Question

The only living member of the order Rhynchocephalia is
A) Sphenodon
B) Hemidactylus
C) Draco
D) Iguana

Answer 1

The term Rhynchocephalia stands for beak like. They belong to the class Reptilia and though presently consists of only one living member was quite widespread during the Jurassic period.

Complete answer:
Rhynchocephalia are lizard-like reptiles with only one living member which is the tuatara whose scientific name is Sphenodon punctatus. Tuataras after they were discovered were classified as lizards but later it was found out that they have several characteristics that are different from lizards. One of them is the presence of a third eye at the top of their heads. This eye though has all the normal parts of an eye like retina, lens and nerve endings that are not used for seeing purpose. It is visible in newly born tuataras but get covered up by scales after a few initial years. Another feature that distinguishes it from lizards is the presence of a diapsid skull. Its teeth are found to be attached superficially to the jawbones and consists of acrodont dentition along with a pair of overhanging incisor like teeth. The teeth are used for grinding of prey after they are captured.

Hence the correct answer is option (A)Sphenodon.

Note: Rhynochocephalians though are not present in large numbers today so must be conserved and knowledge about them and their characteristics is important to get an idea about the evolutionary history of those animals that are related to them. Tuataras are of importance because they are considered as God forms by certain sections of people in the world.