Neocephalopoda
| Neocephalopods | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Clade: |
Neocephalopoda Lehmann & Hillmer, 1980 |
| Subgroups | |
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| Synonyms | |
|
Angusteradulata Lehmann, 1967 |
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Angusteradulata Lehmann, 1967
Neocephalopods are a group of nautiloid mollusks that include the Bactritida. In contrast, the palcephalopoda are defined as the sister group to the neocephalopoda.
The name Neocephalopoda was first published (in Lehmann & Hillmer, 1980) as an Infraclass, which (in a reversal of the usual Linnean hierarchy) included the Subclass Bactritoidea.
These names were applied by later workers running cladistic analyses on the cephalopods. Berthold & Engeser (1987) adopted the name Angusteradulata for the clade comprising ammonoids and coleoids. Later, Engeser (1996) included not only the coleoids, ammonoids, and bactritids, but also some orthocerid families: Michelinoceratidae, Sphaerorthoceratidae, Arionoceratidae, "and probably other groups as well."
Although the name Angusteradulata appeared earlier than Neocephalopoda, both names were coined by Lehmann, who preferred the latter. Engeser and Lehmann later both agreed that Neocephalopoda was a more suitable name than Angusteraduata.
The following characters are thought to be shared, at least ancestrally, by neocephalopods. Most are from Engeser (1996) or from his Fossil Nautiloidea page.
Although there is wide agreement that Bactritida included the ancestors of ammonoids and coleoids, the relations among theseremain problematic. The greatest obstacles may lie among the nautiloids:
Nevertheless, recent descriptions of shells with preserved apical ends have aided in the classification of major taxa. For instance, ascocerids and pseudorthocerids have a cicatrix and so do not belong among the neocephalopods.
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