agnathan

From Agnatha, from Ancient Greek ἀ- (a-, “without”) + γνάθος (gnáthos, “jaw”).

• enPR: ăgʹnə-thən, ăg-năthʹən
• IPA^(key): /ˈæɡ.nə.θən/, /æɡˈnæθ.ən/

agnathan (not comparable)

1. (zoology) Belonging or pertaining to the superclass Agnatha, the jawless vertebrates.
   • 2005, Tim Haines, Paul Chambers, The Complete Guide to Prehistoric Life, BBC Books, page 20:

     Haikouichthys is one of three species of jawless (or agnathan) fish to be found in the Early Cambrian period.

agnathan (plural agnathans)

1. (zoology) A member of the superclass Agnatha of jawless vertebrates.
   • 1956, D. R. Newth, “On the Neural Crest of the Lamprey Embryo”, in Journal of Embryology and Experimental Morphology, volume 4, page 358:

     Thus should the cranial neural crest in cyclostomes prove to be non-skeletogenous this might be a reflection either of its own primitiveness or of the different evolutionary origins and morphological status of the visceral skeleton in agnathans and gnathostomes.

   • 1992, Peter J. Hanley et al., “Hagfish Humoral Defense Protein Exhibits Structural and Functional Homology with Mammalian Complement Components”, in Proceedings of the National Academy of Sciences, volume 89, page 7910:

     The hagfish is an agnathan, a modern representative of the earliest evolved group of vertebrates, the ostracoderms or jawless fishes, which arose prior to the ancient placoderms (3).

• agnath
• agnatha

• vertebrate

• cyclostome
• ostracoderm

• gnathostome