Vertebrate Diversity and Chordata Classification

Vocabulary flashcards covering the diversity, classification, and reproductive strategies of vertebrates, including Chordata subphyla and amniote characteristics.

Subphylum Urochordata

A subphylum of Chordata that includes tunicates and sea squirts.

Subphylum Cephalochordata

A subphylum of Chordata consisting of lancelets.

Agnatha (Cyclostomes)

A group of vertebrates that lack jaws, including hagfishes and lampreys.

Gnathostomata

A group of vertebrates that possess hinged jaws.

Anamniota

Vertebrates whose eggs lack an amnion, specifically fishes and amphibians.

Amniota

Vertebrates whose embryos develop within an amnion, including reptiles, birds, and mammals.

Pisces

Aquatic vertebrates characterized by gills and appendages in the form of fins.

Tetrapoda

Four-limbed vertebrates, which includes taxa that have lost limbs such as snakes and caecilians.

Craniata

A group within Subphylum Vertebrata characterized by a cranium enclosing the brain, olfactory organs, eyes, and inner ear.

Segmented myomeres

Muscle segments found in fishes and amphibians.

Ostracoderm and Placoderm

Extinct groups of "armoured" fish from the Paleozoic era, dating back approximately $550$ million years ago.

Class Chondrichthyes

A class of gnathostomes that includes sharks and rays.

Class Actinopterygii

A class of bony fish characterized by ray-finned structures.

Class Sarcopterygii

A class of bony fish known as lobe-finned fish.

Class Myxini

A class within Agnatha consisting of hagfish.

Class Petromyzontida

A class within Agnatha consisting of lampreys.

Amnion

The extraembryonic membrane that encloses the embryo in fluid, forming a fluid-filled sac.

Allantoids

An extraembryonic membrane in the amniotic egg that stores metabolic wastes.

Chorion-allantoids

A respiratory organ in the amniotic egg specialized for removing $CO_2$ and obtaining oxygen.

Synapsids

A group of amniotes, including mammals, characterized by having $1$ hole behind the eye socket.

Diapsids

A group of amniotes, including lizards, snakes, and birds, characterized by having $2$ holes behind the eye socket.

Anapsids

A group of amniotes characterized by the type of skull found in turtles.

Archaeopteryx lithographica

A fossil species from $150$ mya, first found in Germany in $1861$, representing the origin of birds.

Ornithodelphia (Monotremes)

An ancient clade of mammals that retains an ancestral oviparous state, lacks nipples, and has no placenta.

Metatheria (Marsupials)

A group of mammals characterized by very short gestation relative to lactation and a primitive-transient simple placenta.

Eutheria (Placental mammals)

A group of mammals with high species richness and a complex placenta, where young are born at a later developmental stage than marsupials.