from Wiktionary, Creative Commons Attribution/Share-Alike License.
- proper noun A taxonomic
classwithin the infraphylum Gnathostomata— an extinct class of spiny sharks.
from Wiktionary, Creative Commons Attribution/Share-Alike License
Publishing the results of his research in a recent issue of the journal Nature, Martin Brazeau describes the first-known braincase of Ptomacanthus anglicus, an early jawed fish belonging to a group known as the Acanthodii that lived during the early Devonian period (418-412 million years ago).