BIOL 3070 Lecture Notes - Lecture 2: Squalidae, Acanthopterygii, Buoyancy
Document Summary
All the remaining clades are a part of the craniates. They all have a cranium - a bone or cartilage skeletal enclosure of the brain. The remaining clades after craniates are the vertebrata. Remaining 4 lineages go under the clade gnathostomata. They possess 2 pairs of paired appendages. Jaws but no true teeth set just sharpened edges for slicing food. Eu meaning true because they have a true teeth set. Osteichthyans - bony fishes --- synapomorphy lungs, some used to form a swim bladder (regulating fish bouyancy) Actinopterygians - ray finned fishes --- synapomorphy single dorsal fin. Review: craniates, basal clade: hagfish, vertebrate, basal clade: lampreys, gnathostomata, basal clade: placoderms, jaws, eugnathostomata, true jaws. Teeth = horn like material and not homologous to true bony teeth like humans. Back is the mouth and the long tongue also covered in these horny teeth . Single nostril at the top, on the mid dorsal line.
