Evidence of the biggest venomous snake to ever slither across the earth had long been lost, that is, until recently when researchers found a new fossil in Greece that proves today's king cobras were not always rulers of these reptiles.

Measuring between 10 and 13 feet (3 and 4 meters) long and weighing a whopping 57 pounds, Laophis crotaloides was not only venomous but massive.

"This snake was indeed impressive," researcher Georgios Georgalis told Live Science. "We clearly speak about a monster!"

King cobras may be modern day's longest venomous snakes (growing to about 18 feet [5.5m] long), but they still pale in comparison to Laophis at their scrawny 15 to 20 pounds. And uncharacteristic for such a large reptile, Laophis lived in seasonal grasslands where winters were cool rather than the tropics.

"We've got something that, for its latitudinal placement and the climate reconstruction, it's massively out of proportion," said study researcher Benjamin Kear, a paleobiologist at Uppsala University in Sweden.

This snake is so colossal that it almost seems a creature of myth, but in fact tales of the enormous viper began in 1857 when famous paleontologist Sir Richard Owen found 13 fossilized snake vertebrae near Thessaloniki, Greece. He described his findings in the Quarterly Journal of The Geological Society. However, this evidence has long been lost and with it Owen's credibility.

Now the recent discovery of a single vertebra - barely an inch long - found near Thessaloniki backs up Owen's claim. Though researchers can now confirm the existence of the largest viper ever, little is still known of Laophis. Snakes are notorious for their ill-preserved remains, but even so scientists can say that Laophis slithered alongside large mammals such as deer and horses, and likely ate small mammals.

Georgalis presented the findings Nov. 6 at the 2014 meeting of the Society of Vertebrate Paleontology in Berlin.