Life Finds A Way

Living fossils: 6 ancient animals that are still evolving

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Animals known as “living fossils” are those which evolve relatively slowly, or maintain traits of their ancient ancestors.

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A common misconception about living fossils is that they’ve stopped evolving, which scientists have repeatedly dismissed.

Here are 6 living fossils which illuminate the past — but are still evolving.

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6. Coelacanth

One of the most famous living fossils, coelacanths were thought to be extinct until a living one was found in 1938.

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Coelacanths look nearly identical to their ancient relatives in the fossil record, but new research shows the species evolved 62 genes in recent history.

5. Horseshoe crab

Despite the name, horseshoe crabs are arachnids, with extraordinary blue blood scientists use to test bacterial contamination.

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Their physical similarity to ancient ancestors makes their exact evolutionary path hard to study, but they’ve evolved at a normal rate on a molecular level.

4. Crocodile

Crocodiles are thought to be in a state of evolutionary equilibrium, with a form perfectly suited for their environment.

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Research suggests modern crocodiles have a more complicated evolutionary history than previously thought, however, with frequent moves between land and water habitats.

3. Goblin shark

The goblin shark is the last living member of a 125-million-year-old lineage of sharks, and one of the most bizarre-looking creatures on Earth.

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Once a shallow-water species, the goblin shark now lives in the deep sea, using its extendable jaw to capture the scarce prey in its modern environment.

2. Elephant shrew

More closely related to elephants than shrews, the elephant shrew has existed for at least 45 million years.

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Once considered a lost species, living elephant shrews were found in Djibouti, far from their previously recognized habitat in Somalia.

1. Hoatzin

The hoatzin is the last member of a bird family stretching back 64 million years. Its digestive system ferments the leaves that it eats, more like a cow than a modern bird.

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Hoatzin chicks retain claws on the end of their wings, which they use to climb trees, but scientists are divided on whether these are ancient holdovers, or recent adaptations.

Scientists disagree on the term "living fossil," but these animals provide a unique lens on the history of life.

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Read more stories on animals here.

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