A brand new member of the megaraptoran dinosaur household has been found by a crew of paleontologists from Argentina and the USA.
Joaquinraptor casali. Picture credit score: Andrew McAfee, Carnegie Museum of Pure Historical past.
The brand new dinosaur species lived in what’s now Patagonia, Argentina, in the course of the newest a part of the Cretaceous interval, between 70 and 67 million years in the past.
Dubbed Joaquinraptor casali, the traditional predator was a high predator within the area.
It belonged to Megaraptora, a bunch of large-clawed carnivorous theropod dinosaurs recognized from Cretaceous deposits in Asia, Australia, and particularly South America.
“Megaraptorans had been carnivorous theropod dinosaurs with elongated skulls and highly effective forearms with giant claws discovered throughout Asia, Australia and South America,” mentioned Dr. Lucio Ibiricu, a paleontologist on the Instituto Patagónico de Geología y Paleontología and the Universidad Nacional de la Patagonia San Juan Bosco, and colleagues.
“Nevertheless, our understanding of this group is hindered by the dearth of full fossils.”
A well-preserved and partially articulated skeleton of a single Joaquinraptor casali particular person was discovered within the Lago Colhué Huapi Formation of south-central Chubut Province in central Patagonia, Argentina.
The specimen included a lot of the dinosaur’s cranium, fore and hind-limbs, ribs and vertebrae.
Based mostly on the bone microstructure, the paleontologists recommend that the specimen is an grownup, however probably not absolutely grown.
Extrapolating from different megaraptoran stays, they estimate that Joaquinraptor casali could have been round 7 m in size and weighed greater than 1,000 kg.
Sedimentary proof signifies that this dinosaur lived in a heat, humid floodplain surroundings.
“The presence of a fossilized crocodile leg bone pressed in opposition to the decrease jaws of Joaquinraptor casali offers hints about its feeding habits and suggests it could have been an apex predator within the area,” the researchers mentioned.
“Nevertheless, extra analysis is required to supply additional insights into its habits and ecological function.”
In accordance with the scientists, Joaquinraptor casali and different megaraptorans survived because the dominant predators on this area of South America earlier than going extinct on the finish of the Cretaceous with different non-avian dinosaurs.
“South American megaraptorids seem to have attained bigger physique sizes (7 m or higher in whole physique size) than their usually extra historic kinfolk from Australia (5-6 m),” they mentioned.
“Patagonian megaraptorids could have continued to extend in dimension by way of the rest of their evolutionary historical past — maybe spurred a minimum of partly by the extinction of carcharodontosaurids in the course of the Turonian — with some newest Cretaceous kinds doubtlessly reaching physique lengths of 9 m or extra.”
“Amongst different advantages, this will have allowed megaraptorids to occupy the apex predator niches of their respective habitats.”
“Furthermore, and as evidenced by the Maastrichtian (in all probability Late Maastrichtian) stratigraphic prevalence of Joaquinraptor casali, these theropods could properly have survived to the Cretaceous-Paleogene boundary, solely to in the end perish alongside all different non-avian dinosaurs.”
The invention of Joaquinraptor casali is described in a paper printed within the journal Nature Communications.
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L.M. Ibiricu et al. 2025. Newest Cretaceous megaraptorid theropod dinosaur sheds mild on megaraptoran evolution and palaeobiology. Nat Commun 16, 8298; doi: 10.1038/s41467-025-63793-5
