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Reading bones

How Do We Know About Dinosaurs?

Everything we know comes from fossils, and from comparing them with animals alive today.

1 Bones preservedin rock2 Compared withliving animals3 Areconstructionwe can test
Evidence first, picture second.

  1. Step 1 of 5

    Bones are the starting point.

    Size and shapeHow joints movedScars showing muscleattachment

    Skeletons show size, posture and how joints moved. Muscle scars on the bone reveal where muscles attached and how strong they were.

  2. Step 2 of 5

    Teeth reveal the diet.

    Flat, ridged teeth A plant eaterBlades and points A meat eater

    Flat grinding teeth mean plants; blades and points mean meat. Wear patterns even show what an individual animal was actually chewing.

  3. Step 3 of 5

    Trackways record behaviour.

    1 Fossilfootprints2 Stride lengthgives speed3 Parallel tracksshow herding

    Footprints give speed from stride length, and show whether animals moved in herds. Bones say what an animal was; tracks say what it did.

  4. Step 4 of 5

    Living animals fill the gaps.

    Birds Living dinosaursCrocodiles Closest livingrelatives

    Birds are living dinosaurs, and crocodiles are close relatives. Where both share a feature, the extinct animals in between very likely had it too.

  5. Step 5 of 5

    The picture keeps being corrected.

    Old reconstruction Slow, scaly, taildraggingCurrent one Fast, often feathered,tail held high

    Dinosaurs were once drawn as sluggish and tail-dragging. Fossil feathers and better biomechanics changed that — the reconstructions follow the evidence.

    Some fossils preserve melanin-containing structures, which is how a few dinosaurs' actual colours have been worked out.

The short version

Dinosaurs are reconstructed from bones, teeth and tracks, checked against living birds and crocodiles.

Try it yourself

Compare a chicken's leg bones with a museum dinosaur's. The hollow bones and ankle joint are strikingly similar.

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