Archaeopteryx

Question 1

What are the two antagonistic theories for the origin of flight in birds?

Answer 1

Arboreal (take-off from trees) and cursorial (take-off from running) models

Question 2

Broad acceptance that birds evolved from … and predominantly terrestrial … dinosaurs

Answer 2

bipedal, maniraptoriform

Question 3

despite this, the … model of flight origins has been less successful than the … model

Answer 3

cursorial, arboreal

Question 4

What are the 3 issues contributing to this lack of success?

Answer 4

• Gap between max running speed of Archaeopteryx (2m/s) and its estimated min flying speed (6m/s)
• high energy demands of evolving flight against gravity
• explaining the origin of the ‘flight’ stroke in an earthbound organism

Question 5

This study’s calculations provide a solution to the “… …” problem and shed light on how a … Archaeopteryx (or its cursorial maniraptoriform …) could have achieved the velocity necessary to become airborne by … … …

Answer 5

velocity gap, running, ancestors, flapping feathered wings

Question 6

Evidence in support of archaeopteryx being a tree climber is … … …

Answer 6

weak at best

Question 7

Lacks … muscle of modern birds, which probably limited its capacity for carrying out …, high-… wingbeats

Answer 7

supracoracoid, fast, amplitude

Question 8

Despite this, archaeopteryx’s … musculature was apparently sufficient for …

Answer 8

pectoral, flapping

Question 9

Appears to be predominantly … animal that presumably had to … to take off

Answer 9

terrestrial, run

- flapping wings in similar fashion to large extant birds

Question 10

The bird creates forward … using its … (running) at the same time it … its …. The … increases its running speed

Answer 10

propulsion, hindlimbs, flaps, wings, flapping

Question 11

The residual … due to flapping also relieves the hindlimbs of body weight …, further increasing its … …, and in turn its … ….

Answer 11

lift, support, running speed, residual lift

Question 12

At a certain point, the … … overtakes the bird’s … and so is converted into … … and the bird … …

Answer 12

residual lift, weight, useful lift, takes off

Question 13

… … is now the sole source for generating the velocity necessary for sustained lift

Answer 13

wing thrust

Question 14

Previous calculations for the max running speed of the archaeopteryx assumed that its … alone generated propulsive force and provided … for its full weight during the take off run

Answer 14

hindlimbs, support

Question 15

When the proposed upward force migrations are considered, the study calculated that the Archaeopteryx could run at speeds of …, higher than the 6m/s required for its take off

Answer 15

7.8m/s

Question 16

Thus the … … ceases to exist

Answer 16

“velocity gap”