Question

Provide a detailed account of the geological, environmental and ecological factors leading to evolution and radiation of early tetrapods during the Devonian Period.

Answer 1

ANSWER :- The Devonian period or Devonian era is a geographical period and system of the paleozoic, spanning 60 millions years from the end of the Silurian ,419.2 million years ago(Mya), to the beginning of the carboniferous, 358.9 Mya.

The Devonian is known as the age of fishes. It is famous for the thousands of species of fish that developed in Devonian seas. We know this because of the fish fossils found in Devonian rocks.

The first tetrapods appeared by the late Devonian, 367.5 million years ago; the specific aquatic ancestors of the tetrapods, and the process by which they colonized Earth's land after emerging from water remains unclear. Beside tetrapods, other animals appeared during Devonian period are arthropods, including wingless insects and the earliest archnids etc.

The first tetrapods probably evolved in the Emsian stage of the early Devonian from Tetrapodomorphs fish living in shallow water environments. The very earliest tetrapods would have been animals similar to Acanthostega, with legs and lungs as well as gills, but still primarily aquatic and unsuited to life on land.

Geographical factor that leads to the evolution and radiation of early tetrapods during the Devonian period is the higher level of atmospheric oxygen. Most recent interpretation about the origin of tetrapods leads to conclude that they originated before the middle devonian, and probably in the early Devonian. It is here that the trackway found in the courtyard of Glensia Homestead, in the Grampians Mountains, western Victoria, Australia. And at this a higher level of atmospheric oxygen is detected, but this seems to be coincide with the "elpistostegid-tetrapod changeover". There was also seems to be an increase in terrestrial arthropods orders, autotrophic reed biodiversity, marine invertebrates size and genera during the same time.

Environmental and ecological factor such as sea levels and oxygen rate, leading to evolution and radiation of early tetrapods during the Devonian period. The tetrapods are evolved from marine environment during times of higher oxygen levels. The change in environmental conditions played a major role in their evolution. The evolution occured at about 397-416 Mya, during the early Devonian period. The idea is supported by various environmental factors such as sea levels, and oxygen rate, and biotic factors such as biodiversity of arthropods and coral reefs. The molecular data also strongly supports lungfish as tetrapod's closest living relative.