Clydonautilidae
Encyclopedia
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.
Clydonautilaceae
The Clydonautilaceae is a superfamily within the nautiloid order Nautilida characterized by smooth, generally globular, shells with nearly straight sutures, in early forms but developing highly differentiated sutures in some later forms...
family Liroceratidae
Liroceratidae
Liroceratidae is an extinct family of nautilids, shelled marine molluscs, belonging to the Clydonautilaceae, consisting of generally smooth, involute, nautiliconic forms with a small umbilicus...
, 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:
- Clydonautilus
- Callaionautilus
- Cosmonautilus
- Proclydonautilus
- Styrionautilus
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.
References
- Bernhard Kummel, 1964. Nautiloidea -Nautilida; Treatise on Invertebrate PaleontologyTreatise on Invertebrate PaleontologyThe Treatise on Invertebrate Paleontology published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and...
, Part K. Geol Soc of America and Univ of Kansas press, R.C. Moore (ed)