Finally, ages-old puzzles about the existence of chicken or egg have been chiefly solved. There was a continuous debate on this puzzle about whether the chicken came first or the egg. Now a scientist has solved this ages-old puzzle.
Chicken or Egg?
As per a study published in Nature Ecology & Evolution, the study around amphibians and lizards has almost become clear who has come first, chicken or egg? As per this study, scientists confidently suggest that earlier ancestors of modern-day birds, reptiles, and mammals may have given birth to live young instead of laying eggs.
This analysis has been based on research on 51 fossil species and 29 living species and can be categorized as oviparous or viviparous. Oviparous are known for laying soft or hard-shelled eggs, and on the other hand, species of viviparous are known for giving birth to live young, as per a journal published in Nature Ecology & Evolution.
Researchers of the Chicken or egg puzzle stated that The discovery of oviparity species in this assumed viviparous extinct clade, together with existing evidence, suggests that EER – Extended Embryo Retention was the primitive mode of reproduction. EER means the mother’s retention of the embryo for an extended period, which can vary depending upon the favorable conditions.
As per the research on the Chicken or egg puzzle, before the emergence of amniotes, a group of vertebrates had been undergoing fetal or embryonic development and was the first tetrapods to develop limbs from fish-like fins. They have to live in or near the water for breeding and feeding, which is very similar to modern amphibians like salamanders and frogs.
As Michael Benton, who is a professor from the Bristol School of Earth Sciences, explained, The amniotes, who has been appeared 320 million years ago, were able to break away from the water because they were able to control water loss with various mechanisms and with their waterproof skin. However, the amniotic egg was the key which acted as a private pond and protected the developing reptile from drying out in the warm conditions, thus enabling the Amniota to break away from the water and dominate the terrestrial ecosystems.
Various research has challenged this view, as several lizards and snakes have flexible reproductive strategies and exhibit both oviparity and viviparity. Fossiles revealed that various of these species were live-bearers which means the transition between laying eggs and giving birth to young.
Dr. Joseph Keating has explained that EER is very common and variable today in lizards and snakes as they can release their young either by eggs or as little wriggles using differential strategies. And it has appeared as an ecological advantage of EER, which allows mothers to release their young when food supplies are abundant, and temperatures are warm enough.
However, there is still time for a final conclusion by researchers on the Chicken or Egg Puzzle. Still, the research team suggests that early animals were given the advantage of adaptive parental protection.