Amphibians were first land-dwelling creatures with four legs, known as tetrapods. They evolved from lobe-finned fish in the late Devonian to early carboniferous. They then ventured forth into terrestrial environments, where they would later evolve into reptiles, birds and mammals.
What are lobe-finned fish?
Lobe-finned fish are lungfish., they possessed both lungs and gills and had four fleshy fins supported by bones in a similar structure hand. These fish had the ability to breath both in and out of water.
Similarities between the lobe-finned fish and the early amphibians
- The four fins of the lobe- finned fish and the four limbs of the early amphibians skeletal structures were very similar.
- The limbs were in the same position on their bodies
- They both lacked claws or nails
- The skull morphology, the jaw bone and teeth of the lobe-finned fish and amphibians were very much alike.
- The teeth of both lobe-finned fish and amphibians were complex.
Adaption to life on land
- The development of a girdle connecting the limb bones to the skeleton for better movement on land
- A more robust skeleton strengthening the vertebral column and rib bones, for support on land.
- eyelids formed to help keep eyes moist, as it was no longer submerged in water.
- A tongue formed within its mouth
- Ears addapted so it could detect sound waves through the thin medium of air.
- tail used for balance