When you hear talk of the fiercest extinct predators, dinosaurs probably come to mind, especially the infamous T. rex. But what stalked the land before dinosaurs? Scientists found a 265-million-year-old fossil in Brazil that shines a light on a pre-dino predator that would make you quake in your boots.

The species, Pampaphoneus biccai, is a dinocephalian (Greek for «terrible head») that predates dinosaurs by 40 million years. Dinocephalians are a group of animals that died out during a mass extinction event around 260 million years ago (the event that wiped out the dinosaurs happened about 65 million years ago). In a statement Tuesday, Harvard University described this particular terrible head as «the biggest and most bloodthirsty meat eater of its time.»

An international team published a paper on the find in the Zoological Journal of the Linnean Society earlier this week.  

Researchers unearthed a complete skull fossil, along with some rib and arm bones. It’s the only known dinocephalian species in Brazil. Fossils of other species have previously been found in Russia and South Africa. 

The impressive skull reveals a large terrestrial predator with sharp teeth. 

«This animal was a gnarly-looking beast, and it must have evoked sheer dread in anything that crossed its path,» said study co-author Stephanie Pierce, a paleontologist with the Museum of Comparative Zoology at Harvard. An artist’s rendition shows a dinocephalian with a stocky, lizard-like body and impressive teeth.

A lot can be inferred from the partial remains. The skull measured in at 16 inches long (that’s 40 centimeters). Researchers say Pampaphoneus could weigh as much as 880 pounds (400 kilograms) and reach an overall length of nearly 10 feet (3 meters). That’s on par with some polar bears.

Paleontologist and co-author Felipe Pinheiro of the Federal University of Pampa (Unipampa) likened Pampaphoneus biccai’s ecological niche to that of big cats in modern times. «Its dentition and cranial architecture suggest that its bite was strong enough to chew bones, much like modern-day hyenas,» Pinheiro said.

Extracting the skull was a painstaking task. Pinheiro shared a video to X, formerly Twitter, showing preparation of the fossil with the delicate chipping away of the surrounding rock. 

All the work that went into uncovering the dinocephalian’s remains has paid off in a deeper understanding of the animal’s characteristics and behavior. The researchers suspect they’ve even located some of its prey in nearby fossils, including one of a giant amphibian. Said Pierce, «Its discovery is key to providing a glimpse into the community structure of terrestrial ecosystems just prior to the biggest mass extinction of all time.»