Chapter 2

Question 1

Who claimed birds are “merely glorified reptiles”?

Answer 1

Thomas Huxley, 1867

Question 2

What are 6 characteristics birds share with reptiles?

Answer 2

1. single occipital condyle
2. Three or more mandibular bones on each side
3. one middle earbone (columellar bone or stapes)
4. ankles located in middle of tarsal bones
5. scales on legs of birds similar to reptillian scales in structure
6. feathers and scales of birds are formed of the same protein

Question 3

What is used to depict the history of shared evolutionary relationships

Answer 3

Phylogenetic tree

Question 3

What is the protein that both scales and feathers are mode of

Answer 3

B-Keratin

Question 4

What indicates divergence of lineages or speciation events on a phylogenetic tree?

Answer 4

Node, or branching point

Question 5

Includes all decendents of a single common ancestor, as well as the ancestor

Answer 5

Monophyletic groups (clades)

Question 6

Feathers are a ________ _______, which means it is a trait that originated once in a common ancestor, exclusive of all other living invertebrates, and has been maintained in all members of the lineage

Answer 6

derived character

Question 7

What is the oldest fossilized bird and when did it live?

Answer 7

Archaeopteryx lithographica, between 155 and 135mya.

Question 8

When were Archaeopteryx fossils first discovered?

Answer 8

1860’s and 1870’s

Question 9

What was the size of Archaeopteryx?

Answer 9

crow sized

Question 10

Reptilian traits of Archaeopteryx:

Answer 10

• small teeth
• long, bony tail
• reptille-like cranial bones
• unfused hand bones
• unfused pelvic bones
• lack of a well-developed keel
• free ribs
• claws on each digit

Question 11

Avian traits of Archaeopteryx:

Answer 11

• feathers on wings and tail
• furcula
• partially-fused metatarus
• first toe pointed backwards (hallux)
• backward-pointing pubis

Question 12

Were Archaeopteryx wing shafts asymmetrical or symmetrical?

Answer 12

asymmetrical

Question 13

Archaeopteryx was most likely ______, but was capable of weak flapping and gliding.

Answer 13

terrestrial

Question 14

Historically, many ornithologists thought that birds evolved directly from an early group of reptiles called the…

Answer 14

thecodonts

Question 15

based on abundant evidence to support the hypothesis, most evolutionary biologists would agree that birds evolved from a group of dinosaurs known as the…

Answer 15

theropods

Question 16

How were dinosaures classified?

Answer 16

By their hip structure

Question 17

Lizard-hipped dinosaur order

Answer 17

Saurischian

Question 18

Bird-hipped dinosaur order

Answer 18

Ornithischian

Question 19

Hadrosaures and iguanodontids are part of the clade

Answer 19

Ornithopods

Question 20

Ceratopsians are part of the clade

Answer 20

Marginocephalia

Question 21

Stegosaurids and Ankylosaurids are part of the clade

Answer 21

Thyreophora

Question 22

What are the clades of Order Ornithischian

Answer 22

1. Thyreophora
2. Marginocephalia
3. Ornithopods

Question 23

Are Ornithischian or Saurischians the likely ancestors of birds?

Answer 23

Saurischians, even though they are “lizard-hipped”

Question 24

What are the clades of Order Saurischians?

Answer 24

1. Theropods
2. Sauropods

Question 25

Bipedal carnivores like Tyrannosourus rex and Velociraptor are clade

Answer 25

Theropods

Question 26

Quadrupedal herbivores like Brachiosaurus and Diplodocus are clade

Answer 26

Sauropods

Question 27

Evidence that birds evolved from theropods:

Answer 27

1. pubic boot
2. three fingered, grasping manus (hand) and a four fingered foot

Question 28

Evidence that Birds Evolved from Coelurosaurians (Theropods)

Answer 28

• hollow (pneumatic) ribs, vertebrae, and wing bones
• Anteriar and posterior air sacs
• clavicles fuzed to form a furcula
• presence of feathers in a variety of theropods

Question 29

Criticisms of the Evolution of Birds from the Theropoda

Answer 29

• Although the clavicles of theropods were fused, they did not have the structure of a real furcula.
• Feathers in theropods may have evolved independently.
• fossils resembling modern birds have been aged to 140 mya, while most interesting theropod fossils date <100mya. Archaeopteryx is dated to 145mya

Question 30

Sinornis santensis lived ___ mya and was a toothed, ____ sized bird

Answer 30

140 mya, sparrow sized

Question 31

What were the traits that make Sinornis santensis an intermediate of Archeaopteryx and modern birds?

Answer 31

the skeleton (especially the pectoral girdle and forelimbs) that improved the ability to fly

Question 32

What bird lived 120 mya, was crow sized, and had 3-fingered forelimbs?

Answer 32

Confuciusornis sanctus

Question 33

What was the earlist known bird that could fly for some distance?

Answer 33

Confuciusornis sanctus

Question 34

What lived 115mya and was sparrow sized.

Answer 34

Eoalulavis

Question 35

What gave Eoalulavis imporved flying abilities?

Answer 35

Presence of the alula, a group of feathers along the front edge of the wing that can be controlled separately. This reduced air turbulence over the top of the wing to reduce drag and prevent atalling. Allowed impoved agility .

Question 36

Toothed, loon-like divers with small wings 100-65mya

Answer 36

Hesperornis

Question 37

Toothed, tern-like birds 100-65 mya

Answer 37

Ichthyornis

Question 38

When did modern birds develop?

Answer 38

Approximately 60 mya

Question 39

During the gap between Archeaopteryx and modern birds, what modern traits emerged?

Answer 39

Shorter tails, lack of teeth, tarsometatarsus, alula, uncinate processes, more pneumatic bones.

Question 40

What are the two hypothesis for why/how feathers may have evolved?

Answer 40

1. may have evolved for flight
2. may have evolved for temperature regulation

Question 41

Arboreal Theory

Answer 41

Parachuting and gliding from elevated perches was the first stage in the evolution of flight. Longer glides would have been aided by flapping

Question 42

Cursorial Theory

Answer 42

Forelimbs evolved into wing-like structures because they heightened the leaping ability of bipedal terrestrial reptiles as they jumped in the air for insect prey. The feathers and elongated forelimbs and tail would have increased maneuverability and may have eventually led to flight.