Sphaerorthoceratidae
Encyclopedia
Sphaeorthoceratidae is an extinct family of orthocone
cephalopods that lived in the Paleozoic
Era. They were similar to the nautiloid Michelinoceras
in the apex
, but had shorter necks to their septa that were orthochoanitic or suborthochoanitic.
The sphaerorthoceratids were significant in cephalopod evolution because they may have given rise to the bactritids, which in turn were the ancestors of ammonoids and coleoids.
The family lived in the middle Paleozoic, ranging from the Wenlockian epoch of the Silurian
Period to the Famennian
age of the Devonian
Period, or about 428 to 361 Ma.
Orthocone
An orthocone is a usually long straight shell of a nautiloid cephalopod. During the 18th and 19th centuries, all shells of this type were named Orthoceras, but it is now known that many groups of nautiloids developed or retained this type of shell....
cephalopods that lived in the Paleozoic
Paleozoic
The Paleozoic era is the earliest of three geologic eras of the Phanerozoic eon, spanning from roughly...
Era. They were similar to the nautiloid Michelinoceras
Michelinoceras
Michelinoceras is the oldest known genus of the Michelinocerida, more commonly known as the Orthocerida, characterized by long, slender, nearly cylindrical orthocones with a circular cross section, long camerae, very long body chambers, and a central or near central tubular siphuncle free of...
in the apex
Apex (mollusc)
Apex is an anatomical term for the tip of the mollusc shell of a gastropod, scaphopod, or cephalopod mollusc.-Gastropods:The word "apex" is most often used to mean the tip of the spire of the shell of a gastropod...
, but had shorter necks to their septa that were orthochoanitic or suborthochoanitic.
The sphaerorthoceratids were significant in cephalopod evolution because they may have given rise to the bactritids, which in turn were the ancestors of ammonoids and coleoids.
The family lived in the middle Paleozoic, ranging from the Wenlockian epoch of the Silurian
Silurian
The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
Period to the Famennian
Famennian
The Famennian is one of two faunal stages in the Late Devonian epoch. It lasted from 374.5 ± 2.6 million years ago to 359.2 ± 2.5 million years ago. It was preceded by the Frasnian stage and followed by the Tournaisian stage and is named after Famenne, a natural region in southern Belgium.It was...
age of the Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
Period, or about 428 to 361 Ma.