Dinosaurs and the Evolution of Flight



Download 7.98 Kb.
Date20.04.2016
Size7.98 Kb.
Segment excerpted from “Dinosaurs and the Evolution of Flight,”

Science Teacher, January 2013, p. 21


A new study looking at the structure of feathers in birdlike dinosaurs has shed light on one of nature’s most remarkable inventions: flight. Academics at the Universities of Bristol, Yale, and Calgary have shown that prehistoric birds had a much more primitive version of the wings we see today, with rigid layers of feathers acting as simple airfoils for gliding.

Close examination of the earliest theropod dinosaurs suggests that feathers first developed for insulation, arranged in multiple-layers to preserve heat, before their shape evolved for display and camouflage.

As evolution changed the configuration of the feathers, their important role in the aerodynamics and mechanisms of flight became more apparent.

Natural selection over millions of years modified dinosaurs’ forelimbs into highly efficient, feathered wings that could rapidly change their span, shape, and area – a key innovation.

This basic wing configuration has remained more or less the same for the past 130 million years, with bird wings having a layer of long, asymmetrical flight feathers with short, covert feathers on top. Birds can separate and rotate these flight feathers to gain height, change direction, and even hover. This formation allows birds to move in such a way as to produce both lift and thrust simultaneously – a capability that man, with the help of technology, is still trying to successfully imitate.

The research, published in Current Biology, looked at the dinosaur and the Jurassic bird Archaeopteryx lithographica. The latter is 155 million years old and widely considered to be the earliest known bird, presenting a combination of dinosaur and bird characteristics. Its wings differed from modern day birds’ in being composed of multiple layers of long feathers, appearing to represent early experiments in the evolution of the wing.

“By studying fossils carefully, we can now start piecing together how the wing evolved,” said Nicholas Longrich of Yale University. “Before, it seemed that we had more or less modern wings from the Jurassic onward. Now it’s clear that early birds were more primitive and represented transitional forms linking birds to dinosaurs. We can see the wing slowly becoming more advanced as we move from Anchiornis to Archaeopteryx to later birds.


19

34

53



60

74

88



103

109


122

135


154

171


187

206


218

234


251

266


282

286


302

319


334

352


356

Excerpted from: “Headline Science,” Jan. 2013, Current News in Science Research, The Science Teacher, Jan. 2013, p. 21.

http://bit.ly/UfqwDn












Literature in Action – Fluency – Module 5


Share with your friends:


The database is protected by copyright ©essaydocs.org 2019
send message

    Main page