To keep warm and to catch the eye
Predatory dinosaurs (theropods) with body plumage are now known to predate Archaeopteryx, and their feathers probably provided thermal insulation. Advanced species of predatory dinosaurs and primitive birds with feathered forelimbs may have used them as balance organs when running, like ostriches do today. Moreover, feathers could have served useful functions in brooding, camouflage and display. Indeed, the feathers on the tail, wings and hind-limbs most probably fulfilled functions in display, although it is very likely that Archaeopteryx was also capable of flight. "Interestingly, the lateral feathers in the tail of Archaeopteryx had an aerodynamic form, and most probably played an important role in its aerial abilities," says Foth.
On the basis of their investigation of the plumage of the new fossil, the researchers have been able to clarify the taxonomical relationship between Archaeopteryx and other species of feathered dinosaur. Here, the diversity in form and distribution of the feather tracts is particularly striking. For instance, among dinosaurs that had feathers on their legs, many had long feathers extending to the toes, while others had shorter down-like plumage. "If feathers had evolved originally for flight, functional constraints should have restricted their range of variation. And in primitive birds we do see less variation in wing feathers than in those on the hind-limbs or the tail," explains Foth.
These observations imply that feathers acquired their aerodynamic functions secondarily: Once feathers had been invented, they could be co-opted for flight. "It is even possible that the ability to fly evolved more than once within the theropods," says Rauhut. "Since the feathers were already present, different groups of predatory dinosaurs and their descendants, the birds, could have expl
|Contact: Luise Dirscherl|