Pecold/Shutterstock
Throughout Earth's 4.5‑billion‑year history, colossal creatures have roamed our planet. Today, the Antarctic blue whale remains the largest animal, weighing up to 400,000 lb and stretching 98 ft. On land, giants like the American bison and the African bush elephant continue to impress, but prehistoric megafauna dwarfed them all.
One of the biggest land mammals ever, the Paraceratherium—a rhinoceros relative that lived 34–23 Ma—was estimated to have reached 25 ft in length and weighed five times an elephant. Among dinosaurs, titanosaurs dominated the sauropod clade as the largest terrestrial reptiles.
While the Tyrannosaurus rex was a titan of the theropods, the recent 2024 discovery by Japanese and Mongolian scientists of gigantic footprints in the Gobi Desert suggests an even larger hadrosaur—an enormous Saurolophus that would surpass T‑rex in size.
Marek Duransky/Shutterstock
Previously, T‑rex specimens have been estimated at up to 40 ft long, 12 ft tall, and 15,500 lb. The new Mongolian footprints point to a hadrosaur that exceeded those dimensions.
Hadrosaurs, nicknamed "duck‑billed dinosaurs" for their broad, flat snouts, lived during the Upper Cretaceous (75–65 Ma). Fossils have surfaced across Europe, Asia, and North America. The largest known hadrosaur to date, Shantungosaurus, was uncovered in Shandong Province, China.
Now, an investigation of a 2018‑identified site in western Gobi Desert, conducted June 1–15 2024, revealed a series of 13 footprints spanning 79 ft. Led by Dr. Shinobu Ishigaki of the OUS Museum of Dinosaur Research, the team—collaborating with Okayama University of Science and the Institute of Paleontology, Mongolian Academy of Sciences—found three of the largest hadrosaur footprints ever recorded.
Openfinal/Shutterstock
The largest footprint, measuring 3 ft wide, indicates a Saurolophus that would have measured roughly 50 ft in length—larger than the biggest tyrannosaurs such as Tarbosaurus. This suggests the animal may have been one of the largest bipedal creatures that ever walked the Earth. No skeletal remains have yet been recovered.
Dr. Ishigaki remains optimistic. "Our next goal is to uncover the full skeleton of the large Saurolophus responsible for these footprints," he said in a press release via Phys.org. Even without a skeleton, the trackways provide valuable insight into posture, gait, speed, and social behavior—information that skeletal fossils alone cannot reveal.
The other 13 footprints were also substantial, measuring about 2.8 ft in width, hinting that further discoveries are possible. For now, these traces alone are a fascinating testament to the sheer scale of extinct terrestrial megafauna.
