In a new study, the scientists claimed to have found the answer to one of the most baffling questions in the history of humankind – ‘What came first: Chicken or the egg?’. The question has to date left everyone, from scholars to schoolchildren, stumped. However, scientists now claim to have discovered the answer.
As per the researchers from the University of Bristol, the early ancestors of reptiles and modern birds are likely to have given birth to live young and may have not laid eggs, according to The Times. The Journal Nature Ecology and Evolution published the study which detailed the discovery.
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Scientists, along with researchers from Nanjing University, have challenged the belief which existed so far that hard-shelled eggs were the reason for the success of amniotes, which are animals whose foetuses are developed inside an amnion (membrane or sack) inside the egg.
“The amniotic egg is very different from the anamniotic egg of extant amphibians, which lacks an eggshell and extraembryonic membranes. The amniotic egg consists of a suite of fetal membranes, including the amnion, chorion and allantois, as well as an external shell that can be either strongly mineralized (as in rigid-shelled eggs) or weakly mineralized (as in parchment-shelled eggs),” the study stated.
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Retention of embryos
The research, headed by the University of Bristol’s School of Earth Sciences, went through 51 fossil species and 29 living species which were categorised as viviparous, that give birth to live young, or oviparous, that lay hard or soft-shelled eggs, according to the outlet.
The study emphasised that all the branches of Amniota, which includes mammals, have shown signs of embryos retaining within their bodies for longer periods of time.
In the history of evolution, the hard-shelled egg has often been perceived as one of the greatest innovations, however, this research states that it was this extended embryo retention which provided the ultimate protection to this group of animals.
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Speaking about the study, Professor Michael Benton, from the University of Bristol, stated, “Our work, and that of many others in recent years, has consigned the classic ‘reptile egg’ model of the textbooks to the wastebasket. The first amniotes had evolved extended embryo retention rather than a hard-shelled egg to protect the developing embryo for a lesser or greater amount of time inside the mother, so birth could be delayed until environments become favourable.”
“Sometimes, closely related species show both behaviours, and it turns out that live-bearing lizards can flip back to laying eggs much more easily than had been assumed,” Project Leader Professor Baoyu Jiang stated.
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Tags: #animals, #birds, #chicken, #climate, #discovery, #egg, #environment, #getgreengetgrowing, #gngagritech, #greenstories, #nature, #reptileegg
