Riversleigh Fossil Site, Australia

Riversleigh Fossil Site, Australia

Geological History

Riversleigh covers an area of approximately 80 square kilometres and is located 250 km north-west of Mt Isa. Riversleigh is Australia’s most famous fossil site and fossils were first discovered in the area in 1901. The fossils document the evolution and changes of Australia's terrestrial fauna and ecosystems.

The last remnant of the supercontinent Gondwanaland finally separated into Australia and Antarctica between 30 and 40 million years ago. Isolated on an enormous northward-drifting raft the inhabitants of the Australian continent evolved and diversified over millions of years as the climate cycled through periods of warm and cool, wet and dry.

Fossils Found in Riversleigh

Our

It had a short, deep head, large eyes and three longitudinal ridges along its skull (giving it its name). Trilophosuchus may have been terrestrial rather than aquatic. Its neck musculature, similar to that of other possibly terrestrial crocodiles, suggests that Trilophosuchus held its head above its body like monitor lizards do.

Size range

1.5m long (head to tail)

Distribution

Trilophosuchus is known only from the Riversleigh World Heritage Fossil Site, northwestern Queensland.

Habitat

The Riversleigh area from the early to middle Miocene was mainly forested, with open areas near forest edges and freshwater streams or lakes in a karst (limestone) environment.

Feeding and Diet

Judging by its small size, Trilophosuchus would have taken small vertebrate animals such as mammals, turtles, snakes and fish. The anatomy of the back of the skull in Trilophosuchus suggests that feeding might have involved rapid side-to-side, up-and-down and rotational movement of the head. It would not have 'rolled' its prey, like the living Saltwater Crocodile.

reptilian lung

The most distinctive features of birds is their lungs. Bird’s lungs are small and rigid, but are are highly efficient and meet the metabolic needs of flight. Respiration in birds is unique and involves a set of nine air sacs packed between muscles. The air sacs contain blood vessels and do not undertake oxygen exchange, but rather function like bellows to move air through the lungs.

While fossils generally do not preserve soft tissue such as lungs, a very fine theropod dinosaur fossil has been found in which the outline of the visceral cavity has been well preserved. The evidence clearly indicates that this theropod had lung and respiratory mechanics similar to that of a crocodile—not a bird. There was evidence of a diaphragm-like muscle separating the lung from the liver, much as you see in modern crocodiles. These observations suggest that this theropod was similar to an ectothermic reptile, not an endothermic bird.

Did feathered dinosaurs exist?

Feathers are considered to be unique to birds. All living birds have feathers, while no living creature other than a bird has been found to have an appendage like the