BISC 316 Lecture Notes - Lecture 9: West Indian Ocean Coelacanth, Holostei, Teleost
11 Dec 2016
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4 clades of gnathostomes present: placoderms, acanthodii, chondrichthyes, osteichthyes, class osteichthyes (bony fish) Characteristics of osteichthyes: bony skeleton, dermal bones; teeth attached to bones of jaw, fish scales. Elasmoid scale: bone, very thin layer of enamel internal support for fins ray-finned. No fleshy base; fin rays come directly from side of body lobe-finned: appendage comes out from body and rays come from the appendage, hyostylic jaw suspension (most) Dipnoi autostylic crossopterygii amphistylic: caudal fin. Most homocercal: diverticulum lung or gas bladder. Sturgeon, paddlefish: series holostei gars, bowfins, series teleostei salmon, herring, cod, guppies, infraclass chondrostei. Early forms abundant in devonian to permian. Number of fin rays is greater than the number of radial bones: series holostei. Decrease in bony armour: light ganoid scales; modern forms remnant only around head. Number of fin rays equals the number of radials. Fins tucked close to body to reduce drag. 7-8 bones in upper and lower jaw: pre-maxilla and maxilla.
