Arthropleura: The largest terrestrial arthropod, this ancient millipede could grow up to 8.2 feet long and weighed around 110 pounds, thriving during the Carboniferous period when oxygen levels were significantly higher.

Epicyon hayi: This prehistoric canine, living 12 to 6 million years ago, stood 3 to 4 feet at the shoulder and weighed up to 370 pounds, making it the largest known canine, with powerful jaws adapted for a hypercarnivorous diet.

Elephant Birds: Extinct flightless birds from Madagascar reached heights of 10 feet and weighed up to 1,100 pounds, with eggs that were 150 times larger than chicken eggs, showcasing their colossal size.

Parapuzosia seppenrensis: This giant ammonite from the late Cretaceous period had a shell estimated to be over 11 feet wide, potentially weighing more than 3,200 pounds, making it the largest known cephalopod.

Titanoboa: The largest snake ever discovered, Titanoboa could grow up to 42 feet long and weigh around 2,540 pounds, dominating the food chain in the Paleocene epoch.

Paleoloxodon naidicus: This massive elephant species, existing between 2.5 million and 11,700 years ago, stood an estimated 17 feet tall at the shoulder and weighed up to 24 tons, making it the largest land mammal to have ever walked the Earth.