Three hundred and nine million years ago, the land beneath modern Chicago was a swampy equatorial delta — oxygen at 35%, club mosses thirty meters tall, and dragonflies the size of hawks. The central question of this episode: did early four-legged vertebrates develop through amphibian-style metamorphosis, or did they hatch as miniature adults from the start? Ola and Amara examine the Pardo and Mann 2026 Science paper, which presents hatchling embolomere fossils from Mazon Creek with fully forming limbs and no external gills, then work through the fin-to-limb timeline from Tiktaalik to Romer's Gap, and debate whether Carboniferous animals can legitimately inform models of Devonian development. Listeners will come away understanding why modern amphibian metamorphosis may be an evolutionary novelty rather than the ancestral vertebrate condition.