Transition to Land: Amphibians and Reptiles

Comprehensive vocabulary flashcards covering the evolutionary transition of vertebrates from water to land, including classification and characteristics of amphibians and amniotes.

Gnathostomes

A group of bony vertebrates characterized as "jaw mouths."

Eusthenopteron

A fully aquatic fish from $380\text{ mya}$ with lobed fins.

Tiktaalik

A $375\text{ mya}$ aquatic fossil with lobed limbs intermediate between fins and legs, often called the "missing link" between fishes and land creatures.

Acanthostega

A semiterrestrial tetrapod fossil dating to $365\text{ mya}$.

Pentadactyl Limb

A [five-fingered] limb structure constructed on the same basic pattern across various vertebrates, including humans, moles, horses, and bats.

Cutaneous respiration

The process by which amphibians obtain oxygen through their permeable skin; this mechanism is not possible in fish.

Chytridiomycosis

A disease associated with the permeable skin of amphibians.

Buccal pumping

A breathing method where the floor of the mouth drops to draw air into the buccal cavity, which is then forced into the lungs; used by amphibians because they lack a diaphragm.

Anura

The order of amphibians meaning "without tail," comprising more than $3,500$ species including frogs and toads.

Caudata

The order of amphibians meaning "having a tail," comprising approximately $360$ species including axolotls, newts, and salamanders.

Apoda

The order of amphibians, also known as caecilians, meaning "without foot," characterized as aquatic or burrowing animals.

Spermatophores

Structures used by Caudata (salamanders and newts) for internal fertilization.

Amniotic egg

A shelled egg containing extra-embryonic membranes that allows development to occur on land by bringing the aquatic environment inside the egg.

Amnion

The extra-embryonic membrane that encloses a fluid-filled cavity for the embryo.

Allantois

The extra-embryonic membrane that serves as a respiratory surface and a site for waste storage.

Chorion

The extra-embryonic membrane responsible for oxygen and carbon dioxide transfer.

Anapsids

A branch of early reptiles distinguished by having no temporal fenestrae (holes) behind the eye orbital.

Synapsids

A branch of amniotes with a single pair of lateral temporal openings that eventually evolved into mammals.

Diapsids

A branch of amniotes with two temporal fenestrae (dorsal and lateral) that evolved into modern reptiles and birds.

Metanephric kidneys

The type of kidneys found in reptiles, which distinguish them from amphibians.

Squamata

The reptilian order comprising lizards and snakes, characterized by males with hemipenes and skin that is shed in one piece.

Rhynchocephalia

The reptilian order that contains the Tuataras.

Chelonia

The reptilian order consisting of turtles and tortoises.

Crocodylia

The reptilian order of crocodiles and alligators, which uniquely possesses a $4\text{-chambered}$ heart.

Archosauria

A group within the diapsids characterized by an opening anterior to the eye, an inverted triangle-shaped orbit, and a muscular gizzard.