Scientists have found fossils of a giant salamander-like animal with sharp teeth that ruled the waters before the first dinosaurs appeared. The researchers said the larger-than-human predator likely used its broad, flat head and front teeth to suck and chew unsuspecting prey. Its skull was about 60 centimetres (2ft) long.

“It acts like an aggressive puncher,” said biologist Michael Coates of the University of Chicago, who was not involved in the study.

The fossil remains of four creatures, including a partial skull and spine, collected about a decade ago were analyzed. The findings on Gaiasia jennyae were published in the journal Nature on Wednesday. The creature existed about 40 million years before the appearance of dinosaurs.

Researchers have long studied such ancient predators to discover the origins of tetrapods: four-legged animals that crawled on land with toes instead of fins and evolved into amphibians, birds and mammals, including humans.

Most of the oldest tetrapod fossils come from prehistoric hot coal swamps along the equator in what is now North America and Europe, but the latest remains, dated to about 280 million years ago, were found in what is now Namibia, a region of Africa once covered by glaciers and ice.

This means tetrapods may have evolved in colder climates earlier than scientists expected, raising more questions about how and when they took over the Earth.

“The early history of the first tetrapods is much more complex than we thought,” said study co-author Claudia Marsicano of the University of Buenos Aires, who also participated in the study.

The creature is named after the Gai-As mountain formation in Namibia where the fossils were found, and the late paleontologist Jennifer Cluck, who worked on the evolution of tetrapods.