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Where is Lightning Ridge?
Lightning Ridge is in northern New South Wales, near Walgett (29° 26' S, 147° 59' E).
Why is Lightning Ridge important?
Deposits at Lightning Ridge yield some of the rarest, most beautiful and precious fossils in the world. The sandstone at Lightning Ridge once formed the floor of an ancient shallow inland sea where plants, aquatic life and occasionally the bones and teeth of animals were preserved. As they tunnel through these sediments searching for precious opal, miners sometimes find these fossils.
The most famous and significant fossils from Lightning Ridge are those of some early mammals. Mammal fossils are not often found in Cretaceous fossil deposits, since the generally rare, tiny and delicate mammals of this period were far outnumbered by the more successful and diverse dinosaurs. In Australia Cretaceous mammal fossils are almost unknown, which is why the Lightning Ridge fossils are so important.
Palaeontologists searching for fossils of dinosaurs and primitive mammals at Lightning Ridge consult with opal miners to see what they have found, or obtain permission to sift through spoil heaps and excavate in opal mines. Without the help of miners, many fossils, including Steropodon and Kollikodon, would never have been recognised. As well as being beautiful gems, the rare and often valuable fossils from Lightning Ridge have the potential to solve many mysteries about our ancient mammalian ancestors.
Fossil time period: Lightning Ridge
110 million years ago the supercontinent Gondwana was a wilderness of forests of pines, ferns and palms separated by tracts of shallow sea. Dinosaurs and their relatives dominated this landscape, as well as our rare and tiny mammal ancestors. Near the edge of this ancient continent, fragments of the remains of these animals accumulated in the sands of the inland sea.
Lightning Ridge fossils
Steropodon, was a fossil monotreme and is one of the ancestors of the modern Platypus and echidnas of Australia and New Guinea. The Cretaceous monotremes were probably similar in size and shape to the modern platypus, although in modern monotremes the well-developed teeth of the fossil forms are absent. Steropodon galmani may have used electroreceptors in its snout to hunt crustaceans in a similar manner to the modern platypus.
Fossils of other animals living at the time of these ancestral egg-layers have also been found at Lightning Ridge. Dinosaurs, including giant long-necked sauropods munched on vegetation along with the 1.5m long Lightning Beast Fulgurotherium australe. Perhaps these smaller dinosaurs moved in herds like modern antelope, always on the lookout for predators like the carnivorous theropod Rapator ornitholestoides, which reached a length of about 6m. Pterosaurs flew in the air and fish, lungfish, crocodiles and marine reptiles, such as long-necked plesiosaurs lived in the oceans.