A remarkable new genus and species of small-sized titanosaurian sauropod has been unearthed in Patagonia, Argentina.
Titanomachya gimenezi roamed our planet during the latest Cretaceous period, around 66 million years ago.
The ancient species was a member of a group of derived titanosaurian sauropods called Lithostrotia and shared some features with the family Saltasauridae.
“Titanosaurian sauropods were diverse in the latest Cretaceous ecosystems of Patagonia,” said Dr. Agustín Pérez-Moreno, a postdoctoral researcher at CONICET, and his colleagues.
“The current fossil record is heavily biased towards the better sampled Neuquén Group in northern Patagonia, where two major titanosaur lineages are recorded, Colossosauria and Saltasauroidea.”
“The fossil record in southern Patagonia (Austral Basin) includes colossosaurian titanosaurs, such as Puertasaurus reuili and possibly Nullotitan glaciaris, as well as the large saltasauroid Dreadnoughtus schrani.”
Titanomachya gimenezi was a small-sized titanosaur, around 6-10 tons in body mass.
“Estimates of less than 10 tons are rare among titanosaurs,” the paleontologists said.
“Within the family Saltasauroidea there are a few examples.”
“The lightest titanosaurs are Magyarosaurus dacus and Lirainosaurus astibiae with a mass of less than a ton and two tons, respectively.”
“Among Saltasauridae, the heaviest is Ophistocoelicaudia with a mass of 25 tons, while within the Saltasaurinae the body mass varies between five and six tons.”
The fossilized remains of Titanomachya gimenezi were recovered from the outcrops of the La Colonia Formation in Chubut Province, Patagonia, Argentina.
“The holotype of Titanomachya gimenezi comes from the middle section of the La Colonia Formation, in levels like those of other dinosaurs (abelisaurids, hadrosaurs, ankylosaurs), turtles, and mammals reported from this formation,” the researchers said.
Despite being represented only by fossilized limb elements, the new species exhibits a unique combination of characteristics for a Late Cretaceous titanosaur.
“The small adult size of Titanomachya gimenezi places it in a similar range as Saltasaurus and Neuquensaurus but heavier,” the researchers said.
“Its astragalus displays an intermediate morphology between Colossosauria and Saltasauroidea, allowing for an articulation between zeugopodium and autopodium similar to Colossosauria but with contributions from both the tibia and fibula.”
“Further research is needed to fully understand the diversity and evolutionary significance of titanosaurian sauropods in Patagonia during the Late Cretaceous epoch and to confirm the relationship between body mass and the unique astragalus morphology observed in Titanomachya gimenezi.”
“Overall, Titanomachya gimenezi stands out as an intriguing specimen with its distinctive characteristics and occupies a significant place in the evolutionary landscape of sauropod dinosaurs in Patagonia during the Late Cretaceous epoch.”
The discovery of Titanomachya gimenezi is described in a paper in the journal Historical Biology.
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Agustín Pérez-Moreno et al. A new titanosaur from the La Colonia Formation (Campanian-Maastrichtian), Chubut Province, Argentina. Historical Biology, published online April 10, 2024; doi: 10.1080/08912963.2024.2332997