Wadeichthys oxyops, fossil fish. Photographer: Frank Coffa Museums Victoria

The Koonwarra fossil bed was found by accident in 1961 during roadworks to realign a segment of the South Gippsland Highway. Dating from the early Cretaceous 115 million years ago, they are composed of mudstone sediment thought to have been laid down in a freshwater (possibly cool-climate subalpine) lake. The site is an important element of Australia’s fossil record, with plants, insects (including mayflies, dragonflies, cockroaches, beetles, fleas, flies and wasps), spiders, crustaceans and fish recovered.

Duncanovelia extensa, fossil insect-Museums Victoria
Fossil feather-Photographer: Benjamin Healley Museums Victoria
Tarwinia australis Photographer: John Broomfield Museums Victoria
Wadeichthys oxyops, fossil fish Photographer: Frank Coffa Museums Victoria
Fossil feather. Koonwarra, Victoria Photographer: Martin Kundrat Museums Victoria Dr Martin Kundrat

Among them is the unusual finding of a fossil horseshoe crab  Small segments of a leafy twig have been recovered that were thought to be one of the oldest angiosperms (flowering plants) discovered; more recent examination reports anatomy more typical of a gnetophyte, a group of plants for which there is a scant fossil record.  

 

Six well-preserved 118 million-year-old fossilized dinosaur and bird feathers have been recovered from an ancient lake deposit that once lay beyond the southern polar circle, indicating more complete remains of feathered dinosaurs might be found, however the site has been little-excavated, extensive removal of overlying rock has to take place before further excavation.

 

Feathered dinosaur fossils are known from only a handful of localities worldwide. Examples from the Southern Hemisphere are especially rare, and mainly include only isolated feathers. These fossils were recovered from Koonwarra Fish Beds Geological Reserve, which is a heritage listed site 145 km southeast of Melbourne in Victoria, Australia

 

An international team of scientists has analyzed a collection of 10 such fossil feathers found in Australia, which reveal an unexpected diversity of tufted hair-like ‘proto-feathers’ from meat-eating dinosaurs, together with downy body feathers, and wing feathers from primitive birds that would have been used for flight. The fossil feathers from Australia were all entombed in fine muddy sediments that accumulated at the bottom of a shallow lake close to the South Pole during the Age of Dinosaurs

 

These dinosaur fossil feathers are significant because they are the first to be located in a seasonally cold environment which endured months of polar winter each year. The Koonwarra feathers are preserved in incredible detail. There are even tiny filament-like structures that would have ‘zipped’ the feather vanes together, just as in the flight feathers of modern birds.

 

The discovery of ‘proto-feathers’ at Koonwarra therefore suggests that fluffy feather coats might have helped small dinosaurs keep warm in ancient polar habitats.

The Koonwarra fossil feathers provide the first record of dinosaur integument from the ancient polar regions, and hint what was once a global distribution of feathered dinosaurs and early birds.

Some of the fossil feathers found at Koonwarra are on display in the ‘600 Million Years’ exhibition at the Melbourne Museum in Australia.