Earliest known flightless bird lived alongside flying Jurassic species

Overview

Updated 1 hour ago

A crow-sized bird that lived 150 million years ago in southeastern China never flew. Its fossil, described October 14 in the journal Nature, is the earliest known flightless bird and shows flightlessness appeared almost as soon as birds did.

The species, Yuezhuornis yangyuanensis, had wings a third shorter than its legs. It had a build like a ground-dwelling pheasant and a sickle-shaped claw on its second toe like a Velociraptor. Its mix of bird and dinosaur traits challenges the long-held view that the bird body plan evolved mainly under the pressure of flight.

Why it matters

The find suggests bird evolution branched rapidly into many lifestyles, not a steady march toward flight.

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Key Indicators

150 million years

Age of fossil

Yuezhuornis yangyuanensis lived 148-150 million years ago in the Late Jurassic.

377

Living bird species compared

Researchers compared limb proportions with 377 living bird species to infer Yuezhuornis's lifestyle.

33%

Forelimb length deficit

Forelimbs were one-third shorter than hindlimbs, matching ground-dwelling birds like pheasants.

Voices

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People Involved

Wang (lead author)

Lead author of the study, paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology

Lead researcher on the Yuezhuornis yangyuanensis discovery

Zhou Zhonghe

Co-author of the study, paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology

Co-author of the Nature paper

Fernando Novas

Paleontologist at the Felix de Azara Natural History Foundation, Buenos Aires

Wrote accompanying commentary in Nature

Organizations Involved

Institute of Vertebrate Paleontology and Paleoanthropology

Research institute

Lead institution on the Yuezhuornis discovery

The Chinese Academy of Sciences research institute that led the study.

Nature

Scientific journal

Publisher of the study and accompanying commentary

Peer-reviewed scientific journal that published the Yuezhuornis study.

Timeline

August 2024 October 2026

2 events Latest: Today

October 2026
Nature publishes Yuezhuornis description
Today Publication

Min Wang and colleagues described Yuezhuornis yangyuanensis as the earliest known flightless bird, challenging assumptions about early bird evolution.
Today
August 2024
Fossil discovered in Fujian Province
Discovery

A nearly complete fossil was found near Yangyuang village, Fujian Province, China, in the Upper Jurassic Zhenghe Fauna deposit.
August 2024

Scenarios

More flightless early birds found in China's Zhenghe Fauna

Possible Resolves by End of 2027

Discussed by: Researchers at the Chinese Academy of Sciences and other paleontologists

The Zhenghe Fauna deposit where Yuezhuornis was found is a window on a poorly documented stage of Jurassic bird evolution. Further excavations could reveal more flightless early birds, confirming that flightlessness was common among the first birds.

Flightless interpretation of Yuezhuornis challenged

Possible Resolves by Q2 2028

Discussed by: Paleontologists not involved in the study

The flightless label is an inference from limb proportions, not direct evidence of wing function. Modern pheasants, which Yuezhuornis resembles, can fly in short bursts despite being ground-dwellers. Some researchers may argue the bird retained limited flight ability.

Yuezhuornis reshapes the bird family tree

Likely Resolves by End of 2028

Discussed by: Study authors and commentators including Fernando Novas

The phylogenetic analysis places Yuezhuornis closer to modern birds than Archaeopteryx, despite Archaeopteryx being a stronger flier. This ordering challenges the idea of a steady progression toward flight. Future analyses could confirm or revise this placement.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

1861

Archaeopteryx (1861)

The first Archaeopteryx fossil was found in Germany in 1861, two years after Darwin published On the Origin of Species. It showed a mix of dinosaur and bird traits, including feathers and teeth, and became a key piece of evidence for evolution.

Then

Archaeopteryx sparked intense debate about the origin of birds and flight.

Now

It became the iconic 'first bird' and a cornerstone of evolutionary biology.

Why this matters now

Yuezhuornis, similar in age to Archaeopteryx, shows that early birds diversified into many lifestyles, not just flight.

2003

Microraptor (2003)

Microraptor, a four-winged dinosaur described in 2003 from China, had feathers on all four limbs. It showed that flight-like abilities evolved in multiple dinosaur groups.

Then

Microraptor expanded the known diversity of flying dinosaurs.

Now

It helped establish that flight evolved multiple times among dinosaurs.

Why this matters now

The Yuezhuornis find adds to evidence that flight and flightlessness evolved multiple times among early birds and their relatives.