16. Great basins with dinosaurs
– Mesozoic Era (250-65 million yrs ago)
– recovery from the P/T extinction event
– to decimation by the K/T extinction event
Survivors: From the few survivors of the devastating Permian-Triassic extinction event, new ecosystems evolved in a largely depopulated and devegetated world. Of the survivors Lystrosaurus a robust pig sized burrowing lizard may have been well adapted to eat Dicroidium a seed fern, both of which dominated life in the early Triassic world. For a while Lystrosaurus made up as much as 90% of all land creatures. A smaller carnivorous relative of Lystrosaurus also survived to become the ancestor of all mammals. It took tens of millions of years to re-establish new diverse stable ecosystems on Earth.
Age of Dinosaurs: Archosaurus (ancestor to dinosaurs & birds) also survived in small numbers, but by the mid Triassic (225Ma) began to displace Lystrosaurus, and then diversified & dominated land based eco systems during the remainder of the Mesozoic Era (Jurassic & Cretaceous periods).
Plants: Other plants that survived & eventually flourished include ferns, ginkgos, cycads, conifers & horsetails. Flowering plants evolved in the Cretaceous Period, flourished & by 105Ma made up half the flora of NE Australia. Among the new plant groups were the: banksia family; eucalypt family; casuarina family; & rush like plants.
Great Basins: The sediments of the Sydney Basin well represented in the Blue Mountains, with basal layers of Permian sediments including thick coal beds representing flourishing diverse life in swamp forests prior to the extinction event. The spectacular sandstone cliffs of the Blue Mountains were deposited by a giant river system during the succeeding Triassic Period following the extinction event. There is some evidence that the headwaters of this giant river system may have been in the highlands of Antarctica thousands of kilometres to the south.
During the Mesozoic Era many great sedimentary basins developed in Eastern Australia, the largest of which we know of as the Great Artesian Basin. These would have been perfect habitats for dinosaurs and many dinosaur fossils have been preserved. The Wattle Flat area was then an upland hilly area. The remains of any dinosaurs that may have lived & died here are unlikely to have been preserved.
End of Dinosaurs: Towards the end of the Mesozoic Era the Australian continent finally separates from Antarctica and becomes isolated from other land areas. The Australian dinosaur rich ecosystem thrives for about 5 million years before the K/T extinction event (65Ma) brings all this to an end.