Palaeontologists Dr Matthew McCurry of the Australian Museum and Dr José Carballido of Argentina’s Museum of Palaeontology Egidio Feruglio (MEF) have discovered a new sauropod species in the Patagonian badlands, believed to be an early relative of the 57-tonne titanosaur Patagotitan mayorum. The excavation, conducted near the remote town of Paso de Indios in Chubut province, has yielded articulated tail bones, parts of the limbs and the first complete sauropod sacrum, the triangular 'holy bone' that shields the reproductive organs, ever found in the region.
The bones date from between 110 and 115 million years ago, a little-known phase of the middle Cretaceous. McCurry and Carballido began excavating in March last year after Carballido identified a promising site in 2020 from a femur jutting out of a hillside. The team also uncovered most of the pelvic girdle.
Carballido based his identification on the shape of facets on the vertebrae. 'There were a lot more bones than we realised,' McCurry said. 'That means it's a lot more scientifically important.'
The palaeontologists believe the new species may mark the first branch on the evolutionary tree that gave rise to titanosaurs. 'We need to get a little bit more data into the phylogeny to have it for certain,' McCurry said after a week of rapid analysis at MEF. 'But it's looking good. There's all these characters within the pelvis which show it's probably got quite a wide stance, which is a pretty characteristic titanosaur thing. It's potentially one of the reasons they were able to feed really efficiently, because they had a large area for their internal organs and stomach.'
The wide stance would have allowed for a larger fermentation tank of the gut, enabling the sauropod to strip nutrition from vast amounts of vegetation. The discovery suggests that titanosaurs possessed these traits from the outset of their evolution. Before the species can be named and described, the palaeontologists need to recover the rest of the fossil, including at least a scapula and a humerus. McCurry noted that funding such expeditions has recently become difficult. Protests in Buenos Aires were against cuts to universities and education by Argentina's right-wing populist President Javier Milei.
Some of the new bones are bound for display in Sydney as part of MEF's travelling exhibition, Dinosaurs of Patagonia, which already features Carballido's blockbuster find, Patagotitan mayorum.
Analysis
Why This Matters
- Understanding evolution of gigantism: The new sauropod is a primitive relative of titanosaurs, offering a window into how Earth's largest land animals evolved traits such as a wide stance and an efficient digestive system.
- First complete sacrum from the region: The specimen provides a rare opportunity to study the pelvic anatomy of early titanosaurs and their biomechanics.
- Potential to fill a knowledge gap: The middle Cretaceous is poorly understood; the new fossils could reveal what made the 'Albian' age so conducive to sauropod gigantism.
Background
Patagonia is one of the world's richest dinosaur fossil fields, with the arid steppe exposing bones from the Cretaceous period. Carballido gained international fame in 2017 for describing Patagotitan mayorum, a titanosaur that weighed about 57 tonnes and is a leading candidate for the largest land animal ever. The new species was discovered near Paso de Indios, close to the site where the giant theropod Tyrannotitan chubutensis was found in 1995. The region's gauchos often report exposed fossils to the Museum of Palaeontology Egidio Feruglio in Trelew, which runs the Dinosaurs of Patagonia exhibition.
What to Watch
- Completion of the phylogenetic analysis: McCurry and Carballido are coding the bones into a character matrix to confirm whether the new species is indeed the first branch of the titanosaur lineage.
- Recovery of the remaining skeleton: At least a scapula and humerus are still buried; another field season is needed to extract them.
- Funding and political climate: Argentina's cuts to education under President Milei may affect future palaeontological expeditions in Patagonia.
Checked
8 claims in this story checked against 1 source: 6 supported.
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- SupportedA new sauropod species uncovered in Patagonia may be an early relative of Patagotitan.Brisbane Times - Latest News: “Carballido realised, from the shape of facets on the vertebrae, that a new species was on their hands – a possible early relative of Patagotitan.”
- SupportedThe excavation yielded articulated tail bones and the first complete sauropod sacrum ever found in the region.Brisbane Times - Latest News: “an articulated length of the dinosaur’s tail. Parts of its front and back limbs. Most of its pelvic girdle, including the sacrum”
- SupportedThe newly found sauropod may offer clues to titanosaur evolution.Brisbane Times - Latest News: “The project holds the potential to shed crucial new light on how evolution pulled off its most extreme experiment.”
- Partly supportedThe bones date to a little-known phase of the middle Cretaceous, between 110 and 115 million years ago.Brisbane Times - Latest News: “The rock layer itself dated to a mysterious phase of the Cretaceous – the final age of the dinosaurs before an asteroid felled their kingdom – which we know precious little about. [...] The dinosaur died between 110 and 115 million years ago”
- SupportedMcCurry said, “There were a lot more bones than we realised,” and, “That means it's a lot more scientifically important.”Brisbane Times - Latest News: ““There were a lot more bones than we realised,” McCurry says. “That means it’s a lot more scientifically important.””
- SupportedThe palaeontologists believe the new species may mark the first branch on the evolutionary tree that led to titanosaurs.Brisbane Times - Latest News: “They suspect this dinosaur marks the first branch on the evolutionary tree that led to titanosaurs.”
- SupportedMcCurry said, “We need to get a little bit more data into the phylogeny to have it for certain,” followed by, “But it’s looking good.”Brisbane Times - Latest News: ““We need to get a little bit more data into the phylogeny to have it for certain,” McCurry says [...] “But it’s looking good.””
- Not in the sourcesMcCurry noted that funding such expeditions has recently become difficult.Brisbane Times - Latest News: “But funding such expeditions, of late, has been difficult.”