SUB-CLASS : CHOANICHTHYES
ORDER : CROSSOPTERYGII
There were two main lines in the Crossopterygii, named Coelacanths and Rhipidistia.
Fossil remains indicate how closely they are related. Because somewhat earlier fossils of
the Rhipidistia than those of Coelacanths are known, most scientists today hold the view
that the Rhipidistia came first and the Coelacanths developed from them.
The coelacanth has a deep and stocky body, and its paired dorsal fins are rounded and lobelike as in fossilized members of the order Crossopterygii. The dorsal and anal fins are fan-shaped. The first spine of the dorsal fin is hollow; the fish’s name means “hollow spine” in Greek. The skeletal structure of the pectoral and pelvic fins indicates a close evolutionary relationship between the coelacanth and four-limbed land vertebrates . Underwater pictures show the fish moving like four-legged animals. Coelacanths also have symmetrical three-lobed tails, distinguished by a small central lobe that projects beyond the larger upper and lower lobes. The head is short and deep, and the bones of the skull are considerably reduced. The coelacanth is carnivorous.