Koonwarra fossil bed

The Koonwarra fossil bed of South Gippsland has been described as ‘one of the great fossil localities of the Mesozoic Era’. The site was discovered in 1961 by workmen, who were straightening a bend in the South Gippsland Highway near Koonwarra, 142 kilometres from Melbourne.

The locality has yielded abundant fossils of fishes, plants and insects, exquisitely preserved in thinly layered mudstones deposited in a freshwater lake about 115 million years ago, during the early Cretaceous period. The insects include mayflies, dragonflies, cockroaches, beetles, fleas, flies and wasps. Most of these belong to families still alive today, demonstrating the antiquity of the modern Australian insect fauna.

The plants found include ferns, conifers, relatives of the modern Ginkgo, and possible flowering plants that are among the oldest known in the world. Also present are crustaceans, spiders, possible earthworms, bird feathers and a horseshoe crab. The feathers represent one of the oldest known fossil records of birds.

The Koonwarra site is important scientifically because of the large number of species present, their excellent preservation, and the information they provide on the environment in which they lived. At this time, Australia was still attached to Antarctica, and was situated much farther south than at present, placing southern Victoria in the polar region. The evidence provided by the fossils is consistent with a very cold climate. Some of the insects are similar to forms living today in cool mountain streams and lakes in alpine or subalpine areas, and the abundance of fish indicates that they were killed in large numbers, possibly due to the surface of the lake freezing in winter.