Coleoidea or Dibranchiata, is one of the two subclasses of cephalopods, containing all the various taxa popularly thought of as "soft-bodied" or "shell-less". Unlike its extant sister group Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal shell called cuttlebone or gladius that is used for buoyancy or as muscle anchorage. Some species, notably incirrate octopuses, have lost their cuttlebone altogether, while in some it has been replaced by a chitinous support structure. A unique trait of the group is the ability to edit their own RNA.
Orthocerida, also known as the Michelinocerida, is an order of extinct orthoceratoid cephalopods that lived from the Early Ordovician possibly to the Late Triassic. A fossil found in the Caucasus suggests they may even have survived until the Early Cretaceous, and the Eocene fossil Antarcticeras is sometimes considered a descendant of the orthocerids although this is disputed. They were most common however from the Ordovician to the Devonian.
Trachyteuthis is a genus of fossil cephalopod, comprising five species: T. hastiformis, T. latipinnis, T. nusplingensis, T. teudopsiformis, T. covacevichi and T. chilensis.
Proteroctopus is an extinct genus of cephalopod that lived in the Middle Jurassic, approximately 164 million years ago. It is only known from a single species P. ribeti. The single fossil specimen assigned to this species originates from the Lower Callovian of Voulte-sur-Rhône in France. It is currently on display at the Musée de Paléontologie de La Voulte-sur-Rhône. While originally interpreted as an early octopus, a 2016 restudy of the specimen considered it to be a basal member of the Vampyropoda, less closely related to octopus or vampire squid than either of the two groups are to each other. A phylogenetic analysis by Kruta et. al indicates that Proteroctopus may be more closely related to the Vampyromorpha based on its unique morphology: two fins, head fused to the body, eight arms, two rows of oblique sucker, a gladius and absence of an ink sac. A 2022 phylogenetic analysis also found it to be more closely related to vampire squid than to octopuses.
Niobrarateuthis is an extinct genus of large cephalopod from the Cretaceous. It is closely related to the Cretaceous Tusoteuthis and the Jurassic Muensterella.
Belemnotheutis is an extinct coleoid cephalopod genus from the middle and upper Jurassic, related to but morphologically distinct from belemnites. Belemnotheutis fossils are some of the best preserved among coleoids. Remains of soft tissue are well-documented in some specimens, even down to microscopic muscle tissue. In 2008, a group of paleontologists even recovered viable ink from ink sacs found in several specimens.
Phragmoteuthis is a genus of extinct coleoid cephalopod known from the late Triassic to the lower Jurassic. Its soft tissue has been preserved; some specimens contain intact ink sacs. It had an internal phragmocone and an unknown number of arms.
The cephalopods have a long geological history, with the first nautiloids found in late Cambrian strata, and purported stem-group representatives present in the earliest Cambrian lagerstätten.
Phragmoteuthida is an order of extinct coleoid cephalopods characterized by a fan-like teuthoid pro-ostracum attached to a belemnoid-like phragmocone.
Belemnitida is an extinct order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous. Unlike squid, belemnites had an internal skeleton that made up the cone. The parts are, from the arms-most to the tip: the tongue-shaped pro-ostracum, the conical phragmocone, and the pointy guard. The calcitic guard is the most common belemnite remain. Belemnites, in life, are thought to have had 10 hooked arms and a pair of fins on the guard. The chitinous hooks were usually no bigger than 5 mm (0.20 in), though a belemnite could have had between 100 and 800 hooks in total, using them to stab and hold onto prey.
The gladius, or pen, is a hard internal bodypart found in many cephalopods of the superorder Decapodiformes and in a single extant member of the Octopodiformes, the vampire squid. It is so named for its superficial resemblance to the Roman short sword of the same name, and is a vestige of the ancestral mollusc shell, which was external. The gladius is located dorsally within the mantle and usually extends for its entire length. Composed primarily of chitin, it lies within the shell sac, which is responsible for its secretion.
All extant cephalopods have a two-part beak, or rostrum, situated in the buccal mass and surrounded by the muscular head appendages. The dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like fashion. The beak may also be referred to as the mandibles or jaws.These beaks are different from bird beaks because it crushes bone while most birds don't.
Palaeoteuthomorpha is a superorder of primitive coleoid cephalopods, containing the Boletzkyida, characterized by an orthoceroid-like phragmocone early in ontogeny and a teuthid living chamber later in ontogeny. This contrasts with the later Teuthida which have a reduced living chamber (gladius) throughout.
Muensterella is a fossil stem-octopod known from a handful of specimens from German Solnhofen plattenkalk.
This list, 2018 in paleomalacology, is a list of new taxa of ammonites and other fossil cephalopods, as well as fossil gastropods, bivalves and other molluscs that are scheduled to be described during the year 2018, as well as other significant discoveries and events related to molluscan paleontology that are scheduled to occur in the year 2018.
The Moltrasio Formation also known as the Lombardische Kieselkalk Formation is a geological formation in Italy and Switzerland. This Formation mostly developed in the Lower or Middle Sinemurian stage of the Lower Jurassic, where on the Lombardian basin tectonic activity modified the current marine and terrestrial habitats. Here it developed a series of marine-related depositional settings, represented by an outcrop of 550–600 m of grey Calcarenites and Calcilutites with chert lenses and marly interbeds, that recovers the Sedrina, Moltrasio and Domaro Formations. This was mostly due to the post-Triassic crisis, that was linked locally to tectonics. The Moltrasio Formation is considered a continuation of the Sedrina Limestone and the Hettangian Albenza Formation, and was probably a shallow water succession, developed on the passive margin of the westernmost Southern Alps. It is known due to the exquisite preservation observed on the Outcrop in Osteno, where several kinds of marine biota have been recovered.
Enchoteuthis is an extinct genus of large enchoteuthine cephalopod that lived during the Cretaceous. Although it and its relative Tusoteuthis are often compared to squid, both are now thought to be more closely related to modern octopuses. Examination of gladius remains initially yielded an estimated mantle length about 2 m based on specimen once described as Tusoteuthis longa, close to or equal to that of the modern giant squid, although reclassification of this genus as a muensterelloid results in a much shorter total length, about 3 m (10 ft). Three species are currently recognized as valid: E. melanae, E. tonii, and E. cobbani.
This list of fossil molluscs described in 2022 is a list of new taxa of fossil molluscs that were described during the year 2022, as well as other significant discoveries and events related to molluscan paleontology that occurred in 2022.
Clarkeiteuthis is a genus of extinct belemnoid cephalopod known from the lower Jurassic in Germany and England. Described two species, C. conocauda and C. montefiorei are originally described as species of phragmoteuthid Phragmoteuthis, but got their own genus and moved to Diplobelida.
Antarcticeras is an extinct genus of enigmatic cephalopod from the Eocene of Antarctica. It contains a single species, A.nordenskjoeldi. It is either considered the last of the "orthocone"-type cephalopods, the only member of its subclass Paracoleoidea & a descendant of the orthoceratids, and a remarkable example of convergent evolution with coleoid cephalopods, or an oegospid squid and a transitional form in the development of the modern squid gladius, of which it is the only preserved example.
