Tetrapod

Definition

Tetrapods are vertebrate animals with four limbs or limb-like appendages. This group includes amphibians, reptiles, birds, and mammals.

5 Must Know Facts For Your Next Test

1. Tetrapods evolved from lobe-finned fishes approximately 400 million years ago.
2. They possess a vertebral column and a skeleton that supports their body on land.
3. Amphibians are the earliest group of tetrapods to transition from water to land.
4. Tetrapod limbs are typically characterized by having five digits although some species have variations.
5. Reptiles, birds, and mammals all descended from early tetrapods.

Review Questions

• What are the key characteristics that define a tetrapod?
• From which type of fish did tetrapods evolve?
• Name the three major groups that descended from early tetrapods.

Related terms

Amphibian: A class of cold-blooded vertebrates that includes frogs, toads, newts, and salamanders; they can live both in water and on land.

Lobe-finned fishes: A group of bony fishes with fleshy, lobed fins that are believed to be the ancestors of tetrapods.

Vertebral column: A series of interlocking bones or segments forming the backbone that is characteristic of vertebrates.