At an estimated 85 feet in length, the newly discovered ichthyosaur might just be the biggest prehistoric creature ever recorded.

“Sea monster,” indeed. The ancient, titanic beast would have been nearly as large as the blue whale — currently the largest known creature to exist on our planet. But the blue’s status may be in jeopardy with discoveries like this immense underwater creature. The size of the ichthyosaur was estimated based on the size of a jawbone found by an independent “fossil hunter” and is 25 percent larger than the largest ichthyosaur jaw ever discovered.

Ichthyosaurs were essentially the waterborne contemporaries of the dinosaurs that have dominated our imaginations for as long as we have had knowledge of their existence. They ruled the oceans in the late Triassic period, more than 200 million years ago, looking almost like gigantic dolphins. We do not know exactly what happened to them, but they seem to have disappeared well before the mass extinction event that wiped out their dinosaur brethren.

Fossil hunter Paul de la Salle and his co-authors have published a paper in scientific journal PLOS ONE, arguing that the jawbone which led to this discovery may be only one of many and that bones discovered in “Westbury Mudstone Formation from Aust Cliff” may, in fact, be those of this elusive behemoth. According to de la Salle and his colleagues, “the Aust bones, previously identified as those of dinosaurs or large terrestrial archosaurs, are jaw fragments from giant ichthyosaurs.”

After being shipped de la Salle’s findings, University of Manchester reptile expert Dean Lomax explained that he “compared it with these Aust bones, and as soon as I saw it in person, my jaw just hit the floor. I realized this was a giant ichthyosaur and the biggest thing ever found in the U.K.”