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Lecture 18
Dinosaur Palaeo biology Metabolism and Growth
Dinosaurs models at the time of Richard Olsen
Cold Blooded & Warm Blooded
How long does it take a Velociraptor to reach
adult size?
5 years
Ectothermy and Endothermy are more
Cold/Warm blooded are general terms.
The blood is not actually cold or warm,
but it instead refers to methods of
temperature regulation.
Terms refer to:
Body temperature regulation
Variation in body temperature
Level of resting metabolism
Body Temperature Regulation
Endothermic organisms regulate their body temperature internally and maintain
a nearly constant temperature no matter what the conditions are like outside the
Ectothermic organisms regulate their body temperature externally and the body
temperature responds directly to temperatures of the environment
Body Temperature Variation
Variable or constant
Organism in which the internal body temperature remains constant
Organisms in which the internal body temperature varies
Endothermy is not superior or inferior to ectothermy, nor is homeothermy superior
to poikilothermy.
They are metabolic strategies which are suited to different anatomies and
Resting Metabolism
Level of internal activity
Cellular respiration
Burning food calories
Resting metabolism – level of internal activity when animal is at rest
An animal whose metabolism remains at a high level
burning calories
Metabolic functions at high pace
Typically, but not always endotherms
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An animal whose metabolism slows to a very low level when resting
Typically, but not always ectotherms
Basic biology of metabolism
Metabolism is the process by which all organisms harvest energy and employ it
to drive chemical reactions
Aerobic metabolism
Cellular respiration
Breakdown of carbohydrates (sugar)
If broken through oxidation energy is released
Production of ATP (adenosine triphosphate)
Anaerobic metabolism
Takes place when amount of oxygen supplied through breathing is insufficient
Glycolysis sets in to produce energy
Production of pyruvic acid – lactic acid – muscle pain
Metabolism in Ectotherms vs.Endotherms
Endotherms and Ectotherms vary in regard to the onset of anaerobic
An endotherm’s resting rate is approx. where an ectotherm’s point of lactic
formation occurs.
Endotherms are therefore capable of higher level of activity sustained over
longer periods of time than are their ectothermic counterparts.Warm blooded
animals are likely to walk and run further then reptiles
Ectotherms will generally be more numerous than endotherms because
endotherms cost more energetically to maintain.
What were dinosaurs?
The evidence
Were sauropods Ectothermic?
If it were it would have taken centuries for the sauropods to get that long
Anatomical evidence
Posture and gait
Upright posture and gait – endotherms
Fine neuromuscular control to maintain upright posture – endotherms
Evolution of fully erect posture linked to activity level of endothermy
Long leggedness and bipedalism - endothermy
Speed, levels of activity and agility
Slender, flexible limbs and joints
Balancing tails
Highly active and agile animals
Consistent with endothermic metabolism
Encephalization quotient (EQ)
How large is a brain relative to the skull?
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