agnath

plural agnaths

1. biologyAn agnathan.

   The gnathostomes almost entirely replaced the agnaths, presumably because they were more effective fishes.

   1996, George Christopher Williams, Adaptation and Natural Selection, Princeton University Press,, →ISBN, page 51

   2 more examples

   Evolution of vertebrates was accompanied by a gradual increase in oxygen availability, from the irrespirable atmosphere of the Precambrian to a PO₂ at 7 mmHg with the first vertebrates (agnaths), to the present sea level PO₂ value of 160 mmHg with the first reptiles.

   1979, Stephen C. Wood, Evolution of Respiratory Processes, Marcel Dekker,, →ISBN, page 218

   Thus, although tunicates are presumably intermediate between flatworms and agnaths, the larval tunicate more closely resembles the flatworm and adult agnath.

   2002, Harold J. Morowitz, The Emergence of Everything, Oxford University Press, →ISBN, page 113