Creationists often doubt that any dead ends in evolution are known. Such dead ends would be predicted by the theory of evolution, but never get confirmed. Such dead ends of course get confirmed. Everybody knows teeth. They are a perfect example for such a dead end in evolution.

Fish were the first species with teeth. But many fish species got rid of their teeth again or reduced them either in size (catfish with tiny teeth on a rather microscopic level) or in number (blowfish with frontal teeth only). Batrachians stem from fish. All batrachians waive to grow teeth. But before the batrachians achieved this, the reptiles forked off from them.

Teeth proved to be a disadvantage to reptiles too. So these animals either got rid of their teeth (turtles, lizards) too or reduced them in size (constrictor snakes) too or reduced them in number (venomous snakes) too. The reptiles brought forth birds and mammals beforehand of course. Birds found that beaks made teeth superfluous, so all birds got rid of their teeth.

Mammals went on different ways. The anteater got rid of its teeth, but can feed only on living ants, that are still defending themselves. Cats reduced their teeth in number and kept only the incisors and the cuspids.

Rodents developed a special repair mechanism. It consists of letting the teeth grow continually and shorten them by continuous gnawing. If rodents don’t shorten their teeth this way, then they will soon no longer be able to shut the mouth. When rodents gnaw at plastic, then they don’t want to eat the plastic. These animals aren’t that stupid!

Among cattle do calves prepare more teeth than they will grow for becoming adults. This clearly proves that cows once had more teeth, but reduced them in number. The same mechanism is more impressive in baleen whales. Their embryos prepare teeth, but during the embryonic development all teeth are replaced by the baleen. So baleen whales provide the best proof that teeth are a dead end in evolution.

Humans made the silly mistake to include teeth in the facial expressions, which humans use for communication. This mistake handicaps the development of a baleen or something similar. The only possible facial expression would then be to look stupid. So some humans have to live with terrible difficulties.