Flying Dinosaurs?

In the past decade or so several feathered dinosaur fossils have been found in China. (What? Feathers on dinosaurs!? Didn’t they have scales or leathery skin, like crocodiles?) Feathers rarely last long enough to be fossilized like bones, so these findings have been exceptionally rare; yet several recent discoveries have confirmed that some dinos indeed sported feathers. Until those discoveries, it was thought by paleontologists that only prehistoric birds grew feathers. 

A related finding by scientists in recent years is that birds evolved from dinosaurs. So let's put these two results together: Birds fly and have feathers. Dinosaurs also had feathers but did not fly (among other things, they were too heavy). So what's going on here? What use may feathers have had for dinosaurs? Aren't they supposed to be for flying?

Those who misunderstand the process of evolution are inclined to think that feathers were “designed” for flight. But this is not how evolution works. There is no “intent,” no design to the evolutionary process. Rather, feathers appeared at some point in the deep past (for no “reason” at all), well before birds did—in their ancestral dinos. Hair-like follicles literally began erupting as rudimentary feathers, that slowly evolved into real feathers. When birds later came on the scene, they arrived with these inherited feathers, and then later further evolved the kinds of feathers that enabled them to fly. (Note that not all birds fly; some feathered extant species such as the ostrich can't flap themselves off the ground.) 

So, of what use were feathers to some of the dinosaurs that sprouted plumes; creatures that could not use them to fly? Well, feathers have some advantages over scales and hair, as skin covering. Besides, even today, most types of feathers are not used for flight. (Think of soft down.) Here are some useful functions that feathers can provide, that the flightless dinosaurs may have enjoyed:

1. Insulation—they are excellent for preserving body heat.
2. Colorful and decorative—sexual selection today has resulted in many birds becoming almost psychedelic in appearance, as males seek to attract mates. Dinos may have preceded birds in this swaggering sexual game.
3. Molting—feathers shed and then regrow, allowing a critter to change seasonal color and appearance, or to replace damaged ones.
4. Transformation—feathers can be fanned out and then retracted, to change size and appearance; useful for both sexual selection and to intimidate foes.
5. Maneuvering—feathered appendages can be extended to aid in balancing when running or gliding (the precursor to flying).
6. Defense—horny, stiff feathers can defend a critter, similar to how porcupines and hedgehogs do. (On my 6/17/13 posting, “Whistling Wings,” I wrote about how mourning doves use their wings in battle.)

As an example of a couple of these uses, I once watched my cat round the corner of the house with a bird in its mouth. Lying down to dine on his prize, he momentarily relaxed his jaw and the bird flew away, leaving the stunned cat with a mouthful of dry feathers, which the bird could later regrow.

Science does not yet know what uses dinos may have found for their feathers, or even how feathers further evolved, to be employed for various purposes. So dinosaurs may well have taken advantage of some of the offerings on the list above. We just don't know. Maybe someday more revealing fossils will be found.

New ways of preserving and analyzing fossils are rapidly being developed by paleontologists. DNA analysis is an especially powerful technique. Whether fossils from dinos or mammals or hominids—scientists are rapidly filling the gaps in our understanding of evolution. What fascinating stories they are telling!

(P.S. My 'puter is alive and active again! May it stay so for awhile.)