Although my recent entry about the Rhinogradentia class of animals ("The Most Fantastic Animals You've Never Heard Of") might have contained some dubious information about animals that might have been less than actual, I assure you that the following information is fully documented.You are probably very familiar with the Reptilia class of animals -- Reptiles. You know about the Crocodilia order, which encompasses the families of crocodiles, alligators, gavials, and caimans -- 23 species in all. And you know about the order that includes all the families of turtles and tortoises -- there are about 300 species of those shelled creatures. Finally, you all know about the order with the most species of all: over 7,900 distinct snakes and lizards. However, there is one more order about which you know nothing. If I'm wrong, can you name another type of reptile not mentioned above?
Amphibians? No; they're amphibians, not reptiles. Geckos? No, they're amphibians, which, if you have been paying attention, are not reptiles. Ok, I'll give you a hint: the Sphenodontia order of reptiles. Did that help? This order has only one family, which has only one species.
The Tuatara, presently living only on a few New Zealand islands, is a remnant of the Mesozoic Era, over 200 million years ago. The Tuatara is a unique animal for many reasons:
- It has a third eye. On the forward part of its head is a parietal eye, with its own cornea, lens, and retina.
- It has no external ear. It is able to hear sounds, however.
- It has three rows of "teeth". The two upper rows overlap the one on the lower jaw, and this is unique among all living species. The teeth, in fact, are not actually teeth; they are sharp projections of the jaw bone itself.
- It has unique skeletal features that resemble those of fish rather than reptiles.
- Its locomotion resembles that of amphibians rather than reptiles.
- It has adapted to cold weather conditions.
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