This newly discovered raptor may have hunted like a giant heron

The discovery is based on fossil remains that include teeth, vertebrae, and toe bones. Researchers classified the dinosaur as an unenlagiid, a group of small to medium sized theropod dinosaurs known from Late Cretaceous rocks in South America, Antarctica, Australia, and Madagascar.

By comparing the fossils with those of Neuquenraptor argentinus, another unenlagiid that lived in northern Patagonia around 90 million years ago, scientists estimate that adult Kank australis reached a length of roughly 2.5 to 3 meters (8 to 10 feet).

The species is described by paleontologist Dr. Matías Motta of the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires (Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”) and colleagues in a study published in the Journal of Vertebrate Paleontology.

Life in Ancient Patagonian Wetlands

According to Dr. Motta, Kank inhabited a landscape shaped by winding rivers, streams, and seasonal ponds.

“Kank 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 molluscs,” says Dr. Motta.

Evidence from ancient soils and fossil plants suggests the region looked very different from modern Patagonia.

Based on that evidence, Dr. Motta explains that “70 million years ago the climate was temperate and humid, with seasonal rainfall, very different from the current cold and relatively dry conditions.”

A Dinosaur Adapted for Fishing

The fossilized bones provide clues about how Kank may have hunted.

Researchers found unusual features in the dinosaur’s neck vertebrae that served as attachment points for muscles and helped protect blood vessels. Similar adaptations are seen in modern birds that rely on precise and flexible neck movements.

“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,” says Dr. Motta.

“This suggests Kank may have been an active fisher, contrasting with common portrayal of raptors as agile terrestrial predators, like Velociraptor from the Northern Hemisphere.”

The finding adds to growing evidence that unenlagiids occupied ecological roles different from those of their more famous northern relatives.

Filling a Fossil Record Gap

The discovery also helps scientists better understand the distribution of unenlagiids across South America.

Seven species have previously been identified from northern Patagonia. In contrast, southern Patagonia had yielded only scattered fossils that could not confidently be assigned to a specific species.

“Kank 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 fossils were recovered from La Anita farm near El Calafate in Santa Cruz Province, Argentina.

“Field excavations have been conducted there since 2018, uncovering a wide variety of fossil animals and plants,” says Dr. Motta.

The first remains were discovered in 2018, but researchers initially lacked enough material to recognize them as a new species.

“The first remains of Kank were discovered in 2018, but were too fragmentary to be identified as a new species,” he adds. “Subsequent expeditions recovered additional material, with the discovery of a cervical [neck] vertebra in 2024 proving key to recognising it as a new unenlagiine dinosaur.”

Distinctive Features of Kank australis

Like other unenlagiids, Kank australis possessed the enlarged claw on its second toe that is often associated with raptor dinosaurs.

“However,” Dr. Motta explains, “it differs in having teeth with sharp and pronounced longitudinal ridges and notably pneumatic cervical vertebrae (with internal air chambers).”

The species was also smaller and more lightly built than some of its relatives.

“It is also smaller and more gracile compared to other unenlagiids from the end of the Cretaceous, such as Austroraptor cabazai, a giant (around five meters long) unenlagiine from northern Patagonia.”

Evidence for a Fish-Eating Lifestyle

Scientists believe Kank strengthens the case that many unenlagiids specialized in catching fish.

“Their elongated snouts, numerous teeth and long, flexible necks suggest adaptations for fishing, similar to modern herons,” Dr. Motta explains.

“In the case of Kank, its remains were found alongside fish fossils, reinforcing this idea.”

Although fish may have been an important food source, the dinosaur likely hunted other animals as well. Its ecosystem included frogs, lizards, turtles, and mammals such as Patagorhynchus pascuali, a semi aquatic monotreme related to modern echidnas and platypuses.

Kank also shared its environment with much larger predators.

“Kank coexisted with larger carnivores such as Maip macrothorax, a formidable megaraptorid dinosaur more than 10 metres long, which may have been capable of preying upon it,” Dr. Motta adds.

Inspired by Indigenous Patagonian Mythology

The dinosaur’s name honors the traditions of the Aonikenk people, the southernmost group of the Indigenous Tehuelche peoples of Patagonia.

“Kank refers to an old giant rhea [a large, flightless South American bird] whose powerful running steps left the imprint of its toes in the sky, forming the constellation known as Choiols,” explains Dr. Motta.

“In Latin, this constellation is called Crux, the Southern Cross, which points toward the southernmost region of the planet, where Kank was discovered.”

The species name australis, meaning “from south,” also reflects the location where the dinosaur was found.

More Discoveries Ahead

Researchers plan to continue excavations in the Chorrillo Formation, where the fossils were discovered.

“The site where Kank was discovered has provided extensive information about the Late Cretaceous environment of southern Patagonia, so continuing excavations there is crucial,” explains Dr. Motta.

“Finding more Kank fossils will help us better understand its biology and ecological role.”

At the same time, the team is studying newly recovered fossils from four sites in northern Patagonia.

“These findings indicate that unenlagiids were widely distributed during the Late Cretaceous,” Dr. Motta says.

He adds: “We are particularly interested in investigating the environments they colonized and speciated in, especially in ecosystems dominated by large apex predators such as abelisaurids and megaraptorans.”