belemnoid


belemnoid

Member of an extinct group of cephalopods, possessing a large internal shell, that first appeared с 345 million years ago, in the Early Carboniferous Period, and became extinct during the Eocene Epoch, which ended с 36.

6 million years ago. The internal shell of most species is straight, but that of some species is loosely coiled. The shell served for support and muscle attachment and enabled the animal to compensate for depth and its own body weight. See also ammonoid.

Reconstruction of squidlike belemnoid cephalopods from the Cretaceous System, southern Tennessee

By courtesy of the American Museum of Natural History, New York

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▪ cephalopod order
also called  belemnite 

      member of an extinct group of cephalopods (animals related to the modern squid and octopus) that possessed a large internal shell. Most belemnoids were about the size of present-day squid, approximately 30 to 50 cm (12 to 20 inches) long. Belemnoids lived in ocean waters from the Early Devonian (about 416 million to 398 million years ago) until the end of the Cretaceous Period (66 million years ago). They became extinct during the Eocene Epoch, which ended about 34 million years ago. The internal shell was straight in most species but was loosely coiled in some. The shell was complex in structure and served for support and muscle attachment. It was also used for buoyancy, enabling the animal to compensate for depth and its own body weight, as in the modern chambered nautilus.

      During the Jurassic and following Cretaceous periods, the belemnoids reached their greatest diversity and abundance. Belemnoids may have originated from the nautiloid cephalopods, animals related to the modern pearly nautilus. Many distinctive and easily recognized belemnoids are known. The fossils of some species are widespread and assist in the age correlation of widely separated rocks.

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Universalium. 2010.

Look at other dictionaries:

  • belemnoid — adj. [Gr. belemnon, javelin; eidos, form] Dartlike in shape …   Dictionary of invertebrate zoology

  • belemnoid — Dart shaped. [G. belemnon, a dart, + eidos, resemblance] * * * bel·em·noid bel əm .nȯid, bə lem adj shaped like a dart …   Medical dictionary

  • belemnoid — shaped like a dart Shapes and Resemblance …   Phrontistery dictionary

  • belemnoid — bel·em·noid …   English syllables

  • belemnoid —   a. dart shaped …   Dictionary of difficult words

  • belemnoid — I. ˈbeləmˌnȯid, bə̇ˈlem adjective Etymology: Greek belemnon dart + English oid 1. : shaped like a dart 2. [New Latin Belemnoidea] : of, relating to, or like the Belemnoidea II …   Useful english dictionary

  • belemnoid process — noun : styloid process …   Useful english dictionary

  • Cretaceous Period — Interval of geologic time from с 144 to 65 million years ago. During the Cretaceous the climate was warmer than today. In the seas, marine invertebrates flourished, and bony fishes evolved. On land, flowering plants arose, and insects, bees in… …   Universalium

  • Treatise on Invertebrate Paleontology — The Treatise on Invertebrate Paleontology (or TIP) published by the Geological Society of America and the University of Kansas Press, is a definitive multi authored work of some 50 volumes, written by more than 300 paleontologists, and covering… …   Wikipedia

  • Aulacocerida — Taxobox name = Aulacocerida regnum = Animalia phylum = Mollusca classis = Cephalopoda subclassis = Coleoidea unranked ordo = Cohort †Belemnoidea ordo = †Aulacocerida ordo authority= Stolley, 1919 subdivision ranks = Families subdivision =… …   Wikipedia


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