Mei
MAY
"sleeping"
- Lived
- 126 to 120 million years ago, Early Cretaceous
- Diet
- Omnivore
- Group
- Theropods, Troodontidae
- Found in
- China
- Named by
- Xu and Norell 2004
Where its fossils were found
The evidence
Today
125 million years ago
Habitat
Lakes lay within a volcanic landscape in northeastern China. Sinosauropteryx, Sinornithosaurus and Psittacosaurus also lived in the Yixian Formation.
Field notes
About Mei
What it was like
Mei was a tiny feathered troodontid, about the size of a duck. Its most famous skeleton was found curled up with its head tucked under its arm, like a sleeping bird.
That pose is the oldest known sign of bird-like sleeping in a dinosaur. The animal may have died in its sleep, buried by volcanic ash.
Its world
It lived in the Early Cretaceous in what is now northeastern China. Its bones come from the Yixian Formation, where it shared the land with Sinosauropteryx, Sinornithosaurus and Psittacosaurus.
How it was found
Xu and Norell named Mei in 2004. Its full name means "soundly sleeping dragon." A second skeleton in the same pose was found later.
Field gallery
More views of Mei
Scenes reconstructed from the available fossil evidence.
1 of 3
Lived alongside
Found in the same rock formations
A rock formation can hold fossils laid down millions of years apart, so not every animal here met Mei.
The evidence
The science behind Mei
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- Nearly complete skeletons preserve a short-snouted skull, slender limbs and a long tail.
- The skeletons lie curled up, with folded limbs, the head tucked beside an arm and the tail curved around the body.
- Microscopic study of a small skeleton's leg bones shows that it was mature and its growth had slowed.
Borrowed from relatives
- Almost the whole skeleton is known from its own bones.
- Its likely feather covering is restored from feathered troodontids such as Jianianhualong.
Still unknown
- The color and exact arrangement of its feathers.
- What killed the animals preserved in the sleeping pose.
- How its appearance changed from hatchling to adult.
Discovery timeline
- 2004Named itXu & Norell
- 2012New findGao et al.
- 2014Its worldJiang et al.
- 2017Close relativeXu et al.
- 2023PostureKubo et al.
Key papers
The research behind what we know of Mei
Named it
Named Mei from a skeleton preserved in a bird-like resting pose, linking this behavior to dinosaurs outside the bird lineage.
A new troodontid dinosaur from China with avian-like sleeping posture. Nature 431: 838-841
Read the paper : A new troodontid dinosaur from China with avian-like sleeping posture (opens in a new tab)New find
Described another Mei in the same resting pose and used microscopic bone structure to show that this small animal was mature.
A Second Soundly Sleeping Dragon: New Anatomical Details of the Chinese Troodontid Mei long with Implications for Phylogeny and Taphonomy. PLoS ONE 7: e45203
Read the paper : A Second Soundly Sleeping Dragon: New Anatomical Details of the Chinese Troodontid Mei long with Implications for Phylogeny and Taphonomy (opens in a new tab)Its world
Proposed that volcanic flows killed and buried many animals in the lake deposits of the region where Mei lived.
New evidence suggests pyroclastic flows are responsible for the remarkable preservation of the Jehol biota. Nature Communications 5
Read the paper : New evidence suggests pyroclastic flows are responsible for the remarkable preservation of the Jehol biota (opens in a new tab)Close relative
Described feathers on the troodontid Jianianhualong, providing a comparison for restoring the feather covering of Mei.
Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features. Nature Communications 8
Read the paper : Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features (opens in a new tab)Posture
Found a resting pose like that of Mei in Jaculinykus, showing that this bird-like behavior occurred in another branch of theropods.
A new alvarezsaurid dinosaur (Theropoda, Alvarezsauria) from the Upper Cretaceous Baruungoyot Formation of Mongolia provides insights for bird-like sleeping behavior in non-avian dinosaurs. PLOS ONE 18: e0293801
Read the paper : A new alvarezsaurid dinosaur (Theropoda, Alvarezsauria) from the Upper Cretaceous Baruungoyot Formation of Mongolia provides insights for bird-like sleeping behavior in non-avian dinosaurs (opens in a new tab)
Close relatives
Other members of Troodontidae
Sources: Wikidata