The Trachyceratidae is a family of ceratitid ammonoid cephalopods that lived during the Middle- and Late Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . 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...

 characterized by shells that are more or less involute and highly ornamented.

Trachyceratid shells have their whorl sides covered with flexious ribs that are usually tuberculate. The venters generally have a median furrow bordered by rows of tubercles or continuous keels.

The Trachyceratidae makes up part of the superfamily Clydonitaceae
The Clydonitaceae is a superfamily in the ammonoid cephalopod order Ceratitida characterized by generally costate and turberculate shells with smooth, grooved, or keeled venters and sutures that are commonly ceratitic or ammonitic but goniatic in a few offshoots.-Taxonomy:The Clydonitaceae unites...

 along with such families as the Clydonitidae and Arpaditidae. The Clydonitaceae is also known by the junior synonym Trachycerataceae.


  • Arkell et al. Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology
    Treatise on Invertebrate Paleontology
    The Treatise on Invertebrate Paleontology 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 every phylum, class, order, family, and genus of fossil and...

    , Part L. 1957
  • Bernhard Kummel 1952. A Classification of Triassic Ammonoids. Jour of Paleontology, Vol 26, No.5, pp 847-853, Sept 1952

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