The pineal eye of the tuatara has a remarkably eye-like structure with photoreceptors that in other reptiles
have been shown to exhibit photoreceptive capabilities. The paraphysis appeared to have a secretory function
that is as yet undetermined, whereas the pineal sac had the appearance of a poorly differentiated retina.
Thus, it appears that the complex biochemistry of the human pineal gland is reflected in the complex
anatomical structure of this primitive reptile.
The tuatara is famous because of its dorsally placed “third eye.” TheNeurosurgical Association of Australasia,
appreciating the fascination that the “third eye” instills in us, has incorporated the tuatara into its emblem.
That emblem contains a representation of two lizards: the New Zealand tuatara (Sphenodon punctatus) and
the Australian stumpy-tailed skink (Trachysaurus rugosus). Each of those lizards has a “third eye” that is
situated in the median parietal region. The lizards were chosen for the Society’s emblem “following a witty
after-dinner speechby the lateKen Jamieson inwhichhe emphasized the value of the thirdeye inneurosurgical
hindsight” (www.nsa.on.net).
Ung and Molteno report that today’s tuatara is almost as it appeared in the Jurassic Period and, as such,
is considered to be a “true living fossil.” They explain that the tuatara has characteristics that distinguish it
from a true lizard. They seized the opportunity to examine a pre-term neonatal lizard that had died of natural
causes. Their interesting article shows clearly, in a photomicrograph, that the pineal complex of the tuatara
contains a pineal eye, with an easily discernible lens. A high-magnification photomicrograph shows the retinal
elements in the pineal eye. The authors compare their findings with those of Dendy, who published his
findings in 1911,
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and they remark on the consistency of their findings with Dendy’s.