Paleontologists from the Museo Egidio Feruglio in Argentina have discovered and described a new supermassive titanosaur species. At about 122 feet (37 m) long and weighing about 69 tons in life, Patagotitan mayorum is the largest animal ever to walk the planet and one of the most complete titanosaurs.
Life reconstruction of Patagotitan mayorum. Image credit: Jorge Gonzalez.
Patagotitan mayorum roamed the Earth about 101.6 million years ago during the Albian, the uppermost subdivision of the Early Cretaceous epoch.
The fossil remains of at least six individuals were discovered in 2012-13 at a single site in the Province of Chubut, Patagonia, Argentina.
“When first news of the finding came out in 2013, the dig was still active,” said Dr. José Luis Carballido, of the Museo Egidio Feruglio (MEF).
“We had seen many bones on the field that showed certain features that indicated this was a new species and, apparently, the largest one found until then. From that moment, numerous field trips were carried out to unearth the fossils, which were later prepared in MEF labs.”
“It was only then that we could start studying the material to determine exact features that would allow us to identify this new species.”
“We found three different levels with bones in the same excavation, all of them belonging to one same species,” Dr. Carballido said.
“The environment in which those bones were deposited and buried was a floodplain, where successive river overflows had covered the dead animals’ remains. These overflows energy wasn’t strong enough as to move the bones. In other words, these dinosaurs were there, died there and had gone to that place in at least three different occasions.”
The discovery site is located in the center of the Province of Chubut, about 162 miles (260 km) from the city of Trelew and near the town of El Sombrero. Image credit: Museo Egidio Feruglio.
Patagotitan mayorum averaged 122 feet long and was nearly 20 feet (6 m) high at the shoulder.
The dinosaur weighed 69 tons, which is 10 tons (over 15%) more than the mass estimate obtained for the previous record holder, the giant titanosaur Dreadnoughtus schrani.
“Estimating the body weight of an extinct animal is a challenging task,” noted MEF researcher Dr. Diego Pol.
“We only have left the bones and from these remains we have to infer the body weight through the use of indirect methods.”
“We compared the remains of Patagotitan mayorum with all the species that could be related to it, not only in terms of size, but also those that lived at the same time or had certain features in common,” Dr. Carballido said.
“Among them we included species such as Argentinosaurus, Puertasaurus and Futalognkosaurus, which are other giant species of dinosaurs from Argentina.”
“We performed a detailed comparison against all these species and found some striking differences, despite the fact that some of them were very incomplete, like for example Puertasaurus.”
Skeletal reconstruction of Patagotitan mayorum. Image credit: Museo Egidio Feruglio.
The team’s analysis also revealed the presence of a previously unrecognized diverse lineage of Patagonian titanosaurs.
This lineage is a sister to Rinconsauria, a lineage that includes some of the smallest titanosaurs known so far.
It includes most of the giant species of titanosaurs and represents the major increase in body mass in the history of Titanosauria.
“The phylogenetic study we performed indicates that most of the giant titanosaurs known in Patagonia belong to a single lineage,” Dr. Pol said.
“This means that the evolution of extreme gigantism within titanosaurs happened but only once, and not in multiple separate events. We can see some other cases of size increase relative to the ancestral size of titanosaurs, but none of them was as dramatic as the one seen in this group and exemplified by Patagotitan mayorum.”
“This means that apparently almost all the truly giant dinosaurs were related to each other and form the group known as Lognkosauria.”
“This group of giants probably emerged by the end of the Lower Cretaceous (Patagotitan mayorum would be the oldest) and had survived until the middle Upper Cretaceous (between 100 and 85 million years ago).”
The research is published in the journal Proceedings of the Royal Society B.
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J.L. Carballido et al. 2017. A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs. Proc. R. Soc. B 284 (1860): 20171219; doi: 10.1098/rspb.2017.1219
