A genus and species of rebbachisaurid-mimicking titanosaurian sauropod that stretched over 15 m (50 feet) has been unearthed in Patagonia, Argentina.
The newly-discovered dinosaur roamed our planet during the Late Cretaceous epoch, approximately 86 million years ago.
Dubbed Inawentu oslatus, the animal was a type of titanosaur, a diverse group of long-necked sauropods that lived from the Late Jurassic (163.5-145 million years ago) to the end of the Cretaceous period (145-66 million years ago).
They are known for large body sizes, long necks and wide stance, and include species ranging from the largest known terrestrial vertebrates to ‘dwarfs’ no bigger than elephants. Some species possessed osteoderms (armored plates).
“During the Late Mesozoic, sauropod dinosaurs constituted the predominant herbivorous animals in all the non-polar Gondwanan terrestrial ecosystems,” said Museo Municipal Argentino Urquiza paleontologist Leonardo Filippi and his colleagues.
“With a general bauplan consisting of a quadrupedal and graviportal stance, a proportionally small cranial-to-body ratio, and elongated cervical and caudal series, the sauropods evolved a notable variety of adaptations related to gigantism, locomotion, defense, physiology, and feeding behaviors.”
“They represented the main mid to large-sized herbivorous component of the fauna in most of these southern landmasses, both in diversity and abundance.”
A partially complete specimen of Inawentu oslatus was recovered from fluvial system deposits of the La Invernada site, which is part of the Bajo de la Carpa Formation in the Neuquén Basin, Patagonia, Argentina.
“The recovered skeletal remains were found articulated in a horizon of massive, reddish-colored, edaphized mudstones which are covered by a thin sandy layer (30 cm thick) linked to river overbank flooding deposits,” the researchers explained.
Inawentu oslatus shows remarkable convergent traits of its skull anatomy with rebbachisaurid sauropods, according to the authors.
“Inawentu oslatus belongs to a clade of square-jawed titanosaurian species that were restricted to the last stages of the Late Cretaceous in South America,” they said.
“The discovery of new materials and different data sets that provide new morphological information will allow us to provide better support in future phylogenies that confirm the presence of this clade of square-jawed titanosaurs.”
“Inawentu oslatus and probably other members of this clade, possess apparent trophic adaptations seen in the preceding rebbachisaurid sauropods, such as a broad snout and a relatively short neck.”
“In this context, the shortened cervical series of Inawentu oslatus could be in concordance with low-browsing feeding behavior.”
“This would have paleoecological implications, such as a faunistic turnover in post-Turonian times in the Gondwanan continental ecosystems and low-browsing dietary habits in two different lineages of sauropod dinosaurs.”
The team’s findings were published in the journal Cretaceous Research.
Leonardo S. Filippi et al. 2024. A rebbachisaurid-mimicking titanosaur and evidence of a Late Cretaceous faunal disturbance event in South-West Gondwana. Cretaceous Research 154: 105754; doi: 10.1016/j.cretres.2023.105754