Temporal range: M Ordovician
Adamsoceras is an actinocerid of the family Wutinoceratidae, with spheroidal siphuncle segments like Ormoceras but having a reticular canal system like Wutinoceras. Adamsoceras has a slender, gently expanding, orthoconic shell that is slightly broader than high, i.e. depressed, with close spaced septa that form ventral lobes and a siphuncle that is near the ventral margin.
Adamsoceras is known from rocks of Whiterockian age (early Middle Ordovician) in Nevada, the Baltic, Tasmania, and Manchuria. Adamsoceras may have been derived from Wutinoceras, or from a common ancestor, and give rise to Ormoceras.
- Flower R.H. 1957. Studies of the Actinoceratida, New Mexico Bureau of Mines and Mineral Resources (NMBMMR) Memoir 2, Socorro NM .
- ______ 1968, The First Great Expansion of the Actinoceroids, NMBMMR PartI Memoir 19