Tropical Oceans // Eocene (~30 million years ago) // Cetacea // image source
When fossils of Basilosaurus were first discovered, it was thought to have been a marine reptile, hence its name meaning King’s Lizard. It was later correctly classified as an early whale.
North America // Vulnerable // Squamata // image source
The southern hog-nosed snake is one of several species of hog-nosed snakes. They are known not only for their upturned nose, but also for their ability to dramatically play dead when a predator is near.
South America // Pliocene (~2 million years ago) // Sparassodonta // image source
While it appears to be a sabre-toothed cat like Smilodon, Thylacosmilus was actually a marsupial (or at least a very close relative of them), making it a prime example of convergent evolution.
North America // Conservation Status Unknown // Osteicthyes // photo source
The Alligator Gar can live to be over 50 years old, but the average lifespan in the wild is closer to 20 years. Unusually for a fish, it can survive out of water for up to two hours.
South America // Least Concern // Rodentia // image source
Pacas are closely related to the other large South American rodents (capybara, nutria, etc.), and similarly lives near rivers. It is the only mammal to have a specially adapted zygomatic arch that acts as a sonic resonating chamber.
Europe // Early Cretaceous (137 million years ago) // Sauropsida // image source
Dakosaurus looks like a type of dinosaur or plesiosaur, but it is actually one of many prehistoric crocodiles that developed fins. They reached lengths of up to 15 feet, and had an incredibly powerful bite.
Tropical Oceans // Vulnerable // Chondrichthyes // image source
Sharks and rays are closely related. The aptly named shark ray looks like a combination of both, but it is a large species of ray, growing to nearly 10 feet long. Like many other sharks and rays, it is dying out as a result of overfishing.
North America // Late Cretaceous (80 million years ago) // Hesperornithiformes // image source
Despite its resemblance to the loon, hesperornis has no living descendants. It was about 5 feet long and had actual teeth (not just a serrated bill) to grasp fish easily.
North Pacific Ocean // Recently Extinct (c. 1768) // Sirenia // image source
Fun Fact: Steller’s Sea Cow was closely related to dugongs and manatees, but could grow up to 30 feet in length. It was hunted to extinction within 30 years of its discovery by European settlers.
Northern, Southern oceans // Vulnerable // Chondrichthyes // image source
Fun Fact: Basking sharks feed primarily on zooplankton and other tiny animals. Despite their similarities to the whale shark, they are not closely related (as far as sharks go).
