''Clarkeiteuthis'' is a genus of extinct belemnoid

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

known from the lower

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

and

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

. Described two species, ''C. conocauda'' and ''C. montefiorei'' are originally described as species of phragmoteuthid ''

Phragmoteuthis ''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 ten arms. Previously d ...

'', but got their own genus and moved to Diplobelida.

Description

Two species are described, ''C. conocauda'' is known from

Posidonia Shale The Posidonia Shale (, also called Schistes Bitumineux in Luxembourg) geologically known as the Sachrang Formation, is an Early Jurassic (Early to Late Toarcian) geological formation in Germany, northern Switzerland, northwestern Austria, souther ...

, and ''C. montefiorei'' is known from the

Hettangian The Hettangian is the earliest age and lowest stage of the Jurassic Period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). The Hettangian follows the Rhaetian (part of the Triass ...

strata of the

Blue Lias The Blue Lias is a formation (stratigraphy), geological formation in southern, eastern and western England and parts of South Wales, part of the Lias Group. The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest ...

Formation and from

Charmouth Mudstone Formation The Charmouth Mudstone Formation is a Formation (geology), geological formation in England, dating to the Early Jurassic (Sinemurian–Pliensbachian). It forms part of the lower Lias Group. It is most prominently exposed at its type locality in cl ...

. ''Clarkeiteuthis'' had long

phragmocone The phragmocone is the chambered portion of the shell of a cephalopod. It is divided by septa into camerae. In most nautiloids and ammonoids, the phragmocone is a long, straight, curved, or coiled structure, in which the camerae are linked by ...

and ten short, hook-bearing

arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...

. Although it is originally considered as phragmoteuthid, this classification has been discussed by modern researchers, as it lacked a broad three-lobed proostracum (The anterior prolongation of the guard of the phragmocone), the

autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a Synapomorphy, derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or Outgroup (cladistics), outgroup taxa, not ...

of phragmoteuthid. ''C. conocauda'' had total length about . This species is well preserved, soft tissues such as mantle and

ink sac An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods, all Coleoidea (squid, octopus and cuttlefish) which dwell ...

are visible. One arm had around 30 hooks.

Palaeobiology

Clarkeiteuthis and Leptolepis reconstruction

Well-preserved specimens of ''C. conocauda'' with ''Leptolepis bronni'' (invalid species of ''Leptolepis'') in its arms are known from Posidonia Shale. Preservation of fossil and behavior of living cephalopod suggests that ''Clarkeiteuthis'' probably contracted its arms to pull prey towards its mouth to cut the spine by using its

beaks The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for pecking, grasping, and holding (in probing for food, eating, manipulating and ca ...

, and then feed on it. In all the three specimens of ''C. conocauda'' with catching preys had ''Leptolepis'' in its arms. ''Leptolepis'' is most common fish in the formation, and it lacked thick scales, so it was probably the most common prey of ''Clarkeiteuthis''. Unlike

belemnites Belemnites may refer to: *Belemnitida, an extinct order of cephalopods commonly known as "belemnites" *Belemnites (genus), ''Belemnites'' (genus), a belemnite genus from the Early Jurassic {{disambiguation ...

which are considered as good swimmers, diplobelids like ''Clarkeiteuthis'' were probably less active swimmers, with the capability of occasional short bursts of rapid swimming movements.

References

{{Taxonbar, from=Q111869595 Belemnoidea Jurassic cephalopods Mesozoic cephalopods of Europe Prehistoric life of Europe Early Jurassic first appearances Prehistoric cephalopod genera