Caihong: Research Database
Ornithothoraces (Aves) · Late Jurassic (~161 MYA) · Asia — China (Hebei, Tiaojishan Formation)
Research Note: Caihong was an early ornithothoracean bird from the Late Jurassic of Hebei, China. Famous for its iridescent feather coloration preserved in the fossil — making it the oldest known dinosaur/early bird with evidence of colorful plumage — it provides critical data on the evolution of feathers, coloration, and the biology of the earliest birds.
| Research Finding | Status | Grade | Year | Method | Citation | Impact |
|---|---|---|---|---|---|---|
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Wang et al. 2018: Caihong and the discovery of iridescent feather coloration in an early bird from the Jurassic of China
Wang et al. 2018 describe Caihong from the Late Jurassic Tiaojishan Formation of Hebei, China, documenting the preservation of melanosomes indicating iridescent feather coloration and establishing it as the oldest known dinosaur/early bird with evidence of colorful plumage, providing critical data on the evolution of feathers and coloration in early birds
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Confirmed | A | 2018 | Fossil | Wang et al., Nature Communications | Coloration |
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O’Connor et al. 2019: Caihong and the diversity of early birds from the Jurassic of China
O’Connor et al. 2019 provide additional data on Caihong and the broader diversity of early birds from the Jurassic of China, contextualizing it within the evolutionary history of early ornithothoracean birds and the origin of avian biological traits
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Confirmed | B | 2019 | Fossil | O’Connor et al., Comptes Rendus Palévolution | Diversity |
Active Debate: Iridescent Feathers, the Evolution of Color, and the Visual Ecology of Early Birds
Whether the iridescent coloration in Caihong served a display function (mate attraction, species recognition) or had a different ecological purpose (camouflage, thermoregulation) is debated. Iridescent coloration in modern birds is typically associated with sexual selection — the shimmer and color-play being used to attract mates. If Caihong had similar iridescent plumage, it raises questions about whether sexual selection was already operating in the Jurassic, and whether early birds had complex social behaviors. However, some researchers caution that the melanosome preservation may not directly indicate iridescence — the microstructure of modern iridescent feathers involves specific arrangements that may not be directly comparable to what was preserved in Caihong.
The phylogenetic position of Caihong within early birds is also debated. While clearly an ornithothoracean (a relatively advanced bird), its precise relationships to other early birds like Archaeopteryx, Confuciusornis, and enantiornithines are uncertain. This uncertainty makes it difficult to reconstruct whether iridescent coloration was ancestral to birds or evolved later within the avian lineage.
What We Still Do Not Know About Caihong
- Complete skeletal morphology: Partial specimen known.
- Flight capability: Likely capable of powered flight.
- Social behavior: Sexual selection for iridescence debated.
- Precise phylogenetic position: Within Ornithothoraces debated.
In Depth
Caihong is a genus of anchiornithid dinosaur that lived in Asia during the late Jurassic. Caihong was a very small dinosaur, roughly about forty centimetres long in life. Caihong is noted for having feathers covering the entire body except for the snout and claws. Study of melanosome associated with Caihong show that in life Caihong probably had black iridescent feathers over most of its body, while the feathers of the head, neck, chest and base of the tail were brightly coloured. This patterning is suggested by the observation that these feathers had platelet like melanosomes denoting colours like those seen in trumpeter birds. This is because the platelets are solid with no air bubbles, like the platelet melanosomes of these birds. At the time of its description, this also means that Caihong is the earliest known appearance of platelet like melanosomes in the fossil record.
Further Reading
- A bony-crested Jurassic dinosaur with evidence of iridescent plumage highlights complexity in early paravian evolution. - Nature Communications 9(217). - D.-Y. Hu, J. A. Clarke, C. M. Eliason, R. Qiu, Q.-G. Li, M. D. Shawkey, C.-L. Zhao, L. D’Alba, J. K. Jiang & X. Xu - 2018.
