Agnatha

How To Use Agnatha In A Sentence

• Modern vertebrates are classified into two major groups, the gnathostomes (jawed vertebrates) and the agnathans (jawless vertebrates).
• Notochords are the axial skeleton of invertebrate chordates (cephalochordates, appendicularians, and tadpole larvae of ascidians), of agnathan fish, and of amphibian tadpoles.
• There is also considerable scope for informed speculation about the feeding mechanisms among the extinct agnathans.
• The hagfish, together with lampreys, are living representatives of the jawless vertebrates (class Agnatha) and are considered to be the most evolutionarily ancient vertebrates.
• One landmark event in vertebrate evolution was the evolution of jaws from agnathan ancestors, which was followed by the first appearance of the stomach.
• The hagfish, together with lampreys, are living representatives of the jawless vertebrates (class Agnatha) and are considered to be the most evolutionarily ancient vertebrates.
• Above all, the appearance of diverse chordates and agnathans greatly expands our knowledge of the Cambrian explosion.
• Related agnathans with external armour occur widely from the Late Silurian to the Devonian, but they all became extinct before the start of the Carboniferous.
• During this period the agnathan and gnathostome fishes, too, gave rise to many distinctive groups: the armoured ostracoderm and placoderms, the bony fishes, and elasmobranchs to populate marine and freshwater environments.
• Although a small number of bony fishes have brains of the same relative size as those in agnathans, most bony fishes have considerably larger brains for the same body size.