Belongs within: Endoceratoidea. The Early Ordovician to Silurian Endoceratidae were large straight-shelled cephalopods with simple endocones that may contain bifid or trifid endosiphoblades (Evans & King 2012). Some endoceratids reached immense sizes. The genus Endoceras is known from the Middle to Upper Ordovician and has a shell with annulations varying from low and closely spaced to well… Continue reading Endoceratidae
Category: Cephalopoda
Scaphitidae
Belongs within: Stephanocerataceae.Contains: Scaphites. The Scaphitaceae are a group of often heteromorphic ammonites known from the Cretaceous (Upper Albian to Maastrichtian) with an initial spiral opening into a more or less distinct hook. In many derived genera, the hook becomes less distinct and the conch is more or less consistently coiled. Members of the family… Continue reading Scaphitidae
Orthoceras
Belongs within: Orthoceratidae. Orthoceras is a Middle Ordovician genus of large orthocerid cephalopods. The genus has historically been ill-defined, initially being applied to all straight-shelled cephalopods. Characters (Sweet 1964): Slightly expanding, almost cylindrical orthocones or faintly exogastric cyrtocones; siphuncle empty, cylindrical, suborthochoanitic, subcentral to slightly ventral. Body chamber transversely constricted at mid-length and marked by… Continue reading Orthoceras
Goniatites
Belongs within: Goniatitina. Goniatites was a mid-Visean (Early Carboniferous) genus of ammonoid, the type of the Goniatitida. Like other goniatitids, Goniatites had an angular ‘zig-zag’ suture morphology. The external surface of the shell often bears strong growth lines. Members of this genus have been identified as index fossils in Europe and North America (Ross 1979).… Continue reading Goniatites
Stephanocerataceae
Belongs within: Aptychophora.Contains: Otoitidae, Sphaeroceratidae, Arctocephalitinae, Cadoceratinae, Stephanoceratidae, Perisphinctoidea, Scaphitidae, Turrilitaceae, Desmocerataceae, Bochianitidae, Labeceratidae, Ancyloceratidae, Douvilleiceratidae. The Stephanocerataceae are a Jurassic group of ammonites, the shells of which commonly show sharp ribbing. They include the ancestors of most Cretaceous neoammonoids. These include the Ancylocerataceae and other forms historically included in the ‘Ancyloceratina’, a polyphyletic assemblage… Continue reading Stephanocerataceae
Aconeceratinae
Belongs within: Oppeliidae. Racing ammonites Published 21 April 2026 Ammonites are commonly pictured in the public imagination as large animals, sometimes massively so. But, as might only be expected for such a long-lived and diverse lineage, ammonites came in a whole range of sizes, and smaller exemplars were just as, if not more, diverse than their… Continue reading Aconeceratinae
Teuthida
Belongs within: Neocoleoidea.Contains: Enoploteuthidae, Taoniinae, Loliginidae, Spirulida, Onychoteuthidae, Ommastrephidae, Histioteuthidae. The Teuthida, squids, are a group of elongate-bodied cephalopods with the shell reduced to an internal, feather- or rod-shaped, gladius, and with ten circum-oral appendages including two contractile tentacles. Recent authors have often divided squids between the benthic Myopsida and pelagic Oegopsida, but relationships between… Continue reading Teuthida
Michelinoceratinae
Belongs within: Orthocerida. Straight to the wastebasket Published 5 March 2025 During the period from the Middle Ordovician to the Early Devonian, the cephalopod fossil record was dominated by orthocones. This is the term used for straight, conical to cylindrical shells, the greater number of which were carried by members of the order Orthocerida. Despite their… Continue reading Michelinoceratinae
Gaudryceratidae
Belongs within: Lytoceratida. The Gaudryceratidae are a lineage of ammonites known from the Barremian to the Maastrichtian of the Cretaceous (Wright et al. 1996). Characters (from Wright et al. 1996): Whorl section typically rounded or elliptical, sometimes depressed; shell ornamented with lirae or fine riblets, occasionally smooth, and with constrictions; suture with symmetrically bifid saddles… Continue reading Gaudryceratidae
Tetragonitidae
Belongs within: Lytoceratida. The Tetragonitidae are a lineage of lytoceratidan ammonites known from the Upper Aptian to the Maastrichtian of the Cretaceous (Wright et al. 1996). Characters (from Wright et al. 1996): Whorl section rectangular or trapezoidal in early whorls, sometimes depressed; usually smooth, occasionally lirate or striate; constrictions on internal mold strongly prorsiradiate but… Continue reading Tetragonitidae