Natural History

Posted in West Virginia, wildlife | Tagged gray squirrel, hickory, squirrel | 3 Comments

3 Responses

1. on July 16, 2012 at 8:11 am Jen Robinson

   And creationists say you can’t explain the evolution of flight? Small Jurassic proto birds and mammals lived in similar habitats (ok, no acorns or hickory nuts). The cost of falling is high, as are the advantages of being able to get across gaps or go to the ground and back quickly. Not to mention the advantages, for predators and insectivores, of swooping to catch your dinner. If you’re a dinosaur, selections favors feathers that do the job; if you’re a mammal, skin folds in the hands (Chiroptera) or between the arm and body (flying squirrels, and in an emergent way, domestic cats) do the job (see, eg http://www.dailymail.co.uk/news/article-2154283/Cats-away-Artist-turns-dead-pet-flying-helicopter-killed-car.html?ITO=1490).

   
   
   • on July 16, 2012 at 9:24 am retrieverman

     I think the issue with bats is that bats evolved so early in the history of mammals that they can’t imagine how it would be so hard to find the transitional forms in the fossil record.

     
     
2. on July 16, 2012 at 10:04 am Jen Robinson

   You probably know this . . . but I can’t refrain. I love paleo.

   The likelihood of finding intermediate forms is sensitive to fossilization potential. The missing links in the genus Homo (Canis also) tend to show up because many of our ancestors lived in semi-arid, generally alkaline environments that are good for preserving bone . . . and they had pretty thick bones and some inhabited caves. Forest critters in general, have poor fossil records cause humic acids of the forest floor decompose bone. Flying critters, being generally light boned, are poor candidates for fossilization. Apart from cave flocking modern bats (who survived through ice ages and developed cave flocking habits to keep warm through the winter), flying critters don’t spend a lot of time in good environments for fossilization. The chance of finding intermediates for Pterodactyls, which I don’t think evolved from tree dwellers (I may be wrong there) is probably greater than that of finding intermediates for bats.

   
   

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