Ancient Fish-Eating Raptor Hunted Like Modern Herons in Patagonia

Revolutionary Discovery Rewrites Raptor Behavior

A remarkable dinosaur discovery in Argentina is challenging everything scientists thought they knew about ancient raptors. Scientists have discovered a new species of raptor-like dinosaur in southern Patagonia, Argentina, dating back around 70 million years, described in the Journal of Vertebrate Paleontology by Dr Matías Motta and colleagues from the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires. Unlike the typical image of fast, land-based raptors, Kank australis appears to have been adapted for fishing, with its long, flexible neck and specialised cervical vertebrae resembling those of modern herons.

Fossils recovered from La Anita farm near El Calafate included teeth, vertebrae, and toe bones, with researchers estimating the animal grew to around 2.5–3 metres long. The team found Kank's remains alongside fish fossils at La Anita farm near El Calafate, Argentina, suggesting fish were likely a primary part of its diet, with frogs, lizards, and turtles possibly on the menu, too.

Specialized Anatomy for Aquatic Hunting

The cervical vertebrae of Kank 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, suggesting Kank may have been an active fisher, contrasting with common portrayal of raptors as agile terrestrial predators, like Velociraptor from the Northern Hemisphere. Researchers note that Kank australis differed from related species by having pronounced ridges on its teeth and highly pneumatic neck vertebrae containing internal air chambers, and was more lightly built than larger unenlagiids such as Austroraptor.

The dinosaur belonged to the unenlagiids, a group of small-to-medium-sized theropods related to dromaeosaurs ("raptors"). About 70 million years ago, Kank waded through humid, meandering streams and seasonal ponds, using its elongated snout and specialized, ridge-lined teeth to snap up fish like a modern heron, with Kank's cervical vertebrae possessing structures for muscle attachment and blood vessel protection seen in modern herons.

Ancient Ecosystem Reconstruction

The region at the time was a humid, temperate environment with rivers, seasonal ponds, aquatic plants, and diverse wildlife. Analysis of ancient soil samples and fossilised plant remains shows that 70 million years ago, the landscape consisted of meandering rivers and streams with seasonal ponds, with the climate being temperate and humid with seasonal rainfall, a stark contrast to current cold and dry conditions.

Field excavations have been conducted there since 2018, uncovering a wide variety of fossil animals and plants, with the first remains of Kank discovered in 2018, but were too fragmentary to be identified as a new species, until subsequent expeditions recovered additional material, with the discovery of a cervical vertebra in 2024 proving key to recognising it as a new unenlagiine dinosaur.

Cultural Significance and Scientific Impact

The dinosaur's name comes from Aonikenk mythology: "Kank" refers to a giant rhea whose footprints formed the Southern Cross constellation, while "australis" reflects the species' southern location. Kank comes from a myth of the Aonikenk, the southernmost Tehuelche people of Patagonia, an ancient giant rhea whose running steps left the imprint of its toes across the sky, forming the constellation the rest of the world calls the Southern Cross, with the species name, australis, meaning simply "from the south," creating a creature named for a constellation, found at the bottom of the world, that turned out to hunt like a bird.

The discovery helps fill an important gap in the fossil record of southern Patagonia and shows that unenlagiids were distributed widely across South America during the Late Cretaceous. This finding demonstrates how dinosaurs adapted to diverse ecological niches, suggesting that the Late Cretaceous world was far more complex and varied than previously understood. The discovery opens new avenues for understanding how ancient ecosystems functioned and how predators evolved specialized hunting strategies millions of years before similar behaviors appeared in modern birds.