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One of the common fossils you can find in Arkansas are cephalopods, which are all the squids, octopuses, and in terms of fossils, ammonoids. Arkansas has some very large ones. If one goes to Northeast Arkansas and looks in the Fayetteville Shale, one can find ammonoids with shells several feet long. Here is a preview of some of the fossils you will see Saturday.
Come back tomorrow for more fossil previews. Come to the museum to see much, much more.
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.
Happy St. Patrick’s Day! In honor of the day, today’s Mystery Monday fossil is related to the legend of St. Patrick. You can probably easily notice it is not a fossil shamrock, which has never been found in Arkansas, unlike the previous owner of this fossil. Finding a 4-leaf clover is generally considered lucky, you probably wouldn’t think the same thing if you found one of these alive. I could find no pictures of the actual fossil and I don’t have access to it, so I hope you will forgive me for using an illustration from the paper that described it.
Were you able to solve Monday’s mystery fossil? They aren’t little poop balls, nor are they clams, although they are often mistaken for them.
This photo can be found at the Arkansas Geological Survey website under “Brachiopod.” They look a lot like clams. Brachiopods, often called lamp shells, have two shells and live in shallow marine environments just like clams and the occupy the same niche, feeding on organics filtered from the water. But unlike clams, which are molluscs, just like snails and squid, brachiopods are lophophorates, most closely related to bryozoans, the “moss animals.”.
So what is a lophophorate? Lophophorate means “crest or tuft bearer, so named for their feeding apparatus called a lophophore, which is shaped like a roughly circular or semi-circular ring of tentacles. These tentacles lazily wave through the water passing through the lophophore, catching small particles of food suspended in the currents. Thus, everything in this group are what is known as suspension feeders. These lophophores serve not only to collect food, but for gas exchange as well. In addition, the animals are headless, with the lophophore surrounding the mouth. The food enters the mouth and passes through the digestive tract, which makes a U-turn and dumps out what it can’t digest just outside the ring of tentacles. Clams do essentially the same thing, only they use an entirely different apparatus to do so.
Clams attach themselves to surfaces by secreting a collection of what are called byssal threads. Most brachiopods, on the other hand, form a pedicle, a stalk that holds them in place. Some do not make pedicles, instead just gluing themselves down directly onto the rock.
Another difference that can usually be seen between clams and brachiopods is the symmetry of their shells. Brachiopods are symmetrical from side to side, their left side is the same as their right side. Clams follow a different pattern. They usually have two identical shells, but the shells themselves are not symmetrical. This is not always true though. The Cretaceous oyster, Exogyra ponderosa, has an huge, thick shell on one side and a thin lid for a shell on the other. But as a general rule, this usually works. Another difference that is sometimes stated is that brachiopods use their muscles to close their shells, while clams use their muscles to open their shells, closing them by the use of ligaments; thus making brachiopods more susceptible to predators. This, however, is not true. In truth, brachiopods use their muscles to both open and close their shells. Clams have large adductor muscles that function to close the shells and they have ligaments that open them when the muscles relax.
Brachiopods are quite diverse, with many different types. They range in size from less than a dime to almost 40 cm (15″). There are two general groups, the Articulates, which have toothed hinges holding the shells together, and the Inarticulates, which do not have teeth, so they fall apart easily after death. Probably the most commonly found in Arkansas are spirifers, known for being somewhat wing-shaped , with a prominent sulcus, or depression in the center. Many brachiopods prefer solid substrates, like rock, others were adapted for softer substrates like sand or mud. Productids, like the ones in our mystery fossil, often grew spines, which helped secure them to muddy surfaces. Others, like strophomenid brachiopods, handled muddy substrates by developing large, very flat shells, which floated on the mud like a snowshoe. Still others, like the modern-day lingulids, developed long pedicles, allowing them to burrow down into the sediment.
Brachiopods have been around since at least the Cambrian, over 520 million years ago. They were most abundant in the Paleozoic Era, but suffered greatly during the Permo-triassic extinction event. They recovered to some extent, but never reached their previous abundance due to the appearance of clams, which began taking over some of the spaces they occupied. Nevertheless, there are still several different kinds in the modern ocean and can often be seen clinging to rocks near shore or buried in the sand. In Arkansas, you won’t find any living specimens, but you can find numerous fossil brachiopods in the Paleozoic rocks throughout the Ozarks and Boston Mountains, even in some places of the Arkansas Valley. Stop by any outcrop along Highway 65 between Conway and the north edge of the state, particularly limestone outcrops, and you are likely to find some. You can find a few in the Bigfork Chert in the Ouachitas, but they are not nearly so common as they are farther north.
Despite the snow, we didn’t get a chance to have any other posts this week other than the Monday Mystery fossil. We did, however, have three different school trips in the past couple of weeks to talk to kids about fossils, dinosaurs, and the skeletal system, as well as giving talks on the fossils telling us about the origins of crocodiles and dinosaurs, as well as attending a talk on the origins of birds. So a lot of paleo work, just not much showing up here. Fortunately, some of you had some time to examine our mystery fossil and congratulations to Laurenwritesscience for coming up with the correct answer.
It is indeed a stromatolite. Bruce Stinchcomb has a video on Youtube showing several examples of Ozark stromatolites and providing a good explanation of what they are.
Essentially, stromatolites are microbial ecosystems, built up of layer after layer of microbial mats. The general description is that of blue-green algae, which forms a sticky layer over the surface of a rocky surface in a shallow marine or coastal environment. Blue-green algae are not actually algae and are better referred to as cyanobacteria. These bacteria are photosynthetic, just like plants, so they need sunlight, thus limiting the depth at which they can be found. Actually, they are typically found right at the water’s edge in the tidal zone. This sticky substance, while maintaining their hold on the rock, also tends to collect sand, clay, and organic debris. Over time, all the stuff that sticks to the mat blocks the sunlight from the cyanobacteria and they migrate above the layer and build another mat, which collects more debris, which causes them to build another mat, etc. Stromatolites form much the same way as piles of laundry. By the time you finish washing one set, there is another pile forming in a neverending stream. The life of a cyanobacteria in a stromatolite is a depressing condition of always digging themselves out from under a pile just to get dumped on again. I am sure most people can empathize.
The sticky mucus (properly referred to as extrapolymeric substance, or EPS for short, but we can go with mucus here) forming the mat does more than just cause things to stick to it. The mat protects the bacteria in from ultraviolet radiation. It also allows the bacteria to control the microenvironment around them, keeping such things as pH levels in a good range. It also has an unfortunate aspect for the bacteria. The mucus allows the levels of calcium and carbonate ions to build up until they precipitate out of the water as calcium carbonate, also known as calcite (when referring to the mineral), or limestone (when referring to the rock). So not only are the poor bacteria constantly getting buried, they are getting turned to stone in their very own medusa nightmare. Life is hard as a cyanobacteria. But just wait, it gets worse.
These microbial mats are not just cyanobacteria, though. There are lots of other organisms that live in and on them. There are many other types of bacteria. There are sulfate reducing bacteria, which use sulfur like we use oxygen, only they release hydrogen sulfide instead of carbon dioxide, causing a nice rotten egg smell. There are purple sulfur bacteria that eat the hydrogen sulfide, as well as colorless sulfur bacteria that eat both the hydrogen sulfide and the oxygen released by the cyanobacteria, thus free-loading off of everyone. In addition to bacteria, there are plenty of prokaryotes (organisms without nuclei that holds their DNA) and eukaryotic (with nuclei) single-celled and multi-celled organisms living in the mat. Diatoms, single-celled photosynthetic organisms that grow their own shell, live on top, while nematodes burrow through the mat. In addition to all this, a wide variety of animals love to chow down on the mats. Everything from snails, sea urchins, crabs, crawfish, and just regular old fish happily eat them. As a result, there are not a lot of places left in the world you can find stromatolites growing. The Bahamas and Shark’s Bay, Australia are the best areas to find them.
They may be rare now, but at one time, they ruled the earth. As some of the oldest living communities in the world, they have been around for at least 3.5 billion years (that’s 3,500,000,000, or roughly 600,000 times the length of human civilization) and for more 2/3 of that time, they were the only game in town and in all probability served as the cradle for all eukaryotic and multi-cellular organism on the planet. These days, if you live in Arkansas, the only places you can find them are as fossils in the Cambrian age Cotter Formation and Ordovician age Everton Formation in the Ozark Plateau.
For further information (and the source of the images shown here), check out the stromatolite page at the Arkansas Geological Survey and the Microbe Wiki stromatolite page, as well as the Microbes.arc.nasa.gov site, which supplies a nice teacher’s guide to teaching all about microbial mats, designed for grades 5-8.