Belemnotheutis

Live reconstruction

• Europe ( Germany, England, Poland)

Belemnotheutis is a genus belemnoider squid, who lived in the upper Middle Jurassic and Upper Jurassic period about 161 to about 145 million years ago. Well-preserved specimens were from the English Oxfordton ( from the chronostratigraphic stage of Calloviums ) and the Solnhofen limestones described ( from the stage of the Tithonian ).

Features

The hard parts of the chambered Belemnotheutis consist cuttlebone, with a small aragonitic rostrum and relatively wide, bounded at the back side Proostrakum. The rostrum has two dorsal typical diverging forward longitudinal strips. The apical angle of the Phragmokons is around 20 degrees. The Siphonalstrang located at margins on the ventral side. The animals had ten, only moderately long tentacles, which were provided with 30 to 40 pairs of chitinous, against permanent fishing hooks. They had relatively large eyes, most likely already lens eyes like modern squids, which have been preserved as an impression. The muscle coat constituted more than half of the entire animal was restricted to the ventral side, the muscles placed on the side of the fields of Proostrakums. The animals reached a maximum length of 30 centimeters.

Nutrition and enemies

In some specimens of fossilized remains Belemnotheutis the crop and stomach were found. The remains include fish scales and bones and prove that the genus consists of fish fed ( Piscivorie ). The chitinous hooks of Belemnotheutis and other Belemnoidea squid were relatively frequently found in the stomach contents of ichthyosaurs, this squid so at least formed part of the food that diapsiden reptiles. John E. Pollard calculated according to an estimate of the number of fishing hooks in the stomach contents of an ichthyosaur from the Lower Jurassic, the latter could have eaten between 760-2430 belemnoide squid, which did not belong but in this example the genus Belemnotheutis because the genus occurred during the Middle Jurassic.

System

Belemnotheutis is the type genus of the family in order Belemnotheutidae Belemnitida within the Belemnoidea.

There are three types so far known:

• Belemnotheutis antiquarian Pearce, 1842, Callovian, England
• Belemnotheuthis polonica Makowski, 1952, Callovian, Poland, and
• Belemnotheutis Mayri Engeser & Kidd, 1981, Tithonian, southern Germany

Spelling of the name

The originally selected by the describer Joseph Chaning Pearce notation is Belemnotheutis. This was later improperly altered by some authors in Belemnoteuthis because the ending- teuthis was then more commonly used. After the priority rule, however this notation a secondary incorrect spelling wrong, which, however, often received in the secondary literature. But there is no reason the priority of Belemnotheutis against Belemnoteuthis about by application to the Commission on Zoological Nomenclature ( ICZN ) to change ( see also the discussion in Donovan and Crane, 1990).

Swell