Which Fish Did We Evolve From?
You’ve probably heard that every bony land-dwelling
creature on Earth evolved from fish that grew limbs and crawled out of the water many million
years ago. And yet, over 99% of the fish in today’s oceans, lakes, and rivers have incredibly
delicate fins, formed by a series of spines covered by a thin web of skin. It’s hard
to imagine fins like those evolving into sturdy, weight-bearing limbs…because they didn’t.
But the fins of a far more foreign fish did. Very soon after bony fishes first evolved,
they branched into two groups – those with flimsy ray-type fins, and those with more
meaty appendages that were attached to their bodies by a single strong bone. At first,
those so-called lobe-finned fishes far outnumbered their ray-finned relatives, but just as some
of them were becoming adapted for life in the weedy shallows, global climate fluctuations
caused a mass extinction that devastated life in the oceans. After the catastrophe, the ray-finned fishes
recovered and took over the oceans. The lobe-fins never recovered, but a few survivors in the
shallows managed to find their footing out of the water, and eventually gave rise to
every backboned, four-limbed creature to ever walk, hop, crawl, or fly on land. Hey, this is Emily from MinuteEarth. I just
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