Heminautilus
Encyclopedia
Heminautilus is an extinct Nautiloid
genus from the nautilacean family Cymatoceratidae
that lived during the early Cretaceous
.(Kummel 1964). Nautiloids are a subclass of shelled cephalopods that were once diverse and numerous but are now represented by only a handful of species.
Heminautilus has a discoidal compressed involute shell with flanks converging on a narrow flattened outer margin, the venter. Whorls are higher than wide. The suture is sinuous with a ventral lobe, subtriangular saddles on the ventral shoulders, broad lateral lobes, and narrow rounded saddles on the umbilical shoulders. The siphuncle
is subcentral. (Kummel 1964)
Nautiloid
Nautiloids are a large and diverse group of marine cephalopods belonging to the subclass Nautiloidea that began in the Late Cambrian and are represented today by the living Nautilus. Nautiloids flourished during the early Paleozoic era, where they constituted the main predatory animals, and...
genus from the nautilacean family Cymatoceratidae
Cymatoceratidae
The Cymatoceratidae is a family of Mesozoic and early Cenozoic nautiloid cephalopods and the most abundant of this kind in the Cretaceous. They are characterized by ribbed, generally involute shells of varied form - coiled such that the outer whorl envelops the previous, as with Nautilus, and...
that lived during the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
.(Kummel 1964). Nautiloids are a subclass of shelled cephalopods that were once diverse and numerous but are now represented by only a handful of species.
Heminautilus has a discoidal compressed involute shell with flanks converging on a narrow flattened outer margin, the venter. Whorls are higher than wide. The suture is sinuous with a ventral lobe, subtriangular saddles on the ventral shoulders, broad lateral lobes, and narrow rounded saddles on the umbilical shoulders. The siphuncle
Siphuncle
The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and Spirula...
is subcentral. (Kummel 1964)
See also
- NautiloidNautiloidNautiloids are a large and diverse group of marine cephalopods belonging to the subclass Nautiloidea that began in the Late Cambrian and are represented today by the living Nautilus. Nautiloids flourished during the early Paleozoic era, where they constituted the main predatory animals, and...