When recent fossil evidence of an extinct Australian bird called Genyornis newtoni was published, one of the most eye-catching features was the art that went along with it.
The image (above) shows an old flightless creature dubbed "giga-goose" headed for a drink in a muddy lake by the light of a late afternoon ancient sun.
But this was not how the Flinders University team who discovered the fossils had originally expected the bird to look.
They had envisioned a "bright-eyed, goosey bird", but the group's palaeoartist, Jacob Blokland, ended up creating something which, by his own admission, looks "pretty wrinkly and crusty".
While some features in the image are artistic licence, much of the bird's appearance relies directly on the bones that were discovered, or educated guesses based on how related birds look.
So, should Genyornis newtoni look like a giant goose or a wrinkled old chook?
And what techniques are used to create one look or the other?
I visited Mr Blokland at his studio to see how giga-goose evolved from fossils to art.
What is palaeoart?
Palaeontological art or "palaeoart" has long been a favourite of kids who love dinosaurs — as it brings long-gone ancient creatures back to life.
Mr Blokland, who is a PhD student at Flinders researching a much smaller bird called a rail, has drawn dinosaurs and other ancient creatures since he was a child.
When he went into research, continuing to draw creatures like the giga-goose felt like a good way to marry science and art.
"It's an extension of palaeontology," he says.
"It's a way of understanding things, approaching the truth."
When done well, he says palaeoart can provide the "best guess" of what an animal might have actually looked like.
"There's a saying in art: draw what you see, not what you think you see. I suppose that applies in palaeoart too. You have to draw what the fossils are telling you."
It's a lot of work to reconstruct how an extinct animal looked when it lived and breathed but Mr Blokland is up for the challenge.
"I enjoy the process of mapping all this stuff on — all the muscles, ligaments, the fats. Thinking about how the skin might have sagged in an area, for instance."
Starting with skull fragments
Between 2013 and 2019, while searching for megafauna skeletons at Lake Callabonna in northern South Australia, researchers found a cache of six partial skull fragments from different specimens, along with other skeletal remains.
But even the most complete skulls were crushed and damaged, so Mr Blokland and his colleagues had to piece together the fragments and carefully analyse them to produce a picture of what a complete and undamaged skull might have looked like.
His first step was to create a basic sketch showing how the fragments fitted together — each colour noting a different specimen.
"I had them all out in front of me. Trying to make sense of all of them," he says.
"I think I understood the skull more by drawing it."
Once that was done, he started filling out the smaller details from the lumps and bumps of the skull fossils.
This work, along with the finished artwork, was done digitally on a tablet and took upwards of 80 hours to complete.
Putting flesh on bones
While his drawing of the basic skull shape was based mainly on the fossil fragments, more detective work was required for the next step: putting flesh on the bones.
Mr Blokland needed to add muscles and fat to the creature. To do this, the team looked to where the skull fragments were connected to muscles and created a 3D model of the "brain case" — the back section of the bird's skull, which holds the brain.
Mr Blokland also referred to a living relative of the bird called the "screamer" to work out how the muscles fitted on top of the bones. These South American birds are much smaller than the giga-goose but have similar head and ear structures.
After the muscles came the skin and feathers.
For this, Mr Blokland turned to larger Australian birds like cassowaries and emus to understand what Genyornis might have looked like.
Both emus and cassowaries have shaggy light feathers on their bodies, and the cassowary has a featherless, wrinkly neck.
One of the reasons Genyornis would have had such features was to help keep it cool.
"Birds have a very fast metabolism," he says.
"If you're covered in feathers and you're 230 kilograms, you're going to overheat pretty jolly fast, especially in a hot Australian summer."
The beak and other facial elements also couldn't be determined by the fossil fragments, so Mr Blokland again looked to living relatives to understand what Genyornis's face might have looked like.
For the chapped beak, Mr Blokland added a pink colour to the top to signify blood vessels close to the surface. This occurs in both the magpie goose and the screamers.
One important feature the giga-goose shares with the cassowary is a bony "casque" on its head. In the final art, this is shown as a yellow bump above its beak.
"We know this casque [is] unusual. It doesn't seem to have any anatomical benefit in terms of function," Mr Blokland says.
"So, maybe it was used in sound generation or sexual display … maybe both."
Extending the body
While the published artwork only shows the head and shoulders, Mr Blokland also sketched the full body of the bird based on other skeletal fossils of the giga-goose found at Lake Callabonna.
The body image has a number of interesting features.
The first is that there are no wings visible under the feathers. According to Mr Blokland, the tiny wing bones found indicate the bird's wings would have been just too small to poke out.
"Its wing was literally as long as a chicken's," he says.
"Guaranteed, you would not see those wings outside of the feathers."
While the wings might be small, the leg bones were huge.
Researchers also found other bones of Genyornis newtoni while finding the skull, and one of the biggest was the shin bone, which reached up to half a metre in length.
"That part of the leg becomes the drumstick," Mr Blokland says.
Setting the scene
The final piece of the palaeoart puzzle is placing the creature in an appropriate scene.
While not every palaeontology image includes a background, it is an opportunity to communicate more about where this animal existed.
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For example, according to Mr Blokland, the giga-goose would have lived in difficult times.
"Around 50,000 years ago, the big lakes in that region were starting to dry out," he says.
"You've got this mud under the surface that animals can walk into, but not get back out of."
"If you don't have anything to help you get out of it, I think it's all over."
One of the specimens of Genyornis newtoni the team found actually broke their leg in a fall before it died.
The scene Mr Blokland drew is set during sunrise or sunset, giving a darker tone to the piece. Adding to that are eucalyptus trees bending in towards the bird, while the water is an uncomfortable muddy shade.
The whole thing feels a bit ominous.
"I can't seem to break out of [that] particular style," Mr Blokland laughs.
And after spending months on the project, Mr Blokland is confident that his "old bull" of a bird is the current best guess for what Genyornis newtoni may have looked like.
While it might not be the bright-eyed goose the team originally imagined, the artwork ends up telling its own interesting story about the ancient bird.
"Like bulls, even though they eat plants, I wouldn't want to get on the wrong side of one," he says.
Want to know more about these ancient creatures? Catch the two-part program Megafauna: What Killed Australia's Giants? on ABC iview.
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