The first vertebrates to evolve four limbs were the amphibians, also known as tetrapods.
The tetrapod classification includes a wide variety of vertebrates such as amphibians, birds, mammals, and reptiles. This group encompasses all land-dwelling vertebrates, as well as certain marine-dwelling vertebrates that evolved from land-dwelling ancestors. These marine tetrapods include species such as dolphins, whales, seals, sea turtles, sea lions, and sea snakes. A defining characteristic of tetrapods is the presence of four limbs, or the evidence of four limbs in their evolutionary history.
Interestingly, some animals that have lost their limbs through evolution, such as whales and snakes, are still classified as tetrapods. This is due to their ancestry and the evolutionary path that led them to their current form.
Further Reading:
- Understanding the Differences between Invertebrates and Vertebrates
- Exploring the Differences between Tetrapods and Amphibians
- Comparing Reptiles and Amphibians
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