Plants

Tonnes of opalised plant fossil is extracted from Lightning Ridge opal mines each year. Although some is exquisitely preserved, most is too fragmentary to be informative – other than to show how richly vegetated the area once was. A large diversity of exquisite pine cones, drupes, stems and seeds are found, sometimes glittering with gem colour. Those that have not been through mining machinery retain remarkable detail. 110 million years ago, Lightning Ridge was heavily forested with primitive conifers such as Araucarian, podocarp and Kauri pines, which towered over ferns, seed ferns, ground pines, fungi and lichens, mosses, liverworts and horsetails. Large pieces of silicified wood are found in the opal mines; however, these larger pieces are rarely opalised. Molluscs

Bivalve and gastropod molluscs (mussels and snails) are the most commonly-found opalised fossils at Lightning Ridge. These freshwater species differ from the molluscs found at White Cliffs and in South Australia, which lived in a marine environment. Mines that intersect with palaeochannels sometimes contain rich deposits of bivalve molluscs. Occasionally, concentrations of whelks form dense death assemblages in sandstone. Many different species of opalised mollusc have been found at Lightning Ridge. Although some are relatively common, others are rare. Freshwater crayfish

The opalised gastroliths of freshwater crayfish are known locally as ‘yabby buttons.’ Crayfish use gastroliths to store calcium from their exoskeletons (‘shells’) before they moult, then release the calcium to harden their new protective coating. Fossil yabby buttons are usually around 10-12mm across. Sharks

Fossil shark teeth are rare at Lightning Ridge. Nevertheless, quite a few have been found over the years, suggesting that at the time the opal-bearing sediments were laid down, although Lightning Ridge was on land, it wasn’t too distant from the shore of the sea that then covered much of inland Australia. Lungfish

At least three species of lungfish lived at Lightning Ridge in the Early Cretaceous period. We know them from the opalised toothplates found in the mines. Bony fish

A variety of freshwater bony fish lived in the streams and billabongs of ancient Lightning Ridge. We have mostly their jaw bones and backbones. Not that many have been recovered yet, but that’s probably because most are so small and fragile that they either are not noticed, or are destroyed by the mining machinery. Frogs

The oldest frog fossil known in Australia is a tiny opalised upper jaw found in a mine at the Coocoran fields, Lightning Ridge.

Turtles

Lightning Ridge’s fossils include at least three kinds of land- and swamp-living turtles, including the world’s oldest horned turtle (meiolaniid). Crocodiles

Three different species of crocodile have been identified so far among Lightning Ridge’s opalised fossils. All appear to have been from relatively small crocodiles. The Australian Opal Centre has teeth, back bones and scutes (bony armour from beneath the skin) of these 110-million-year-old crocs. Plesiosaurs

Plesiosaurs were swimming reptiles that lived during the dinosaur era – the reptilian ‘dolphins’ of their time. Some lived in the sea, some in fresh water and some sea-living plesiosaurs swam upstream to breed.At Lightning Ridge, opalised plesiosaur teeth are found but, strangely, plesiosaur bones are extremely rare. The teeth indicate at least a couple of different kinds of plesiosaur. Dinosaurs

Ah, the dinosaurs. Lightning Ridge is blessed with the opalised remains of several kinds of dinosaur: sauropods, prosauropods, theropods, ornithopods, ornithomimosaurids and hypsilophodontids. They range in size from the ridiculously enormous to little chicken-sized dinos – sublime! At the Australian Opal Centre we have opalised dinosaur teeth, limb bones, back bones, toe bones, claws and pieces of rib, pelvis and shoulder. Most are in grey, black or amber-coloured potch, but some shimmer with colour.In the roofs of some opal mines you can even look up to see the underside of dinosaur footprints. Pterosaurs

Pterosaur limb bone.Pterosaurs were flying reptiles that lived with the dinosaurs, went extinct with the dinosaurs and left no living relatives. Uncrushed pterosaur fossils are quite rare globally, because the bones were hollow and thin-walled. A small number of opalised pterosaur bones have been found at Lightning Ridge. Snakes

Snake bones are very delicate and fragile. So far we know of only one opalised snake fossil from Lightning Ridge – a tiny fragment of lower jaw – but as greater care is taken to retrieve tiny fossils from underground, it is likely that further snake fossils will be found. Birds

Just a few tiny bird bones have been found, and here’s something wonderful: bird teeth! Mammals

Lightning Ridge made the cover of the prestigious journalÂ NatureÂ when its first opalised monotreme mammal was found – the jaw of a platypus-like creature named Steropodon. Since then, other rare but important monotreme fossils have been discovered, including vertebrae (back bones) that have been donated to the Australian Opal Centre. These are the only opalised monotreme vertebrae in a public collection anywhere in the world.