Wellsoceras
Encyclopedia
Wellsoceras is a tetragonoceratid
that starts off with an evolute shell in which whorls are in contact, but has a mature living chamber that diverges and becomes free. The whorl section is slightly wider than high and is faintly subquadrangular. Flanks are slightly convex and tend to comverge very slightly toward the venter. All shoulders are strongly rounded. The suture is straight ventrally or with a slight ventral lobe, well developed lateral lobes, and a broad, low dorsal saddle. The siphuncle is located half way between the center and the ventral margin.
Wellsoceras has been found in Middle Devonian sediments in eastern North America, in Ohio, Indianna, and Ontario.
Tetragonoceratidae
The Tetragonoceratidae is a small family of nautilitids constituting a part of the superfamily Tainocerataceae in which shells are coiled with a generally quadrate whorl section. Coiling is either gyroconic or evoluute with a slight dorsal impression. Flanks diverge from the umbilical to the...
that starts off with an evolute shell in which whorls are in contact, but has a mature living chamber that diverges and becomes free. The whorl section is slightly wider than high and is faintly subquadrangular. Flanks are slightly convex and tend to comverge very slightly toward the venter. All shoulders are strongly rounded. The suture is straight ventrally or with a slight ventral lobe, well developed lateral lobes, and a broad, low dorsal saddle. The siphuncle is located half way between the center and the ventral margin.
Wellsoceras has been found in Middle Devonian sediments in eastern North America, in Ohio, Indianna, and Ontario.