Paleontologists working in northern Patagonia, Argentina, have unearthed the fossils of a previously unknown species of small rinconsaurian titanosaur.
Chadititan calvoi. Image credit: Gabriel Lio.
The newly-discovered dinosaur roamed Earth during the Late Cretaceous epoch, some 78 million years ago.
Named Chadititan calvoi, the ancient species belongs to a group of Argentinian titanosaurs called Rinconsauria.
“Rinconsauria was first established in 2007 with the aim to encompass the genera Rinconsaurus and Muyelensaurus,” said Dr. Federico Agnolin, a paleontologist at the Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’ and the Fundación de Historia Natural ‘Félix de Azara,’ and his colleagues.
“This clade includes slender, lightly built and small-sized titanosaurs — all being less than 11 m long — with straight limbs and a strongly modified pelvic girdle.”
According to the researchers, Chadititan calvoi was a very small and gracile-built rinconsaur titanosaur.
“When compared with the femoral length of Bonatitan, the estimated body length of Chadititan may be estimated at about 7 m long,” they said.
“The new titanosaur indicates that rinconsaurians were characterized by a body shape that was different from other titanosaurs, with brachiosaur-like posture, gracile limbs, and protonic tail.”
The fossilized bones from several individuals of Chadititan calvoi were found at a new fossiliferous locality of the Anacleto Formation near General Roca city, Río Negro province, Argentina.
“This new locality is located within the Marín family Farm, which is located close to Paso Córdoba locality, at 10 km at the southwest of General Roca city,” the scientists said.
“The locality consists of few scattered badlands and low hills that delimit the eastern margin of the ‘Salitral Moreno’ lowlands.”
“In spite of the relatively small size of the outcrops, they yielded a large number of fossil specimens.”
“It is worthy to mention that no single osteoderm from Chadititan calvoi was found in the area,” they added.
“Since no osteoderms were found in association with other rinconsaurians, it is possible to speculate that they were absent in these titanosaurs.”
In addition to Chadititan calvoi, the authors unearthed a new assemblage of invertebrate and vertebrate fossils.
The assemblage includes garfishes, lungfishes, turtles, crocodile relatives, dinosaurs, snails and clams deposited in what was a small pond surrounded by sand dunes and palm trees in what was an otherwise arid environment.
The team uncovered the first fossil record of Neocyclotidae (a family of tropical land snails) and the first undisputed record for the subulinid genus Leptinaria, a kind of small, tropical air-breathing land snail.
“In addition to Chadititan calvoi, the fossils we identified of mollusks, fish, and turtles, enriches our understanding of this ancient ecosystem and expands our knowledge of life in Patagonia near the end of the dinosaur era,” said Dr. Diego Pol, National Geographic explorer and researcher at the Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia.’
“Just by looking at the presence or absence of species in an area can suggest what makes the environment unique.”
“In this case, the abundance of turtles and scarcity of crocodiles compared to regions in Europe and North America during the same period further highlights how Patagonian ecosystems were distinct as the continents drifted apart during the Cretaceous.”
“One of the most remarkable aspects of the discovered fauna is the overwhelming abundance of freshwater turtles, which make up more than 90% of the recovered fossils.”
“This high percentage is highly unusual, as in coeval sites from North America and Europe, turtles rarely account for more than 50% of the fauna,” Dr. Agnolin added.
The team’s paper was published in the journal Revista del Museo Argentino Ciencias Naturales.
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Federico L. Agnolín et al. 2024. New fossiliferous locality from the Anacleto Formation (Late Cretaceous, Campanian) from northern Patagonia, with the description of a new titanosaur. Rev. Mus. Argentino Cienc. Nat 26 (2): 217-259; doi: 10.22179/revmacn.26.885
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