Lecture 6 - functional morphology and behaviour

Question 1

describe part 1 after finding a dinosaur fossil?

Answer 1

-reconstruct the animal - use anatomical knowledge based on nearest living relatives i.e. crocs or birds

Question 2

describe part 2 of finding a dinosaur fossil

Answer 2

‘fleshing up’ the skeleton - occasionally there is exceptional preservation of soft tissue however more commonly you look at nearest living relatives and how their muscles are attached to their bones

Question 3

how do you flesh up a skeleton?

Answer 3

• can be done 3 dimensionally on computers to work out the capabilities of the dinosaur i.e how strong were their legs

Question 4

describe reconstructing capabilities of dinosaurs - BIOMECHANICS

Answer 4

• has improved dramatically in recent years as technology has improved
• 3D computer animation based on complex engineering algorithms

Question 5

what use are trackways?

Answer 5

• for most animals the length of a footprint is a quarter of the length of the limb - therefore work out length of limbs and measure how far apart the trackways are and you get dimensionless speed to work out how quickly the animal moved

Question 6

who came up with dimensionless speed?

Answer 6

Alexander Neil

Question 7

which dinosaurs were the fastest?

Answer 7

small bipedal theropods and ornithopods - 40km/hr

Question 8

what were the slowest dinosaurs?

Answer 8

quadrupedal stegosaurs and ankylosaurs

Question 9

describe reconstructing capabilities - INTELLIGENCE

Answer 9

• measured by EQ (brain size) - compared to body mass

- take endocasts of skulls or CT scans

Question 10

which dinosaurs famously have very low intelligence?

Answer 10

sauropods

Question 11

what lifestyle increases intelligence?

Answer 11

living in herds - they must cooperate to avoid predation

Question 12

which dinosaurs have the biggest brains?

Answer 12

theropods - hunters

Question 13

why do birds have a high EQ?

Answer 13

as they got smaller their brains got larger helping with the evolution of flight

Question 14

describe reconstructing capabilities - SENSES

Answer 14

• look at eye socket size to understand sight
• know very little about smell but can look at the brains of reptiles and birds to see what part of the brain is used for what

Question 15

describe reconstructing capabilities - DIET

Answer 15

• much easier to reconstruct
• evidence : teeth form, jaw adaptations, co-occurence (what organisms lived together), coprolites , gut contents (gastroliths), fortuitous finds (e.g. animals found in death locks - frozen in time as buried by land slide)

Question 16

describe reconstructing capabilities - BEHAVIOUR

Answer 16

• can often be overinterpreted
• discovery of nests indicates breeding behaviours
• trackways can suggest her compositions and migrations etc
• bones in skull can tell you info e.g. if they butted each other in sexual displays
• ornate skull structures - dimorphism of the sexes
• work out noises made by looking at nasal structures

Question 17

describe reconstructing capabilities - PHYSIOLOGY

Answer 17

• more difficult because you only have the bones - rarely get organs preserved
• size of the animal can be an indicator of physiology - the bigger you are the increasing amount of cystolic pressure is required - huge heart structures to pump blood around

Question 18

big debate over if they were cold or warm blooded - how can stance and activity levels give evidence of thermoregulatory physiology

Answer 18

• if your warm blooded you can be more active
• different groups of dinosaurs have very different stances and levels of activity suggesting some groups were cold blooded and some warm blooded

Question 19

what do adaptations for processing high volumes of food tell you?

Answer 19

• being warm blooded is much more costly - energy requirements are significantly more
• cold blooded animals can eat much more rarely and use up little energy
  e. g. look at the large sauropods, it would be hard for them to eat enough to maintain warm blooded energy levels - opposite for theropods

Question 20

what do haemodynamics (structure of the heart) tell you?

Answer 20

• birds and mammals have 4 chambered hearts
• reptiles have 3 chambered
• crocs have half way between 3 and 4 and have the ability to swap suggesting the could have had warm blooded ancestors
• overall not enough evidence to know when birds 4 chambered hearts evolved

Question 21

what does brain size suggest?

Answer 21

brains use alot of energy

• big brains = warm blooded - theropods
• as brains get bigger body gets smaller in the case of birds

Question 22

what does nose morphology suggest?

Answer 22

• birds have advanced noses to heat up air - most dinosaurs had simple noses
• different arguments have been put forward - no conclusion yet

Question 23

what can you infer from bone histology and growth rates?

Answer 23

• warm blooded bones and cold blooded bones had different types of secondary growth - however there is debate over how credible this is

Question 24

what can paleogeography tell us?

Answer 24

it is thought polar dinosaurs must have been cold blooded to withstand the temperatures

Question 25

how can you work out core and peripheral temperatures?

Answer 25

• certain isotopes from ratios that reflect temperature
• look at dinosaur bones at the extremity of the body and internal bone structures from the centre of the body to work out temp gradient
• in warm blooded animals you dont get as much of a gradient as cold blooded?

Question 26

what is one more indicator of thermoregulatory physiology?

Answer 26

predator-prey ratios

Question 27

what is the conclusion about dinosaurs thermoregulatory physiology?

Answer 27

• still massive debate
• doesnt have to be binary (one or the other) - must have evolved independently in birds and mammals so has it perhaps been lost many times in different lineages based on lifestyle as it is expensive in terms of energy
• or is it something that not only evolves independently but there are different degrees of it

Question 28

one mystery is what the giant bones on the back of the stegosaurs used for - what are suggestions?

Answer 28

1) blood vent through them and they warmed up the blood of the cold blooded animals by basking in the sun - lots of veins suggesting high blood flow
2) used for defence, could flap down over the back - probably wrong as they are incredibly thin and there is no evidence of articulation - however they would make the animal look bigger and couldve been used for sexual display

Question 29

what is the main accepted hypothesis about the stegosaurs bones?

Answer 29

-thought that the initial use was for defence as there is also spines on tail which are most derived and then they evolved a secondary function as they grew all over back
(never really know but can try to test hypotheses)