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What are the biggest animals that have ever lived?

Check out the Newsround gallery of the biggest animals on the planet - past and present.
Scientists in the US say they've discovered the fossilised remains of largest bird ever to have flown. The giant creature would have looked like an enormous seagull and has been called Pelagornis sandersi. Here's a Newsround gallery of the biggest beasts on the planet - past and present.
Artist impression of Pelagornis sandersi
The saltwater crocodile is the largest living reptile and it's not unusual for adult males to grow seven metres long.
Saltwater crocodile
African elephants are currently the largest animals on land. They have a similar life-span to humans and can live to be 70 years old.
An African elephant
The largest living bird is the ostrich. They live in Africa and have the largest eyes of any land animal - each eye is 5cm wide.
An ostrich running across the desert
The biggest mammal that ever roamed the land was Paraceratherium. It was related to the modern rhinoceros and used to eat the leaves of tall trees.
Artwork of a female Paraceratherium eating leaves from a tree
A group of animals called arthropods includes insects, spiders and crabs. The largest ever was a sea scorpion called Jaekelopterus which could grow to 2.5m long, but it went extinct millions of years ago.
Sea scorpion Jaekelopterus
Blue whales are the largest animals ever to have lived. They are bigger than even the largest of the dinosaurs. They can grow to be as large as a jumbo jet!
Blue whale artwork
The largest arthropod still living today is the Japanese spider crab. This one is small-fry compared to a whopper caught in 1921 which had an arm-span of 3.8 metres.
Japanese spider crab
The largest dinosaurs to roam the Earth were the Sauropods - a family of herbivorous dinosaurs. The longest dinosaur found as a complete skeleton is Diplodocus which was 25 metres long! We know bigger dinosaurs existed but have only found some of their individual bones.
Diplodocus skeleton recreation at the Natural History Museum