Sand Bay

Monday the 25^th of February, we went on a short fieldtrip with half the first-year geology group to Sand Bay in Weston-super-Mare, near Bristol.

The rocky shore we were at is within the tidal zone, so during high tide, it lies under water. We were therefore working under considerable time pressure, and the slightest delay could mean the lives of every single member of the group!

No, just joking… (I gave up puns for lent, so I have to make do with other forms of low humour.) The tide does not come in that fast, and as long as you always keep an eye on the water level, you should be fine. The greatest danger here would be standing too close to those cliffs for too long.

But, again, be careful with where you stand, and, if you have to go up close, do it quickly and then go back immediately. If you do that, there is little risk.

The beach was full of round limestone rocks, nicely polished by the washing waves every day. It did not take long before all paleontologists were scanning them for fossils.

As always, there is this mysterious lag period where you walk around, staring at the ground, but find nothing. You bend down to have closer look, but still don’t see a thing of note. It is not until you find the first that the rest start to crop up everywhere, even where just had just passed – which ironically turns out to be packed with nice fossils that you for some reason were blind to a minute ago.

The point of this fieldtrip was to teach us certain geological field skills. The university staff here seems to have a fetish for the word ‘skill’, and gladly apply it to anything that relates to an ability, no matter how undeveloped. I guess it is just that it sounds good when you say that the students are acquiring skills in the field. It makes us sound professional. (The same goes for the word ‘feedback’, but this is not the place to be bitchy about the meaning of words…)

We had four exercises to do. So, get on with it.

I don’t want to sound cranky, but it is difficult not to, when the teachers do not even care to show us how to do the things we are tasked to do in the exercises. Half of us have never done fieldwork in geology before. In the blistering cold winds, and surrounded by fascinating fossils, the motivation for walking around and trying to guess what they want us to do dropped to the bottom.

Luckily, James, Nigel and I had done many of these things before, so we did fine, but there was still much hesitation and standing with the notebook and pencil in cold-shivering hands glaring at an outcrop in front of us, each probably having an internal struggle to find any point in this. We want to search for and find nice fossils!

In the end, we did what we had to, but, in hindsight, it could have been done half as painfully and in half the time if we had just been prepared properly by the staff that has years of experience of these things and therefore should be able to go through each step clearly and give tips from personal experience on how to make things more efficient.

They did not give much introduction to the history of this place, except for the brief notes they had given us in a handout earlier. All we knew was that the rocks were Carboniferous of age and formed in a shallow marine environment, and that there were some volcanic sediments mixed around here as well.

The idea was for us to start to investigate the environment for ourselves and try to puzzle some pieces together, rather than having someone give us all the answers. Brilliant pedagogical thinking, in theory at least. Honestly, I am glad they at least try.

But argh, don’t let me spoil this post by complaining so much! It was a really good day! It had been so long since I saw fossils (in real life).

What I really was hoping to find was a rugose coral, since I don’t have any yet. I have plenty of tabulate corals – the other main type of corals at that time – including my very first fossil. Both types of corals lived on the bottom of shallow seas, filtering food particles directly from the water. That is about as much as they did… (I’m not sure of how they reproduced, but cnidarian life cycles tend to be quite interesting, so maybe the fun bits happened then!) The tabulate corals grew in tight colonies, and so were very important for building ancient reefs; the rugose corals were more solitary.

And some were small enough to bring back home.

What has been preserved is the calcareous outer skeleton it secreted outside its body; the actual animal would live inside, protected from most danger, and let out its tentacles to feed from the currents. Perhaps not the most fantastic of organisms, but they make very nice fossils!

A really amazing one I found embedded in a huge block of rock (too big to carry) (and too stuck in the rock to pick out) could be a rugose coral preserved in very nice, large, clear calcite crystals, but it could also be a crinoid (sea lily), another filter-feeder, but related to starfish and sea urchins.

I found at least one fossil that is surely a crinoid.

But only a cross section of one of the hard plates of its stalk, so not really much to see. Nigel, on the other hand, found a fantastic bit of its mouth and tentacles! It was so incredibly nice, that James and (mostly) I were bitter and jealous for hours (not really, but we pretended, because it was the best we could do… damn Nigel! hahaha).

And as if it was not enough, Nigel later found a huge rugose coral, only half attached to a rock, the other side nicely showing its cone shape. Damn that man again!

I did find a pretty fun crinoid fossil with its stalk plates sort of separated a bit.

I also picked up something I am quite sure is a brachiopod.

And, finally, a rock that looks just like the typical textbook model of dip-slip faults!

(If you are unfamiliar with what that is, don’t worry… it is really only funny if you have seen tons and tons of those diagrams before.)

In two weeks or so, it is time for another fieldtrip, but this time probably with less fossils. *sob*

Preparation for fieldtrip

Today I have done something unprecedented in my time as a student: I have done some background reading on the locality we are visiting on a fieldtrip with the geology group tomorrow. Not really because I feel I need to, but I would like to experiment and see if it does any good.

Much of this year has been about experimenting with how hard I need to work to achieve certain things. Being ‘independent’ means there is many more things that demand time, so realising how much time is needed to spend on schoolwork to achieve a high grade is crucial if I am to do well at university. (So, it is not that I am lazy… hahaha!)

This time, however, I want to test if it is worth the extra effort to be well prepared for a fieldtrip. When it comes to an oral presentation or a written examination, preparation is of course essential, but I suspect a field trip is more or less like a practical or lab session: if you just follow the instructions given when you are there and use your head, everything goes nice and smoothly.

We are going to a site called Sand Bay, near Weston-super-Mare, a bit away from Bristol. We will be examining (early) Carboniferous rocks and fossils – so, quite a bit older than those I saw in Estonia last April. The field guide says there are crinoids, brachiopods and corals. That’s all I need to know. Fossils, here I come!!

On the powerpoint slide they showed us during our safety meeting (which wasn’t about safety at all), there was at least one picture of a rugose coral, so I hope to find one and fill that hole in my collection. Also, if I could find a crinoid calyx (feeding cup) with tentacles, the day would be a success regardless of weather! (Note that I am not allowed to make puns during lent time; that’s why I didn’t this time.)

Then there is also some volcanic stuff…

I really hope they will let us take some fossils back home. (As long as we do the work we are meant to do, I don’t see why not…)

Um… I realised there is really not much more worth mentioning at the moment… I’m sure there will be lots more to tell tomorrow when we come back from the real thing!

Breathing and warm-bloodedness – another old post

Having just started on my science post, and realising it will be longer than expected, I figure I should feed you some of the last useful posts from my old website. Also, this Monday we are having a one-day fieldtrip (we just found out...), so I might bring something worth telling from there as well. Meanwhile, I apologise for the time it is taking to write the big thing up, but stuff keeps coming up that need to be done – such is university! 

Tetrapods (land-living vertebrates) breathe because our internal chemical reactions consume oxygen. Without oxygen, we would simply not be able to live. (This should not surprise you.) 

The chemical reactions in question are described in detail in the article about aerobic and anaerobic metabolism. Here, I will briefly summarise the key points. Aerobic metabolism refers to a series of chemical reactions involved in aerobic cell respiration, which basically uses oxygen to release energy from food for the cells to carry out their functions. There is an alternative way of extracting energy from food without the use of oxygen – anaerobic cell respiration – but it consumes about twenty times as much food to provide a given amount of energy. 

There is a limit to how much oxygen an animal can absorb; this depends on its lung capacity. A large influx of oxygen is essential, because when the oxygen supply cannot meet the energy demand of the cells (e.g. during intense activity), anaerobic cell respiration must be used to supply the additional energy required – which is undesirable since it consumes much more food. 

Lung capacity can partly be related to posture. Dinosaurs, just like mammals and birds (as well as some archosaurs, such as pterosaurs and rauisuchians) had an erect or parasagittal limb posture – they held their limbs vertically under their bodies (seen from the front). This is contrasted by the sprawling limb arrangement of most other reptiles, and amphibians, where the upper bones of the arms and legs are held almost horizontally and pointing away from the trunk.

Picture from http://en.wikipedia.org/wiki/File:Sprawling_and_erect_hip_joints_-_horiz.png

Animals with a sprawling posture move very differently from those with a parasagittal limb arrangement. Sprawlers move by alternately contracting their left and right flanks. This helps moving the limbs forward, making each step considerably longer, but at a fatal cost: when contracting each side, the lungs are also compressed, preventing air from flowing in. Consequently, sprawlers cannot breathe while they run. Thus, their lung capacity, and therefore also oxygen influx, is severely limited during strenuous activity – precisely when they need oxygen the most. When animals with parasagittal limbs move, the lung capacity is not affected. There is, of course, still a limit to how much oxygen they can extract, but the lungs are not impeded by movement, allowing them to maintain a continuous inflow of oxygen, reducing the need for anaerobic supplement. 

How does this relate to warm-bloodedness, then? The above example illustrates that animals with a parasagittal limb posture can rely on a predominantly aerobic metabolism – i.e. they extract their energy mostly by aerobic cell respiration. This allows them to extract more energy from a given amount of food. 

Modern animals with parasagittal limbs (mammals and birds) exploit this advantage by spending a substantial amount of energy on producing heat internally. They can afford this because their energy economy is so efficient. The heat is produced by speeding up chemical reactions in their cells – they are said to have a high basal metabolic rate (BMR), or being tachymetabolic. In other words, they are actively consuming considerable amounts of food even when at rest, in order to keep their bodies warm. Their efficient respiratory system enables them to maintain high metabolic rates even when engaged in active movement.  Sprawlers, however, cannot have high BMRs because their respiratory system is too limited (either, they are not able to maintain elevated metabolic rates even at rest, or the additional demand during strenuous action simply becomes too much). 

Another way the parasagittal limb posture is linked to warm-bloodedness is by activity levels. Warm-blooded animals have a superb advantage over cold-blooded ones because they can be active for a considerably longer proportion of the day. Cold-bloods tend to spend a lot of time lying still, either in ambush or for behavioural thermoregulation (sun basking to warm up, or cooling down in the shade), while mammals and birds are active for a substantial proportion of the day (or night). And a parasagittal stance is designed for being capable of long-term, energy-efficient activity.  

There is nothing saying that dinosaurs must have been tachymetabolic and/or highly active because they had a parasagittal limb posture. But the fact that the only tachymetabolic animals today are those with parasagittal limb arrangement suggests that there is a tight relationship. We may infer that dinosaur at least were capable of being warm-blooded thanks to their erect stance. 

Birds have the by far most efficient respiratory (breathing) system known. For a detailed account of this system, please see the article on birds. In brief, they rely on so-called air sacs – cavities in their bones – where they pass the air after gas exchange (i.e. oxygen has been replaced with carbon dioxide), before it is exhaled; this allows the birds to maintain a continuous flow of air through the lungs – in contrast to other tetrapods, where the lungs are alternately filled and emptied – and so enables optimal oxygen extraction from the air. It is thanks to this ingenious design that birds can fly across oceans in their long seasonal migrations: not only does it allow for extensive aerobic respiration; it also makes their skeletons lighter. 

Ample fossils of dinosaurs with pneumatised bone have been found. This bone contains air cavities like those of birds, inviting the idea that dinosaurs possessed a similar, if not identical respiratory system to that of modern birds. Although few dinosaurs flew, impressive stamina and a light body can provide many advantages, such as allowing predators to engage in fast, lengthy pursuit of prey. 

However, since mammals do not possess such adaptations, bone pneumatisation does not have a strong connection with warm-bloodedness. It is not a requirement, but more of an extension to enhance the efficiency of the fundamental feature – aerobic metabolism. Pneumatic bones supports the idea of dinosaurs as using aerobic metabolism to a considerable extent – perhaps more, perhaps less, than modern warm-bloods. On the other hand, this is not compulsory: it is possible that the sole purpose of the pneumatisation was weight reduction, which may have been important for the larger dinosaur forms. However, this line of reasoning does not explain why the bone pneumatisation was most well-developed in the smaller forms! 

A final piece of evidence related to the aspect of breathing is the possession of a secondary palate – the structure dividing the nasal and oral cavities and so enables breathing while chewing – by hadrosaurids and ankylosaurids, as well as mammals. This is highly useful for herbivores employing extensive chewing of their food. Without the secondary palate, there would have been a greater risk of food ending up in the lungs, if the animal would try to breathe during mastication. The ability to chew and breathe at the same time removes the need to compromise between food and oxygen intake, both being crucial to sustaining a high metabolic rate. 

Now, a secondary palate is by no means necessary for warm-blooded herbivores: birds do not possess them. Moreover, cold-blooded animals such as crocodiles and turtles also have secondary palates, making arguments for dinosaurian warm-bloodedness based on this correlation very weak. Rather, it seems that the secondary palate, like bone pneumatisation, would improve warm-bloodedness, if already present. (Note that it can improve the conditions of cold-blooded animals too – recall the crocodiles and turtles!)

PalQuiz 4 (dinosaur theme!!)

The promised post on the scientific method will take even longer than expected now, because the need to do hard schoolwork and apartment seach for next year has caught up with me, and I need to focus on that. So, for now, I hope I can entertain you with another PalQuiz!

But, first, of course, the answers to the previous quiz.

1.  B is correct here. It is a curious thing that Bakker later turned out to be right about most of his ideas! However, his evidence for it was as poor as his reasoning was sound. Indeed, he writes very eloquently and convincingly. He sounded like he must be right, because he only mentioned the evidence that spoke in favour of his theory, plus the pieces of evidence against it that he could explain away – in other words, his arguments were very very biased. So, Bakker did seem to have good ideas (or lucky guesses?), but was unfit to present them convincingly to more scrutinising readers.

He repeatedly wrote himself that the main friction to his theories were the stubbornness of the contemporary authorities to accept that their ‘orthodox’ view was erroneous. However, this is what he wrote in his book, what he perceived as his main issue. (My intention with this alternative was to set a trap for those who have read the book; if you have, do not feel bad if you were fooled by this – Bakker knows how to make it sound as if he knows what he is talking about.) Naturally, he would not admit that his reasoning was poor and invalid, so he needed another explanation as to why his ideas had not been accepted. Calling the opposition inert morons is a common escape.

The alternative about heredity was the most significant challenge to Darwin’s theory of evolution by natural selection, but does not apply here.

2. The picture (from here) shows a crinoid, colloquially called sea lilies (not sea tulips; I hope I fooled at least someone with that, hehehe). Crinoids are relatives of the echinoid in the picture of the secondquiz, and, like them, have a five-fold symmetry. If you count the number of pinnules (the feather-like thingies that fan out), you can see that there are five pairs of them. The five-fold symmetry is a diagnostic feature of echinoderms, and, within this group, only the crinoids have this typically long stalk through which they attach to the seafloor (some forms have lost their stalk and float around, however). They are filter-feeders, trapping food particles with their pinnules and bringing it to their calyx, which is a round, cup-shaped structure that functions as its mouth. They look deceptively similar to kelps, but are animals, not brown algae. Sea anemones are animals, but of a completely different group – cnidarians, which also includes the medusas – with a similar body symmetry, but not identical: cnidarians have a radial symmetry, meaning that their bodies will form two equal halves if cut in any plane along their long axis (so, if you cut them top-down, centrally in any direction from above, they will produce two identical halves).

Radial vs. bilateral symmetry. Image from http://www.millerandlevine.com/ques/symmetry.html

3. This can be a tricky question, as it requires us to think about what having feathers actually means. What are feathers used for? There are several uses of feathers, just as there are several different types of feathers. Downy feathers are excellent insulatory structures, which is connected to warm-bloodedness (in a way that is too complex to be worthwhile attempting to explain here), which in turn connects to an active lifestyle. Indeed, warm-bloodedness helps nocturnal behaviour, as the animals are warm enough to be active in the cool nights, but the relationship does not go the other way around. Many nocturnal animals are warm-blooded, but few warm-blooded animals (of the total) are nocturnal. Feathers are essential for birds to fly, but all birds that have feathers cannot fly. Natural examples are the ratites (including the ostrich) and penguins (albeit furry-looking, their bodies are actually covered in downy, insulating feathers). Flight feathers are clear adaptations to flight, but all dinosaurs with feathers did not have fathers designed for flying: some were insulatory, as mentioned before, and some were merely ornamental – for visual display – and therefore brightly coloured. If they are covered in colour, it only makes sense to assume that they had colour vision (otherwise, there would be no point in developing special colour pigments and patterns). Therefore, I would say that D is the most correct answer (though that can be discussed…).

4. There are of course various definitions of paleontology, depending on who you ask, really. However, I think the study of extinct organisms is the most precise description. It is not concerned with now-living (extant) organisms, except for when comparing to the fossils. Also, it is not only about fossils; a large part of paleontology is about the past environment and ecology of these organisms.

5. Paleontologists study all of that… not just dinosaurs, unfortunately…

*sob*

This quiz:

1. Which if these dinosaurs did not have a toothless (edentulous) beak?

A. Gallimimus (theropod)

B. Edmontosaurus (ornithopod)

C. Diplodocus (sauropod)

D. Therizinosaurus (theropod)

2. Was Therizinosaurus (Theropoda, Coelurosauria) a…

A. … carnivore (meat-eater)?

B. … herbivore (plant-eater)?

C. … piscivore (fish-eater)?

D. … omnivore (eats basically everything)?

3. What type of dinosaur is this?

A. Coelurosaur (theropod)

B. Heterodontosaurid (ornithopod)

C. Compsognathid (theropod)

D. Plateosaurid (prosauropod)

4. What does this diagram show?

A. The amount of energy each dinosaur type had

B. The hypothetical body temperature of each dinosaur type

C. The relative head size of each dinosaur type, compared to a standard mammal

D. The range of intelligence levels of each dinosaur type

5. Which of the following statements about the ‘Bone Wars’ is true?

i. It was led by Edward Drinker Cope on one side and Othniel Carl Marx on the other

ii. The two leaders named dinosaurs in honour of the other – with insulting meanings

iii. The dispute destroyed a good friendship between the leaders

iv. In his will, Cope donated his brain to science, so that its size could be measured, and urged his rival to do the same, so that it could be proven that he was the more intelligent

v. It resulted in hundreds of new dinosaur discoveries

A. i, ii, v

B. i, iii, v

C. ii, iii, iv, v

D. All statements are true

Giving up bad habits for lent

For lent, the period starting tomorrow and going on until Easter, during which the English (and probably many others) give up bad habits and take up good habits, I have decided to dedicate my giving-ups to making the environment better.

One thing is to stop taking uneccessarily (but oh so nice) long showers. I will not set a time limit, since then I will only be rushed and risk starting to sweat again right after, so it will all be pretty pointless. Instead, I will simply do the washing I need and nothing more. No daydreaming to the sound of pouring and splashing water and enjoying the warmth enveloping you. This just has to stop; I have had my good time so far, but now I will make a serious effort to be less wasteful with hot water.

The other thing I am giving up is puns. Puns are the most pure and wonderful type of jokes, but everyone around me seem to develop aggression issues or suicidal tendencies whenever I make a decent pun (so, on a daily basis, then). It is almost as if they are giving up hope, having lost faith in humanity and despair over their coming years of acquaintance with me.

Therefore, as an act of mercy, and as a test of my dicipline, I will also stop making puns, for the good of the people and the sake of the environment (if they turn to alcohol and drugs to drown their sorrows, they will start littering all over the place...). Making puns is sort of an instinct for me; it is a deeply rooted part of my personality, so fighting the urge to throw out these provocative jokes will not be easy.

But then again, if it was easy, there would be little point in it, and not much of a sacrifice for the greater good!

PalQuiz 3

Here are the answers to the second quiz:

1. Gallimimus is a theropod, the group containing the meat-eating dinosaurs. However, Theropoda also includes some herbivorous dinosaurs, and some groups where the experts disagree about whether they were (predominantly) carnivorous or herbivorous. Gallimimus belongs to the ornithomimid family (so, if you answered B on this question, it is understandable – you fell into my trap – but the ornithopods were a completely different group, including the duck-billed dinosaurs) within the theropod group; many paleontologists have begun to change their views on the feeding habit of this peculiar group: more and more evidence point toward them not being efficient predators, and that they perhaps were mostly plant-eaters. It is indeed a quite intriguing group when you look into it in more detail. Ornithomimdae basically means ‘bird mimic’, and the emphasis is on the word mimic: they are not birds, but very similar in many respects, although their lineage did not give rise to the birds. Gallicusaurus is completely made up…

2. ‘Mammal-like reptiles’ is the colloquial term for the synapsid group – the ‘reptiles’ that were intermediate between ‘reptiles’ and mammals. I put ‘reptiles’ within inverted commas because it is a group that is vanishing from formal use, because scientists have realised that the grouping is chaotic and there is little that unifies them as a group without including non-‘reptiles’. Diapsids are a group that includes most of what we mean by the colloquial term ‘reptiles’ (excluding turtles, but including birds), but none of these were ‘mammal-like’. Cynodonts are indeed a type of advanced synapsids, but all ‘mammal-like reptiles’ are not cynodonts, so B is incorrect. Mammoreptilians is just another word I made up…

3. This was a real tricky question, which I suspect is impossible to figure out if you have not seen an echinoid – or sea urchin – without its spines before. Those knobs you see on the surface are where the spines are held in life. However, if you were aware that sea urchins are echinoderms, i.e. relatives of starfish, and that the group is distinguishable by its five-fold symmetry, you may have noticed that the surface if divided into five plates, each with two parallel rows of spine attachment sites (if you had counted only the spine rows, you would have made out ten, which is divisible by five, so there is a five-fold symmetry). However, I made this one level trickier: both C and D were different types of sea urchins: regular and irregular. This one s a regular echinoid, a form with the mouth facing downward (though that is not easy to see on the picture, I give you that) and a nearly perfectly spherical shell; irregular echinoids have more elongate shells (and shorter spines), because they live as burrowers, so a narrower shape is easier to dig down in the sea bottom.

Picture from here.

Here are some drawings of irregular echinoids, from here.

4. The oldest known land plants appeared in the late Ordovician period, about 450 million years ago, the earliest of the options. They don’t seem to have made much fuss during the following Silurian period, but in the Devonian (when they evolved to be able to grow far away from large water bodies), they spread quickly and widely across land. The next period, the Carboniferous, is known for its vast swamp forests, from which most of our fossil fuels are taken. However, they all originated much earlier, in the Ordovician.

5. Test is the more formal word for the invertebrate shell. Carapace is the shell of turtles, so it could easily be confused. Tectum sounds like it could be an actual latinate term, but I do not know what it would mean in that case… The same goes for urca.

Now, over to the questions for this time.

1. In his book The Dinosaur Heresies (1986), the paleontologist Robert T. Bakker proposed several highly controversial theories about dinosaurs, but was not taken seriously until many years later. Why?

i. He presented poor evidence

ii. His arguments were highly biased

iii. The ‘orthodox’ authorities at that time were too stubborn and close-minded to change their world view

iv. Heredity was no understood at that time

A. i only

B. i and ii

C. iii only

D. All of the above

2. What type of marine organism is this?

 

A. Kelp

B. Sea tulip

C. Crinoid

D. Sea anemone

3. What does the idea of dinosaurs having feathers strongly suggest?

i. They were active animals

ii. They were nocturnal (night-hunting) animals

iii. They could fly

iv. They could see in colour

A. i only

B. iii only

C. ii, iii and iv

D. i and iv

4. Paleontology is…

A. The study of past life

B. The study of fossils

C. The study of extinct organisms

D. The study of fossilised past life

5. What do paleontologists examine?

i. Fossils

ii. Climate

iii. Rocks

iv. Decaying organisms

v.  Living organisms

A. i only

B. i and iii

C. i, iv and v

D. All of the above