By exploreodisha.in 
Earth has been home to an astonishing variety of life forms, many of which have dwarfed even the largest creatures alive today. From ancient marine giants to towering dinosaurs, here’s a look at the 10 largest animals ever known to have roamed the Earth, both past and present.
1. Blue Whale (Balaenoptera musculus)
Length: Up to 100 feet (30 meters)
Weight: Around 200 tons
The blue whale is not just the largest animal alive today—it’s the largest known to have ever lived. These gentle ocean giants are even heavier than any known dinosaur. Despite their immense size, they feed almost exclusively on tiny krill.
2. Argentinosaurus
Length: Around 100 feet (30 meters)
Weight: Estimated 80–100 tons
Among the largest land animals to ever exist, Argentinosaurus was a long-necked, plant-eating dinosaur that roamed South America during the Late Cretaceous period. Its exact size remains debated due to limited fossil evidence, but it’s widely regarded as one of the heaviest and longest land creatures in history.
3. Patagotitan Mayorum
Length: Approx. 122 feet (37 meters)
Weight: 70 tons
Another contender for the title of largest dinosaur, this titanosaur from Argentina is known from more complete fossil remains than Argentinosaurus. Its discovery has helped scientists better understand the anatomy and scale of gigantic sauropods.
4. Spinosaurus
Length: Around 50–59 feet (15–18 meters)
Weight: Estimated 7–20 tons
Spinosaurus was one of the longest carnivorous dinosaurs ever, even larger than the infamous Tyrannosaurus rex. What sets it apart is its semi-aquatic lifestyle—unique among large predators—and the sail-like structure on its back.
5. Megalodon (Otodus megalodon)
Length: Up to 60 feet (18 meters)
Weight: Approx. 50–70 tons
This extinct prehistoric shark ruled the oceans about 23 to 3.6 million years ago. Megalodon’s jaws could open wide enough to swallow a human whole, and it preyed on whales and other marine mammals.
6. Shastasaurus
Length: Up to 69 feet (21 meters)
Weight: Estimated 75 tons
Shastasaurus was the largest known marine reptile, living during the Triassic period. Unlike the sharp-toothed image we associate with sea monsters, Shastasaurus had a toothless snout and likely fed by suction.
7. Paraceratherium
Height: Up to 16 feet (5 meters) at the shoulder
Length: About 26 feet (8 meters)
Weight: Around 15–20 tons
Often called the largest land mammal ever, Paraceratherium was a hornless relative of the modern rhinoceros. Roaming Central Asia over 20 million years ago, it was a browser, feeding on leaves from treetops.
8. Mosasaurus
Length: Up to 56 feet (17 meters)
Weight: 15 tons
Popularized by movies like Jurassic World, Mosasaurus was an apex predator of the Late Cretaceous oceans. It had powerful jaws and a streamlined body, allowing it to hunt effectively in deep water.
9. Leedsichthys
Length: Over 50 feet (15 meters)
Weight: Around 40 tons
Leedsichthys was the largest bony fish to have ever existed. Unlike predatory giants, it was a filter feeder, consuming plankton in vast quantities. It lived during the Jurassic period and filled a similar ecological role to today’s baleen whales.
10. Titanoboa
Length: About 42 feet (13 meters)
Weight: Estimated 1.5 tons
After the extinction of the dinosaurs, Titanoboa slithered its way into the top predator spot. Living in what is now South America around 60 million years ago, this colossal snake likely ambushed prey in swampy waters.
Final Thoughts
The sheer size of these ancient giants reminds us of how diverse and extraordinary life on Earth has been. From towering dinosaurs to modern marine leviathans, these creatures continue to fascinate scientists and animal lovers alike. Studying them not only gives us a glimpse into Earth’s evolutionary past but also helps us understand how life adapts, grows, and survives through time.