Agnathans. Family overview: Lampreys may not look like fish, but they are. Their round, sucking mouth, lack of pectoral and pelvic fins, and eel-like.
Chordates Notocord Dorsal hollow nerve cord Gills Postanal tail.
Life in the Paleozoic Era Chapter 13 Section 2. The Cambrian Period The Cambrian Explosion: a span of about 15 million years when many new types of invertebrates.
