‘Like an ostrich on steroids’: Prehistoric 600kg bird had tiny brain

The largest flightless bird ever to have walked the earth may have weighed up to 600 kilograms, but recent research has shown its skull had little room for a brain.

Lead author of a recent study and Flinders University researcher, Warren Handley, said the Dromornis stirtoni stood up to 3 metres high and lived on a diet of soft leaves and fruit, much like the modern-day cassowary. 

The new study took fossilised skulls of the big birds and put them in a CT scanner. 

“The Dromornis’ are pretty well known around paleontologists in Australia,” Dr Handley said. 

“What we did was take five very rare fossils of Dromornis’ skulls and we CT-scanned them using both conventional and neutron CT-scanning technology to basically … make models of the brains from inside.”

Once the skulls were scanned, the shape of the space for the animals’ brain was compared in each image and showed a tight squeeze for any brain matter.

Two men hold pieces of animal skull while sitting at a table in a lab.
Warren Handley and Trevor Worthy hold the skull (L) and partial upper bill (R) of the mihirung Dromornis planei.(

Flinders University: T. Bawden


Fossil site ‘critical’

Dr Handley said North West Queensland’s world heritage-listed Riversleigh fossil sites were “critical” to the research. 

“Riversleigh fossil collections provided the oldest known skull that we have of this species,” he said.

 “It’s around 10 million years older than the next one we have in line.

The research project lasted three years and was part of a larger investigation into understanding the palaeobiology of the birds.

A large skeleton on display in a museum.
The most complete Dromornis planei skull known was discovered in the late 1980s filled with solid limestone.(

Supplied: Flinders University


‘Ostrich on steroids’

Dr Handley said the prehistoric bird could be compared to an emu or an ostrich.

“They ranged from the size from about a cassowary-sized bird right through to one of the largest birds ever known … the species was 600kg.

“They had big, large forward-facing eyes and their upper beaks and lower beaks were much longer than their skulls.”

Dr Handley said there were fossil records of the extinct animal’s remains for at least 25 million years. 

Sir David Attenborough sits on a rock at the Riversleigh fossil site.
Sir David Attenborough visited the Riversleigh fossil site in 2001.(

Supplied: Henk Godthelp


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