A multinational group of paleontologists has described a new titanosaurian dinosaur, named Dreadnoughtus schrani, from Upper Cretaceous sediments in southern Patagonia, Argentina. It is the most complete giant titanosaur yet discovered, and provides new insight into the morphology and evolutionary history of these supermassive dinosaurs.
Rendering of Dreadnoughtus schrani in life. Image credit: Jennifer Hall.
“Titanosaurs are a remarkable group of dinosaurs, with species ranging from the weight of a cow to the weight of a sperm whale. But the biggest titanosaurs have remained a mystery, because, in almost all cases, their fossils are very incomplete,” said Dr Matthew Lamanna, a team member and a co-author of a paper describing Dreadnoughtus schrani in the journal Scientific Reports.
Dreadnoughtus schrani lived in temperate forests in what is now the south of South America during the Upper Cretaceous period, around 77 million years ago.
At about 26 meters long and a mass of 59.3 tons, it is the largest land animal for which a body mass can be accurately calculated.
“Dreadnoughtus schrani was astoundingly huge. It weighed as much as a dozen African elephants or more than seven Tyrannosaurus rexes,” said first author Dr Kenneth Lacovara of Drexel University.
“With a body the size of a house and a weaponized tail, it would have feared nothing,” the scientist said. As a result, he chose the name Dreadnoughtus, meaning ‘fears nothing.’
Dreadnoughtus schrani was substantially more massive than any other supermassive dinosaur for which mass can be accurately calculated. The lower image shows the reconstructed skeleton and body silhouette of Dreadnoughtus schrani; fossil bones that were found are shown in white; scale bar – 1 meter. Image credit: Lacovara Lab / Drexel University.
To grow as large as Dreadnoughtus schrani, a dinosaur would have to eat massive quantities of plants.
An adult Dreadnoughtus schrani was likely too large to fear any predators, but it would have still been a target for scavengers after dying of natural causes or environmental disasters.
During four field seasons from 2005 to 2009, Dr Lacovara, Dr Lamanna and their colleagues from the United States, the United Kingdom and Argentina have excavated a total of 145 bones and a single tooth representing two individuals of Dreadnoughtus schrani – 115 bones and the tooth from the larger specimen and 30 bones from a second, smaller individual.
The larger specimen is exceptionally complete, with over 70 percent of the bones, excluding the head, represented. This is far more complete than all previously discovered giant titanosaurian dinosaurs.
To better visualize the skeletal structure of the new dinosaur, the paleontologists digitally scanned all of the bones from both specimens and made a ‘virtual mount’ of the Dreadnoughtus schrani’s skeleton.
The 3D laser scans show the deep, exquisitely preserved muscle attachment scars that can provide a wealth of information about the function and force of muscles that the dinosaur had and where they attached to the skeleton – information that is lacking in many sauropods.
Efforts to understand Dreadnoughtus schrani’s body structure, growth rate, and biomechanics are ongoing areas of research within Dr Lacovara’s lab.
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Kenneth J. Lacovara et al. 2014. A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina. Scientific Reports 4, article number: 6196; doi: 10.1038/srep06196
