Chapter 5 - Evolutionary origin of amniotic egg: the transitional form between amphibians and reptiles in the doubt clear session

Abstract

The evolutionary biologists and the paleontologists contemplated that in the 340–270 mya, amphibians (e.g., Eryops) were diverged out of Pisces and “Temnospondyls” (Carroll, 2009; Lopez-Bosch, 2015). The features like exogenous fertilization, laying of soft eggs (without shell) nearby water bodies, and lack of protective shell around its eggs were found to be disadvantageous in the course of environmental changes and it attracts a big number of predators to devour its natural regeneration of amphibians (Lopez-Bosch, 2015). The evolution of reptiles with its advantageous (in respect to amphibians) features like endogenous fertilization and laying of eggs (with calcified shell) on the terrestrial habitat started with phylogenetic divergence from amphibian root-stock and ended in the successful effort of terrestrialization on Earth around 315 mya (Ruta et al., 2003Janke, 2010). Seymouria appeared with calcium-coated or “shelled egg” in the tetrapods. The evolutionary-link between amphibians and reptiles was found to be 280 million years old (Gumbs et al., 2018).