A new species of giant dinosaur is the largest ever found in Australia, with some individuals close enough behind similar counterparts found elsewhere that it might turn out to be the largest land-dwelling species of all time.
Once regarded as a dinosaur backwater, the last two decades have shown Australia had plenty of big sauropods. Now the announcement of Australotitan cooperensis, which lived 92-96 million years ago, proves earthshaking beasts were a global phenomenon.
A. cooperensis is thought to have been 25-30 meters long (80-100 feet) and 5-6.5 meters high at the hip (17-20 feet), making it at least a third longer than its largest known compatriot species. One of its discoverers, Dr Scott Hocknull of the Queensland Museum, described the find as “As long as a basketball court and as tall as a b-double,” in a statement. Its weight is less certain, estimated at anywhere between 23 and 74 tonnes. The current world record-holder Patagotitan mayorum reached 37 meters (121 feet). Nevertheless, A. cooperensis ranks among the top 10-15 largest dinosaur species ever found. With the specimens so far discovered showing substantial variation, Hocknull told IFLScience it's possible giants that could exceed the South Americans might still be found.
The newly discovered sauropod has been described in PeerJ, with the species name coming from Cooper Creek, the storied ephemeral waterway. All Australotitan specimens so far have been found near one of the creek's tributaries, hundreds of kilometers south of previous sauropod discoveries. “We compared the three species found to the north, near Winton, to our new Eromanga giant and it looks like Australia’s largest dinosaurs were all part of one big happy family,” Hocknull said in a statement. “We found that Australotitan was the largest in the family, followed by Wintonotitan with big hips and long legs.”
Within the space of a kilometer Hocknull and colleagues have already found five sauropods. They believe all of them are Australotitans, but some are too fragmentary to confirm this. The type skeleton, nicknamed Cooper, has left us most of its forearm, hindlimbs, and pelvis.
The first Australotitan bones were found in 2004. Part of the 17-year delay to publication was extracting them from the rocks in which they were buried. Hocknull told IFLScience Australia’s geology has left the bones encased in rocks much harder than themselves, requiring years for safe extraction. Hocknull told IFLScience his theories on what he was looking at had to be repeatedly rethought as each bone emerged from its encasing.
This was followed by the challenge of confirming this was indeed a new species. Hocknull and co-authors created three dimensional digital versions of each fossil so they can share them with researchers worldwide who could compare the new discoveries with existing objects in their own collections.
The Queensland Museum team was the first to routinely make the 3D digital reconstructions, and these will greatly speed evaluation of future discoveries, Hocknull said.
Despite this advance, there are plenty of obstacles to revealing Australia’s sauropod store. The continent's flatness, and the lack of turnover from volcanic uplift or glacial weathering, means bones are much less likely to be exposed at the surface. The sparse population in the most promising areas reduces the chance of accidental finds – the first Australotitan bones were found by sheepherders riding quad bikes who happened to notice something unusual.
Moreover, Hocknull added, he is the only person in Australia with a permanent job studying dinosaurs. Everyone else is doing it as a side project, or for a 3-year postdoc position, which he calls, “clearly inadequate” to take a new species from discovery to description. He hopes the establishment of a tourist industry around the fossil sites will fund more ongoing positions.