Dinosaur Feathers

Even before Archaeopteryx took flight, dinosaurs were covered in feathers.  What was the point?  Feathers evolved for flight didn’t they?  Many examples of non-flying dinosaur fossils have been discovered with evidence of feathers.   That cute little bird chirping merrily outside your window – the one with the heart of a dinosaur – it uses feathers just for flying right?  If that is the case, then what would have been the point of all of these non-flying dinosaurs sporting feathery attire?

This is the Point!

We use feathers in boas or hats or hair accessories to enhance our desirability.  In Ask a Biologist,23 uses of bird feathers are presented.  I’ve listed a few of the more interesting or less well-known ones below:

  • for warmth – especially downy ones;
  • snow-shoeing – the grouse
  • tobogganing – the penguin
  • bracing or balancing – tail feathers support the bird’s body on the ground;
  • feeling – they are attached to nerves which are stimulated when feathers move;
  • hearing – feathers on the owl create funnels to direct sound to ‘ears’;
  • muffling the sound of flight – in nocturnal birds such as owls, silent flight is important in capturing prey
  • eating – rictal bristles around the mouth aid insect-eating birds in capturing their prey;
  • aiding digestion – some fish-eating birds have a feather-lined digestive tracts to protect against sharp bones;
  • transporting water – some birds soak their belly in water to keep their eggs from drying out and giving chicks a drink;
  • visual signals – to mates and rivals (this is the largest, most used function);
  • camouflage – colors and patterns that blend in with environment and make them harder to see

    It has been argued that dinosaurs did not die out,but just evolved wings and flew away. At a certain level,this reasoning is sound…. Birds, as a group, did descend from dinosaurs and … all 8,600 species of birds living today carry some inheritance from their reptilian ancestors — DAVID RAUP, Extinction: Bad Genes or Bad Luck

So….there are many reasons for the evolution of feathers apart from flight.  What came first, the chicken or the egg?… The dinosaur or the chicken?….. Flight or feathers to attract mates?  The point is feathers evolved before feathered fliers.  There are compelling reasons why this was possible.

 

Relationship of Dinosaurs and Birds and the Reason for Feathers

At the time of Charles Darwin it was thought that birds and dinosaurs might be related.  It wasn’t until over 100 years later that proof began to surface in fossil finds primarily in China.  Many fossilized remains with evidence of feathers have been discovered and it is now known that birds evolved from theropods – medium-sized predatory dinosaurs.  T-rex, velociraptors and the Deinonychus pictured above, made famous in the movie Jurassic Park are all theropods and perhaps had feathers too.  Many feathered dinosaur fossils that predate Archaeopteryx, which some consider one of the first ‘birds’, have been unearthed.

Feathers are unique appendages.  Compared to fur, their structure allows for a variety of color.  Early feathers were similar to mammalian fur and primarily protected the smaller predatory dinosaurs from losing too much body heat.  However, these insulating pre-feathers were mainly in earth tones or black and white much like mammalian fur.  As mammals evolved as mainly nocturnal to avoid larger and faster reptilian predators, lack of color was not a big deal.  However, dinosaurs were active during the day.  The development of broad feathers made of interlocking strands of keratin, allowed the constant refraction of light creating bright color, metallic colors and even color in the UV spectrum.  This development is important because it has been determined through the analysis of genetic relationships that dinosaurs not only have the three color receptors for red, green and blue but they also possess a receptor to see short-wave and UV light like their closest living relatives, birds and crocodiles.

“The prevailing theory is that small Cretaceous theropods evolved feathers for insulation purposes, then benefited from their feathers’ enhanced “lift” while chasing prey (or running away from predators).” — Bob Strauss, Dinosaur Expert

Feathers provided unlimited color and pattern variety while at the same time allowing them, as warm blooded animals, to reduce the loss of body heat.  Communication, attracting mates and thus procreation in addition to insulation were the most important factors in the evolution of feathers in dinosaurs.  These functions of feathers are still important to our modern feathered friends today.  Respect the birds!!  Within their DNA lurks the genes of their feathered dinosaur ancestors!

Want to introduce some dinosaur-themed experiments and activities into your classroom or homeschool?  Check these out!


 

SOURCES

Strauss, Bob.  Why Aren’t Birds Dinosaur-Sized?  About Education.  November 5, 2014.

Universität Bonn. “Seeing dinosaur feathers in a new light.”  October 20, 2014.  ScienceDaily. October 31, 2014.

 

 

 

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