|Notice the fearful claws & and the murderous look in his eye? Black-capped Chickadee photo by Eric Bégin.|
Yesterday, as I pulled out of the garage, something in the driver’s side view mirror caught my eye. A fuzzy ball of black and white—a bit larger than a prickly gumballs—came crashing down from the sweet gum tree. Then the ball broke apart into at least three Carolina Chickadees. They rolled on the ground, kicking, punching, and talking about each other’s mommas.
I recently attended a presentation by David Peters about the evolution of birds, sponsored by Webster Groves Nature Study Society, St. Louis Audubon and Eastern Missouri Society for Paleontology. The boundary of the Cretaceous and Jurassic is not my area, so most of what was said went right over my head. I apologize in advance for the mistakes I'm about to make. Peters’ theories about the taxonomy of pterosaurs is somewhat controversial; again, for reasons that are beyond me. His website is fascinating. He explained how the shoulder (coracoid bone) and fused clavicles (furcula, or wishbone) allowed the arm/front leg of a reptile to become the abducted, elongated wrist/claw/wing of a pterosaur.
|Largest pterosaur, by Mark Witton|
Now I hadn’t really thought of pterosaurs as the direct ancestors of birds. They looked like bats to me. I didn’t realize they had the modified scales we call feathers. Think of Quetzalcoatlus—the largest pterosaur, with a 40-foot wingspan, a spear-shaped head, and a ring finger that functioned as the wing. It looked even less like a bird when Peters analyzed the fossils of its tracks, demonstrating that it walked on its wings/knuckles like a reptile walks with its front limbs.
When he showed Nemicolopterus crypticus, another pterosaur with a wingspan roughly the same as a chickadee’s, I began to see the family resemblance. The ruckus under the sweet gum makes more sense now that I no longer see them as charming chickadees, but tiny, terrible, pterosaurs.