Definition of Agnatha in English:

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Pronunciation: /ˈaɡnəTHə/
A group of primitive jawless vertebrates that includes the lampreys, hagfishes, and many fossil fishlike forms. Compare with cyclostome.
  • Superclass Agnatha: the living forms are in the classes Myxini (hagfishes) and Cephalaspidomorphi (lampreys).
Example sentences
  • Here, we use the sequences of 35 nuclear protein-encoding genes to provide definitive evidence for the monophyly of the Agnatha (jawless vertebrates, a group encompassing the hagfishes and lampreys).
  • The earliest fossil vertebrates belong to a group called the Agnatha or jawless vertebrates.
  • In modern classification schemes, living vertebrates consist of two main groups, the jawless Agnatha (represented by hagfishes and lampreys) and the jawed Gnathostomata.



noun& adjective
Example sentences
  • Modern vertebrates are classified into two major groups, the gnathostomes (jawed vertebrates) and the agnathans (jawless vertebrates).
  • Above all, the appearance of diverse chordates and agnathans greatly expands our knowledge of the Cambrian explosion.
  • Sufficient articulated material exists to show that these animals were agnathans (jawless vertebrates), with a bony exoskeleton, and they appear to have inhabited shallow-marine environments.


From modern Latin Agnatha (superclass name), from a-1 'without' + Greek gnathos 'jaw'.

For editors and proofreaders

Syllabification: Ag·na·tha

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