The Family Tree

Tough Skin

The first reptiles descended from ancestral amphibians. They distinguished themselves from their ancestors through mutations that allowed them to free themselves from their dependence on water for reproduction. Among these adaptations, the amniotic egg stands out, but equally important were the development of sex organs that favored internal copulation, an impermeable skin, and the formation of a low volume of urine that eliminates uric acid instead of urea. These adaptations to its environment were necessary to the reptilian dominance of the greater part of the Mesozoic Era. •

ARMOR

Sharp points formed a protective armor against predators.

Scutosaurs were quadrupeds with massive legs, similar to strong columns with wide bases, which sustained the weight of their bodies. These reptiles belonged to the extinct genus Scutosaurus species. They were large herbivores that lumbered through the pines and firs of Permian forests in search of food, such as herbs and soft buds.

Weight 1,100 pounds (500 kg)

REPTILE EVOLUTION

Ichthyosaurs

Marine Reptiles

MMbioHiyytähu

Scutosaurus

Hylonomus

CAPTORHINIDS AND HYLONOMUS

Archelon

ANAPSIDS

Lizards

Snakes, Lizards, and Sphenodonts

CROCODILIANS

SAUROPTERYGIANS

ARCHOSAURUS Antorbital fenestra

Diapsid skull

Canine teeth in the upper mandible

REPTILES

Great Turtle

The Archelon ischyros was a giant marine reptile that measured 15 feet (4.6 m) in length. It inhabited North America during the Upper Cretaceous (between 75 and 65 million years ago). An omnivorous feeder, it passed slowly through shallow waters by means of the propulsion provided by its flippers. The females laid eggs in holes just like the sea turtles of today.

ANAPSIDS

Canine teeth in the upper mandible

REPTILES

SHELL

was a structure formed by bony ribs that developed from the vertebrae of the spine.

Weight

ARCHELON

MOUTH

had a beak like a hook. It did not cut, but its bite was deadly.

ARMOR

Sharp points formed a protective armor against predators.

SHIELD LIZARD

SAUROPTERYGIANS

were appropriate for the animal's body weight. It moved slowly.

Animals The Permian Period

TAIL

was short in relation to the animal's body size.

ORDERS OF REPTILES EXIST TODAY.

TEETH

Small and irregular, they allowed the animal to cut buds for food.

Weight 1,100 pounds (500 kg)

Skull Types

^^ The fossils of the most primitive reptiles correspond with the Lower Carboniferous Period. These reptiles were terrestrial animals, somewhat similar to the Mesozoic reptiles. The diapsid lineage originated with them.

SHIELD LIZARD

Scientific Name Scutosaurus sp.

Diet

Herbivore

Habitat

Land

Location

Europe (Russia)

End of Permian

End of Permian

TAIL

was short in relation to the animal's body size.

ANAPSID

A group of reptiles without openings in the skull near the temples. This is the condition seen in fish, amphibians, and earlier reptiles. Today's turtles belong to this lineage.

Cranial

TEETH

Small and irregular, they allowed the animal to cut buds for food.

SHELL

was a structure formed by bony ribs that developed from the vertebrae of the spine.

were appropriate for the animal's body weight. It moved slowly.

ORDERS OF REPTILES EXIST TODAY.

FLIPPERS

maintained the body's balance while it moved.

DIAPSID

During the Permian Period, another group of reptiles emerged that had temporal openings in the skull behind each eye socket.

Weight

ARCHELON

Scientific Name Archelon ischyros

MOUTH

had a beak like a hook. It did not cut, but its bite was deadly.

4,900 (lUodkg)

IS WHAT THESE SEA TURTLES COULD HAVE WEIGHED.

Scientific Name Archelon ischyros

Diet

Omnivorous

Habitat

Marine

Location

North America

Era

Upper Cretaceous

FLIPPERS

maintained the body's balance while it moved.

DIAPSID

During the Permian Period, another group of reptiles emerged that had temporal openings in the skull behind each eye socket.

Metriorhynchus Crocodile

METRYORHYNCHUS

Scientific Name Metriorhynchus sp.

This genus of reptiles owes its name to its members' long snouts. The sea crocodile was a dangerous hunter, capable and opportunistic. It preyed on squid and pterosaurs, and it chased fish up to 20 feet (6 m) long—twice its own size. Its tail got thinner toward its end, which had a flipper. There was a small bump between its eyes. Sea crocodiles lived near the end of the Jurassic Period.

Weight 660 pounds (300 kg) 10 feet (3 m)

METRYORHYNCHUS

Scientific Name Metriorhynchus sp.

This genus of reptiles owes its name to its members' long snouts. The sea crocodile was a dangerous hunter, capable and opportunistic. It preyed on squid and pterosaurs, and it chased fish up to 20 feet (6 m) long—twice its own size. Its tail got thinner toward its end, which had a flipper. There was a small bump between its eyes. Sea crocodiles lived near the end of the Jurassic Period.

Diet

Squid and Pterosaurs

Habitat

Marine

Location

South America

(Chile) and Europe

(France and England)

Era

Jurassic

Common Lizards Missouri

A Living Fossil

Despite looking like lizards and sharing some common traits with crocodiles, tuataras are a unique type of reptile. The tuatara is the last living sphenodont, and, because it has changed very little 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.«

TUATARA

Sphenodon punctatus

TUATARA

Sphenodon punctatus

Habitat

Stephens Island

Reproduction

Oviparous

Lifestyle

Burrower

The males are much larger than the females.

Weight

25 ounces (700 g)

"Average Length: 16 to 24 inches -

"Average Length: 16 to 24 inches -

HEAD

is large compared to the body, and it lacks auditory structures.

PINEAL EYE -

can be distinguished in younger specimens. In adults, it is covered by the scales that grow over it.

SPINES -

These smooth and conspicuous spines are more prominent in males.

SKULL

has two openings (temporal fenestra) on either side of the skull.

SPINES -

These smooth and conspicuous spines are more prominent in males.

Openings behind each eye (temporal fenestra)

is large. The pupil is a vertical slit, and the iris is a dark brown color.

SKULL

has two openings (temporal fenestra) on either side of the skull.

Openings behind each eye (temporal fenestra)

is large. The pupil is a vertical slit, and the iris is a dark brown color.

COLORATION Tuataras' tones vary from grayish to olive to brick red. Tuataras undergo significant variations in color throughout their lives.

TEETH

are not separated structures but rather a sharpened extension of the edges of both jaws.

NUTRITION Tuataras are carnivores. Their diet consists of insects, earthworms, snails, and crickets. Occasionally they eat shearwater eggs and nestlings.

150 million years

THE LENGTH OF TIME TUATARAS HAVE EXISTED WITHOUT UNDERGOING EVOLUTIONARY CHANGES.

IS THE MEANING OF "TUATARA" IN THE

MAORI LANGUAGE

percent chance that the eggs will hatch female.

Behavior percent chance that they will hatch female.

percent chance that they will hatch male.

BURROW

A tuatara can dig its own burrow or inhabit that of another.

LENGTH OF HIBERNATION

"Spiny back"

IS THE MEANING OF "TUATARA" IN THE

SCALES on its back are small and granular, while the ones on its stomach are arranged in transverse rows.

Tuataras can shed their tails to avoid being captured. The lost portion grows back, but it differs both in color and in design from the original tail.

REPRODUCTION Females are ready to mate once every four years. The male—the only modern living reptile without a penis—uses its cloaca to transfer its sperm directly into the female cloaca.

THE EGGS

take a year to form inside the body of the mother and another year to incubate.

MAORI LANGUAGE

FEET

have four toes apiece.

months

There is an 80

There is a 50 There is an 80

percent chance that the eggs will hatch female.

Behavior

^^ Tuataras are nocturnal. During the t^t day, they rest on rocks basking in the sun, and at night, they go out hunting near their burrows. Tuataras, unlike other reptiles, thrive in cold weather. Temperatures above 77° F (25° C) are lethal to tuataras, but they can survive temperatures as cool as 40° F (5° C) by hibernating. Tuataras are solitary, skittish animals.

percent chance that they will hatch female.

percent chance that they will hatch male.

LENGTH OF HIBERNATION

BURROW

A tuatara can dig its own burrow or inhabit that of another.

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Responses

  • andrea
    What is unique about the hylonomus family?
    1 year ago
  • Rachele
    Which era means reptiles and dinousaurs?
    2 months ago

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