A recently identified member of the Megaraptran dinosaur family has been unveiled by a collaborative effort of Argentine and US paleontologists.
This newly discovered dinosaur species inhabited Patagonia, Argentina, during the later stages of the Cretaceous period, approximately 70 to 67 million years ago.
Dubbed Joaquinraptor Casali, these ancient predators were the apex carnivores in the region.
It is a member of the Megaraputra, a lineage of large, clawed carnivorous theropod dinosaurs recognized from Cretaceous deposits across Asia, Australia, and especially South America.
“Megaraptrands were carnivorous theropods characterized by elongated skulls, large claws, and robust forelimbs found in Asia, Australia, and South America,” stated Dr. Lucio Ibilik, a paleontologist at Patagonico de Geología y Paleontología.
“Nevertheless, our comprehension of this group is limited due to the scarcity of complete fossils.”
A well-preserved, partially articulated skeleton of a single Joaquinraptor Casali specimen was uncovered in the Lago Corfue Huapi Formation, situated in the South Central Chubut province of central Patagonia, Argentina.
The specimen comprised numerous dinosaur skulls, anterior limbs, hind legs, ribs, and vertebrae.
Based on the microstructure of the bones, paleontologists propose that the specimen is an adult, albeit possibly not fully matured.
Drawing from other megaraptran remains, they estimate that Joaquinraptor Casali measured about 7 meters in length and weighed over 1,000 kg.
Evidence from sediment suggests this dinosaur thrived in a warm, humid floodplain environment.
“The discovery of bones within the fossilized remains of a crocodilian’s leg pressed against the lower jaw of Joaquinraptor Casali provides insights into its feeding habits, suggesting it may have been a primary predator in its habitat,” the researchers noted.
“However, additional studies are necessary to enhance our understanding of its behavior and ecological role.”
According to scientists, Joaquinraptor Casali and other factions of Megaraputra remained dominant predators in this area of South America, ultimately facing extinction alongside other non-avian dinosaurs at the end of the Cretaceous period.
“It seems that South American megaraptolids achieved larger body sizes (over 7 m in length) than their generally smaller counterparts in Australia (5-6 m),” they added.
“The Patagonian Megaraputrids may have continued to grow throughout their evolutionary history, possibly influenced by the extinction of Carcharodontosaurus during the late Cretaceous.”
“Furthermore, this could have permitted Megaraptorids to fill a niche as apex predators within their ecosystems.”
“Moreover, as suggested by the stratigraphy of the Maastrichtian (likely late Maastrichtian), Joaquinraptor Casali may have survived until the Cretaceous-Paleogene boundary, perishing alongside all other non-avian dinosaurs.”
The discovery of Joaquinraptor Casali has been detailed in a paper published in the journal Nature Communications.
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lm ibiricu et al. 2025. The latest Cretaceous Megaraptolid Cellopod dinosaurs shed light on the evolution and paleontology of megaraptrans. Nut commune 16, 8298; doi:10.1038/s41467-025-63793-5
Source: www.sci.news
