconch is flanked by lappets and has no constriction.The suture is ammonitic.

Phaulostephanus was named by Buckman in 1927 and consideed a subgenus of Stephanoceras

Stephanoceras

Stephanoceras is a Stephanoceratacean genus and type for the Stephanoceratidae, which lived during the Bajocian but is now extinct....

by Arkell, et al(1957) in the Treatise. It was elevated to genus in Pavia (1983) and Westermann (1984) (ref't in Sandoval and Westermann 1986 )