The dodo and thylacine are special creatures to former Tamworth author and illustrator Sami Bayly.
They are among 49 extinct animals and 11 critically endangered ones to feature in her new book, The Illustrated Encyclopaedia of Extinct Animals.
Ms Bayly, who is currently based in Newcastle, dedicated the book to "all the species to have vanished from the earth".
"Ninety-nine per cent of species that ever roamed the earth are now extinct," she said.
Most prehistoric animals no longer exist due to five mass extinctions over 540 million years, including a cooling climate, volcanic eruptions and an asteroid strike.
Animals featured in Ms Bayly's book include the western black rhino, thylacine, dodo, South Island giant moa and Tapanuli orangutan.
Megafauna such as the giant wombat-like diprotodon and the crocodile-like Quinkana are also included.
Ms Bayly said the dodo and thylacine were her favourites.
"I was very hesitant to paint them until I was ready. These are such important animals to me, I needed to make them look perfect," she said.
She said the last dodo, a flightless bird, was "thought to have been seen in 1688".
Humans didn't discover the dodo's existence until the year 1598.
"After 90 years of being around humans, they went extinct," she said.
"The thought was they didn't have big predators in their natural habitat. So when humans arrived they weren't naturally scared.
"They'd sit there and be heavy, slow-moving animals. Humans were able to take advantage of them easily."
Ms Bayly said the dodo had offspring slowly, producing "just one egg a year".
"It was not able to keep up with the predators that were eating them," she said.
The thylacine, also known as the Tasmanian tiger, has been officially extinct since 1986.
"I've loved thylacines since I was a kid. I had a thylacine T-shirt," Ms Bayly said.
"I've always had this funny fascination with them. I thought they were awesome."
While some believe the creature still exists, Ms Bayly said "they are most likely not around any more".
"I hope they're out there, being left alone and their population regrows.
"But I think realistically we as humans have to accept that our decisions led to their extinction.
"It's important we learn from our mistakes in the past, so we don't continue to repeat them."
The extinction of the western black rhino "shows we're not acting quick enough" to save species.
Sadly, she said the rhino didn't have power and politics behind it.
"They were a nuisance to crops, so farmers hunted them for years. They couldn't withstand it," she said.
"Their horns were sold for profit, so it was an example of something that was beautiful to some and a nuisance to others.
"They both worked together to send the species extinct."
The rate at which species are now becoming extinct is thought to be 1000 to 10,000 times higher than the natural extinction rate.
The causes include hunting, overfishing, habitat destruction, pollution, climate change and invasive species.
It's humans who are driving the "sixth mass extinction".
Since the year 1500, more than 900 species have been classified as extinct.
And more than 45,000 species are now threatened with extinction, the International Union for Conservation of Nature's "Red List" states.
The book will be published on September 25.
