Clydonautilidae
| Clydonautilidae Temporal range: M -U Triassic |
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|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | Nautilida |
| Superfamily: | Clydonautilaceae |
| Family: |
Clydonautilidae Hyatt, 1900 |
The Clydonautilidae are Middle and Upper Triassic nautiloid cephalopods, which are derivatives of the clydonautlicean family Liroceratidae, that have generally smooth, involute, globular to compressed shells, characterized by a suture with prominent lobes and saddles. The family is known to contain five genera', These are:
Of these only Styrionautilus is known from the Middle Triassic. The other four are so far restricted to the Upper Triassic.
The five genera in the Clydonautilidae form a sequence of increasing sutural complexity, beginning with Styrionautilus and ending with Clydonautilus. Styrionautilis, which has the simplest suture of the five, has a broad ventral saddle with a flat bottom and a gently curved lateral lobe. Clydonauatilus at the opposite extreme has a secondary ventral saddle within the ventral lobe modifying the primary ventral saddle and a deep, asymmetric lateral lobe. Callaionautilus, Cosmonautilus, and Proclydonautulus fall in between.
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