LIFE × EVOLUTION

Feathers Before Flight

~240 to 160 million years ago

Phanerozoic · Mesozoic · Triassic

Feathers turn up on animals that could not fly, and the same gene network builds scales, feathers and hair, which makes them variations on one another rather than three inventions. A Jurassic dinosaur feather, analysed for its proteins, turns out to be made of a softer mixture than a modern one: the stiff keratin that a flight feather needs came later, during the change from dinosaur to bird.

Why it matters

The classic story has a structure evolving for the job it does now. Feathers are the standing refutation: they were insulation, display and touch first, and the material was reformulated for flight afterwards. Hair appears at about the same time on our own side of the tree, in the same warming-up of both lineages after the end-Permian catastrophe.

Dating & uncertaintyDisputed

Filaments are reported from dinosaurs far from the bird line, and from pterosaurs. If those are feathers, the structure is eighty million years older than birds; if they are something else, it is not. Preservation is incomplete enough that both readings survive.

Sources

1. Benton et al. (2019), Trends in Ecology and Evolution · The early origin of feathers
2. Pan et al. (2019), PNAS · The molecular evolution of feathers with direct evidence from fossils

Earth history as one day

22:43:521 h 16 min before midnight

if Earth’s 4.54 billion years were compressed into a single day