Dimetrodon

Dimetrodon basked in the swamps of the Eldergrowth with a sail rising from

its back like a banner — a fan of skin stretched over elongated spines that

drank the sun's heat and fed it into a body that the world was not yet warm

enough to sustain on its own. It is one of history's great misidentifications:

everyone calls it a dinosaur, but Dimetrodon lived and died tens of millions

of years before the first dinosaur drew breath. It belonged to an older

branch entirely — a lineage that split from the reptiles and, through paths

no one could have predicted, would eventually lead to the mammals. To

everything warm-blooded. To you. Dimetrodon did not know this. It knew the

sun, and the swamp, and the slow satisfaction of being the most dangerous

thing in its world. It was a bridge between ages — standing at the fork in

the road where life chose two paths, and walking the one the world would

eventually forget.