Page 40 - Reptiles & Dinosaurs (Britannica Illustrated Science Library)

36 REPTILES: BACKGROUND REPTILES AND DINOSAURS 37

A Living Fossil

“Spiny back” TAIL
Tuataras can shed their tails to
espite looking like lizards and sharing some common traits with IS THE MEANING OF “TUATARA” IN THE avoid being captured. The lost
portion grows back, but it differs
crocodiles, tuataras are a unique type of reptile. The tuatara is the MAORI LANGUAGE both in color and in design from
D last living sphenodont, and, because it has changed very little the original tail.
from its original form, it is called a living fossil. Two known species of
tuatara have been identified, both of which inhabit the islands that lie
off the coast of New Zealand. They live in burrows, and their great
tolerance for cold allows them to survive at very low temperatures.
Tuataras grow slowly and can live up to 80 years.

FEET
SPINES have four toes
These smooth and
PINEAL EYE apiece.
TUATARA can be distinguished in conspicuous spines are
Sphenodon younger specimens. In more prominent in males.
punctatus adults, it is covered by
the scales that grow
over it.
Habitat Stephens Island
Reproduction Oviparous
Lifestyle Burrower
REPRODUCTION
Females are ready to mate once every
The males are much Weight
larger than the females. 25 ounces four years. The male—the only modern
(700 g) living reptile without a penis—uses its
cloaca to transfer its sperm directly into
Average Length: 16 to 24 inches
(40 to 60 cm) the female cloaca.
THE EGGS
take a year to form inside the body of the
mother and another year to incubate.

68° F 70° F 72° F
(20°C) (21°C) (22°C)
HEAD
is large compared to the body, There is an 80 There is a 50 There is an 80
and it lacks auditory structures. percent chance percent chance percent chance
that the eggs will that they will that they will
hatch female. hatch female. hatch male.
SKULL
has two openings Behavior
(temporal fenestra)
on either side of EYE Tuataras are nocturnal. During the
the skull. is large. The pupil is day, they rest on rocks basking in
a vertical slit, and the sun, and at night, they go out hunting BURROW
the iris is a dark A tuatara can dig its
Openings brown color. near their burrows. Tuataras, unlike other own burrow or inhabit
behind each reptiles, thrive in cold weather.
eye (temporal Temperatures above 77° F (25° C) are that of another.
fenestra) lethal to tuataras, but they can survive
COLORATION SCALES temperatures as cool as 40° F (5° C)
Tuataras' tones vary on its back are by hibernating. Tuataras are
from grayish to olive to small and solitary, skittish animals.
brick red. Tuataras granular,
undergo significant while the ones
variations in color on its
throughout their lives. stomach are
NUTRITION arranged in
Tuataras are carnivores. transverse rows.
TEETH Their diet consists of
are not separated insects, earthworms, snails, 150 million years 6
structures but rather a and crickets. Occasionally
sharpened extension of they eat shearwater eggs THE LENGTH OF TIME TUATARAS HAVE EXISTED LENGTH OF
the edges of both jaws. and nestlings. WITHOUT UNDERGOING EVOLUTIONARY CHANGES. months HIBERNATION