The Chunky Whale!

Who was allegdly a whopping 750,000 pounds, that calculates to 340194.278 KG

The whale's name was Peructus Colossus, and they lived in the shallow parts of the Ocean Depths.
The artist's depiction is not 100% accurate, as the Paleontologists from Peru have not yet found a skull.

Many of the mammal's preserved bones have taken over a decade to evacuate from a 100 Foot Hill.
Each Field campaign could only transport two of the huge vertebrae at a time, after 13 years, 13 vertebrae has been discovered, each weighing 220 pounds, with 4 Ribs each over four feet long and a hip bone has also been found.

Eli Amson commented "Besides the Guinness Book aspect of it, from a scientific perspective, the most important part is the understanding of what conditions can yield extreme gigantism" “This changes a lot of our understanding of gigantism and basically provides another evolutionary path to it.” Eli Amson is a staff member of the State Museum of Natural History in Stuttgart, Germany

It is believed that Peructus Collosus moved from Land to Water around 40 Million Years ago

Skeletal Fragments from Peructus Collosus are now on Display at the Museum of Natural History in Lima

Nicholas Pyenson, a paleobiologist who is the curator of of fossil marine mammals at the Smithsonian National Museum of Natural History says "I think what the authors are proposing is perhaps the chonkiest whale ever"