Monday, 12 December 2011

evolution of amphibians

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

No comments:

Post a Comment