Birth, Growth and Reproduction

Question 1

what is the term given to the idea that male and female of the same species are actually different

Answer 1

sexual dimorphism

Question 2

it is common for _____ features to be ontogenetic changes

Answer 2

sexual dimorphic

Question 3

Amniotic eggs are:
a) watertight
b) airtight
c) both
d) neither

Answer 3

a) watertight

Question 4

What is the name given to animals that lay amniotic eggs?

Answer 4

amniotes

Question 5

what two dinosaurs did palaeontologists suggest were sexually dimorphic

Answer 5

ceratopsian protoceratops and the ancient bird, confuciusornis

Question 6

What is the evolutionary significance of the amniotic egg?

Answer 6

watertight –> retain water and can be laid in dry habitats –> allow amniotes to colonize terrestrial environments

Question 7

Describe the shell of the an amniotic egg.

Answer 7

• tough, leathery, hard
• has tiny holes

Question 8

Why do amniotic eggs have tiny holes?

Answer 8

allow gas exchange

Question 9

How big is the largest known dinosaur egg? What law explains why there is a limit on how large a dinosaur egg can be?

Answer 9

• largest egg is half a meter long
• cube-square law: amount of oxygen that a dinosaur in an egg requires is a function of its volume

Question 10

What are bone cells called?

Answer 10

osteons

Question 11

TRUE of FALSE: as dinosaurs grow, they add osteons to their bones

Answer 11

TRUE

Question 12

What does LAG stand for? What can they be used to determine? What are LAGs analogous to?

Answer 12

• LAGs - lines of arrested growth (seen as rings in a bone cross-section)
• determines how long it took a dinosaur to grow to a particular size and at what speed it grew
• analogous to rings of a tree trunk

Question 13

what are some ways to determine if the dinosaur was a female or male

Answer 13

1. if the skeleton was found with eggs preserved inside its body cavity - it is a female (other reasons do have to be ruled out, such as eating the eggs before they died)
2. if the dinosaur has grown a medullary bone

Question 14

how does the medullary bone tell us that the dinosaur is a female

Answer 14

in order to lay eggs, the female needs to provide a lot of calcium and the medullary bone contains a large concentration of calcium. the medullary bone acts as a storage prior to the development of the eggs

Question 15

why is the evidence of medullary bone and association with females limited

Answer 15

medullary bone is only grown prior to egg production and not at other times. so if we find a skeleton with medullary bone we cannot assume it is male because it may have been a female that was not ready to lay eggs

Question 16

what are two living relatives of dinosaurs

Answer 16

crocodiles and modern birds

Question 17

true or false - skeletons of young dinosaurs are never found alongside the adult dinosaurs

Answer 17

false - they are

Question 18

what species is the largest of all dinosaurs

Answer 18

sauropods

Question 19

true or false - mother sauropods are able to lay large eggs

Answer 19

false - instead they are able to lay many eggs

Question 20

what kind of strategy did sauropods use in terms of their eggs

Answer 20

predator satiation - they produced so many offspring at one time so that the predators could not have been able to eat them all while young

Question 21

in order to produce a new generation of sauropods….

Answer 21

only a small amount of the eggs laid needed to hatch and mature

Question 22

what other modern animal uses the predator satiation

Answer 22

sea turtles

Question 23

why are female crocodiles good parents

Answer 23

they guard their nests and protect their children for a long period of time after hatching

Question 24

what are examples of amniotes

Answer 24

mammals, birds, dinos and reptiles

Question 25

true or false - growth slows down during winter

Answer 25

true

Question 26

what dinosaur took only 20 years to grow to its adult size

Answer 26

T rex

Question 27

what are two features of bones in younger dinos

Answer 27

high vascularity - many blood vessels
lamellar bone - collagen

Question 28

true or false - younger bones undergo remodeling

Answer 28

false - mature bones do

Question 29

after remodeling, the new bone is called ____ or _____

Answer 29

Haversian or secondary bone

Question 30

what does an external fundamental system tell us

Answer 30

the skeleton of a dinosaur is fully mature and has stopped growing

Question 31

what does the external fundamental system contain

Answer 31

spaced series of lines of arrested growth

Question 32

define ontogenetic changes

Answer 32

changes of an organism as the dinosaur matures

Question 33

given two examples of ontogenetic changes mentioned in the lecture

Answer 33

crests of hadrosaurs formed as they matured

no armour or tail cubs in ankylosaurs until they mature

Question 34

explain the important features of Baby

Answer 34

it is a Chasmosaurus and they provide an example of non-isometric changes
-> the frill on the adult is proportionally longer than the younger one
-> the frill develops at a faster rate than any other part of the skull

Baby also provides an example of ontogenetic changes
-> nasal horn only develops as they mature

Question 35

what is an example of a non-isometric change in T rex

Answer 35

in young dinosaurs, tibia is longer than femur
-> in adults the tibia and femur are the same length

Question 36

________ are changes in absolute size but not proportions

Answer 36

isometric ontogenetic changes

Question 37

provide an example of isometric ontogenetic change

Answer 37

ceratopsian hind legs changed proportionally as it grew

Question 38

what are marrow cavities

Answer 38

they are spaces for medullary bone to grow

Question 39

true or false - eggs are all the same shapes and sizes

Answer 39

false