AMPHIBIAN - eggs require aquatic environment
running from time
Emergent Vertebrates I
4 legged animal, limbs derived from fish fins, that bridges vertebrate fish with vertebrate terrestrial animals
AMNIOTES! - eggs develop in an internal "pond", protected by amnion
conodont: an extinct marine, fish-like chordate, with gill arches, muscular segments, and fins, abundant from the Precambrian to the LateTriassic periods, having a long wormlike body, numerous small, hook-like teeth, and a pair of large eyes, believed to possibly be the earliest vertebrate (Biology, 10th ed., p. 680, G-10).
vertebrate: also called craniata, an animal derived from the phylum: chordates, sub-phylum vertebrata, having a backbone and bony skull that partly encloses a central nervous system. The hollow, dorsal nerve tube is now replaced by the spinal cord, which is now protected by a segmented vertebral, or spinal, column, composed of cartilage and/or bone. The head and brain house paired sense organs, that coordinate movement and sensation. Fish were the first vertebrates. Sub-phylum vertebrata includes 8 classes, including 4 classes of fish (including agnatha, chondrichthyes, and osteichthyes), and the additional classes: amphibia, reptilia, aves (birds), and mammalia (Anthro.Palomar.edu; Vertebrates, 2012, pp. 82-84).
coelacanth: thought to have become extinct 75 mya, rediscovered in the 1930's off the coast of southern Africa, this "living fossil", a sarcopterygian (fleshy-finned or lobe-finned) fish, also known as latimeria, its fins resembling limbs, represents an evolutionary transitional organism, linking the aquatic, vertebrate, bony fishes with tetrapod, terrestrial vertebrates. (Vertebrates, p. 46, 102).