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Homework Help: Thermodynamics and the frill of members of Ceratopsidae

  1. Nov 24, 2012 #1
    1. The problem statement, all variables and given/known data
    I have to write a ~2000 word essay using principles of fluid mechanics to address whether or not the frill on Triceratops is mainly for behavioral display or for thermoregulation. I'm not really that proficient in my knowledge of physics and have been struggling with quizzes and tests in this class, so I'm hoping to do well on this paper as it's a large chunk of my grade. I have a good source to back up what my professor taught on using fluid dynamics to show how the frill may have been used for thermoregulation, but I feel as though most of my paper is going to end up being on this study, which was not done using fluid mechanics but by studying the bone structure and heat flow measured with oxygen isotopes. I'm worried I may be making errors on what I say regarding physics, and about my lack of knowledge to expand on what was said about fluid mechanics. Help pointing out errors, correcting them, and expanding upon fluid mechanics would be greatly appreciated.

    This is a video of my professor explaining his work using models and fluid mechanics to predict whether the frill was used for thermoregulation.

    3. The attempt at a solution
    This is what I have so far.

    The Triceratops is a well known dinosaur from the Ceratopsidae family, which are characterized by their horns and frills. Past studies, such as The Behavioral Significance of Frill and Horn Morphology in Ceratopsian Dinosaurs by Farlow and Dodson explain the presence of the horn and frill as instrumental in dominance and sexual displays, and in defense. However if thermodynamics and physics are taken into account then one can say that it is more likely that the frill was used to regulate body temperature, and that behavioral use was a secondary function. Triceratops were large homeotherms, and as such had a low thermal diffusivity of body tissues. Large animals have much higher thermal inertias and the Triceratops has a high volume to surface area ratio, so they would therefore lose body heat very slowly. If this animal was exposed to high ambient temperatures or carried out sustained activity, it would likely experience core hyperthermia. The central nervous system (CNS) is very sensitive to high temperatures, and therefore organisms develop ways of moderating their temperatures via physiology to effectively cool the brain to prevent thermal damage to the CNS. The horns of modern bovids are known to play a small part in heat dissipation (Taylor 1966) and therefore it is likely that they did such in the horns of Ceratopsids as well. The frill found in members of Certopsidae has a large surface area and were highly vascularized, and due to this would be useful in dissipating heat from the body If these structures were used as “biological heat radiators” (cite) then they would have a way to radiate excess heat from the body into the environment and prevent hyperthermia and harm to the brain. (Wheeler 1978)

    As Triceratops are extinct, it is not possible to use one in studies to discover the actual use of the frill. However, using the Reynold's number one can estimate how thermodynamics acting upon a small triceratops model might apply to the extinct dinosaur. By calculating a Reynold's number for the small model in water using the size of the model and velocity of water, you can match that Reynold's number to the actual historic dinosaur at a certain wind velocity.

    Turner, a physiologist at SUNY-ESF, performed a small experiment using a calculated Reynold's number, a small 0.18 meter (m) Triceratops model, and fluorescent dye in water moving at a velocity of 0.03 m/s to visualize how air at a velocity of 0.01 m/s would affect a 9 m Triceratops. He found that when the water was angled towards the dinosaur model from high off the ground, the frill diverted air upwards off the back. Closer to the frill produced a vigorous generation of turbulent vortexes on the frill margin, and retained these along the rear surface of the frill. Further down the forehead produced a strong retrograde flow. Turbulence was generated when the flow was coming at the Triceratops from eye level, and produced vigorous turbulence behind the frill. When the horn was involved a retrograde flow was produced along the snout and horn. When the flow was lateral to eye level, the frill diverted air flow towards itself. When the flow was coming from behind it promoted heat exchange along the Triceratops' face. Models with smaller frills did not generate much turbulence when the flow was directed at their face, but from behind generated considerable turbulence. This brings to the conclusion that when a Triceratops is standing into the wind there is a strong generation of turbulence along frill margins. When downwind, there is a strong retrograde flow on the front surface of the frill. Both of these promote heat exchange.

    A study done by various scientists, published in 1998 in the Journal of Vertebrate Paleontology, specifically set out to research what part the frill and horns of Triceratops might play in thermoregulation... (this is where I'm starting implementing the other study, but I haven't gotten to it as of yet.)
  2. jcsd
  3. Nov 25, 2012 #2
    Anyone? Even if you do not have the time to suggest things to further the thermodynamics of fluids or go over it in depth, does the way I explained the fluid mechanics seem correct?
  4. Nov 25, 2012 #3


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    Homework Helper

    The physiology/physics sounds reasonable at first glance. The paragraph needs to be edited for grammar and style (switching between it/are in the first sentence, a missing punctuation mark or two throughout the paragraph, different typeface or something to indicate the book/paper/study name are a few things I noticed).

    I would specify that you are calculating the Reynolds number of the air. At first I thought you were going to calculating the Reynolds number of the blood in the frill and was wondering what the point of that was before I realized you wanted to calculate it for the air (and water in the model situation). I would also elaborate on the meaning of the Reynolds number in your paper. What is it, and what is its significance? Do you know? You should usually assume your reader doesn't know these sorts of things.

    I would explicitly say how the air flows promote heat exchange. The paragraph as it just says they do, not why or how. It's leaving it up to the reader to make the connection between turbulent air flows and heat exchange. Why doesn't laminar flow help with heat exchange?

    Some other things you might look into for your paper are how rabbit ears help with thermoregulation. Whales might also be another good example to look at (though there it might be a reverse case, as they are trying to keep in heat). Specifically, I might try to understand how blood flow in the ears of rabbits helps with thermoregulation, and think about if any of those principles apply to the Triceratops. It might help with some heat exchange in the frill, I would guess, but in the rest of the triceratops it probably won't help much unless the Triceratops body is very good at pumping blood from the body through the frill. I don't know much about hypothetical Triceratops physiology, so I'm not sure a dinosaur could efficiently pump blood through that frill to help with heat loss. It might be only a second order effect and the air flows over the bulk of the dinosaur's body are responsible for most of the heat exchange. It's just a thought.
  5. Nov 26, 2012 #4
    Thank-you for your help! I've now explained the Reynolds number, how air flow and turbulence increases convection, and information about how hares' ears work in helping regulate body temperature.
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