| Trachyteuthis | |
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| Reconstruction of Trachyteuthis hastiformis | |
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| Trachyteuthis hastiformis, Jura Museum | |
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| Family: | Trachyteuthididae Naef, 1922 |
| Subfamily: | Trachyteuthidinae Naef, 1921 |
| Genus: | Trachyteuthis Meyer, 1846 |
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Trachyteuthis is a genus of fossil cephalopod, comprising five species: T. hastiformis, T. latipinnis, T. nusplingensis, T. teudopsiformis, [2] T. covacevichi [3] and T. chilensis. [1]
The taxonomic placement of Trachyteuthis is uncertain. Though often assigned to the order Vampyromorphida, the discovery of fossilised Trachyteuthis beaks in the Upper Jurassic limestone of Germany suggests a close phylogenetic relation to the Octopoda. [4] [5] It is clear that it does at least belong in the Coleoidea. [2] It is thought to be very closely related to Teudopsis . [3]
Fossils are scarce but have been reported from the Kimmeridge clay of the UK; the Solnhofen limestone of Germany, Jurassic deposits in Antarctica, [6] and Oxfordian deposits in Chile. [3]
First described in 1773 as the remnants of a fish, Trachyteuthis was considered comparable to a Sepia cuttlebone by Rüppell in 1829. A separate genus was erected for the material in 1846 by Meyer. [2] English material discovered in 1855 was termed Coccoteuthis latipinnis; this was later synonymised with the identical Solnhofen deposits. A 2007 survey of museum collection established that there were ground for the erection of three species within the genus. [2]
The vampire squid is a small cephalopod found throughout temperate and tropical oceans in extreme deep sea conditions. Unique retractile sensory filaments justify the vampire squid's placement in its own order, Vampyromorphida, as it shares similarities with both octopuses and squid. As a phylogenetic relict, it is the only known surviving member of its order. The first specimens were collected on the Valdivia Expedition and they were originally described as an octopus in 1903 by German teuthologist Carl Chun, but later assigned to a new order together with several extinct taxa.
Subclass Coleoidea, or Dibranchiata, is the grouping of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less," i.e., octopus, squid and cuttlefish. Unlike its extant sister group Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal cuttlebone, gladius, or shell that is used for buoyancy or support. Some species have lost their cuttlebone altogether, while in some it has been replaced by a chitinous support structure.
Nautiloids are a large and diverse group of marine cephalopods (Mollusca) belonging to the subclass Nautiloidea that began in the Late Cambrian and are represented today by the living Nautilus and Allonautilus. Nautiloids flourished during the early Paleozoic era, where they constituted the main predatory animals, and developed an extraordinary diversity of shell shapes and forms. Some 2,500 species of fossil nautiloids are known, but only a handful of species survive to the present day.
Neocephalopods are a group of cephalopod mollusks that include the coleoids and all extinct species that are more closely related to extant coleoids than to the nautilus. In cladistic terms, it is the total group of Coleoidea. In contrast, the palcephalopoda are defined as the sister group to the neocephalopoda.
Boletzkyida is a primitive order of teuthid coleoid cephalopod: the boletzkyids are thought to be the earliest forms of coleoid cephalopods, and appear to form a link between nautiloid orthocerids and more advanced coleoids. Boletzkyida was named and described by Bandel, Reitner, and Sturmer in 1983 (B.R.&S) from specimens found in the Lower Devonian black slate in Germany.
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.
Cricosaurus is an extinct genus of marine crocodyliforms of the Late Jurassic, belonging to the family Metriorhynchidae. The genus was established by Johann Andreas Wagner in 1858 for three skulls from the Tithonian of Germany. The name Cricosaurus means "Ring lizard", and is derived from the Greek Cricos- ("ring") and σαῦρος -sauros ("lizard").
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, and others, gills. It had an internal phragmocone and ten arms.
Neocoleoidea is a large group of marine cephalopods. This cohort contains two extant groups: Decapodiformes and Octopodiformes. Species within this group exist in all major habitats in the ocean, in both the southern and northern polar regions, and from intertidal zones to great depths. Whilst conventionally held to be monophyletic, the only morphological character for the group is the presence of suckers: although the presence of these features in the belemnites suggests that they do not support the Neocoleoidea, and hence that the group may be paraphyletic.
Teudopsis is a genus of the coleoid cephalopod family Teudopsidae, known only from Lower Jurassic gladii. It has been reported from Alberta, Canada and Europe. The life appearance of Teudopsis is probably best inferred by its close relative Trachyteuthis. A fossil with soft tissue preservation shows that this animal may have had two mantle fins, which may also be the case for Teudopsis.
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.
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