Paleontologists in Argentina have identified a previously unknown species of unenlagiid dinosaur that stalked freshwater wetlands during the Late Cretaceous epoch, adding to evidence that some dinosaurs specialized in catching fish.
Life reconstruction of Kank australis. Image credit: Gabriel Díaz Yantén.
The newly-described dinosaur species roamed our planet about 70 million years ago (Late Cretaceous epoch).
The ancient reptile lived in a landscape of meandering rivers and streams with seasonal ponds, inhabited by aquatic plants such as water lilies and animals including fish, insects, and various mollusks.
Dubbed Kank australis, the animal grew up to some 2.5-3 m (8.2-9.8 feet) long.
It belonged to Unenlagiidae, a group of feathered, bird-like theropods related to the famous Velociraptor and known from South America, Antarctica, Australia and Madagascar.
“The paravian clade Unenlagiidae is represented by fossils from different Cretaceous basins in South America, Madagascar, Australia, and Antarctica, but the best-known species come from the Neuquén Basin, in northern Patagonia,” said Dr. Matías Motta from the Bernardino Rivadavia Natural Sciences Museum and his colleagues.
“These include at least eight species, all of which are from Cenomanian-Santonian beds, with the exception of the Maastrichtian-aged Austroraptor cabazai.”
“The evolutionary history and diversity of unenlagiids in South America is still poorly known.”
“Kank australis helps bridge a distributional gap for the Late Cretaceous of southern Patagonia, connecting known records from northern Patagonia and Antarctica, and showing that this family was dispersed across different latitudes of South America.”
The fossil remains of Kank australis — including teeth, vertebrae and toe bones — were recovered from the Chorrillo Formation exposures at La Anita farm, near El Calafate city, Santa Cruz, Patagonia, Argentina.
“Field excavations have been conducted there since 2018, uncovering a wide variety of fossil animals and plants,” Dr. Motta said.
“The first remains of Kank australis were discovered in 2018, but were too fragmentary to be identified as a new species.”
“Subsequent expeditions recovered additional material, with the discovery of a cervical vertebra in 2024 proving key to recognizing it as a new unenlagiine dinosaur.”
The fossils also offer insights into lifestyle and behavior of Kank australis.
“The cervical vertebrae of Kank australis show special structures for muscle attachment and the protection of neck blood vessels — features particularly important in modern birds with complex neck movements, such as herons,” Dr. Motta said.
“This suggests Kank australis may have been an active fisher, contrasting with common portrayal of raptors as agile terrestrial predators, like Velociraptor from the northern hemisphere.”
“Like other unenlagiids, it sports an enlarged, raptorial claw on the second toe of its foot.”
“However, it differs in having teeth with sharp and pronounced longitudinal ridges and notably pneumatic cervical vertebrae (with internal air chambers).”
“It is also smaller and more gracile compared to other unenlagiids from the end of the Cretaceous, such as Austroraptor cabazai.”
The discovery adds to mounting evidence that unenlagiids were piscivores (fish-eaters).
“Their elongated snouts, numerous teeth and long, flexible necks suggest adaptations for fishing, similar to modern herons,” Dr. Motta said.
“In the case of Kank australis, its remains were found alongside fish fossils, reinforcing this idea.”
“However, it is possible that Kank australis also preyed on other animals that lived in the same ecosystem, which included frogs, lizards, turtles, and even mammals like Patagorhynchus pascuali, a semi-aquatic monotreme related to modern echidnas and platypuses.”
“Kank australis coexisted with larger carnivores such as Maip macrothorax, a formidable megaraptorid dinosaur more than 10 m (33 feet) long, which may have been capable of preying upon it.”
The findings were published this week in the Journal of Vertebrate Paleontology.
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Matías J. Motta et al. New unenlagiid from the Chorrillo Formation (Late Cretaceous, Maastrichtian), SW Patagonia, Argentina. Journal of Vertebrate Paleontology, published online May 28, 2026; doi: 10.1080/02724634.2026.2656456
