Researchers have discovered 161 million-year-old fossils of a tiny bird-like dinosaur named Caihong juji from China that sported flashy rainbow feathers and a bony crest on its snout to attract mates.
According to Julia Clarke, a professor at the University of Texas at Austin, it is the earliest evidence in dinosaurs and the iridescent colouration is well known to be linked to sexual selection and signalling.
Significance of the Discovery
• The dinosaur has features, which are both ancient and modern.
• The bony crest is a feature usually seen in dinosaurs from earlier eras, while its neck feathers show evidence of microscopic wide, flat, pigment-containing packages, or melanosomes, which may represent the first known occurrence of iridescence similar to that found in a variety of hummingbird species living today.
• Caihong is also the earliest known dinosaur with asymmetrical feathers, the feather type found on the wingtips of modern birds, which helps control flight.
• However, unlike birds today, Caihong's asymmetrical feathers were on its tail, not its wings, a finding that suggests that early birds may have had a different steering or flight style.
• The slab of rock from China's Hebei Province where the dinosaur was discovered by a farmer in 2014 contained a nearly complete skeleton surrounded by impressions made by feathers.
• The impressions preserved the shape of the melanosomes.
• Researchers compared the melanosome impressions to melanosomes found in living birds and found that they most closely resembled those in the iridescent, rainbow feathers of hummingbirds.
Caihong is a part of a group of small, bird-like dinosaurs that lived in China during the Jurassic Period, but it stands out even among its closest relatives.
While the other dinosaurs have bird-like, triangular skulls and long forearm bones in comparison to birds today, Caihong had a long and narrow skull and unlike many of these other dinosaurs, its short forelimbs show proportions more similar to modern birds.