The natural world has witnessed some truly colossal creatures throughout history, many of which were far larger than their modern-day descendants. From the ocean’s ancient predators to the giants of the land, these prehistoric animals commanded the earth, sea, and sky. Here are 12 creatures that were once far bigger in ancient times, showcasing the incredible scale of life long before our modern world.

1. Sharks – The Megalodon

Sharks are among the most well-known ocean predators, and while modern great whites can grow up to 19 feet (5.8 meters), they pale in comparison to their ancient ancestors. The Megalodon, or Otodus megalodon, was a massive shark that lived between 23 and 3 million years ago. Estimated to reach lengths of 67 feet (20 meters), this giant could take down whales and other large prey with its powerful bite, making it the ocean’s most formidable predator.

2. Crocodiles – Deinosuchus

Today, crocodiles like the saltwater croc are feared predators, reaching lengths of 18 feet (5.5 meters). But millions of years ago, their ancient relatives, such as Deinosuchus, dwarfed them. Living around 82 to 73 million years ago, this prehistoric crocodilian grew up to 35 feet (10.7 meters), making it one of the largest reptiles to ever walk the earth. Deinosuchus was a terrifying ambush predator that likely took on even dinosaurs in its time.

3. Elephants – Palaeoloxodon

Modern elephants are already giants, with African elephants reaching heights of 12 feet (3.7 meters). However, the ancient Palaeoloxodon, which lived from 2 million years ago to around 11,000 years ago, was even larger. These elephants could grow up to 13 feet (4 meters) tall, and their massive frames allowed them to dominate the land. Unlike woolly mammoths, these animals thrived in warmer climates, and their towering size marked them as true giants in their era.

4. Bears – Cave Bear

While modern bears like the Kodiak and polar bears can stand 10 feet (3 meters) tall when on their hind legs, the cave bear (Ursus spelaeus) was even more massive. Living during the Ice Age, this ancient bear reached up to 12 feet (3.7 meters) in height when standing upright and weighed as much as 2,000 pounds (900 kg). Their sheer size and weight helped them survive the harsh, cold conditions of prehistoric Europe, where they fed on plants and other animals.

5. Millipedes – Arthropleura

Millipedes today are relatively small, with the largest species growing to about 15 inches (38 cm) in length. However, their ancient relatives were far larger. Arthropleura, a giant millipede that lived during the Carboniferous period, could grow up to 6.5 feet (2 meters) long. These massive creatures roamed ancient forests, feeding on plant material and potentially even smaller animals. Their size was likely a result of the high oxygen levels in the atmosphere at the time.

6. Dragonflies – Meganeura

Dragonflies are familiar to many, with wingspans that typically range between 2 and 5 inches (5-12 cm). However, during the Carboniferous period, one species dwarfed all modern dragonflies: Meganeura. With wingspans reaching up to 2.5 feet (75 cm), these ancient insects were some of the largest flying creatures to ever live. They hunted other insects with incredible agility, soaring through the dense forests of prehistoric Earth.

7. Sloths – Megatherium

Megatherium, the giant ground sloth, was an immense herbivore that inhabited the Americas during the Pleistocene epoch. Growing up to 20 feet (6 meters) in length and weighing several tons, it was vastly larger than today’s modern sloths. Unlike their tree-dwelling relatives, Megatherium was terrestrial and could stand upright on its hind legs to reach vegetation. This slow-moving giant is an excellent example of how evolution allowed certain species to grow to massive sizes in ancient times.

8. Penguins – Palaeeudyptes

Palaeeudyptes was an ancient penguin species that lived between 37 and 34 million years ago. These prehistoric penguins dwarfed modern species, growing to over 5 feet (1.5 meters) in height. They were much taller than the largest penguins we have today, such as the Emperor penguin. Palaeeudyptes likely hunted in the waters of what is now Antarctica, using its size and agility to capture prey. Its massive size helps us appreciate the variations in penguin evolution over millions of years.

9. Turtles – Archelon

Archelon, a prehistoric sea turtle that lived during the Cretaceous period, is considered one of the largest reptiles to have ever existed. It had a shell that reached lengths of over 13 feet (4 meters) and weighed several tons. Unlike modern sea turtles, Archelon was much larger and spent most of its life in the oceans, where it likely fed on jellyfish and other marine organisms. The sheer size of this ancient turtle highlights the dramatic differences between its time and the present-day reptiles we know today.

10. Rats – Josephoartigasia

Josephoartigasia holds the title of the largest rodent to have ever lived. This giant rodent, which lived in South America around 4 million years ago, reached lengths of up to 10 feet (3 meters) and weighed more than a ton. Josephoartigasia had large, powerful jaws and teeth capable of cutting through tough vegetation. Its massive size and herbivorous diet make it a fascinating example of how rodents evolved into giant forms in prehistoric ecosystems. This giant rodent would have dwarfed any modern-day rat.

11. Snakes – Titanoboa

Titanoboa is the largest snake species to ever inhabit the Earth, growing to an astounding 42 feet (12.8 meters) in length. This giant serpent roamed the tropical rainforests of what is now Colombia around 60 million years ago. Titanoboa was a dominant predator in its environment, preying on large animals like crocodiles and even other reptiles. Its size allowed it to control the food chain in its ecosystem, and its fossilized remains give us valuable insights into prehistoric climates and biodiversity.

12. Birds – Argentavis

Argentavis magnificens was an ancient bird species with one of the largest wingspans in history. Its wingspan reached an impressive 26 feet (8 meters), far surpassing any modern bird. Argentavis lived approximately 6 million years ago in South America and is believed to have used its massive wings to glide over the plains, hunting smaller prey. This giant bird could weigh up to 150 pounds and would have been an awe-inspiring sight as it soared across the skies, representing one of the most remarkable examples of prehistoric bird evolution.