By: Derek Gerry
Dramatic events led to the mass extinction of life on Earth millions of years ago. But even amid these mass disappearances, some plants and animals managed to survive. We call these animals living fossils because they haven't changed much in the millions of years since they first appeared on our planet. Some of them are as close as your own back yard; when you see them, remember that you're looking at something that has survived for hundreds of millions of years!
- Ferns: Look around a watery area, and you're bound to see ferns. Ferns first appeared on Earth 400 million years ago. If you're in a tropical area, look for ferns that grow from the top of treelike, woody stems, and you'll see a plant that once dominated the world's landscape. Ferns have an unusual method of reproduction. Rather than growing flowers and spreading seeds, ferns release spores that grow into new plants. This adaptation may be one of the keys to their survival.
- Dragonflies: Everyone's seen a dragonfly, with it's long body and four wings. But did you know that dragonfly fossils can be more than 150 million years old? Our modern dragonfly has evolved from an ancient insect known as Odonata. These ancient insects had the same body shape and wing design as dragonflies, but they were much larger, with some having a wingspan 30 inches across.
- Coelacanth: This large, saltwater fish has been found in waters off the coast of South Africa, Indonesia and Madagascar. This six-foot fish can weigh up to 175 pounds and is older than the dinosaurs themselves. The earliest Coelacanth fossils date to 400 million years ago, when life on Earth was still confined to the oceans. coelacanths are believed to be the ancestors of lungfish, the very first fish to adapt to life on land. Modern coelacanths live in deep ocean waters and have a lifespan of around 100 years, two traits that may have helped them survive the mass extinctions of life on Earth.
- Sharks: As a group of animals, sharks haven't changed much since they first appeared in the oceans around 400 million years ago. Early sharks were smaller and had longer bodies, but the fearsome jaws and sharp teeth of these fossils are nearly identical to modern sharks. Deep in the Pacific Ocean, the Frill Shark, named for the ruffles around its gills and on its tail fin, has been hunting prey for 50 million years. In 2007 a live Frill Shark was caught and videotaped by the Japanese.
- Crocodiles: Around 200 million years ago, a group of dinosaurs left the land for the water, beginning a cycle of evolution that would give rise to modern crocodiles. Very little has changed in these animals since the time of the dinosaurs; they're a bit smaller, they've developed muscles for swimming and their nostrils moved from the tops of their heads to the tips of their snouts. Crocodiles can survive for months without feeding and will enter a lethargic state similar to hibernation when conditions are cold or dry, two adaptations that may have helped them to survive. Seeing a crocodile is the closest you can come in today's world to seeing a living dinosaur.
