Chapter 8 & 9: Tetrapod Origins

Question 1

Sarcopterygians

Answer 1

Lobe-finned fishes — paraphyletic sense

Monophyletic includes the tetrapods

Question 2

Characteristics of Division Rhipidistia

Answer 2

1. Skull roof bones homologous with skull of tetrapods
2. Proximal paired fin bones homologous with limbs of tetrapods
3. Labyrinthodont teeth present

Question 3

Rhipidistia

Answer 3

Eusthenopteron

Question 4

Taxa of Division Rhipidistia

Answer 4

1. Order Osteolepidoidea

2. Order Elpistostegida

Question 5

Division Tetrapoda

Answer 5

Weird lobe-finned fish that are adapted to life on land

Question 6

Taxa of Division Tetrapoda

Answer 6

1. Amphibia

2. Amniota

Question 7

Amphibia

Answer 7

1. Living amphibians are “tied to water”
2. Reproduction = anamniote eggs
3. Respiration = skin must remain moist

Question 8

Amniota

Answer 8

Mammals, reptiles, and birds

Question 9

Advantages to invasion of land

Answer 9

1. New food resources
2. Avoidance of aquatic predators and competitors
3. Oxygen abundant

Question 10

Disadvantages to invasion of land

Answer 10

1. Water becomes limiting factors in distribution
2. Gravity
3. Water has high heat capacity

Question 11

Tiktaalik

Answer 11

early feet

Question 12

Class Amphibia

Answer 12

A paraphyletic group of non-amniotic tetrapods

Question 13

Anapsids

Answer 13

Dermal skull roof completely covered with bone; turtles are typically included as anapsids; this is primitive for the amniotes

Question 14

Synapsids

Answer 14

Single opening low on the cheek, bordered by the jugal, squamosal, and postorbital; condition found in mammals

Question 15

Diapsids

Answer 15

Two pairs of temporal openings; one pair ventral to the postorbital and squamosal; the second pair dorsal to the postorbital and squamosal and lateral to the parietal

Question 16

Euryapsids

Answer 16

Derived from the diapsid condition by loss of the lower temporal opening; evolved independently in plersiosaurs and ichthyosaurs

Question 17

Plersiosaurs

Answer 17

Lower temporal bar lost

Question 18

Ichthyosaurs

Answer 18

Opening closed by enlargement of bones of the cheek region

Question 19

Characteristics of Amniota

Answer 19

A. Amniotes are fully terrestrial and lay eggs on land
B. Exclusively internal fertilization, no larval stages, no metamorphosis
C. More effective jaw musculature
D. Skeletal structure improved – greater strength and agility
E. Otic notch absent

Question 20

Extraembryonic membranes

Answer 20

1. Amnion
2. Chorion
3. Allantois
4. Yolk sac
5. Albumin

Question 21

Amnion

Answer 21

Inner part of a double membrane that surrounds the embryo; located directly outside of the embryo; encloses the developing embryo

Question 22

Chorion

Answer 22

Outer membrane which is part of the double membrane; located outside of the amnion; serves as a surface for gas exchange through the shell

Question 23

Allantois

Answer 23

A chamber which stores nitrogenous wastes produced by the embryo during development

Question 24

Yolk sac

Answer 24

Contains the embryo’s food and energy reserves in the form of lipids

Question 25

Albumin

Answer 25

Protein source and holds water

Question 26

Characteristics of Class Reptillia

Answer 26

1. A variety of skull characters 2. Skin tough, leathery, and covered with keratinous scales 3. Well-developed lungs 4. Heart has 3 chambers and 4 in crocodiles 5. Ectothermic heterotherms 6. Paired metanephric kidneys 7. Developed nervous system