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You might recognize it as a fish—it has fin webbing and scales on its back.
What makes you think it’s related to the first vertebrate animals to walk on land?
It has a head that’s shaped like some of the earliest land-living creatures. It has a neck—the head can move separately, unlike any fish but very similar to land animals—and an upper arm, a forearm and even parts of a wrist. It blurs the distinction between fish and land-living animals. We think this animal was able to support its body on the ground, whether that ground is underwater, or in the shallows, or even on land for brief periods.
Tiktaalik lived about 375 million years ago. What was its world like?
You would see some of the earliest forests and some invertebrate animals—centipede-like things. In the water you’d see a pretty hostile place, with lots of predatory fish with giant fangs.
Is that why Tiktaalik—or its descendants—left the water?
That’s a compelling explanation, but there’s also the fact that some of the invertebrates on land were large, pretty defenseless and probably nutritious.
