Question

Mention the general characters of Rhynchocephalia.

Answer 1

Hint: The order of lizard-like reptiles is called Rhynchocephalia. This order includes only one living species that is tuatara. Tuatara is a lizard in body form.

Complete answer:
Characters of rhynchocephalia
>The Rhynchocephalia is the sister group to the squamata that are lizards .
>They derive the skin structure by shedding mechanisms.
>There is presence of opening in the pelvis called thyroid fenestra.
>Paired male hemipenes are rudimentary in male Tuatara which are organs that help in delivering the sperms to females.
>Have specialized foot and ankle structure.
>Enlarged palatine tooth row .
>Teeth are fused to the crest of jaw bone with no sockets- Acrodont dentition.
>Transverse cloacal opening.
>Fracture planes in the tail vertebrae.
>Tongue notched distally and used to capture prey.
>Most of the Rhynchocephalians belong to the group Sphenodontia .The sphenodontia is characterized by hooked beak like structure which is formed by enlarged premaxillary teeth.
>The unique feature of tuatara is the presence of the Third eye on the top of the head but it is not used for seeing.

Note:The tuatara were classified as lizards in 1831. According to the fossil records it is called a living fossil. The tuatara has a diapsid skull but lacks a complete lower temporal bar. The tuatara is more active during night. The only extant Rhynchocephalians are the tuataras which occur only in New Zealand.