LIVE MINT
Was it the egg, or the chicken that came first? The question has left many scratching their heads in confusion for the right answer. But after a lot of research, a new study, published in Nature Ecology and Evolution, is near to finding out the answer to the question. The study is based on amphibians and lizards.
The study is near to conclusion after analysing 51 fossil species and 29 living species. These organisms can be categorized as oviparous(laying eggs) and viviparous(giving birth to young ones).
“The discovery of oviparity in this assumed viviparous extinct clade, together with existing evidence, suggests that EER (Extended Embryo Retention) was the primitive reproductive mode,” the researchers stated in the paper.
EER is the extended retention of embryos by the mother for a range of time. The duration of the retention of embryos likely depended on when conditions are most favourable for survival.
The research sheds light on the fact that before the emergence of amniotes, a group of vertebrates undergo embryonic or fetal development. The research said that the first tetrapods to develop limbs from fish-like fins showcased amphibious characteristics and habits.
The tetrapods had to live near water for food and reproduction, just like amphibians like frogs and salamanders.
Professor Michael Benton from the Bristol School of Earth Sciences explains that when amniotes came into existence 320 million years ago, they were able to break away from water by evolving waterproof skin and other mechanisms.
The key to protection was the amniotic egg. The egg acted as a private pond, which protected the developing reptile from drying out in warm climates. This also enabled the Amniota to move away from the water and survive in the terrestrial system.
