Evolution of the Alligator

Evolution of the Crocodile


Three feet long, 5-10 pounds. Lived in the swamps of modern day eastern Asia and ate small animals.
Split off into the modern crocodile and the dinosaurs.


Extremely related to the crocodilian family. These were herbivorous.


Bipedal, and did not resemble the crocodile at all except for the shape of the head.

American Alligator

Lives in southeastern America. Usually lives for 35 to 50 years, and grows to a length of 10-15 feet during that time.


40 feet long and 10-15 tons. Ate dinosaurs and fish near the rivers of modern day Africa. Looked and behaved like the crocodile, but twice as long and 10 times as heavy. Informally known as the, "super-croc".


36 feet long and weighed roughly 10 tens. Oddly enough, it ate plankton and krill despite it huge pelican-like jaw.


Lived in the rivers of modern day North America. Roughly 33 feet long and 10 tons, with a 6 foot long skull. Fed on fish, shellfish, and various land creatures. Fossils show that it attacked Tyrannosaurs.


Five feet long and 25-50 pounds, ate fish and lived in the rivers of modern day North America and western Europe. Survived the mass extinction in 65,000,000 BC along with many of its relatives.


The modern day crocodile, which includes the saltwater, Nile, and American variants. They are spread throughout the world with various adaptations for specific climates and habitats.


9 feet long and 500 pounds. Had very long legs unlike the modern crocodile's short legs. The crocodile continuously gets smaller due to environmental changes.

Crocodylus Thorbjarnarsoni

Very close relative of the modern day crocodile, large skull with a small raised rim in front of the eyes. Most likely hunted early human. Lived in the Turkana basin in Kenya and may be the largest known true crocodile.

Major Events

Permian-Triassic Extinction

Killed off 90% of life on Earth.
Largest mass extinction to ever.

Triassic-Jurassic Extinction

Killed off 76% of life on Earth.
Killed the archosaurs with the exception of the crocodiles.

Cretaceous-Paleogene Extinction

Killed off 75% of life on Earth.

Holocene Extinction

Mass extinction currently active. Primarily caused by humans.
May prove to be more devastating than the Cretaceous-Tertiary Extinction.

Hunted to Near Extinction

Humans started hunting the American Alligator for its hides, almost went extinct.