FISH 310: Extinct & Extant Agnathans

A series of vocabulary flashcards focused on key terms related to the study of agnathans and chordate evolution, useful for understanding lecture material.

Agnathans

Jawless fishes that include living groups like hagfish and lampreys.

Notochord

A rodlike, semirigid body of fluid-filled cells that provides stiffness to the body and serves as a support structure in early chordates.

Synapomorphy

A shared derived trait that is used to determine evolutionary relationships among organisms.

Vertebrata

A subphylum of chordates that includes animals with vertebrae, an endoskeleton, and a tripartite brain.

Cephalochordata

A subphylum of chordates including lancelets, characterized by having a notochord that extends to the tip of the head.

Conodonts

Extinct jawless vertebrates known for their tooth-like elements, which are important for stratigraphy.

Ostracoderms

An extinct class of armored jawless fishes with a bony dermis, most of which had no paired fins.

Myxini

The class of hagfishes, which are mostly deep-sea scavengers that produce slime.

Petromyzontida

The class of lampreys, which are mostly anadromous and can be parasitic.

Tripartite brain

A brain divided into three regions, characteristic of vertebrates.

Endostyle

A structure that secretes mucus in early chordates and forms the thyroid in more derived chordates.

Chordata synapomorphies

notochord, dorsal hollow nerve cord, pharyngeal slits, endostyle, and postanal tail

Vertebrata synapomorphies

vertebrae, endoskeleton, muscularized pharynx, gills, chambered heart, tripartite brain, paired sense organs, liver & pancreas, glomerular kidney