Lecture 6 - functional morphology and behaviour Flashcards
describe part 1 after finding a dinosaur fossil?
-reconstruct the animal - use anatomical knowledge based on nearest living relatives i.e. crocs or birds
describe part 2 of finding a dinosaur fossil
‘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
how do you flesh up a skeleton?
- can be done 3 dimensionally on computers to work out the capabilities of the dinosaur i.e how strong were their legs
describe reconstructing capabilities of dinosaurs - BIOMECHANICS
- has improved dramatically in recent years as technology has improved
- 3D computer animation based on complex engineering algorithms
what use are trackways?
- 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
who came up with dimensionless speed?
Alexander Neil
which dinosaurs were the fastest?
small bipedal theropods and ornithopods - 40km/hr
what were the slowest dinosaurs?
quadrupedal stegosaurs and ankylosaurs
describe reconstructing capabilities - INTELLIGENCE
- measured by EQ (brain size) - compared to body mass
- take endocasts of skulls or CT scans
which dinosaurs famously have very low intelligence?
sauropods
what lifestyle increases intelligence?
living in herds - they must cooperate to avoid predation
which dinosaurs have the biggest brains?
theropods - hunters
why do birds have a high EQ?
as they got smaller their brains got larger helping with the evolution of flight
describe reconstructing capabilities - SENSES
- 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
describe reconstructing capabilities - DIET
- 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)
describe reconstructing capabilities - BEHAVIOUR
- 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
describe reconstructing capabilities - PHYSIOLOGY
- 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
big debate over if they were cold or warm blooded - how can stance and activity levels give evidence of thermoregulatory physiology
- 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
what do adaptations for processing high volumes of food tell you?
- 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
what do haemodynamics (structure of the heart) tell you?
- 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
what does brain size suggest?
brains use alot of energy
- big brains = warm blooded - theropods
- as brains get bigger body gets smaller in the case of birds
what does nose morphology suggest?
- birds have advanced noses to heat up air - most dinosaurs had simple noses
- different arguments have been put forward - no conclusion yet
what can you infer from bone histology and growth rates?
- warm blooded bones and cold blooded bones had different types of secondary growth - however there is debate over how credible this is
what can paleogeography tell us?
it is thought polar dinosaurs must have been cold blooded to withstand the temperatures
how can you work out core and peripheral temperatures?
- 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?
what is one more indicator of thermoregulatory physiology?
predator-prey ratios
what is the conclusion about dinosaurs thermoregulatory physiology?
- 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
one mystery is what the giant bones on the back of the stegosaurs used for - what are suggestions?
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
what is the main accepted hypothesis about the stegosaurs bones?
-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)
