A boundary between countries. Grade A harsh scraping or cutting; a grating. Mark A tract of land in medieval England and Germany held in common by a community. Grade (systematics) A taxon united by a level of morphological or physiological complexity that is not a clade. Mark (Computers) A...
Archosauria (lit. 'ruling reptiles') is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of term which includes birds. Archosaur Any of various vertebrates of the group Archosauria, having...
(systematics) A taxon united by a level of morphological or physiological complexity that is not a clade. Grade (medicine) The degree of malignity of a tumor expressed on a scale. Grade An eyeglass prescription. Grade To assign scores to the components of an academic test, or to overall ac...
Actinopterygii (New Latin actino- ('having rays') + Greek πτέρυξ (ptérux 'wing, fins')), members of which are known as ray-finned fishes, is a clade (traditionally class or subclass) of the bony fishes.The ray-finned fishes are so-called because their fins are webs of skin...