due in 5 hours sharp
Chapter 14 Homework
1. Endothermic metabolisms typically are _____.
2. All living bipeds are _____.
3. Most dinosaurs have relatively high estimated blood pressures; a notable exception is _____.
4. All birds are _____.
d. inertial homeotherms
a. relatively more
b. relatively less
c. relatively the same
d. none of the above
6. True or False–Ectothermy is an inferior type of metabolism.
7. True or False– The possibility of migration supports the case for dinosaur endothermy.
8. True or False– Complex social behaviors are characteristic of many endotherms and uncommon among ectotherms.
Key Terms: While reading Chapter 14, define the following terms.
9. Alveolar lung
10. Blood pressure
11. Bone microstructure
12. Brain complexity
14. Compact bone
17. “Food Processor”
18. Four-chambered heart
24. “Polar night”
25. Respiratory turbinate
27. What are some common misconceptions about ectotherms, and why are they wrong?
28. Which of the 13 lines of evidence presents the most convincing evidence for endothermic dinosaurs? Which presents the weakest?
29. Explain the surface-area-to-volume relationship and its bearing on dinosaur metabolism.
Directions: For this lab you will be able to download the document and TYPE your answers on it. You can then submit it to Dropbox on Pilot. You will also need to utilize your book and/or Google to help with answering the questions.
Laboratory objective: The purpose of this laboratory is to introduce the student to dinosaur metabolism and what factors cause the debate over whether the dinosaurs were cold or warm blooded.
Laboratory discussion: The debate over whether dinosaurs are warm or cold blooded is a complex one. Many factors such as growth rate, respiration, scaling, and temperature regulation can affect the dinosaur’s metabolism.
Part I: Growth Rates
The curves above represent the body mass (in tons) of the giant crocodilian Deinosuchus (line A) and the ceratopsian Triceratops (dashed line B), both of which are found in the Montana Group deposits of the American West.
1) At what age does Triceratops growth level off?
2) At what age does Deinosuchus growth level off?
3) Which of these reptiles grew at a rate more like a modern mammal (i.e., fast)? [Triceratops | Deinosuchus]
Part II: Dinosaur Respiration (Lungs)
Food is only part of metabolism. Another important aspect is respiration: without oxygen, there isn’t much metabolism!! Recent work by Colleen Farmer, David Carrier, and Elizabeth Brainerd on modern animals has revealed a lot more diversity in vertebrate respiration than previously known. For example, mammalian breath (which uses the ribs plus a muscular diaphragm, but doesn’t use a throat pump) is just plain weird!
Here is a look at some of the techniques used to get air down into the lungs:
• Buccal pumping (swallowing air): used by air-breathing fish and amphibians
• Gular pumping (using an actively pumping throat): used by lizards and crocodilians
• Costal breathing (moving ribs in and out): all amniotes but rib bless frogs
• Diaphragm breathing: mammals
• Hepatic piston (liver pumping): crocodilians
• Air Sac pumping: birds
Interestingly, both crocodilians and birds use their pelvic (hip) muscles in breathing. In the figure on the previous page, A is a modern alligator. When the rectus abdominis muscle contracts it pulls the pubis forward, pushing the liver forward and forcing air out of the lungs (expiration). When the ischiopubic and diaphragmatic muscles contract, it pulls the liver backwards, causing the lungs to expand and draw in air (inspiration). B shows respiration in a pigeon. During inspiration the sternum rotates downward and the longissimus dorsi muscles contracts to pull the tail up: together, these inflate some of the air sacs in the body. During expiration the infrapubic and suprapubic abdominal muscles contract to pull the sternum up and the tail down, pushing air out of the sacs. Below is a drawing showing the air sac system of a bird, in left lateral view. C, I, AT, PT, and AB are different individual air sacs—you don’t need to worry about that level of detail. The bold arrows show how the air sacs invade the vertebrae:
Farmer and Carrier have extrapolated back to suggest the following as the ancestral breathing condition for archosaurs (that is, the condition in the common ancestor of birds and crocodilians). To the left below is the primitive archosaurs Euparkeria. As the ischiotruncus muscle contracts, it pulls the gastralia (belly ribs) down, which would expand the lungs. It seems that such a mode of breathing might be possible for primitive theropods. On the next page is the hypothesized breath cycle for Allosaurus.
4) Dinosaurs tend to have long pubis bones and ischia for archosaurs. How might these skeletal changes be related to an increased lung capacity?
5) Ornithischian dinosaurs lack gastralia. Would it be possible for them to use the ancestral archosaur mode of breath?
We see that above are the pelvis’s of some advanced ornithischians, so that the pubis (or the pubis plus ischium) can move relative to the ilium.
6) A is the pelvis of Triceratops in left lateral view. Like other ceratopsids, but unlike more primitive ceratopsians and most other ornithischians, the pubis and ischium can move together as a unit. As the rectus abdominis (RA) muscle contacted, it would have pulled the pubis and ischium forward; as the ischiocaudalis contracted it would have pulled the two bones back. This motion is most similar to the breathing system in [birds | mammals | crocodilians | ancestral archosaurs].
7) Other than advanced ornithopods and ceratopsids, the pelvic elements of ornithischians are immobile. If mobile pelvic elements exist to help increase the oxygen flow, and an increased oxygen flow is an indication of higher metabolic rate, this suggests that the metabolic rates of advanced ornithopods and ceratopsians was [ greater | the same | slower ] than other ornithischians.
Part III: Dinosaur Respiration (Noses)
There is more to breathing than lungs. As physiologist John Ruben has pointed out, endotherms (with their rapid rate of breathing) risk drying out their lungs unless they can recapture moisture during expiration. In mammals this is achieved by a large complex system of nasal turbinate’s (bony scrollwork supporting soft tissues that capture outgoing moisture and humidify incoming air). Birds have smaller nasal turbinate’s, which are part of a more complex system of air sacs in the skull. Incidentally, the avian antorbital fenestra is one region in which such an air sac fits. The antorbital fenestrae of all dinosaurs (and other archosaurs) are presumed to have held such an air sac. Additionally, the skulls of theropods (and coelurosaurs in particular) show that many of the other additional air sacs were present in these dinosaurs.
As an animal size increases, it needs an increasingly large surface area to collect moisture in order to maintain wet lungs. Let’s see if there is evidence for this in dinosaurs. Here is a list of skulls from small and large representatives of some of the major groups of dinosaurs. You will need to find pictures of these skulls and paste them under their names. Then compare the two skulls from each group.
Skull length- 15cm Skull length- 100cm
Skull length- 10cm Skull length- 65cm
Skull length- 10cm Skull length- 50cm
8) In these pairs of dinosaurs, the nares of the larger dinosaurs are proportionately
[Smaller | the same | larger] than in their smaller relatives.
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