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Dinosaurs > Lecture 17: Dinosaur Metabolism > Flashcards

Lecture 17: Dinosaur Metabolism Flashcards

1
Q

What is ectothermy?

A

Cold bloodedness

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2
Q

What is endothermy?

A

Warm bloodedness

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3
Q

Why are ectothermy and endothermy more meaningful?

A

A cold blooded animal can move into the sun and heat up considerably and is not cold blooded anymore

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4
Q

These terms refer to:

A

Body temperature regulation
Variation in body temperature
level of resting metabolism

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5
Q

Body temperature regulation: Endothermy

A

Endothermic organisms regulate their body temperature internally and maintain a nearly constant temperature no matter what the conditions are like outside the body

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6
Q

Body temperature regulation: ectothermy

A

Ectothermic organisms regulate their temperature externally and the body temperature responds directly to temperatures of the environment. An ectotherm regulates body temperature by moving itself to an environment that will allow the animal to heat up cool down, does not use internal biological processes

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7
Q

What is homeotherm?

A

organism in which the internal body temperature remains constant

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8
Q

what is a poikilotherm?

A

organism in which the internal body temperature varies

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9
Q

What are ectothermic poikilotherms?

A

most modern reptiles

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10
Q

What are endothermic poikilotherms?

A

bats and hummingbirds

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11
Q

what are endothermic homeotherms?

A

humans

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12
Q

Endothermy is not superior or inferior to ectothermy

A

2 metabolic strategies which are suited to different anatomies and behaviors

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13
Q

Resting Metabolism

A

Metabolism: level of internal activity, meaning cellular respiration and burning food calories. Resting metabolism- level of internal activity when animal is at rest

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14
Q

What is tachymetabolic?

A

an animal whose metabolism remains at a high level, burning calories, metabolic functions at high place, typically but not always endotherms

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15
Q

What is bradymetabolic?

A

An animal whose metabolism slows to a low level of activity when resting, typically but not always ectotherms

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16
Q

basic biology of metabolism

A

Metabolism is the process by which all organisms harvest energy and employ it to drive chemical reactions. Metabolism takes place in form of cellular respiration, a process by which the energy stored in a glucose molecule is released by oxidation

17
Q

What is cellular respiration

A

breakdown of carbohydrates (sugar) if broken through oxidation energy is released, ATP breaks down into ADP and energy. Heat production when energy is released, point of maximum rate of oxygen consumption, when exceeded lactic acid forms within cells, detrimental to organisms when in great concentrations

18
Q

Anaerobic Metabolism

A

Takes place when amount of oxygen supplied through breathing is insufficient, glycosis sets in to produce energy. Production of pyruvic acid-lactic acid- muscle pain

19
Q

Metabolism in ectotherms vs. Endotherms

A

Endotherms and ectotherms vary in regard to the onset of anaerobic metabolism. An endotherms resting rate is approx. where an ectotherms 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

20
Q

Will ectotherms or endotherms generally be more numerous?

A

Ectotherms, because endotherms cost more energetically to maintain

21
Q

Anatomical evidence

A 
Posture and gait: upright-endotherms, fine neuromuscular control to maintain upright posture, evolution of fully erect posture linked to activity level of endothermy, long leggedness and bipedalism
Speed levels of activity and agility- slender flexible limb joints, balancing tails, high active and agile animals, consistent with endothermic metabolism. Brains (encephalization quotient (EQ) (brain size and EQ exceed that of modern lizards
Feeding adaptations
Body Size (small dinosaurs vs. large dinosaurs)
22
Q

Body size

A

were large dinosaurs mass homeotherms? maintaining a constant temperature
Gigantotherms? maintaining relatively constant temperature bc of their larger size

23
Q

Gigantotermy

A

modified mass homeothermy, large size and relatively slow metabolic rates, control of blood circulation in peripheral tissue, low surface to voulme ratios retains heat, problem of overheating

24
Q

Histological Evidence?

A

Bone Microstructure: Haversian bone, as organisms grow their bones grow with them, bones grow through remodeling, resorption of primary bone, redeposition of secondary bone

25
Q

Haversian bone

A

It is secondary bone has vascular canals, haversian canals, dense haversian bone is only found in endotherms, modern mammals and birds

26
Q

Haversian bone in fossils

A

Dinosaurs, pterosaurs, advanced synapsids (mammals), a variety of factors is responsible for haversian bone: age, nutrients, stress

27
Q

Bone growth

A

Lines of arrested growth (LAG’s) bands in bone- yearly increments. In modern ectotherms Lag’s grow when growth stops due to temperature fluctuations caused by seasonality, not well developed due to preferred regions

28
Q

Growth rates in dinosaurs

A

Comparison of dense haversian bone with overall limb development.
Maiasaura: 3 M per year
LAG’s are in many dinosaurs, responding to seasonally induced temp. changes, lags have not been correlated with climate change yet

29
Q

Ecological evidence

A

Predatory endotherms need more food, predatory ectotherms need less food. Predator-prey ratio for endothermic predators is lower. Dinosaurian communities had low ratio.

30
Q

Zoogeographic evidence

A

Modern ectotherms restricted to tropical regions, dinosaurs migrated in colder regions.

31
Q

Phylogenetic evidence

A

Endotherms have insulation: feathers/fur. So why would the early feathered animals develop insulation when they were ectotherms? A prerequisite for endothermy is a four chamber heart, high blood pressure, provision of high oxygenated blood separated from deoxygenated blood

32
Q

Geochemical evidence

A

oxygen isotope compositions vary with temperature, oxygen isotope composition of bone, measuring the temperature when bone formed.

33
Q

Geochemical evidence in ectotherms vs endotherms

A

Ectotherms: temperature difference between bones in the centre of skeleton and in the extremities
Endotherms: even temperature through circulating fluids of constant temperature

34
Q

Research on T rex bones

A

Temperature difference of 4 degrees or less,was T rex endothermic? Problems: recrystallization of bone, T rex was mass homeotherm rather than true endotherm

35
Q

Active theropods and ornithopods were _____

A

endothermic, others ectothermic?

36
Q

Sauropods and other large dinosaurs were mass homeotherms or ______ as adults

A

Gigantotherms

Dinosaurs (15 decks)

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