It is not uncommon to unearth valuable objects on mine sites, but it is extremely rare to discover the bones of the world's tallest kangaroo.

Palaeontologists have potentially uncovered a new giant species of kangaroo in north Queensland.

A mine west of Mackay, in north Queensland, initially came to the attention of palaeontologists back in 2008 when traditional owners discovered an unusual bone.

Dr Scott Hocknull says the kangaroo stood at more than two and a half metres tall in resting position. ( ABC Tropical North: Sophie Kesteven )

Since then, using hammers, chisels and brushes, palaeontologists have since come across wide range of fossils dating back to more than 30,000 years ago.

Palaeontologist with the Queensland Museum Dr Scott Hocknull said one of the fossils might have belonged to a new species of kangaroo.

"Based on the size of its shin bones it was probably two and a half metres tall just in a resting position," Dr Hocknull said.

"But we need to continue to excavate the site, and it will come out in the wash over the years whether this new species is legitimate or not.

"But certainly it is the tallest kangaroo found anywhere on the planet."

Nine Moranbah State High School students had the privilege of joining palaeontologists on site. ( ABC Tropical North: Sophie Kesteven )

A number of school students had the privilege of helping palaeontologists unearth the site in August.

Among them was 17-year-old Misty Boegheim from Moranbah State High School.

"It was great to look at the bones we saw this morning and all the replicas they made up," she said.

"It's pretty interesting how you can see the claw marks and have a peek into the past.

"Everyone has got their head in the dirt and they're looking around.

"It's a bit of a competition against each other to see who can find the first bone."

Misty Boegheim, 17, was one of nine Moranbah State High School students helping unearth fossils on site. ( ABC Tropical North: Sophie Kesteven )

Dr Hocknull said it was a great opportunity for students to discover what used to exist in their own backyards.

"Palaeontology is like a gateway to science — especially for kids — because they always love dinosaurs and now they get to learn about megafauna which are well after the time of dinosaurs," he said.

Dr Hocknull said dinosaurs differed to megafauna before they existed 65 million years ago, whereas megafauna roamed tropical north Queensland between 30,000–50,000 years ago.

"But these are enormous animals and finding their bones and seeing a real fossil in the ground is mind-blowing for most kids, and it certainly was for me when I saw my first fossil and it locked me into science for the rest of my life," he said.

Crocodiles played crucial role in fossil preservation

Dr Hocknull said the reason for the fossils being so well preserved was because huge crocodiles preyed on the megafauna that existed at the time.

"Crocodiles were living in the rivers and these giant megafauna — giant kangaroos and wombats — were coming down the water's edge to drink, and then bam they're being taken by these huge crocodiles," he said.

He explained the parts the crocodiles did not swallow would end up in the fossil deposit.

"Fast forward 30,000 years and here we have them in the fossilised clay and soil from inside those rivers," he said.

"It's also the first time anywhere in Australia where we've got this tropical megafauna where we can systematically excavate and tell what was happening so long ago."

Giant megafauna bone being unearthed on the South Walker Creek mine site near Nebo. ( ABC Tropical North: Sophie Kesteven )

Arduous task of unearthing fossils

According to Dr Hocknull, uncovering fossils could be a very slow and pain-staking process.

"We slowly chip away at the clay looking for everything because not only do we find the big bones of the animals, we find fossil plants, insects … [and] the molluscs that were living in the environment," he explained.

Once the fossils have been uncovered they get wrapped in plaster cases and get sent down to Brisbane where they get cleaned with tiny dentist drills.

"They slowly take the mud away from the bone … then we digitalise the whole lot and put it into a three-dimensional model and that helps us research it," he said.

"So over the years we have built up a picture of what existed here 30,000 years ago … and then we try to answer the ultimate question of why aren't they here today? What drove them extinct?

"30,000 years ago we had three different species of crocodiles living together in what was clearly a well-watered river system and habitat.

"Now it is entirely dry with a little bit of a flood here and there.

"Clearly there have been some big climatic changes that have occurred over the past 30,000 years to drive all these environments extinct, and that holds some really interesting questions about how we will further adapt to climate change."

Palaeontologists have visited the site each year since 2011, and Mr Hocknull said they would continue to work with BHP over the next three to four years to continue uncovering more ground.