Adamsoceras is an actinocerid

Actinocerida

The Actinocerida comprise an order of generally straight, medium to large cephalopods that lived during the early and middle Paleozoic, distinguished by a siphuncle composed of expanded segments that extend into the adjacent chambers, in which deposits formed within contain a system of radial...

 of the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Wutinoceratidae

Wutinoceratidae

The Wutinoceratidae is a family of early actinocerids defined by Shimazu and Obata in 1938 for actinocerids with thick connecting rings and a complex irregular canal system...

, with spheroidal siphuncle

Siphuncle

The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and Spirula...

 segments like Ormoceras

Ormoceras

Ormoceras is an actinocerid genus of the family Ormoceratidae which is found in North America from the late Chazyan though the early Cincinnatian of the Middle and Upper Ordovician, but continued through the Devonian worldwide....

but having a reticular canal system like Wutinoceras

Wutinoceras

Wutinoceras, orthoconic actinocerids with ventral siphuncles composed of broadly expanded segments.and the type genus of the Wutinoceratidae. -Distinguishing Characters:...

. 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

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

) in Nevada, the Baltic, Tasmania, and Manchuria. Adamsoceras may have been derived from Wutinoceras, or from a common ancestor, and give rise to Ormoceras.

The genotype is Adamsoceras isabelae from the upper Pogonip Group in Ikes canyon in the Toquima Range

Toquima Range

The Toquima Range is a line of mountains in northwestern Nye County, in central Nevada in the western United States. From Hickson Summit on U.S. Route 50, the range runs for approximately 71 miles to the south-southwest. To its west are Big Smoky Valley, scenic State Route 376, and the large...

 in Nevada, named and described by Rousseau H. Flower

Rousseau H. Flower

Rousseau Hayner Flower was an extremely prolific 20th century paleontologist, known for his eccentric personality.- Career :Although trained as an entomologist, and a specialist in dragonflies and orthopterans, Flower began studying paleontology in the middle of the 1930s...

in 1957.