Etched into the rugged sandstone coastline of Western Australia, thousands of wonderfully preserved tracks provide evidence for the existence of one of the world’s most diverse dinosaur faunas. But just like the magnificent creatures that left them, these tracks could have been lost to the ages if not for the efforts of the region’s Traditional Custodians; members of the Broome community; environmental, political and business groups; and a dedicated team of palaeontologists.
Welcome to Jurassic Park
Looking at this ancient Western Australian landscape, it’s easy to imagine the giant beasts that roamed here millions of years ago.
The Indigenous people of the Dampier Peninsula and West Kimberley have been telling their stories for thousands of years, with the tracks left around Walmadany (James Price Point) forming an important part of the region’s cultural heritage.
Today, the area is home to one of the most significant palaeontological sites in the world, with 21 different types of dinosaur tracks identified along a 25-kilometre stretch of coastline.
Palaeontologists from UQ’s School of Biological Sciences and James Cook University’s School of Earth and Environmental Sciences braved sharks, crocodiles, massive tides and the threat of development to unveil the most diverse assemblage of dinosaur tracks in the world in rocks that are between
127 million and 140 million years old in the remote Kimberley region.
Dr Steve Salisbury, from UQ’s School of Biological Sciences, said the diversity of the tracks was globally unparalleled and made the area the “Cretaceous equivalent of the Serengeti”.
“It is extremely significant, forming the primary record of non-avian dinosaurs in the western half of the continent and providing the only glimpse of Australia’s dinosaur fauna during the first half of the Early Cretaceous Period,” he said.
“It’s such a magical place – Australia’s own Jurassic Park in a spectacular wilderness setting.”
Dr Salisbury said there were thousands of tracks around Walmadany. Of these, 150 could confidently be assigned to 21 specific track types, representing four main groups of dinosaurs.
“There are five different types of predatory dinosaur tracks, at least six types of tracks from long-necked herbivorous sauropods, four types of tracks from two-legged herbivorous ornithopods, and six types of tracks from armoured dinosaurs,” he said.
“Among the tracks is the only confirmed evidence of stegosaurs in Australia, and some of the sauropod tracks are about 1.7 metres long.
A stegosaur track found along the coastline near Walmadany, Western Australia. Image: Damian Kelly
“These were probably some of the largest animals to walk the planet, and they did so in the Kimberley.”
Dr Salisbury said most of the tracks had been preserved in the same geological horizon and many of the sites at Walmadany appear to have once been connected.
“The track surface extends over several square kilometres, and most of the tracks were probably made around the same time,” he said.
The three-toed tracks of Marala, the 'Emu Man'. Image: Damian Kelly
“Walmadany in the Cretaceous Period would have looked similar to the Limpopo River of sub-Saharan Africa – a vast river plain, criss-crossed with abandoned channels and sand bars, opening into a delta system farther south.
“Wandering across it would have been herds of lumbering sauropods, stegosaurs and giant ornithopods, making their way to fern-dominated swamp forests on either side. A lone predatory theropod might have stalked the herds from afar, like a lion.
“That scene has been written in stone on the reefs around Walmadany. Once you can read the rocks, it’s not hard to imagine.”
The three-toed tracks of Marala, the 'Emu Man'. Image: Damian Kelly
Most of Australia’s dinosaur fossils come from the eastern side of the continent, and are between 90 million and 115 million years old. Dr Salisbury said the tracks at Walmadany were considerably older.
“The results of our study show that the general composition of Australia’s better-known, younger dinosaur fauna was already in place by 127 million to 140 million years ago,” he said.
“Both sauropods and ornithopods were diverse and abundant, and stegosaurs and ankylosaurs were the only type of four-legged, bird-hipped dinosaurs.
“The dinosaur fauna from the Broome Sandstone is a lot like what we see in similarly aged faunas from South Africa and South America, and is probably similar to the more globally distributed dinosaur faunas of the Late Jurassic Period.
“The disappearance of stegosaurs and the apparent drop in diversity of theropods by 115 million years ago suggests that, similar to South America, Australia passed through a period of faunal turnover during the Early Cretaceous Period.”
Despite the existence of these tracks, less than a decade ago it was assumed the area preserved little in the way of natural or cultural heritage.
In 2008, the then Western Australian Government selected Walmadany as the preferred site for a $40 billion liquid natural gas processing precinct.
In response to the government’s proposal, the area’s Traditional Custodians, the Goolarabooloo people, contacted Dr Salisbury and his team, who dedicated more than 400 hours to investigating and documenting the dinosaur tracks.
It was challenging work. The rocks in which the tracks are preserved are in an intertidal zone, with daily tides of up to 10 metres, strong currents, and the constant threat of sharks and crocodiles.
Up to 48 discrete track sites were identified during the course of the team’s six-year study, preserving thousands of dinosaur tracks. A combination of high-resolution aerial photography, on-ground survey work (on foot and in kayaks), and laboratory analysis of the rock samples was used to map the area.
Important tracks were cast using silicon, from which rigid polyurethane replicas have been made.
Dr Salisbury said a lot of the survey work was carried out during the height of the campaign to save Walmadany from the proposed gas precinct, and the surrounding political issues made the project “particularly intense”.
He was relieved when National Heritage listing was granted to the area in 2011 and the gas project collapsed in 2013.
Goolarabooloo Law Boss Phillip Roe said it was important that the world saw what was at stake if this area was developed.
“The unbroken song cycle and dinosaur tracks are what make country so strong. We need to keep them alive to keep our culture alive. The two go hand in hand,” he said.
The tracks form part of a song cycle that extends along the coast and inland for 450 kilometres. They trace the journey of a Dreamtime creator known as Marala, the ‘Emu Man’.
“Marala was the lawgiver. He gave country the rules we need to follow, how to behave, how to keep things in balance,” Mr Roe said.
Six of the new tracks identified needed to be formally named. The researchers worked with Goolarabooloo Law Bosses and The University of New South Wales ethnographer Professor Stephen Muecke to come up with names that incorporated words from the traditional Nyulnyulan language groups.
Goolarabooloo Law Boss Richard Hunter and a sauropod track. Image: Damian Kelly
Walmadanyichnus hunteri, a new type of track made by a large, Muttaburrasaurus-like ornithopod dinosaur means ‘Hunter’s mark of Walmadany’. Oobardjidama foulkesi, a type of sauropod track, means ‘Foulkes’s little thunder’. And Garbina roeorum, a type of stegosaur track, means ‘The Roe family’s shield’.
“We wanted the names to be a reflection of the place, its people and their culture,” Dr Salisbury said.
Mr Roe said it was great to work with UQ researchers on such a significant project for the region.
“We learnt a lot from them and they learnt a lot from us.”