People have often debated the question of which came first, the chicken or the egg. This is a topic that is debated by people of all ages but none of them can find an easy answer. But scientists seem to have an answer to this paradox.
In a study published in JEE News, researchers hypothesized that the ancestors of current birds and reptiles gave birth to juveniles.
Giving birth to live young allows the female to better protect her developing embryo until it is ready to be born.
Researchers from the University of Nanjing and Bristol challenged the belief that hard-shelled eggs are key to the success of amniotes – animals whose embryos develop inside an amnion inside the egg.
“The amniotic egg is very different from the anamniotic egg of extant amphibians, lacking the eggshell and extraembryonic membranes,” the study noted.
“The amniotic egg consists of a set of fetal membranes, including the amnion, chorion, and allantois, as well as an outer shell that can be either strongly mineralized (as in hard-shelled eggs) or weakly minerals (as in parchment-shelled eggs), the study said.
The University of Bristol’s School of Earth Sciences led the research, which classified 51 fossil species and 29 living species as oviparous, which lay hard- or soft-shelled eggs, according to the Times. or viviparous, which give birth to live young.
“All phyla of amniotes, including mammals, show signs of long-term retention of embryos within their bodies,” the study found.
Professor Michael Benton of the University of Bristol said: “Our work, and that of many others in recent years, has consigned the classic ‘reptile egg’ model of textbooks to the dustbin.”
“Earlier amniotes extended the embryo rather than the hard-shelled egg to protect the developing embryo inside the mother for more or less time, so birth could be delayed until the environment became favorable.”
Project leader Professor Bao Jiang added, “Sometimes, closely related species exhibit both behaviors, and it turns out that living lizards can flip to lay eggs more easily than assumed. was done.”
