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Why the Tuatara Developed a Third Eye. You can’t see a tuatara’s third eye, at least in the adults. The eye is covered in scales and can only be seen in young juveniles. As mentioned above ...
Like some other living vertebrates, including some lizards, the tuatara has a third eye on the top of its head called the parietal eye (also called a pineal or third eye) formed by the parapineal organ, with an accompanying opening in the skull roof called the pineal or parietal foramen, enclosed by the parietal bones. [63]
The parietal eye is found in the tuatara, most lizards, frogs, salamanders, certain bony fish, sharks, and lampreys. [7] [8] [9] It is absent in mammals but was present in their closest extinct relatives, the therapsids, suggesting that it was lost during the course of the mammalian evolution due to it being useless in endothermic animals. [10]
In the living tuatara and some lizards, as well as in many fossil tetrapods, a small opening, the parietal foramen (also called the pineal foramen), is present between the two parietal bones at the midline of the skull. This opening is the location of the parietal eye (also called the pineal or third eye), which is much smaller than the two ...
The tuatara has an average total length of 34.8 and 42.7 centimetres (13.7 and 16.8 in) for females and males respectively. [28] Clevosaurus sectumsemper has an estimated total length of 12 centimetres (4.7 in), [ 29 ] while large individuals of the largest known terrestrial sphenodontian, Priosphenodon avelasi reached total lengths of just ...
With a maximum length of around 5 to 6 m (16 to 20 ft) and a mass of over 450 kg (1,000 lb), it is the largest living species of the family Alligatoridae, and the third-largest crocodilian in the Neotropical realm. True to its common and scientific names, the black caiman has a dark greenish-black coloration as an adult.
The tuatara and some extinct rhynchocephalians have a more rigid skull with a complete lower temporal bar closing the lower temporal fenestra formed by the fusion of the jugal and quadrate/quadratojugal bones, similar to the condition found in primitive diapsids. However early rhynchocephalians and lepidosauromorphs had an open lower temporal ...
It is a part of the epithalamus, which can be divided into two major parts; the epiphysis (the pineal organ, or pineal gland if mostly endocrine) and the parietal organ, often called the parietal eye, or third eye, if photoreceptive. It arises as an anterior evagination of the pineal organ or as a separate outgrowth of the roof of the diencephalon.