The Oldest Living Fossils

The Queensland Lungfish

• The Queensland lungfish, or Neoceratodus forsteri, is the most primitive of the six surviving lungfish species. Lungfish are freshwater fish which are able to breathe air. Lungfish fossils as old as 380 million years have been found. This particular species appears to have gone almost totally unchanged for over 100 million years, making it one of the oldest living vertebrates. As long as it is kept moist, it can survive outside water for several days.

Lampreys

• Lampreys, jawless, parasitic, eel-like fish, are among the most primitive living vertebrates. A 360 million-year-old fossil discovered by scientists from the University of Witwatersrand in South Africa shows that lampreys have changed very little since then. Lampreys use their sucker-like mouths to latch on to fish and feed on their blood and tissues.

Crocadilia

• Members of the order Crocadilia, including crocodiles, alligators and gharials, have changed very little over the last 84 million years. These large reptilians are highly adapted predators whose ancestors survived the catastrophe which caused the extinction of the dinosaurs.

Horseshoe crabs

• The oldest horseshoe crab fossils date back to 450 million years ago, making this one of the oldest invertebrate species. Horseshoe crabs may look like crustaceans, but they are actually more closely related to spiders and scorpions. Their blood is blue, because along with many mollusks and some other arthropods, their blood contains hemocyanin instead of hemoglobin.

Stromatolites

• Stromatolites are layered structures created from sediment trapped by films of blue-green algae. They are not technically alive themselves, but the cyanobacteria which create them are among the oldest unchanged life forms on the planet. Modern stromatolites are found only in a few extremely salty lakes. Stromatolite fossils as old as 2.7 billion years have been found. Evidence suggests that they existed as far back as 3.4 billion years.