EVOLUTION × LIFE

The First Birds

~150 million years ago

Phanerozoic · Mesozoic · Jurassic

Feathers, wishbones and hollow bones all appeared among small meat-eating dinosaurs long before anything flew. What the Late Jurassic adds is variety: alongside Archaeopteryx, with its long reptilian tail, a Chinese site has produced a bird whose shoulder and hip are already close to a modern one while its hand is still that of a dinosaur, and a wishbone from a lineage more modern still.

Why it matters

A bird is not an invention but an assembly, and the pieces arrived out of order and at different speeds. Where the line is drawn is a convention. What is not a convention is the outcome: one branch of these animals came through the impact that ended the Cretaceous, and about ten thousand of its species are alive now.

Dating & uncertainty

The avian body plan was assembled piece by piece across theropods over some 160 million years, so any single first bird is a convention. Archaeopteryx at about 150 Ma is the traditional marker, and short-tailed forms are now known from the same interval.

Sources

1. Xu et al. (2011), Nature · An Archaeopteryx-like theropod from China and the origin of Avialae
2. Brusatte et al. (2015), Current Biology · The origin and diversification of birds
3. Chen et al. (2025), Nature · Earliest short-tailed bird from the Late Jurassic of China

Earth history as one day

23:12:2547 min 35 s before midnight

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