Story perspectives

Ancient tetrapod hatchlings lacked larval gills, overturning metamorphosis theory

6/19/2026

Summary

Story summary

Paleontologists Jason Pardo and Arjan Mann reported that hatchlings of three tetrapod groups lacked amphibian-like larval features, overturning the view that vertebrates needed metamorphosis to colonize land.
Scanning-electron microscopy of 308-million-year-old newborn fossils from Illinois’s Mazon Creek site revealed limbs, skin, no external gills, and no bones.
One embolomere retained a yolk sac while a megalichthyid and an aïstopod likely had lungs, a result Laura Porro said may reshape textbooks.

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Story summary

Paleontologists Jason Pardo and Arjan Mann reported that hatchlings of three tetrapod groups lacked amphibian-like larval features, overturning the view that vertebrates needed metamorphosis to colonize land.
Scanning-electron microscopy of 308-million-year-old newborn fossils from Illinois’s Mazon Creek site revealed limbs, skin, no external gills, and no bones.
One embolomere retained a yolk sac while a megalichthyid and an aïstopod likely had lungs, a result Laura Porro said may reshape textbooks.