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Information about Bactritida

Bactritida
Scientific classification
Kingdom:Animalia
Phylum:Mollusca
Class:Cephalopoda
Subclass:Nautiloidea
Order:Bactritida
Bactritida are a small and poorly studied order of more or less straight-shelled ("orthocone") nautiloids which first appeared during the Emsian Stage of the Devonian Period (390 million years ago) and persisted until the Carnian Stage of the Triassic Period (235 million years ago). They are considered ancestors of the ammonites as well as of the coleoids (octopus, squid, cuttlefish, and the extinct belemnites).

The bactritids are distinguished from the other, more primitive nautiloids by the globular shape and small size of the shell's first chambers, the so-called embryonic shell. All nautiloids have relatively large embryonic shells, and living species lay a few large eggs. In contrast, bactritids produced large numbers of small eggs, each housing a small embryonic shell -- just like the ammonites.

The adult bactritid shell consists of a linear series of chambers, each having been successively occupied by the body of the animal over the course of its life. Bactritids likely fed on animals caught in the tentacles. Although horizontal movements was probably slow, acceleration directly forward and backward was likely swift and unencumbered.

During early Emsian evolution, there was a trend toward increasing curvature; simultaneously, the orientation of the aperture moved from oblique upward to horizontal (40–70°). In more derived bactritids with curved shells, the aperture reached an oblique downward orientation (Cyrtobactrites: 20-30°). Evolution of the coiled ammonoid shell from the uncoiled bactritid shell was probably coupled with changes in manoeuvrability and swimming velocity.
Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. Scientific classification also can be called scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis.
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Mollusca
Linnaeus, 1758

Classes

Caudofoveata
Aplacophora
Polyplacophora
Monoplacophora
Bivalvia
Scaphopoda
Gastropoda
Cephalopoda
† Rostroconchia
† Helcionelloida
† ?Bellerophontida
The molluscs
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Cephalopoda
Cuvier, 1797

Orders

Subclass Nautiloidea
  • †Plectronocerida
  • †Ellesmerocerida
  • †Actinocerida
  • †Pseudorthocerida
  • †Endocerida
  • †Tarphycerida
  • †Oncocerida

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Nautiloidea
Agassiz, 1847

Orders

Palcephalopoda
  • †Plectronocerida
  • †Ellesmerocerida
  • †Actinocerida
  • †Pseudorthocerida
  • †Endocerida
  • †Tarphycerida
  • †Oncocerida

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Nautiloidea
Agassiz, 1847

Orders

Palcephalopoda
  • †Plectronocerida
  • †Ellesmerocerida
  • †Actinocerida
  • †Pseudorthocerida
  • †Endocerida
  • †Tarphycerida
  • †Oncocerida

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The Emsian is one of three faunal stages in the Early Devonian epoch. It lasted from 407 ± 2.8 million years ago to 397.5 ± 2.7 million years ago. It was preceded by the Pragian stage and followed by the Eifelian stage.
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Devonian is a geologic period of the Paleozoic era spanning from roughly 416 to 359 million years ago. It is named after Devon, England, where rocks from this period were first studied.
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For the Carnian Alps, see Carnic Alps.


The Carnian (less commonly, Karnian) is the first stage of the Upper Triassic, Mesozoic. Its boundaries are not characterized by major extinctions or biotic turnovers, but a climatic event (known as the
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The Triassic is a geologic period that extends from about 251 to 199 Ma (million years ago). As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events.
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Coleoidea
Bather, 1888

Orders
  • †Belemnoidea
  • †Aulacocerida
  • †Belemnitida

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Octopoda
Leach, 1818

Suborders

†Pohlsepia (incertae sedis)
†Proteroctopus (incertae sedis)
†Palaeoctopus (incertae sedis)
Cirrina
Incirrina
Synonyms

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For other uses, see Squid (disambiguation).


Superconducting Quantum Interference Devices (SQUID) are very sensitive magnetometers used to measure extremely small magnetic fields, based on superconducting loops
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Sepiida
Zittel, 1895

Suborders and Families
  • †Vasseuriina
  • †Vasseuriidae
  • †Belosepiellidae
  • Sepiina

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Belemnoidea

Extinct Orders

Aulacocerida
Phragmoteuthida
Belemnitida
Diplobelida
Belemnoteuthina

Belemnites (or belemnoids) are an extinct group of marine cephalopod, very similar in many ways to the modern squid and closely related to the
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Nautiloidea
Agassiz, 1847

Orders

Palcephalopoda
  • †Plectronocerida
  • †Ellesmerocerida
  • †Actinocerida
  • †Pseudorthocerida
  • †Endocerida
  • †Tarphycerida
  • †Oncocerida

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The Emsian is one of three faunal stages in the Early Devonian epoch. It lasted from 407 ± 2.8 million years ago to 397.5 ± 2.7 million years ago. It was preceded by the Pragian stage and followed by the Eifelian stage.
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