Last post, I covered two of the six most common mistakes people make in their thinking. Today I will cover the next two: appreciating the role of chance and misperceiving the world around us. Both of these are huge topics, so as Inigo Montoya said, “Let me ‘splain. No, there is too much, let me sum up.” 3. We rarely appreciate the role of chance and coincidence in shaping events. Last time we discussed just how much people hate and misuse statistics. Another way our inbred antipathy for statistics comes into play is not understanding the role of chance. People seem to need to have a cause for everything. If something goes wrong, something must be to blame. We hate to admit that anything is left to chance (which, considering that quantum physics makes everything in the universe a probability, make explain why people don’t understand it). As even Einstein said, “God doesn’t play dice with the world.” However, given enough time or occurrences, even rare events occur. I once had a geology professor who told me that given enough time, events that are almost impossible become likely and rare events become commonplace. This is quite true, over enough time and with enough attempts, even the rarest events will happen. Sometime in your life, you are almost certainly going to see something that is incredibly, inconceivably rare. People talk about 1 in a million chances being so rare as to be inconceivable and not worth thinking about, but that chance happens to over 7000 people worldwide, it will happen to eight in New York alone. Occasionally, you will be among that 7000.
Have you ever called someone only to find out they were trying to call you at the same time? I have done that with my wife. Many people invoke something mystical or a psychic connection that made us call at exactly the right time because surely, what are the chances of two people just happening to call each other at the exact same time? However, I talk to my wife on the phone far more often than I talk to anyone else. Considering the number of times that my wife and I try to contact each other, it is almost inevitable that sooner or later, we would try at the same time. There are those that seem to be consistently lucky or unlucky. If it were really just random chance, then it should all even out and everyone should be equally lucky (or not), right? Here again, with enough people, some people will just randomly be consistently luckier than others, no supernatural force required. There will always be outliers that don’t follow the typical pattern just through random chance.
You can see this same type of mistake when people incorrectly tie independent chances together. When flipping a coin, a string of 20 heads will do nothing to change the chance that the next flip will be heads or tails. This sort of mistake is often seen in gamblers and people playing sports in their belief of winning and losing streaks, in which the results of a series of chance occurrences is thought to affect the odds of future events. So how do we avoid this mistake? Never put much stock in one occurrence. Look at the accumulated data and weigh occurrences accordingly.
Probably one of the biggest fallacies people make in this regard is mistaking correlation for causation. Just because two events occur at the same time does not necessarily mean they are connected. Wearing a specific shirt when you win a game does not make it lucky. It will not influence the outcome of any other game except in how it affects your thinking. I can think of no better example of this than the Hemline Theory, which states that women’s skirt lengths are tied to the stock market. Sadly, despite such an absurd premise, it is still commonly believed and one can still find articles debating the merits of the hypothesis. Needless to say, even if they do tend to cycle together, it would be foolish to say that the stock market is controlled by what skirts women are wearing. What might be plausible is that both are influenced by some common factor. Thus, any study which claims to have found a correlation between two events or patterns has only taken the first step. Once a correlation has been found, it is then necessary to demonstrate how one affects the other. Often, it is found that there is no direct connection, but they may both be influenced by an altogether different factor. Check out the site Spurious Correlations to see almost 30,000 graphs showing correlations between totally random occurrences, such as the graph showing that increased Iphone sales are correlated with a drop in rainfall in Mexico, or that US STEM spending is associated with the suicide rate. How to avoid this problem? Look for multiple lines of evidence and a causal mechanism that explains how one could affect the other. Without that mechanism, you can only say that two things have something in common, you should avoid saying one thing caused the other until you can point to a direct connection.
4. We sometimes misperceive the world around us. Many people make the assumption that that their eyes work like cameras, recording faithfully everything in their field of view and the brain accurately records everything that goes into it. Unfortunately, this is not true. Our senses are imperfect. They neither record all the information, nor does the brain provide a complete image of what is around you. Simply put, you cannot trust your senses. Magicians count on this. One of the best I have seen is Derren Brown, who uses a mixture of psychology and good old-fashioned stage magic to perform his tricks. Visual and aural illusions abound. Take our eyes for example. Unlike a video camera that records the whole scene within the confines of its lens at the same time. We put together images from fragments. We rapidly move our eyes all around our field of view in what are called saccades, focusing on one small bit, then another. The light enters the eye and is picked up by the retina, with rods detecting intensity of light and cones detecting color. Signals from these receptors do not enter the brain as a picture. They are filtered through specialized cells, some of which detect boundaries to sharpen focus, some detect movement, etc. All of these separate signals gets sent to the brain which puts together a patchwork image, an image with a lot of gaps. We don’t usually see these gaps because our brains fill them in with what past experience tells it to expect. This is a really important point. Past experience affects what we see. Our hearing works this way as well.
The fact that past experience affects what we see plays out in various ways. We overlook things that change between eye movements. We fill in the gaps with what we expect to see. Thus, how we view the world is in part dependent on what we expect to see and our expectations are based on our experiences. People with different experiences may view the same thing very differently. This happens so much that when we see something that does not fit our expectations, our brains can even go the point of overwriting the visual input with our prior expectations. And it gets worse. If we focus on something, this tendency to be blinded to other things increases. Most people have heard of ignoring the elephant in the room. A couple of researchers at Harvard did what they call the invisible gorilla experiment. People were asked to observe a group of people wearing shirts that were two different colors. They were told to count the number of times a ball was passed between members of the group wearing the same color shirt. Most people could successfully do this. However, many people missed the man in a gorilla suit who walked into the middle of the group, paused to look at them, and then walked off.
How could someone miss such an obvious thing? They were focused on the ball and missed the bigger picture. This problem is called selective attention or “inattentional blindness.”. This experiment has been done with hearing, in which the participants were to listen to only one of two conversations going on at the same time. This time, part way through, someone started saying, “I’m a gorilla,” multiple times. If just told to listen to the recording, everyone could hear it easily. But if told to listen carefully to only one conversation, most people never heard the gorilla. There are many, many examples like this of selective attention. This is exactly why eyewitness accounts in trials are not worth very much. You might hope it stopped at this level, but it doesn’t. Even if we accurately see what is there, our prejudices will affect our interpretation. Different colors affect our moods and perceptions. Religious or political beliefs affect our perceptions to the point we will literally see things differently, even our views of sports games. Space allows only a cursory mention here, but it is easy to find many, many studies, books, and shows that demonstrate just how unreliable our personal observations are. So how do we avoid this? To begin with, we recognize that our perceptions are fallible. Thus, the more independent observations we can make and the more people that observe it, the more likely it is to be valid. Take recordings that can be viewed and listened to at different times. Try this out for yourself. Watch a movie with other people. Have someone prepare a list of questions in advance about a particular scene. After everyone has viewed it, have everyone answer the questions on their own and then compare them. Most likely, you will find some things people answered differently, other things some people did not see at all. Or just listen to the responses from political leaders after any speech by any President. The best way to get around this problem is through multiple, independent observations. Never trust just one observation and always question the biases of the observer.
Next post we will wrap up this series with the last two common mistakes. Stay tuned.
When I was a kid, I was always taught the scientific method is a matter of developing hypotheses, testing them, and using the observations from the tests to revise the hypotheses. Very straightforward, but overly simplistic. My teachers rarely, if ever, talked about the crucial strategy of multiple working hypotheses, coming up with every imaginable way that could explain our observations before we started trying to test them. But the most important thing that was never taught was how to think explicitly and clearly. Logical and clear thinking is the heart and soul of science. In fact, there is no decision that cannot be improved by clearly thinking about the question and the available data. We just celebrated Independence Day in the United States. It is time we celebrate our independence from fuzzy, ill-defined, and confused thinking. In the last post, I discussed the critical importance of clearly defining a problem in terms of actionable questions. The first step is to understand a problem well enough that it can be clearly articulated and defined. Then all factors that contribute to the problem can be clarified. But you can’t stop there. Once you have a list of known factors, you have to decide which ones you can actually do something about and not waste time arguing about those you can’t change. Focusing on the definable and workable factors produces results. Wasting time on things you can do nothing about is counterproductive. In this post, I am going to briefly discuss the first three of six general mistakes that EVERYONE makes from time to time. You can never be completely rid of them, but you can be aware of them and try to reduce their influence in your life. If you do this, I promise you will make better decisions. You will improve your life and the lives of those you touch. These six mistakes are outlined and fully discussed in the book Don’t Believe Everything You Think: The 6 Basic Mistakes We Make in Thinking, by Thomas Kida. I highly recommend you get this book and read it.
1. We prefer stories to statistics. People are terrible at statistics, even people who really should know better, so bad in fact, that they make them up to sound smart. You can easily find numerous variations of the statement, “80% of all statistics are made up on the spot, including this one.” Or, as often (likely incorrectly) attributed to Mark Twain, “there are three kinds of lies: lies, damn lies, and statistics.” So it’s no wonder that people suck at them and prefer stories. There are abundant studies illustrating how our brains are wired to listen to stories, how personal stories influence our behavior more than statistics, such as this one, or this one. Statistics happen to abstract groups, stories happen to identifiable people. We even prefer to dress up our information to make it more personal, more interesting, but the very act of storifying information makes that information less likely to be true. It is much more likely that Bill robbed Peter than it is that Bill robbed Peter AND paid Paul. The more complicated things get, the less likely. But this mental shortcut can cause serious problems. This is well illustrated by the anti-vaccination scaremongering going about. The whole anti-vax movement can really be traced to one report by Dr. Andrew Wakefield in 1998 that found a correlation between vaccines and autism, research that has been completely discredited and proven fraudulent. Since then numerous studies have linked into the alleged link and found nothing, such as this one. But no matter how many studies find no link, many people hear Jenny McCarthy talk about her autistic son, they hear others talk about their autistic children, and come to the conclusion that all the studies must be wrong, because the stories carry more weight with them. Disregarding the millions of children who get vaccines that never develop autism, people focus only on the stories of people that claim otherwise. Thus, thousands of children are getting sick and dying because of a belief in stories over statistics.
2. We seek to confirm, not to question. Have you ever read something that you disagreed with and instantly dismissed it or conversely, have you ever accepted evidence simply because it agreed with what you thought? If so (and you have, everyone does), you are guilty of confirmation bias. Confirmation bias causes people to seek out and weigh information that already agrees with their point of view and disregard evidence that disagrees with them without ever really analyzing the data. If you get all your news from either FOXNews or MSNBC, you are likely to rarely, if ever, hear contrary points of view and are thereby limiting input to only that which you already agree. Thus, people who do so will weigh that evidence in favor of their preconceptions and will assume that their view is more prevalent than it really is. If one gets all their information about evolution from the Institute for Creation Research, they will never get accurate information about the theory as the ICR is based on the belief that evolution is false, so they seek only information that discounts it. The only way to avoid this is to seek out diverse news outlets. While you read them, remind yourself that you will suffer from confirmation bias, so you may (hopefully) be able to give evidence from all sides a thorough critique.
Lest you think that only untrained laymen fall into this trap, confirmatory bias is rampant in science as well and it is a serious problem. Even the ivied halls of Harvard do not protect one from poor thinking and confirmatory bias as this article by Neuroskeptic clearly illustrates wherein he takes a fellow neuroscientist to task for not recognizing the fallacy of only looking for confirmatory results. There is a publication bias in the scientific literature towards positive results, the negative results get mentioned much less often. While this is true in all fields, it is particularly important in medical research, and psychology research has been hit particularly hard lately.
Next post, I will cover the next two common mistakes. Stay tuned.
If ink was blood, the discussion of the lack of women in STEM fields would exsanguinate the whole of the human species. Yet for all the talk, the problem remains. Why? Let me answer that by bringing to your attention a post by Dr. Janet Stemwedel, a professor of philosophy at San José State University who writes on this and other topics concerning the thinking underlying how science is done. The post is not long, so I will post most of it here, you may find the original here. To clarify the post in case it doesn’t come across clearly: she quotes a block of text discussing the gender gap in the sciences and then provides her response to it.
However, there are times when people seem to lose the thread when they spin their causal stories. For example:
“The point of focusing on innate psychological differences is not to draw attention away from anti-female discrimination. The research clearly shows that such discrimination exists—among other things, women seem to be paid less for equal work. Nor does it imply that the sexes have nothing in common. Quite frankly, the opposite is true. Nor does it imply that women—or men—are blameworthy for their attributes.
Rather, the point is that anti-female discrimination isn’t the only cause of the gender gap. As we learn more about sex differences, we’ve built better theories to explain the non-identical distribution of the sexes among the sciences. Science is always tentative, but the latest research suggests that discrimination has a weaker impact than people might think, and that innate sex differences explain quite a lot.”
What I’m seeing here is a claim that amounts to “there would still be a gender gap in the sciences even if we eliminated anti-female discrimination” — in other words, that the causal powers of innate sex differences would be enough to create a gender gap.
To this claim, I would like to suggest:
1. that there is absolutely no reason not to work to eliminate anti-female discrimination; whether or not there are other causes that are harder to change, such discrimination seems like something we can change, and it has negative effects on those subject to it;
2. that is is an empirical question whether, in the absence of anti-female discrimination, there would still be a gender gap in the sciences; given the complexity of humans and their social structures, controlled studies in psychology are models of real life that abstract away lots of details*, and when the rubber hits the road in the real phenomena we are modeling, things may play out differently.
Let’s settle the question of how much anti-female discrimination matters by getting rid of it.
Dr. Stemwedel hits directly on a error that is seen throughout every facet of social interactions, to say nothing of public understanding of science. The discussion had strayed into unproductive areas and away from any attempt to resolve the problem. Dr. Stemwedel attempted to bring the focus back to the problem needing to be solved.
In this instance, going back to the original post to which Dr. Stemwedel was responding, the initial question put to Neil DeGrasse Tyson was “Why are there fewer women in science?” The true answer to that question is that there are multiple reasons for the gender gap, one of which happens to be that there is a clear discriminatory bias against women in science (this fact is so well documented that linking to only one or two articles seems pointless as a quick Google search will immediately turn up a very long list of sources). Tyson did not deny there were other factors, but he focused on the sociological aspect as that problem is highly prevalent and something that can be changed.
Chris Martin, the author of the post Dr. Stemwedel was responding to, goes to great lengths to talk about all the other issues involved in the gender gap, ignoring the reason Tyson focused on the sociologic aspect. Contrary to the claims of Mr. Martin, the point was indeed to draw attention away from anti-female discrimination. He clearly states in his post that he believes evolutionary pressures explain the gender gap better than sociological ones and that the sociological factors are therefore unimportant. His whole post is a response to the assertion that this bias prevents many women from entering the field.
Unfortunately for Mr. Martin, the evolutionary factors Mr. Martin espoused are not as well understood and nowhere near as well documented in humans as is the discrimination against women. But here is the important thing: We can’t do anything about past evolutionary pressures. We CAN do something about the discrimination. No one is arguing there aren’t other reasons. But if you want to solve the problem, you focus on the aspects of the problem you can fix.
This problem in thinking is so widespread, one could easily argue that everyone does it. Certainly, unless taught to do otherwise, everyone does indeed make this mistake. In all of science and engineering, there is one basic rule that is critically important you must do: clearly define the problem in terms that can be dealt with. You have to be able to understand the problem in clear enough terms that you can parse out what things are relevant from those that are not. In this case, claiming there are evolutionary pressures is irrelevant to the problem of reducing the gender gap. We know that anti-female discrimination occurs. We know it is widespread. Of all the problems that Mr. Martin mentioned, this is the one that most obviously lends itself to resolution because it involves behaviors that the vast majority of people can agree on that needs to end. Unless one can reasonably expect to fix evolutionary pressures, distracting attention from the problem that can be solved is counterproductive. The good news is that when people do focus on the problems, things can and have gotten better. We still have a long ways to go, but it is improving.
The point of this post is not really to argue about anti-female discrimination in science, although that is a hugely important topic and something that every teacher needs to be aware of and help to stop. The real point of this post is to highlight the importance of knowing your question well enough and clearly enough that you can make progress on answering it, solving the problem. This particular topic just happens to allow me to highlight two really important topics at the same time. The next post will cover some more vitally important mistakes in thinking that anyone trying to teach the nature of science, and really, any other subject, needs to understand so you can work hard on helping your students overcome them.
In the last post, I covered good places to find 3D fossils. This post I want to cover how to make your own 3D images using photogrammetry. Photogrammetry is the process of turning a bunch of 2D photos into an interactive 3D image. Since I am not an expert on doing this, I am simply going to link you to a series of tutorials put together by Dr. Heinrich Mallison. Dr. Mallison describes himself as “a dinosaur biomech guy working at the Museum für Naturkunde Berlin.” If you would like to read more of his work, I suggest you check out his blog, Dinosaurpaleo, in which he blogs about his research. He also has links to a lot of his research papers and will happily send you pdfs of any other papers of his you want. Dr. Mallison is an expert on making 3D reconstructions using photogrammetry and has already done the legwork to give you all the information you need to get started.
Getting the Right Photo
Photogrammetry tutorial 1 begins with the logical starting point: the equipment. He recommends getting a good DSLR camera with a Life View touchscreen, circular polarizing filter, good tripod, turntable, and a ring flash for optimal pictures. Also, don’t forget the scale bar and stickers. The stickers will be helpful if you have to take our photos in two sets (for instance, if you have to move the object between sets). This will require making two models and stitching them together, which will be aided by small stickers that will serve as easily findable common points so you can properly align the models.
Photogrammetry tutorial 2 discusses general suggestions on how to take good pictures that you can use for the 3D model. Here he gives advice, such as maximizing the F-number to increase depth of field, balancing your exposure, the use of HDR (high dynamic range) images, and proper cropping of the images.
Photogrammetry tutorial 3 covers the use of turntables. He covers the type of specimens that work best, how to place the camera for the needed pictures and how to photograph with an eye for aligning the 3D models you create.
Photogrammetry tutorial 4 discusses techniques for photographing large, bulky specimens.
Photogrammetry tutorial 5 provides a ideo of the turntable method described in part 3.
Making the 3D Model
Finally in tutorial 6, Dr. Mallison finally gets around to actually building the model from the photos. If this indicates to you that getting good photos is essential to making good models, you would be correct. To add more to this, the writers of the blog Sauropod Vertebra Picture of the Week, or SV-POW, have a series of useful posts on how to take good photographs, manipulating them for good effect, making stereoscopic images, and much more great advice.
In this tutorial, Dr. Mallison discusses some of the programs that are available. He prefers Photoscan Pro from Agisoft. The downside to this program is that it costs $549, which is probably out of the price range for many people. The upside is that it is a versatile program designed for non-specialists. He discourages use of Autodesk 123D even though it is free because all of your work becomes the property of Autodesk 123D. He also states that others prefer Image Modeler, which is the professional version of Autodesk. It can do more than Photoscan Pro, but it will cost you much more. He also mentions VisualSFM and Meshlab, open source programs which together can be used to make 3D models and provides a link to a tutorial by a fellow paleontologist, Peter Falkingham, who tells you how to use those programs.
Of course, this isn’t the only wayto make 3D objects. Photogrammetry is only way to make quality 3D images. Laser-scanning is another great way to do so. If you have a few thousand dollars, I might recommend the NextEngine 3D laser scanner. It is not as expensive as some of the other laser scanners and does quite a bit at a comparable or better quality. As a caveat, neither the photogrammetry nor the 3D laser scanning will create the most detailed images. If you want truly detailed, high resolution images, then you really need a computed tomography, or more commonly just called CT, scanners. The downsides to that is that CT scans do not preserve the color of the objects, so you lose surface details related to color, and they are hideously expensive. But at least they are not as expensive as synchotron scans. Synchotron scanners are similar to CT scanners, but are much more powerful and can create images with much greater detail, but with only five available scanners, probably not something your average paleontologist, much less a hobbyist, is going to ever see.
Once you have your 3D objects of course, there is always the next possibility: 3D printing! For that, contact your local high-tech Maker Spaces, such as the Arkansas Regional Innovation Hub. There are several places you can go to buy your own 3D printer, such as Quintessential Universal Building Device, or QU-BD, in Little Rock, AR.
Full Disclosure: I have no monetary interests or any other vested interests in any of the people or companies linked to in this essay.
Jim Lane is talking about something that has been on the mind of a lot of education researchers lately. If you read much in the way of education literature at all, I am sure you will have run across many a discussion of how to improve learning by engaging the students with materials they find interesting and challenging them to solve relevant problems in a creative manner. Doing that means moving beyond the simple worksheets and memorization. It means using the newly available tools to bring the material to life and having the students work on, as one of Mr. Lane’s students called it, the edge of science.
Some of those new tools are in the realm of 3D scanning and modelling. This has allowed many museums and researchers to put some of their work online in a way that allows much more interaction than simple photos. You can, for instance, examine the head of a 2,200-year-old Chinese terracotta warrior housed at the Emperor Qin Shi Huang’s Mausoleum Site Museum or skeletons in an underwater cave from the comfort of your own home. This has great benefits for conservation and research, allowing digital preservation of fragile artifacts and researchers from all over the world to view the objects without having to spend the money to physically examine them. Much of the time, researchers will still want to see the real thing, but there are numerous studies that can be done with only the scanned images. There is even some research that can only be done on the scanned items, making the scans in a way, more important than the item itself. More to the point here, 3D scanning also opens up the object to viewing by people the world over, the vast majority of whom will never have the chance to visit the museum and see the real item.
So where can you see some of these items? There are several places on the net you can go. Here we will focus on those useful for evolutionary topics, such as fossils and anatomy (comparative anatomy with modern organisms is the heart of paleontological research). Many of the sites allow you to download the scans and print them out if you have access to a 3D printer, which are becoming increasingly common as the prices drop down to the point many individuals can buy their own and schools are starting to make them available to their students. Be warned, interactive 3D elements generally take a lot of graphics computation, so try to limit any other graphics you have up, i.e. close other browser windows, don’t try running a game in the background, the general rules of using a program with a lot of graphics. But as long as you have an up-to-date browser with Quicktime and Java, most computers these days should be able to handle it just fine (although a warning about Java, the security updates in the past year or so have made the more recent versions of java incompatible with earlier versions, so unless the developer for the site has updated their program, it may not work).
The following sites are in no particular order, so with that in mind, the first place on this list you might want to visit is Smithsonian X 3D, a website the Smithsonian recently put up showcasing objects from their collection they have scanned. At the moment, there is not a lot, but the site is new and they will be adding much more as they go along, so be sure to check back regularly. Right now, you can see 3D images of whale fossils, a mammoth, a blue crab, an orchid, a bee, and several other historical objects. Included in the collection is a scan of President Obama, the first ever 3D Presidential portrait. The basic 3D viewer is easy to use, although a few of the more advanced controls are not altogether intuitive. The website provides a brief description of each item, along with articles and videos on some of the items and the process of scanning them, including a page for educators on the use of the objects in the classroom. The Smithsonian also has more 3D collections on their human origins site. You might think that they would only have human fossils, but they have much more. You can certainly find hominid fossils, but along with them are numerous primates from Aye-Ayes to gorillas, and a large variety of other animals, from bears and cheetahs to komodo dragons and vultures. While you are there, you can a diverse array of information on human evolution, including teacher guides, lesson plans, multimedia, current research, everything you need to teach a human origins unit.
Another place you will want to check out is the Visual Interactive Anatomy pages by Dr. Lawrence Witmer at Ohio University. He and his students spend a lot of time scanning fossils and modern animals using a medical CT scanner at nearby O’Bleness Hospital or a micro-CT scanner on campus. They have put together several pages that illustrate the anatomy of several modern animals, including an opossum and the heads of a human, rhino, iguana, alligator hatchling, and ostrich. They have also collaborated with Dr. Casey Holliday on an adult alligator. The adult alligator page even has individual pages for every bone in the skull. On these pages, you will find interactive 3D pdfs and videos of the scans and reconstructions, which have a variety of structures labeled, identifying the bones, brain cavity, nasal passages, etc. In addition, you will find news and behind the scenes excerpts, and links to the published research on the specimens. On the 3D Visualizations page, you will find similar movies and 3D pdfs for a variety of dinosaurs (including Tyrannosaurus rex, Majungasaurus, and Euoplocephalus, along with several birds) and mammals from the platypus to deer to Archaeotherium, one of the group of animals often called “terror pigs”.
A website that is sure to grow is the NIH 3D Print Exchange. This site allows people to share their own 3D files for other people to download and use. The website focuses on biomedical applications, but currently you can find a variety of brains, bones, molecules, DIY lab equipment, and more. The more part I am sure will grow as people explore the site and add their own models. You can also find tutorials for making your own 3D models using 3D visualization software, and links to open source software such as Blender, FreeCAD, and Google Sketchup, as well as 3D printing services such as i.materialize and Makexyz and others.
Digimorph, or more properly Digital Morphology, a National Science Foundation Digital Library, is a site run by the CT facility at the University of Texas at Austin, one of the premier CT facilities in the country and the primary place American paleontologists go to get their fossils scanned. Digimorph provides access to these scans for the public and researchers the world over. On this site, you can find videos of scans and 3D reconstructions, some of which can be downloaded for 3D printing, for hundreds of animals, including a variety of avian and non-avian dinosaurs, along with extinct and modern species of mammals, reptiles, amphibians, fish, and even plants, coral, crustaceans and other invertebrates. Along with the scans and 3D reconstructions, you can find descriptions of each specimen, a bibliography of research published on them, and links to useful sites for software, information on CT scanning, and other related sites. The downside to the site is they provide nothing specific for educators and the specimens that have downloadable 3D renderings are a small fraction of the total specimens available in video form, and none of them of the dinosaurs, which are only available as video animations. Nevertheless, for sheer quantity of 3D images for a diversity of animals, there is no place better.
The final site on the list is swiftly becoming the place to go for virtual fossils.GB3D Type Fossils Online project, or simply GB3D, is a website run by the British Geological Survey, Amgueddfa Cymru (National Museum of Wales), Oxford University Museum of Natural History, and the Sedgwick Museum of Earth Sciences. As the name suggests, the site is a repository for information of “type” fossils. If you don’t know what a “type” is, they have a handy guide explaining the different types. In this case, they aren’t talking about what kind of fossil it is, but things like holotypes, fossils designated in the original description of the fossil, which all others are compared to, which make them very important to scientists studying those kinds of fossils. If you want to see United Kingdom fossils, this is the place to go. They have hundreds of fossils in 3D and hundreds more in 2D. On this site, you will find a great diversity of plants and animals with high quality photographs, many of them also have stereophotos (get your 3D glasses with those red and blue lenses) and 3D models. In addition, you will find information about the fossil, such as what it is, when and where it was collected, how old it is, and contact information for the institution that holds the fossil itself. They also have a page describing the more commonly found fossils, all of which happen to be various invertebrates or fish. You will also find free programs used to view and work with 3D images you can download. They have available MeshLab, SPIERSview, and Adobe 3D Pdf Reader. Finally, you will also find links to a variety of educational resources for primary and secondary schools, universities, and the public.
If you want to inspire people to learn, you have to bring them right up to the edge of that knowledge cliff so they can peer over it at the wondrous space beyond, exposing them to the unknown in all its glorious mystery. Help them understand the foundations of the cliff, teach them how to build their own wings, and then push them off that cliff so they can soar into uncharted regions. When they return, they will have a better grasp of how the cliff is formed and what its boundaries are. They just might also find that cliff sticking out a little farther than when they flew off it. And when they do, you won’t have to push them, they will leap on their own. Of course, you will then have another problem: keeping up with your students. So keep your own wings in good repair. I do hope I have helped you build your wings a little stronger. If you know of any other sites that may be of use, please let us know in the comments section.
I will let Dr. Witmer finish this out and let him explain a bit about his projects and why approaches like this, particularly with dinosaurs, are useful educational tools.
The Tangled Bank: An Introduction to Evolution
Publication date (2nd ed.): 2013 according to publisher (my copy says 2014), 452 pg.
Roberts and Company Publishers. ISBN: 978-1-936221-44-8.
Author: Carl Zimmer is one of the best science writers in the business. You can keep up with him on his blog, which is part of the National Geographic “science salon” called Phenomena, a collection blogs by Carl Zimmer, Brian Switek, Ed Yong, Virginia Hughes, and Nadia Drake, all of whom are experienced science writers with a talent for accuracy and clarity. They cover everything from dinosaurs to DNA to dark matter and are the first place I go to in the morning for interesting science news. If it sounds like I am selling them, I am in order to convince you that a book by Carl Zimmer is both more accurate than the current textbook you are using and better written. Zimmer and the others are not just authorial guns for hire, they care about science communication and they do it well. My first introduction to Carl Zimmer was a book called “Parasite Rex“. You probably are thinking that a book about parasites would not be the most interesting of books, but you would be wrong. Read it and it will open up a whole new (albiet disturbing) world for you.
The name of the book is derived from the opening line of the last paragraph in The Origin of Species, by Charles Darwin, a fitting name for a book introducing evolutionary topics. While I have a few complaints, none are major and I highly recommend the book. My chief complaints are that I always want more, but there is only so much one can put into a book, especially an introductory text.
The book is filled with high quality pictures and graphs that break up the text, but whereas many books have flashy graphics that serve little purpose other than to distract from the text, all the figures in the book clearly relate to the topic at hand without excessively cluttering up the book. They also provide data that get the reader to go beyond the “because I told you” format so many books use and actually look at some of the data supporting the scientific concepts (and serve as a great way to integrate math, geography, and art standards into the science). Each chapter also have a list of resources for further reading and an extensive bibliography, so anyone can check the data presented in the primary and peer-reviewed literature for themselves.
One thing that might make some teachers and students a little annoyed is that important terms are not in bold font, nor does it have problem sets. However, it explains all the terms as they come up, it does not require flipping to the end of the book for every new term, although there is also a glossary for those that need it. The book is designed to be read, not just skimmed through while one picks out the bold words, like so often happens. However, there is also a study guide for the book written by Dr. Alison Perkins, which includes all the learning objectives, questions, activities, and pedagogical suggestions that teachers are looking for.
The book begins with a detailed discussion of whale evolution as an example to introduce several general concepts of evolution and various ways in which evolution may be studied. It covers fossils, placing them into phylogenetic and geologic context, DNA studies, embryology, and ecology from their earliest beginnings to today. Zimmer doesn’t go into the disputes that arose about whale origins, instead just focusing on what has become the consensual understanding, which I find a bit disappointing, but perfectly understandable for the context of this book and especially this introductory chapter. Nevertheless, I like presenting disputes because it shows the dynamic nature of science as an exploration, not just a book of facts. He presents the exploration through a discussion of the fossils being discovered and how they were interpreted, he just cleans up the historical path and makes it neater than it really was.
Chapter 2 brings a history of evolutionary thought, starting in the 1600s and the development of evolutionary concepts before Darwin. Zimmer correctly explains that Darwin was not the first to conclude that organisms evolved, but he did provide a plausible mechanism for how it happened. He then continues with a discussion of the changes and additions to evolutionary theory in the decades since Darwin. He tackles the important misconceptions of evolution, including the common misunderstanding of what a scientific theory really means, which form the basis of most people’s arguments against evolution.
Chapter 3 presents geological data, including how radioactive decay is used to date rocks and biomarkers to detect traces of life within rocks. He tells us how fossils tell us about the past, followed by a brief overview of the major transitions in life from the dawn of life to today.
Chapter 4 is probably one of the most important chapters that is left out of many introductory biology texts. Zimmer tells us what phylogeny is and how to read a phylogenetic tree to understand evolutionary relationships. It is particularly disturbing so many books skip this step because it is vital to understanding much of what comes after. Misunderstandings here reverberate throughout one’s ability to understand evolutionary theory, yet reading phylogenetic trees is not as intuitive as most teachers think. He talks about homology and how that affects our understanding of evolution. After he introduces the concepts, he demonstrates the concepts through a series of phylogenetic trees, such as early mammals, dinosaurs, and hominids.
Chapter 5 talks about DNA and how variation is introduced. Zimmer does a great job of discussing the various types of mutations and showing the typical view of point mutations is but the smallest way of introducing variation. His discussion of the role of sexual selection in creating diversity is short, although his description of Mendel’s experiment with peas helps somewhat. He also gives short shrift to lateral (aka horizontal) gene transfer, in which genes are transferred not through descendants but sometimes through completely unrelated organisms by, for instance, viruses. Zimmer also completely ignores endosymbiosis, which helped create mitochondria and chloroplasts, and hybridization, which makes this chapter not as satisfying for me.
Chapter 6 covers the role of genetic drift and selection well, although he leaves out a discussion of gene flow from one population to another. I like that he talks about fitness in terms of more than one gene, showing that what may be good for one gene is not necessarily good for another in terms of fitness, so that evolution is limited by the interplay between genes that each have their own optimal conditions. This would have been a good place to address the misunderstanding of “survival of the fittest,” which is commonly viewed as a tautology (the fittest survive, but how do you determine who is fittest? The ones that survive) but he does not mention it. This is a very common misconception. First, the phrase was never used by Darwin and is incorrectly and second, it is being incorrectly interpreted. It is not the overall fitness of a particular organism that matters, but a measure of how many offspring successfully survive and reproduce. It doesn’t matter evolutionarily if you are the toughest guy on the block if you don’t breed and produce successful offspring.
Chapter 7 discusses molecular phylogenies, figuring out evolutionary relationships from their DNA or protein sequences. One complaint I have here is that he talks about how successful the molecular clock is, how you can tell time using the amount of mutations separating species. In all actuality, the molecular clock has some serious issues, as in, it doesn’t work very well. Fortunately, he does discuss some of the challenges of the molecular clock (genes don’t mutate at the same rate either between each other or within different parts of the same gene, or through time, it requires fossils to calibrate and then tries to claim better results than the fossil data, etc.). The problems with the molecular clock mean that its usefulness and accuracy are limited and requires statistical manipulation of the data to try to take into account the known issues. Unfortunately, the figures lead one to believe the molecular clock actually acts clock-like, reducing the impact of the text describing its problems and the examples in the text downplay the problems. A bonus to this chapter is that he brings back the topic of horizontal gene transfer and shows its importance in a box at the end of the chapter. I might have put this in the last chapter and discussed it more, but it could be that Zimmer thought it might confuse people by introducing too much complexity at once and wanted the readers to develop a bit more understanding before throwing another wrench in the works.
Chapter 8 gives a great discussion of adaptation, taking it from the gene to species evolution. I particularly like his discussions showing how gene duplications and rewiring without the need for further point mutations can make huge differences. This is a really important concept to understand, that variation is more than just the single point mutations most people think about. He ends the chapter with a discussion of the limits of evolution based on physical limits and baggage from previous evolutionary steps, although I would have liked to see a brief mention at least of the constraints imposed by having genes with different optimal conditions that all have to be balanced.
Remember when I said chapter 5 gave short shrift to variation through sexual reproduction? That is because chapter 9 is completely devoted to the topic. Here he goes into several aspects of sexual selection, including trade-offs that may limit evolution in any one particular direction. Trade-offs in this case refer to the fact that improving one thing takes away from another. The genes with different optimal conditions are an example of this. Improve and you hurt another until a balance is achieved.
Chapter 10 defines what a species is (which is nowhere near as easy as it sounds) and how species evolve into other species. Chapter 11 extends that to evolution on a grand scale, showing the development of global biodiversity through time. I would have preferred to see a discussion of the difficulties in determining fossil biodiversity, such as the relationship between the amount of outcrops of a particular time and the number of species known, but there is only so much one can put into a textbook. Inevitably, the chapter discusses the major extinctions of the world, although he only talks about two of them, the Permo-Triassic and the Cretaceous-Paleocene extinctions, probably because they are better known by far than the others. His discussion of the Permian extinction doesn’t mention that the reason the volcanoes at the time put out so much carbon dioxide was that they apparently burned through huge coal deposits, which pumped up the carbon dioxide way beyond what the volcanoes would have done alone, but he gets the gist of the cause of the extinction. He also discusses briefly the debate in why the extinction occurred at the end of the Cretaceous, which is good. The chapter ends with a discussion of the current mass extinction taking place and the causes for it.
Chapter 12 discusses coevolution, both mutualistic and antagonistic. Here Zimmer finally discusses endosymbiosis and the important role it played in evolutionary history. Chapter 13 is an interesting discussion about the evolution of behavior in both plants and animals.
Chapter 14 will of course be the most controversial chapter because it deals with human evolution. Zimmer does a good job with this chapter, although I would have preferred a clearer statement that hominids and apes both evolved from a common ancestor, but where our ancestors became adapted for savanna life, the apes evolved more towards forest life. He talks about the interbreeding that happened between neanderthals and Homo sapiens, as well as with the Denivans, according to the genetic research published recently, which will make a few people uncomfortable, but is the truth nevertheless. The chapter wraps up with a discussion of some evolutionary psychology, which is highly controversial, but the parts he discusses are well supported by experimental evidence.
The last chapter is arguably the most important one in the book. Here Zimmer discusses the role of evolution in medicine, with examples of disease progression, vaccines, antibiotics, and cancer. If, by the time people have worked their way through the book and are still asking themselves why it is important they understand evolution, this chapter is a sledgehammer wake-up call. One cannot finish the book without having a strong understanding of the importance of this concept of evolution and why biologists consider it the central tenet of all biology. As Dobzhansky said, “Nothing in biology makes sense except in the light of evolution.”
Taphonomy Tuesday? What the heck is taphonomy, you ask? Taphonomy is the study of burial processes and all the changes that take place betwixt death and being collected as a fossil. One might also include the effect of sexiness in what fossils get studied and forgotten about, way more people are interested in tyrannosaurs than fossil mosquitos, for instance. Change comes to all things and paleoaerie is no exception. You may have noticed that the answer to Monday’s mystery fossil did not get posted on the blog last week, although it was posted on the Facebook page. That will be rectified today. But first, a couple of pieces of news.
Mystery Monday and Fossil Friday will be suspended for the summer so I can work on other aspects of the website. I would like to make some different posts and add more to the site. however, for those of you who are primarily interested in the fossils, they will return along with school, teachers, and homework, although hopefully a bit more fun than either doing or, even worse, grading homework (trust me, having been both a student and teacher, grading is almost always more painful than doing the assignments). In the meantime, you can look forward to more varied posts, the addition of a couple of things, such as a techno page for recommended apps and multimedia and an Amazon store in which you can peruse recommended items (and in a small way support the work of paleoaerie, which while free to you, is not to me). So I hope you will stick with me through these Darwinian changes and avoid the pitchforks and torches (ed. note: in keeping with the medieval theme of the picture, I thought about saying burning faggots, but so few people these days know that in olden times, faggot simply meant a bundle of sticks, language too evolves).
The other big news is that I have started a collaboration with the Museum of Discovery in Little Rock to host a celebration of National Fossil Day in October. I am really looking forward to it and, between me and the museum educators at the MoD, we have a lot of ideas for things to do. I hope everyone can come out and enjoy the festivities and learn about fossils in Arkansas and beyond firsthand.
Now, for that fossil…Did any of you recognize this as the skull of a mosaaur, specifically that of Platecarpus? To picture a mosasaur, imagine a komodo dragon, replace the feet with flippers, and compress the tail so it is taller than it is wide (aka laterally compressed) so it looks more fish-like than lizard-like, and you have a pretty good view of a mosasaur. There is a reason for that. Komodo dragons are part of a group of lizard called monitor lizards, which are thought to be close relatives of mosasaurs and so are likely an excellent model for what the ancestral animal of mosasaurs looked like before they became aquatic.
Platecarpus was a carnivorous marine reptile that swam in the Cretaceous seas. While dinosaurs like Tyrannosaurus rex and Triceratops roamed the land, Platecarpus and its relatives patrolled the oceans. This is one of the most common mosasaurs, so much of what we know about them comes from fossil of this genus. It was smaller than many of the other mosasaurs. Some, like Kronosaurus, could reach up to 17 meters, but Platecarpus only averaged around 4-7 meters. Its name means “flat wrist,” alluding to the flippers, although it hardly distinguishes them from other mosasaurs in this regard. What did make them stand out from the other mosasaurs was a relatively shorter snout with eyes that faced more forward, so it probably had better stereoscopic vision, that is, it had better depth perception than most others of its kind. This may be why it had a shorter snout, to prevent the snout from blocking its field of view. Like other mosasaurs, Platecarpus had two rows of teeth on its palatine bones, forming the roof of its mouth. This arrangement actually isn’t all that unusual in lizards and snakes, it is really common in fish. The teeth (all of them, not just the palatal teeth) were pointed and conical, although not as sharp as some of its kin, indicating it went after small, soft prey, like small fish and soft invertebrates like squid or perhaps even jellyfish. They could have gone after larger prey like crocodilians do, but unlike crocodilians which have a strong skull capable of withstanding the forces of ripping a prey item apart, Platecarpus had a much weaker skull which would likely not have stood up to the stresses of the crocodilian death roll (this is when they grab a limb and spin until the limb is ripped off, the moral of the story is of course, never dance with a gator). The overall shape of Platecarpus is stockier than most mosasaurs. This would have had the effect of decreasing surface area relative to body weight, which could have increased its metabolism by holding in heat better.
One of the things that makes Platecarpus as a genus so interesting is the fossils that have been found with soft tissue preservation. In one, along with parts of the skin, parts of the trachea (windpipe) were preserved. Originally, they were interpreted as part of a dorsal fin, thus all the early pictures of mosasaurs with fins along their backs. However, it was quickly discovered what the traces really were. To his credit, Williston, the scientist who had reported in 1899 the traces as a dorsal fins was the one who published another short paper three years later saying he had made a mistake and the fossil really showed the cartilaginous rings found in trachea. The tracheal rings have also been interpreted as showing the branching point between the two lungs, which is important because it answered a question about their origins. Every researcher agrees that mosasaurs are lepidosaurs, the group including lizards and snakes, but what wasn’t known was whether or not mosasaurs were derived from aquatic lizards or from snakes. The discovery of a trachea showing two lungs confirms the origin within lizards (snakes only have one lung). It may still be that snakes evolved from mosasaurs, but that is not very likely.
The other piece of soft tissue that has been found is the outline of the tail showing a lobe on the tail forming a very shark-like tail. Until this time, many people had thought the mosasaur swam with an eel-like motion, but the tail and the deep caudal fins indicate a much faster shark-like swimming motion. This in turn has caused people to reevaluate the view they were slow ambush predators, supporting a more active predatory forager. Whether or not other mosasaurs had this fin is currently unclear, so there may have been specializations within this group not seen in the larger mosasaur family. Another such example is the discovery of what has been interpreted as thicker eardrums, which may have allowed them to dive to deeper depths.
The southwestern corner of Arkansas was at the edge of the Late Cretaceous Western Interior Seaway, so we have several fossils of them in places like Clark, Hempstead and Howard counties, although you can find them all over the world in the right type of rocks. You can find them in the Brownstone and Marlbrook Marl Formations. These formations are indicative of warm, shallow seas, much like the Bahamas today, which considering the locations, shouldn’t come as too much of a surprise to people. If you were taking a nice vacation on the warm Cretaceous beaches 80-85 million years ago, you might have tried fleeing into the water to avoid the dinosaurs on the beach, but you would have been no safer in the water.
I would like to thank Rachel Moore, who supplied a lot of the research involved in putting this post together.
Today’s Google doodle celebrates the 215th birthday of Mary Anning. She was one of the first people to help usher in the modern age of paleontology as a science and was the prime worker on the Jurassic Coast near Dorset, England, probably the most important fossil site for marine reptiles in the world. The Natural History Museum of London calls her “the greatest fossil hunter ever known..” Among other finds, she is credited for finding the first correctly identified skeleton of an ichthyosaur, the first complete specimens of a plesiosaur, the first pterosaur outside Germany, and identifying coprolites as fossil feces. Until that time, they were called bezoar stones, indigestible masses found within the digestive system. They were rumored to be an almost universal antidote for poisons and were used as such in J.K. Rowling’s Harry Potter series. The first woman to receive a eulogy at the London Geological Society, an honor given only to distinguished member scientists (she wasn’t even a member because the society did not accept women at the time, they just took her work and published it under their names), Mary Anning was widely sought after by researchers in her time for her expertise.
This brings up an interesting debate. It is hotly debated what role commercial fossil dealers have in paleontology. The current majority consensus as presented by the Society for Vertebrate Paleontology is that they should be stopped because all the fossils they collect are sold, almost always, to private collectors, thereby removing them from scientific study. Fossils that are not in the public trust (like a museum) are not accessible to other scientists to study, so all the knowledge that may be gleamed from their study is lost to the public. They explicitly state this in their bylaws. Section 6, Article 12 states: “The barter, sale or purchase of scientifically significant vertebrate fossils is not condoned, unless it brings them into, or keeps them within, a public trust. Any other trade or commerce in scientifically significant vertebrate fossils is inconsistent with the foregoing, in that it deprives both the public and professionals of important specimens, which are part of our natural heritage.”
They have a point. Few fossils collected by commercial fossil dealers ever get scientifically studied. Who knows how many priceless and important fossils are locked away in someone’s private collection. Museums do not have the resources to compete with private competitors to buy fossils except in the rarest of occasions and even then, it depends on the finances and good will of private individuals willing to donate to the museum for that purpose. The tyrannosaur named Sue sold at auction for $7.6 million to the Field Museum in Chicago, who needed the help of the California State University system, Walt Disney Parks and Resorts, and McDonald’s, along with numerous individual donors to raise the money. Researchers collecting fossils must always be on their guard to protect their dig sites due to the common occurrence of thieves stealing fossils from their dig sites to sell them. Many paleontologists have stories of finding a skeleton at the end of the season and having no time to collect it, only to come back the next season to find someone has collected the sellable parts and not uncommonly have smashed the rest. Even if the fossils find their way to a public institution where they can be studied, most commercial fossil collectors do not take sufficient notes about location and all the details at the site to make the find reliable enough to study well. It is often said that a fossil without provenance data has little more worth than having no fossil at all and for good reason. If you don’t know where a fossil came from, there is little you can say about it and it is impossible to place it in context with other fossils.
On the other hand, commercial fossil collectors say that without them, most of the fossils they collect would have eroded away and been gone completely with no record of them ever having existed at all. There simply aren’t enough paleontologists and money in academia to collect all the fossils they do and they are right. The tyrannosaur Sue is a great example of a dinosaur fossil that may not ever have been found if it were not for commercial fossil dealers. What makes this point important for this essay is that Mary Anning was a commercial fossil dealer. She funded her research and supported herself by selling fossils. Without the income she received from fossil sales, she would never have been able to make the discoveries she did.
So who is right? Maybe they both are. It is undeniable that unscrupulous poachers and fossil dealers steal and destroy priceless fossils which never enter the public and academic consciousness, but it is also undeniable that commercial fossil dealers have contributed greatly to our knowledge of paleontology. The AAPS, Association of Applied Paleontological Sciences, an organization representing commercial fossil dealers, advocates for responsible collecting, having a professional academic work with commercial fossil dealers so any finds can be studied. Their position would indeed help bridge the gap between the academic and the commercial dealer. However, this requires the benevolence of the collectors and many, possibly most, are uninterested in letting academics study their fossils. While the fossils may be able to be studied during the time they are found and prepared (removing the encasing rock and putting the pieces together), most of the study comes after this point. A fossil in private hands can easily become lost and access is at the mercy of the owner. A museum, on the other hand, is required to maintain records of the fossils and provide access to anyone who wants to study them.
So what is to be done? Currently, it is illegal to collect vertebrate fossils on Federal land. The reasoning is that Federal land is owned by everyone. As such, anything on Federal land must be protected for all citizens, making collections for private sale not in the interests of the country as they take fossils out of the public trust and therefore inaccessible to the public. States have their own rules, some make it illegal, others have no specific laws concerning fossil collections. On private land, there are no restrictions. Any fossils found on private property are the property of the land owner and they can do whatever they want.
What is the correct answer? That depends on your point of view. Certainly the collective point of view has changed through time. What do you think?
For today’s Mystery Monday fossil, see if you can identify this creature.
It’s Friday, time for the answer to Monday’s mystery fossil. Were you able to identify it?
These fossils are from a fish called Enchodus, the “saber-fanged herring.” Teeth of Enchodus are commonly found in the Cretaceous-aged rocks in southwestern Arkansas, especially near Malvern and Arkadelphia in the Arkadelphia and Marlbrook Marl Formations, up into the Paleocene rocks of the Midway Group a bit farther north. In other places you can even find them in rocks of Eocene age, although you will have much better luck in the Cretaceous rocks. At this time, southern Arkansas was shallow to coastal marine. Go to the Bahamas, imagine Enchodus, mosasaurs, plesiosaurs, and plenty of sharks in the water around the islands and you would have a good picture of the landscape back then. They were abundant at the end of the Mesozoic Era and survived the asteroid impact that rang the death knell for many animals, including the non-avian dinosaurs. But they never regained their prominence as a key member of the marine ecosystem, eventually dying out completely in the Eocene sometime around 40 million years ago (the Eocene lasted from 55 to 34 million years ago).
The fish reached sizes over 1.5 meters, which makes them on the large side, but not really big, considering there were mosasaurs in the same waters that surpassed 10 meters. Still, with fangs longer than 5 cm, they would not have been fun to tangle with. They were clearly effective predators on smaller fish and possibly soft animals like squid. At the same time, fossils have been found showing they were themselves prey for larger predators, such as sharks, the above-mentioned mosasaurs, plesiosaurs, and even flightless seabirds such as Baptornis. Baptornis was a toothed, predatory bird, but as it only reached 1 meter or so, it would have only been able to hunt young Enchodus. So like many of us today, Baptornis was always up for a good fish fry.
Enchodus is often called the “saber-fanged herring,” although it is unrelated to herrings. So what then was it? Herrings are what is known as forage fish, meaning they are mostly prey items of larger fish and other animals. Most of the fish called herrings are in the family Clupeidae in the groups Clupeiformes, which includes such well-known fish as sardines and anchovies. Enchodus, on the other hand, has been placed into the group Salmoniformes, which includes trout, char, and of course, salmon. When one typically thinks of trout and salmon, one doesn’t think of bait fish, they think of the fish that eat the bait fish. Thus, Enchodus would better better described as a fanged salmon (they were a bit large to call them fanged trout).