| Heminautilus Temporal range: Aptian
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| Family: | Cenoceratidae
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| Genus: | Heminautilus Spath 1927
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Heminautilus is an extinct genus of nautiloids from the nautilacean family Cenoceratidae that lived during the Early Cretaceous.[1] Fossils of Heminautilus have been registered in rocks of Barremian and Aptian age.[2] 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 they are 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.[1]
The following species of Heminautilus have been described:[2]
Fossils of Heminautilus have been found in Bulgaria, Colombia (at Caballos Formation, Boyacá, Tolima and Une Formation),[3] Egypt,[4] France, Hungary,[5] Japan, Mexico, Spain, Switzerland, Tunisia,[6] the United Kingdom, the United States (Arkansas), Venezuela.[2]
