Birds are dinosaurs, more specifically, avian dinosaurs. They vary from their non-avian brethren by having “bird-like” characteristics such as feathers and a toothless beak. Feathers, understandably, help with insulation and flight dynamics. Nevertheless, the evolution of toothless beaks in place of a toothed jaw remained a mystery.
Many non-avian dinosaurs had various types of teeth specialized in performing a multitude of functions. From stripping leaves off branches to shredding prey, teeth are essential. So, birds losing out on teeth may seem like undoing millions of years of progress.
There have been many speculations as to why birds lost their teeth. One of the most widely accepted theories is that birds lost their teeth to shed weight. This strategy would result in improved flight dynamics and better flight capabilities. Less weight also means less energy is required to keep the organism in the air.
Other scientists have speculated that birds lost their teeth to speed up their incubation period. Fossil evidence showed that non-avian dinosaurs which had teeth had an incubation period as long as six months.
It happens because the development of teeth takes up almost 60% of the embryo’s development time. In the real world, this can leave the egg vulnerable to predation or natural calamities.
Furthermore, since avian dinosaurs do not have teeth, they have a short incubation period, averaging about 2-3 weeks. Hence, toothless beaks are a trade-off for a shorter incubation period. However, this theory does not hold good for turtles (turtles and birds are technically reptiles), as they have incredibly long incubation periods.
Despite the drawbacks, we can now see the after-effects of this evolutionary trade-off: All dinosaurs, except for birds are extinct. However, we cannot attribute the extinction of the non-avian dinosaurs solely to this factor.
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