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Extinct order of molluscs From Wikipedia, the free encyclopedia
Phragmoteuthida is an order of extinct coleoid cephalopods[1] characterized by a fan-like teuthoid pro-ostracum attached to a belemnoid-like phragmocone.
Phragmoteuthida | |
---|---|
Comparation of hard parts of Phragmoteuthida, Belemnitida and Diplobelida | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Cephalopoda |
Superorder: | †Belemnoidea |
Order: | †Phragmoteuthida Jeletzky in Sweet, 1964 |
Families | |
See text. |
Jeletzky[1] characterized phragmoteuthids as having a large tripartite, fanlike pro-ostracum forming the longest portion of the shell, attached to about three-quarters of the circumference of a comparatively small breviconic phragmocone with short camerae and superficially belemnitid-like siphuncle, an absent or much reduced rostrum at the apical part of the phragmocone, belemnite-like arm hooks, an ink sack, beaks resembling those of Recent teuthids, and a muscular mantle.
Donovan (2006), gives a similar description for Phragmoteuthis: Phragmocones as having an apical angle of between 20 and 30 degrees, and relatively few chambers compared with belemnoids; a multi-layered conotheca, thick-walled siphuncle, and a long, three-lobed pro-ostracum as in the Triassic species. Arms are short and bear pairs of slightly curved hooks.[2]
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