Iridescent displays by birds play a major role in courtship. Could this be among the reasons that feathers evolved?
From the very beginning, feathers may have served as tools of courtship, raising questions about how important a factor this may have been in their evolution.
According to a University of Texas release, ‘Scientists have uncovered what they say is the detailed feather pattern and colour of Microraptor, a pigeon-sized, four-winged dinosaur that lived about 120 million years ago.’
‘An ancestral form of modern birds, the animal boasted a glossy iridescent sheen, like a crow, and a thin tail adorned with a pair of ‘streamer’ feathers’, researchers have reported in the journal Science.
The investigators compared the patterns of pigment-containing organelles, or cellular compartments, from a Microraptor fossil, with those of modern birds. The findings mark the earliest record of iridescent colour in feathers, they say. A new reconstruction of the dinosaur is also expected to help scientists approach the controversy of how dinosaurs began the transition to flight.
Once thought to be a broad, teardrop-shaped surface or with a shape more like that of a paper aeroplane meant to help generate lift, the Microraptor’s tail fan is actually much narrower, with two long feathers off its tip, researchers say. They believe the tail feathering may have been ornamental rather than practical, and probably evolved for courtship and other social interactions.
“Most aspects of early dinosaur feathering continue to be interpreted as fundamentally aerodynamic, optimised for some aspect of flying,” says Julia Clarke, one of the paper’s co-authors. “Some of these structures were clearly ancestral characteristics that arose for other functions and stuck around, while others may be linked to display behaviours or signalling of mate quality. Feather features were surely shaped by early locomotor [flying] styles. But, as any birder will tell you, feather colours and shapes may also be tied with complex behavioural repertoires and, if anything, may be costly in terms of aerodynamics.”
Based on the new data from the Microraptor and other finds, the scientists contend a complex palette of colours including iridescence is likely ancestral to a lineage of dinosaurs called Paraves that originated at least 140 million years ago and includes dinosaurs such as the Velociraptor as well as the Archaeopteryx, Anchiornis and living birds.