100-million-year-old fossil reveals ancient outback bird - ABC News & Headlines – Australian Broadcasting Corporation

The elongate and fragile nature of the bones are synonymous with birds. (Supplied: University of New England)

A rare fossil find in outback Queensland has revealed a new species of prehistoric bird that lived more than 100 million years ago.

Roughly the size of a bush turkey, Tenuicruris piscanexum is only the second Australian bird to be formally described from the Cretaceous period.

Researchers hope the discovery can help build a better understanding of Australia's prehistoric bird life and ecology.

An "extremely rare" fossil discovery in outback Queensland has revealed a new species of prehistoric bird that roamed Australia more than 100 million years ago.

While digging in the remains of an ancient inland sea near Richmond, about 500km inland from Townsville, Kevin Petersen uncovered a long, slender bone.

The then-curator of marine fossil museum Kronosaurus Korner sent a picture to University of New England palaeontologist Matt White, who drove to Richmond to have a look.

"I was first looking at bones that looked quite similar in China … over 20 years ago, so I knew exactly what they were," Dr White said.

Tenuicruris piscanexum is believed to have been roughly the size of a bush turkey. (Supplied: Artwork by Travis Tischler)

A week later, another bone was found.

"We usually find a lot of marine reptiles out at Richmond, but to find bird bones, it's extremely rare," Dr White said.

Researchers used the fossilised tarsometatarsus, a fused foot bone found in birds, and tibiotarsus, the longest leg bone, to formally describe a new bird species, Tenuicruris piscanexum, which experts believe lived during the Cretaceous period about 100 million years ago.

Dr White said the bird likely had teeth and was roughly the size of a scrub turkey, with completed fossils found in China and Germany from the same period used to fill critical gaps in the animal's appearance.

"[There's] a little bit of artistic licence," he said.

"But we have had a lot of birds where we have more complete skeletons and we can do reverse dissection and go, right, these are roughly what the legs look like."

Matt White says the discovery of bird bones is "extremely rare". (Supplied: University of New England)

University of New South Wales Professor Mike Archer, who was not involved in the research, said primitive birds that lived during the Cretaceous period, such as Tenuicruris piscanexum, shared many features synonymous with their reptilian ancestors.

"Some of the birds have become so dinosaurian-like, like our cassowary, that you have to worry more about that than you would have had to worry about a velociraptor."

Despite the diversity of birds living in the country today, Dr White said Australia's Cretaceous bird record remains remarkably sparse.

Before the Richmond discovery, only a handful of bird bones from the period had been found in Australia, with just one other primitive species described in 1986.

Mike Archer says the fragile nature of bird bones means very few survive the fossilisation process. (Supplied)

Professor Archer said the same traits that allowed birds to fly made them less likely to survive fossilisation.

"The problem with bird fossils is that they're incredibly fragile," he said.

"Their bones are paper thin, and it's much harder and much less likely to have them survive the processes of fossilisation."

"Every time a fossil of one of these kinds these flying animals turns up, we all have to cheer because they're very rare."

Professor Archer said the location of the discovery also supported theories that some primitive birds in the group fed on fish and travelled across large stretches of water.

"It's quite likely that the part of the [inland sea] where it came from was not near the land," he said.

"It might well have been fairly far out to sea … reinforcing the idea that some of these birds could have been foraging for fish."