Have you ever wondered why birds don't have teeth? Maybe you hadn't thought about it! The study of ancient fossils has revealed that the ancestors of modern-day birds did have teeth. So where did they go? Scientists have long believed that birds evolved into toothless creatures to aid their powers of flight as the absence of teeth reduced their body weight. But a new theory completely contradicts this idea and proposes a new theory.
German research
Recent research by scientists at the University of Bonn suggests that the absence of teeth in birds has nothing to do with the need to be lighter for efficient flight. The study suggests that birds lost their teeth so that they could hatch more quickly from their eggs. When still in their eggs, bird embryos are highly vulnerable to predators and natural disasters. Unborn chicks are unable to pass on their genes and so evolution has seen to it that they are able to hatch more quickly.
Teeth and gestation
Lizards also hatch from eggs but after a much longer period of time than birds because the embryos have to develop teeth. This process can account for up to 60% of the incubation time. The researchers in Bonn believe that birds gradually lost their teeth to speed up their incubation process and hatch more quickly. This change enhanced the chances of survival of each individual and so promoted the survival of the various species.
Toothless dinosaurs
The new theory is supported by the fact that some dinosaurs which were not related to birds, including carnivorous species, independently evolved similar toothless beaks to the birds. As these species were flightless, their loss of teeth could not have been related to the need to reduce body weight for flight. A recent study into this phenomena concluded that the non-flying dinosaurs with evolved beaks had previously taken took too long to hatch. An analysis of growth lines in the teeth of two dinosaur embryos enabled scientists to establish that slow dental formation caused the increased gestation period. It was concluded that the flightless dinosaurs must also have evolved to have beaks instead of teeth in order to hatch more quickly, just like the birds.
Fascinating stuff!
It is likely that further research will be conducted to gain further proof that the new theory is the correct one. Unfortunately, evidence is hard to come by due to the lack of fossils from the relevant period to study. We may never know for sure!