Litoceras
Encyclopedia
Litoceras is a trocholitid
(Tarphycerida) genus that has been found the Lower and early Middle Ordovician
of Newfoundland. Whorls in Litoceras have a broadly rounded cross section with the width greater than the height and somewhat resembles the tarphyceratid
Pionoceras from the same time, except for the siphuncle being dorsal of the center.
Trocholitidae
The Trocholitidae are Tarphycerida with whorls in close contact as with the Tarphyceratidae, but in which the siphuncle, similar in structure, becomes dorsal. The Trocholitidae are derived from the Tarphyceratidae, perhaps from different tarphyceratids....
(Tarphycerida) genus that has been found the Lower and 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...
of Newfoundland. Whorls in Litoceras have a broadly rounded cross section with the width greater than the height and somewhat resembles the tarphyceratid
Tarphyceratidae
The Tarphyceratidae are tightly coiled, evolute Tarphycerida with ventral siphuncles. The dorsum is characteristically impressed where the whorl presses against the venter of the previous. The Tarphyceratidae are derived from Bassleroceras or possibly from some member of the...
Pionoceras from the same time, except for the siphuncle being dorsal of the center.