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Tomorrow is Halloween, so I thought this week’s mystery fossil is particularly appropriate. Herman Diaz was able to guess that it was some sort of bovid, something along the lines of a bison. Were you able to get any closer?
This picture is indeed a bovid, although it’s not a bison. The skull cap, adorned with horns is from an animal called Bootherium bombifrons, also known as Harlan’s muskox, , woodland muskox, bonnet-headed muskox, or my personal preferred term second to the great Bootherium, the helmeted muskox.
Muskox are ungulates (hoofed animals) in the order Artiodactylia, even-toed ungulates such as pigs, deer, camels, and antelopes. Artiodactyls also include hippos and whales, which is why some people prefer the term Cetartiodactylia. Bovids are a group of artiodactyls known for having blunt snouts and unbranched horns. In addition to the ever-popular cows, they include bison, sheep, goats, antelopes, and of course, the muskox. It is a large group, with over 400 known species.
Muskox today consist of a single species, Ovibos moschatus. Muskox are commonly misunderstood to be related to oxen, which are really just cows (or more correctly, cattle, as cow technically only refers to females) that have been trained as draft animals and not a separate species at all. Muskox are really more closely related to goats than cattle. They are adapted for cold weather and live in Arctic regions of North America, Eurasia, and Greenland.
Bootherium, unlike its modern cousin, lived in more temperate climates. It lived throughout North America during the Pleistocene Epoch between 300,000 and 1.8 million years ago, but was most common in the southern United States. It is not a common fossil in Arkansas, but has been identified from Newton County in the northern part of the state along the Buffalo National River. Sadly, the paper referencing this find is chiefly about a cave in Maryland from 1938, which is a great indicator of a lack of decent mammalian paleontological research in Arkansas. Nevertheless, during the Pleistocene, Bootherium has been listed as the most common form of muskox in North America.
Bootherium is reported to have been taller and thinner than modern muskox, with a finer and shorter fur coat, as befitting the warmer climate. They also had large horns that were fused together across the top of the skull.
Considering that it shared a similar habitat with mastodons, which we have in a fair abundance within the state, it would be expected that there should be more evidence of them being in Arkansas. It may be that they are usually mistaken for the bones of modern cattle, which are not uncommon throughout the state. So perhaps there are more around here than we know about.
For more information on Bootherium, check out the website of the Yukon Beringia Interpretive Centre.
I haven’t posted a mystery fossil this fall, much to my own disappointment. But I have the perfect specimen for this week. With Halloween this Saturday, I had to post this one. See if you can figure out what it is. Check back Friday for the answer.
I couldn’t find a picture of the Arkansas fossils, so one from Ohio will have to do.
National Fossil Day is today. The Museum of Discovery is having their second annual National Fossil Day event this Saturday. In celebration of these events, I am reviewing important fossils of Arkansas. Last post I stated my picks for the most famous fossils of Arkansas. This time I will discuss what I think are the most common fossils in particular regions of the state.
In the Ozarks, you can find an abundance of marine fossils. There are ammonoids, bryozoans, brachiopods, clams, corals, echinoids, and many others. The Pitkin limestone is so chocked full of Archimedes bryozoans that it is sometimes referred to as the Archimedes limestone. But overall, I have to go with crinoids as the most commonly found fossil in the Ozarks. Crinoids lived throughout the Paleozoic Era, making them potential finds throughout the region. They survived even up to the present day in deep marine settings, but in the Paleozoic, they lived throughout the shallow marine realm, which is where fossils are most common.
Known as sea lilies today due to their plant-like appearance, they are actually echinoderms, making them relatives of sea urchins and sea stars. While not common today, they were quite abundant during the Paleozoic. Most of the fossils of crinoids are of their stems, which look like stacks of circles with the centers punched out, sort of like flattened rings. But occasionally, you can find the tops of the crinoids with the body (called a calyx) and the arms still intact. These are rare because, like all echinoderms, the body is made of plates that fall apart into indistinguishable fragments shortly after death.
You will not find many fossils in the Ouachitas, but two types of fossils are commonly found there, conodonts and graptolites. Conodonts are the toothy remains of the earliest vertebrates. Unfortunately, you can place several of them on the head of a pin, so unless you are looking at rocks under a microscope, you probably won’t see them. That leaves graptolites, which can be found in several places fairly easily. Unless you know what you are looking at, they can be easy to miss. On black shale, they often appear as pencil scratches that are easy to overlook. But look closely and you will see that many of them look like tiny saw blades. These are what remains of animals we call today pterobranchs. These animals are the closest an animal can get to being a chordate, the group that includes vertebrates, without actually being one. So the Ouachita mountains have fossils that bracket that hugely important transition from spineless to having a backbone.
For the third choice, one could always argue for shark teeth, which are commonly found in southwest Arkansas, but can be found most anywhere in the state. But if we limit our discussion to the southwest part of the state, the easiest to find on the basis of quantity and size I think has to go to Exogyra ponderosa. These are Cretaceous aged oysters known for their thick shells adorned with a curled hornlike shape. They are big, sturdy, and can be found by the thousands. One can only imagine that the Cretaceous was a great time to be an oyster. At that time, southwest Arkansas was beachfront property. with lots of shoreline and shallow marine deposits of sand, shale, limestone, and the famous Cretaceous chalk deposits. Dinosaurs walked along the beach, marine reptiles like mosasaurs and elasmosaurs plied the waters, along with sharks and fish of all kinds. And between them lay mountains of oysters.
You may notice that I left out pretty much all of eastern Arkansas. That is because that region of the state is covered in fairly recent Mississippi river sediment, so you don’t find that many fossils in that part of the state. Some have been found, such as the Hazen mammoth, mastodons, sea snakes, and the occasional giant ground sloth or whale, but the fossils are few and far between. So while they have several fascinating fossils, they aren’t going to show up on anyone’s list of commonly found fossils.
So those are my choices. Do you have other suggestions?
This week is Earth Science Week, with National Fossil Day on Wednesday. The Museum of Discovery is holding its second annual National Fossil Day event on Saturday, the 17th, between 10 am and 3 pm. So in honor of the week and in preparation for the museum event on Saturday, I thought I would briefly talk about what I consider the three most famous fossils found in Arkansas. You may notice this list is exclusively vertebrates. That is because of the rather large bias in popularity vertebrates have over invertebrates. Vertebrates are much less common in Arkansas than invertebrates, but they get almost all the press. Let me know in the comments section if you have any other contenders.
The first contender for Arkansas’s most famous fossil is Arkansaurus, the only dinosaur to have been found in the state. Found in 1972 in Sevier County, the only bones found comprised the front half of one foot. Despite considerable searching, nothing else has ever been found. The lack of diagnostic bones has made it impossible to determine exactly what kind of dinosaur it was. All that can really be said is that it is some kind of coelurosaur, a type of theropod, but not a tyrannosaurid, ornithomimid, or any other more derived form related to birds. We can also say it was a medium-sized dinosaur, meaning it wasn’t terribly small, as the front half of the foot measures just over two feet long. A statue was made by Vance Pleasant, which was recently seen at the Museum of Discovery as part of a dinosaur exhibit. How accurate is it? It’s a reasonable estimate based on what we know right now, which is not much, except that the real animal probably had some form of feathers not seen on the statue. The fossils are currently housed at the University of Arkansas at Fayetteville.
My vote for the Arkansas fossil that is more widely known outside the state better than inside it is Ozarcus, a primitive shark found by the paleontologists Royal and Gene Mapes in the Ozark Mountains near Leslie. The reason for the fame of this fossil is that it is the oldest known shark fossil that preserves the gill supports, known as the branchial basket. These normally do not preserve because they are made of cartilage, much like most of the rest of the shark skeleton. The gill supports here indicated that both sharks and osteichthyans, or bony fish, evolved from an ancestor that looked more like bony fish than it did the cartilaginous sharks, meaning that the original sharks were not primitive to bony fish, but possibly evolved after the appearance of bony fish. Due to this, Ozarcus got international coverage and became well known to paleontologists. The fossil currently resides at the American Museum of Natural History in New York.
The last contender for Arkansas’s most famous fossil is the Hazen Mammoth, the only mammoth known from the state. Found in 1965, it consisted of the skull, tusks, and some vertebra. There was a lot more of the skeleton found, but unfortunately, the bones were very soft and were severely damaged or destroyed before they could be collected. The bones were identified as Mammuthus columbi, or the Columbian Mammoth, a less hairy version of the more commonly known woolly mammoth, indicating warmer temperatures than found in areas in which the woolly mammoth is known. Even though only one mammoth has been found in Arkansas, upwards of two dozen mastodons have been found. Mastodons were smaller cousins of the mammoths and preferred forest habitats over the grassy plains in which the mammoths lived. This provides evidence that much like today, the state was mostly forested during the Pleistocene Period in which they lived. Today, the mammoth is a resident of the University of Arkansas at Fayetteville.
So what would you call the most famous fossil of Arkansas?
If you are ever in London, the Natural History Museum (NHM) is a must see attraction. It ranks among the top natural history museums around. Schedule more than one day to see all the exhibits if you can, including their popular dinosaur exhibit that always draws large crowds. Many people have complained about the poor lighting and limited viewing space in that particular exhibit, but even with that, it is not to be missed. Accompanying the dinosaurs in the museum is an extensive online collection of fossil information, covering a wide range of dinosaurs. So given this, it should not surprise anyone that the NHM has put out a dinosaur book. The first edition of the book came out in 1993, with three more editions published since then, the latest one in 2006. We know a lot more about dinosaurs now than we did even ten years ago though, so how well does it hold up? Pretty well, for the most part, although a few Americans might be a bit perplexed by the British spelling that is occasionally different from American English. The NHM has a nice website on dinosaurs, which serves as a nice supplement to the book.
It is a long review, so if you want to skip to the summary conclusions, click here.
The Natural History Museum Book of Dinosaurs
Publication Date: 2006. 144 pg.
Carlton Books. ISBN: 1-84442-183-X, 978-1-84442-183-1
AR Book Level: Not listed
Recommended for 10-14 year olds
Angela Milner has been a well respected paleontologist for decades and has been the leading researcher for dinosaurs at the NHM since the eighties, so if anyone is going to write a book about dinosaurs for the museum, it’s Dr. Milner. Tim Gardom is primarily known for this book, but he has had extensive experience writing for museum exhibits, including the dinosaur exhibit at NHM, meaning that he has practiced the art of writing technical material in a way that can be readily understood by nontechnical and diverse audiences.
This book can be considered an extension of the exhibit at the museum, taking what is there and expanding upon it considerably, forming an extended guidebook. It is not a catalogue of dinosaurs, though, such as Brusatte and Benton’s Dinosaurs. This book places dinosaurs in context within their world, focusing more on what dinosaurs were and how they lived over listing the different types, although it does that as well. More importantly, it talks about how paleontologists came to the conclusions they have, what is the evidence for what we think.
While extensively illustrated with a wide array of photographs of real fossils, paintings and illustrations of reconstructed dinosaurs, and the people and places, it is not a picture book. The text is extensive, but easily readable and should be readily accessible by any interested kid of middle school age or beyond, while still being a good read for adults.
The book has ten chapters broken up into an introduction to dinosaurs and the Mesozoic Era, five chapters on the lifestyles of the dinosaurs, an obligatory chapter on dinosaur extinction, a chapter on the history of dinosaur research, a chapter dealing specifically with how paleontologists piece together the clues to interpret the fossils, and finally ending with the now seemingly obligatory chapter on the evolution of dinosaurs to birds.
Chapter one is noteworthy for its debunking of some popular myths about evolution in general and dinosaurs in particular. It starts immediately with dispensing with the old chestnuts of “survival of the fittest” and the idea that dinosaurs died out because they were not “fit”. They properly describe evolution as being a product of those who are more capable of surviving in a particular environment and successfully reproducing, not necessarily the biggest and strongest. They go on to discuss what types of fossils are found and how they are formed which, while in general good, neglects the important contributions of microbes to the fossilization process. But to be fair, we know much more about that now than we did then and the purely physical processes listed here are still described the same way in almost every book published today. They also do a good job describing what a dinosaur is and is not. They separate animals commonly thought to be dinosaurs, such as dimetrodons, pterosaurs, and marine reptiles, from true dinosaurs. The biggest problem with this section is that the illustrations are poor. The Tyrannosaurus would not pass muster in the first edition, much less now, and the Deinonychus is out of date. Moreover, they continue to use the term “mammal-like reptile”, rather than the more accepted term synapsid, which makes this section appear severely dated. They still use the term “thecodont” to describe the earliest archosaurs that led to dinosaurs, although they at least do say it is an informal term, not one that is formally accepted. The problem with thecodont as a term is that it throws everything with a similar jaw together, whether or not they are related. The bulk of the chapter is a good, but necessarily brief description of the Mesozoic Era, including the position of the continents, the changing climate, and the evolution of plants and animals during this time, focusing of course on the dinosaurs, but not to the exclusion of everything else, which provides the necessary context for dinosaur evolution during this time.
Chapter two is all about movement and tells the story of how dinosaurs went from a lizard-like sprawl to a fully erect posture and the advantages that gave. There is discussion of some of the evidence we have for different gaits and stances, including a lot of discussion about trackways, as well as the diversity in the ways an erect stance has been utilized. The stories of early ideas is an interesting read, although they make one serious error by saying all sauropods had their nostrils on the top of their heads, when in fact they had their noses at the end of their snouts like every other terrestrial animal. I also think they give too much time to the debate over whether or not tyrannosaurs were scavengers or hunters, even though they do eventually come down on the side of hunters, as pretty much every paleontologist does. The tyrannosaur as scavenger debate was getting a lot of press during the time of publication, but it died down pretty quickly, with no one really accepting it anymore, considering there is evidence of active hunting by tyrannosaurs. Go to the Denver Museum of Nature and Science and you will see an edmontosaur with a healed bite taken out of its back.
Chapter three discusses food, how different dinosaurs ate, so one can expect several pictures of skulls and teeth. This chapter gets high marks for discussing current research at the time, such as Emily Rayfield’s work using Finite Element Analysis to determine bite force in several dinosaurs. Criticisms of the chapter include too much credence given to the idea that tyrannosaurs were scavengers which they revisit in this chapter, the discussion of neck posture in sauropods, and missing an important aspect of the tyrannosaur coprolite studies. These criticisms are mostly due to advances since the book was published, not a fault of the authors. The neck posture study has the problem of not sufficiently allowing for cartilage between the vertebrae, nor the fact that living animals bend their necks farther than allowed by that study on a regular basis. The tyrannosaur coprolite study also found remnants of muscle, which indicates a short digestion time. This is a strong indicator of an endothermic animal. Either that or an animal suffering some serious diarrhea. Finally, the chewing cycle of hadrosaurs is no longer as accepted as it was then. Casey Holliday makes a good case that the bones of the skull thought to move during chewing were really much better bound together in life, the supposed joints more an accommodation of quick growth, not for chewing (sadly, the link to the pdf of the paper in the linked article is no longer valid, but the article provides a good summary of the paper).
Chapter four is attack and defense. Interestingly, this chapter discusses tyrannosaurs as hunters, ignoring the scavenger discussion of the previous chapter, providing some indication on where the authors fell in that debate. This chapter does a great job of discussing different techniques for combat and predator avoidance. High marks to this chapter for balanced discussion of current research. I particularly liked the discussion about the role of color in camouflage and display. The biggest gripe about this chapter is the presentation of theropods like Troodon as scaly when we know they were covered in feathers. It doesn’t change the discussion in the text, which is still valid and interesting, but it is a flaw in the presentation.
Chapter five is about social organization, a topic not often covered well in books like this and is possibly my favorite chapter in the book. There are some interesting discussions here that will make one think about these animals as living animals within an ecological context. I would note that there is more evidence of group behavior of tyrannosaurs than was known at the time of publication, so they may have been more gregarious than thought then. I would have liked a bit more explicit discussion of the possibility of Deinonychus as opportunistic groups rather than a cohesive pack, but the discussions do a great job of keeping facts that we know and speculation about behaviors.
Chapter six is titled “Living animals”. This chapter gets into the detailed work of anatomy and molecular studies used to figure out how the animals were put together functionally and metabolically, as well as what their anatomical details tell us about behaviors. It serves as a nice introduction to the real work of paleontologists as more than just digging up fossils. It is a nice chapter and a great read. There are a few things that are a bit off, but not much. They discuss the discovery of actual soft tissue reported from a few dinosaur bones, such as proteins, blood cells, and blood vessels. They do not mention, however, that not everyone accepts those discoveries, instead concluding that what was found were more modern bacterial traces and not dinosaur soft tissue. Nevertheless, it is a good inclusion in the chapter. Our understanding of just how many dinosaurs had feathered has also grown dramatically since the book was published. Few people took the idea of a feathered, adult tyrannosaur seriously ten years ago, but we now have evidence some large tyrannosaurs were indeed feathered. They also make determining brain size in dinosaurs sound much easier than it really is because the amount of non-brain material in the cranial cavity varies substantially in animals other than mammals and birds. The evidence of color vision in dinosaurs, on the other hand, is stronger than presented in the book and we can pretty securely state that dinosaurs had not only color vision, but better color vision than we do. The book also uses a picture of a tyrannosaur with ridiculously large olfactory lobes that we now know is wrong. Tyrannosaurs had large olfactory lobes, indicating a good sense of smell, but they weren’t as large as presented in the book. The book devotes a decent chunk of space to the question of thermoregulation, although it is still necessarily brief, which they acknowledge, as it is a complicated discussion. For what space they have, they did a good job. I would say the idea of dinosaurs being endothermic for the most part is more accepted now than at the time of publication with new evidence pushing the debate in that direction.
Chapter seven concerns the mass extinction at the end of the Cretaceous. It does a good job of discussing the extinction event, including what did NOT go extinct, which complicates the picture. The evidence of a massive impact has been firmly established even more so than when the book was published. The role it played and whether it was the sole cause or the giant nail in the coffin, adding to the volcanism and changing climate, is still debated.
Chapter eight is called “Dinosaurs and people” and is mostly a short history of dinosaur discoveries. Chapter nine discusses what it takes to go from a discovered fossil to an understanding of the life and relationships of the animal in question. Between this chapter and chapter six, the work of paleontologists is given a good accounting and should make for a useful read for any budding paleontologist. What has been added since is a huge increase in technology which has increased data sharing, allowed people to form collaborations easier, and made modeling and experiments much easier, allowing more people to make significant contributions.
The final chapter discusses the evidence that birds are dinosaurs. The book discusses several feathered dinosaurs, but our knowledge of them and the diversity of feathered dinosaurs has grown by orders of magnitude since then. We have even found evidence of melanosomes, subcellular organelles that provide the pigment, which has allowed the determination of color in a few cases. The chapter has a good section on the origin of flight, providing the classic hypotheses, but also includes newer ideas that have greatly added to our understanding of flight, making the old hypotheses incomplete, with portions of both providing a much better answer. The book does state one thing that I would cross out. They state “It seems likely that a simple insulating cover arose first and was later modified for display, signalling, and finally flight.” This is a common belief even among paleontologists, but it is simply wrong. It is highly unlikely that feathers first arose as an insulating cover as the initial stages would have done the exact opposite of providing insulation by increasing surface area without a concurrent increase in insualtion. It is far, far more likely that feathers evolved for display purposes and were then adapted for insulation.
The book ends with a section providing data on several specific dinosaurs, a glossary, suggested sources for further reading, and a useful index.
In summary, the book is a great read. It provides an excellent look at dinosaurs as more than a stamp collection of strange creatures, but as living animals within the context of a real ecosystem. The book gives a better view of the real work of paleontologists than you will find in almost any other source. There are several places in which the science has advanced, making some specifics here and there in need of updating, but the meat of the book is still solid and provides substantial benefit to interested readers. It provides commentary in a much more thoughtful manner than is found in most other books and will make the reader think about concepts in a way rarely seen. The book shows science as a dynamic, changing field where no matter how many answers you get, there are always more questions and every piece of data requires a reexamination of the answers you already have to see if the answers are still valid. Dinosaur science is not extinct, it is still evolving and you definitely get that feeling here.
Now that Labor Day has come and gone, everyone should be back to school by now. I have been absent for much of the summer and not posted nearly as much as I had hoped to. I have been working on some projects which I hoped to have up by now, but are still in process. Working two jobs right now while trying to maintain some semblence of a personal life has left me precious little energy to work on Paleoaerie. But hopefully, that should end soon and I will be back to posting on a regular basis.
In the meantime, there are some news and upcoming events I would like to share so you can put them on your calendar.
- I have received the audio for my talks at the Clinton Presidential Library. Unfortunately, the video was not successful. So as soon as I get the chance to sync the audio to the powerpoint, I will post it here.
- I have joined forces with TIES, the Teacher Institute for Evolutionary Science, sponsored by the Richard Dawkins Foundation for Reason and Science. They have a number of excellent resources on their webpage and will allow an improved opportunity to offer workshops on evolution to teachers and other interested parties. These workshops are designed by teachers for teachers and are aligned with the Next Generation Science Standards. If you are interested in a workshop, please either contact me or Bertha Vasquez, the TIES Director. You can also find them on Facebook and Twitter.
- I will be appearing at the Forest Heights STEM Academy in Little Rock on Friday, September 11, to discuss how the scientific method is really used by scientists.
- I will be appearing at the next quarterly meeting of the Arkansas STEM Coalition meeting on September 25 to talk about TIES and National Fossil Day.
Speaking of National Fossil Day, make sure to put Saturday, October 17th on your calendar. The Museum of Discovery is hosting the second annual National Fossil Day event, even bigger and better than last year. Don’t miss it. National Fossil Day is a part of Earth Science Week, sponsored by the American Geosciences Institute, designed to “help the public gain a better understanding and appreciation for the Earth Sciences and to encourage stewardship of the Earth.”
Now that all the business is out of the way, I will get on with more educational material. In honor of everyone going back to school, I thought I would start a few posts about some definitions that most people generally get wrong. Today, I am going to discuss a few of the types of scientists that study past life.
Whenever a scientist tells people they are an archaeologist or paleontologist, they tend to brace themselves for the almost invariable questions about the other field. In most people’s minds, all the different sciences seem to be interchangeable, with little understanding that just because someone studies the past, they don’t necessarily study everything in the past. I won’t even get into the difference between scientists who study past life and historians. I will leave that for any archaeologists who wish to tackle that issue. I get this question so often that I bought this Tshirt.
Even though we all study past life, there are important differences. Here is a Venn diagram I created that may help explain how they differ.
As you can see, there are two main divisions in scientists who study past life: those who study humans and those who study everything else.
Anthropologists study humans, so don’t ask them about dinosaurs or mammoths or giant sharks. Don’t bring them a fossil you found. If you find a pottery shard or an arrow head, find an anthropologist. If you found a book, you might also try a historian. Ok, I said I wouldn’t get into this, but maybe just a little bit. Historians deal with written human history. So one might say that historians are a subset of anthropologists, in that they only deal with relatively recent anthropology. Many would also argue that they should not be included at all because they do not approach the endeavor with a scientific approach. While I can see the point, I can also see the point that this would also include many anthropologists, so comes across as sounding like the argument about can bloggers be considered journalists. The correct answer is that it is not as simple as that. But it’s not my field and my view of the topic is strictly as an outsider.
Paleontologists study everything that does not include humans. So please feel free to ask us about extinct organisms, as long as they don’t make pottery or arrow heads.This doesn’t mean to say that every paleontologist studies all extinct organisms. There are innumerable specialities within the field. If you ask a paleoclimatologist to identify a bone, he won’t have a clue what you are talking about. They study past climates, not bones. Just like one wouldn’t ask a podiatrist (foot doctor) to do brain surgery, don’t expect an expert in Pleistocene pollen to help you identify which type of trilobite you have, although I expect they could tell you that you do indeed have a trilobite.
But what do you do if you find a fossil of a hominid, something not quite human, but not quite an ape? That is where paleoanthropologists come in. They deal with that intersection between paleontology and anthropology, where the lines blur into shades of grey. In point of fact, all these terms are arbitrary boundaries and only serve to help us break up the studies into something manageable. Like everything else in nature, we have taken a continuous spectrum and cut it into defined sections to satisfy our need to categorize everything.
Even though there is far more life that is not human than there is that counts as human, for obvious reasons. The study of humans is more discussed than anything else. So while it is not my field, i will attempt to separate the major divisions within anthropology. Anthropologists, as mentioned study anything to do with humans. This can be broken down into two main categories. Physical anthropologists study the biology and evolution of humans. If you have human bones, they are the ones to talk to. Cultural anthropologists study human culture, their behaviors, what they make, how they interact with others. If it’s not a bone, but related to humans, ask a cultural anthropologist.
But what then are archaeologists? Do they not do the same thing as anthropologists? Yes, because they are anthropologists. They are just a subset that happens to be so well known that many people lump archaeologists and anthropologists together as if they are the same thing. But they aren’t, not quite. All archaeologists are anthropologists, but not all anthropologists are archaeologists.
Archaeologists study past human life through physical remains. Thus, they include some of both physical and cultural anthropology. They are the ones to talk to about pottery shards, arrow heads, and the like. Any physical evidence of a preexisting culture could be brought to the attention of an archaeologist. However, anthropologists cover a lot more ground, so to speak. There are cultural anthropologists that study current, existing culture. This is in fact a large field within cultural anthropology. There are even physical anthropologists that study evolutionary changes taking place within humans right now. Neither of these would count as archaeologists though.
Just as in anthropology, as I mentioned earlier, there are several different subspecialties within paleontology. Here is how the University of California Museum of Paleontology breaks it down.
Paleontology is traditionally divided into various subdisciplines:
- Study of generally microscopic fossils, regardless of the group to which they belong.
Paleobotany: Study of fossil plants; traditionally includes the study of fossil algae and fungi in addition to land plants.
Palynology: Study of pollen and spores, both living and fossil, produced by land plants and protists.
Invertebrate Paleontology: Study of invertebrate animal fossils, such as mollusks, echinoderms, and others.
Vertebrate Paleontology: Study of vertebrate fossils, from primitive fishes to mammals.
Human Paleontology (Paleoanthropology): The study of prehistoric human and proto-human fossils.
Taphonomy: Study of the processes of decay, preservation, and the formation of fossils in general.
Ichnology: Study of fossil tracks, trails, and footprints.
Paleoecology: Study of the ecology and climate of the past, as revealed both by fossils and by other methods.
Each one of these can be broken down into even more specific specialties. Paleoecologists can specialize in biogeography, limnology, pedology, tempestology, schlerochronology,and many others. Vertebrate (and invertebrate) paleontologists can specialize in taxonomy, systematics, functional morphology, etc., but I think you get the point. There is far more that can be studied by any individual. paleontology, like any other science, is a team sport.
There are no hard and fast boundaries between these of course. Vertebrate and invertebrate paleontologists can and do study taxonomy, biogeochemistry, paleoecology, and taphonomy, and others all at the same time. Paleontology is highly interdiscplinary and requires knowledge in a lot of different fields. But many scientists tend to spend most of their time in a specific area.
So if you have a question, you will get the most detailed answers from someone in the right specialty. Choose wisely and you will get your questions answered. If you don’t, go to grad school, discover them for yourself and let everyone else know about it.
Chase, from Odyssey of Time (nice blog, check it out), guessed the answer for this puzzle. See below for what amazing animal this picture represents.
If one thinks about cliff-diving geese, nothing fits the bill better than barnacle geese, also known as Branta leucopsis. They live in the North Atlantic and can be found along the coasts and islands around Greenland, the United Kingdom, and most recently in the Baltic Sea around some of the Nordic countries.
The day they are born they face a daunting task. To protect the eggs from predators, the adults make their nest high up on cliff faces, oftentimes 400 feet (150m) above the base of the cliff. Unfortunately, the food is at the bottom of the cliff and the parents do not bring food to the chicks. So what is a hungry newborn to do? They jump.
It’s a rough life. Between the dangers of the fall, the predatory birds above, and the foxes below. they are fortunate is half of the chicks survive their first day. Personally, I don’t see how any of them survive. The fall is just brutal. Listen carefully to the video and you can hear the chick squeak as it hits the rocks repeatedly on the way down. Amazingly, the chick just brushes itself off and carries on, a little dazed, but seemingly no worse for wear.
Sir John Mandeville, in the 14th century, had an interesting view of them. According to Sir Mandeville, “in our country were trees that bear a fruit that become birds flying, and those that fell in the water live, and they that fall on the earth die anon, and they be right good to man’s meat. And hereof had they as great marvel, that some of them trowed it were an impossible thing to be.”
it is truly amazing how easy it is to completely fall out of a routine if you break it for any stretch of time. Fortunately, or unfortunately, it is also often just as easy to fall back into it. in this case, I am hoping it will be easy to get back into writing for Paleoaerie after my unexpected extended break. There is much that will be coming as soon as I can. most notably the recordings of talks I gave at the Clinton Presidential Library in Little Rock, AR in the past month or so. One is on engineering a dinosaur, given just in time for the opening of Jurassic World. Speaking of Jurassic World, it is a great monster movie, as long as one is not looking for accuracy in its dinosaurs. But as the geneticist in the movie states, the real dinosaurs would have looked considerably different, but they wanted bigger, scarier, with more teeth. The other talk is on Arkansas fossils and why we need a natural history museum in Arkansas.
For now, I will just leave you with this puzzle. The pictures represent one of my favorite extant animals, simply because their young are so incredibly amazing. Leave your guesses in the comments section and stay tuned for the answer.
Last week I posed this challenge. What real animal combines traits from the kiwi, anteater, and hedgehog. Chase and Herman Diaz came up with the correct answer.
The animal that has the traits of these three animals is the echidna, also known as the spiny anteater. Named for the “mother of all monsters” in Greek mythology, the real echidna looks like a combination of other animals, much like the mythical Echidna herself, who was part woman, part snake.
When people think of weird mammals, echidnas are very often at the top of people’s lists. It has several traits that are commonly mentioned. First, it is a monotreme, a group of mammals that lay eggs. Today, monotremes consist only of echidnas and platypuses, but in there were several others in the distant past. Platypuses are so strange that people at first thought it was a fraud. Who would believe an egg-laying mammal with the face of a duck?
Second is their fur, which has numerous sharp spines, similar to that of a hedgehog. Because these spines are modified hairs, they have limited control of them. Just like other mammals can make their hair stand up (humans know this chiefly as “goosebumps”), the echidna can make its spines stand up, although they can’t shoot their spines like some people would have you believe.
That fact the echidnas lay eggs makes their reproductive system rather different from almost all other mammals. Internet sites always want more people to click on their site, so echidna reproduction gets a lot of discussion. An internet search will immediately turn up comments and pictures of the four-headed penis of the males and the fact that the females have no nipples, instead feeding their young (called puggles) through glands in their pouches (yes, they have pouches like marsupials) which secrete the milk that the young lap up. You can even find talk of the mating trains echidnas can form during mating season, in which the males form a line behind the female and follow her around for upwards of six weeks until she finally decides to mate. Then they dig a trench around her, jump in and try to push each other out like some sort of bizarre sumo contest. The last male still in the trench wins the right to breed first.
Much like many reptiles, which have what is termed a hemipenis (a two-headed penis), the male echidna only uses half of its penis at a time. In the echidna’s case, that means that they use two out of the four heads at any one time, which is good, because the female echidna has two uteruses. We’re still not done with the weirdness. Because the female may mate with several males, the sperm joins into one large mass, a super-sperm if you will, that together, can swim faster and stronger than any of them separately.
There are several traits that the echidna shares with the platypus, in addition to laying eggs. The echidna is edentulous, meaning it has no teeth. It does, however, have an incredibly fast tongue; able to slurp up the ants, termites, and other insects at the rate of 100 licks/minute; thus its name Tachyglossus, which means “swift tongue”. It also has a very sensitive beak that is electroreceptive, meaning it can detect the tiny bioelectrical signals given off by the insects for which it forages. Additionally, echidnas have a spur on its hind legs, although unlike the platypus, it is not venomous.
So what does it mean to be a monotreme? The Tree of Life web project has an excellent and clear summary of what a monotreme is scientifically. Evolutionarily, the monotremes are the oldest true mammalian lineage, splitting off the line that led to placental mammals sometime around 200 million years ago (as a point of reference, the oldest known dinosaur was found in rocks dating to 230 million years ago). Much of what we consider to be mammalian had yet to evolve by this point, so there were still several traits monotremes shared with reptiles that were derived from the common ancestor of both the reptiles and mammals. This split was so early in fact, that the middle ear bones developed independently from other mammals.
My personal favorite of all the strange things about the echidna is its thermoregulation. When people think of mammals, besides for milk glands and fur, they think of “warm-bloodedness”. Thermoregulation is far more complex than most people realize. There is much more than “warm- or “cold-bloodedness”. Better descriptions of thermoregulation are endothermy (temperature controlled internally)/homeothermy (maintains constant temperature) and ectothermic (temperature strongly influenced by environment)/poikilothermic (temperature fluctuates). But these are just endpoints on a spectrum. Perhaps no other animal illustrates the variation better than the echidna.
The echidna does it all. At various times, the echidna displays endothermy, ectothermy, homeothermy, and poikilothermy. It hibernates, it goes into torpor on a regular basis. The echidna is also a eurytherm, meaning that it can operate just fine at a variety of temperatures without loss of function or activity levels. Whereas most mammals would lose function and coordination if their bodies cooled even a couple of degrees and would completely shut down if they cooled ten or more degrees, the echidna gets along just find even when its body cools to 20 C (that is 68 F for those in the US, a temperature at which we would be long dead).
Needless to say, it is a heterothermic animal. Heterothermy is when an animal lets its body temperatures fluctuate. While it is a broad term that includes poikilothermy, it is typically distinguished from poikilotherms by being under the control of the animal and/or by being regional, meaning that different parts of its body have different temperatures. The classic example of this is the deer, in which the legs are allowed to get cold while the body stays warm. African elephants do this somewhat in reverse, shunting blood to their ears allowing them to heat up, thereby dumping heat from their core body to their ears, which can then cool off more readily due to their large surface area. Of course, few mammals can beat the camel, allowing their temperatures to vary as much as 7 C throughout the course of a day.
Anyway, back to the echidna. Check out this graph. In this study, the researchers measured the body temperatures of a female echidna for 13 years. The graph shows temperature ranges for one year. Another study found that the echidna typically maintained temperatures when active at around 32-33 C (as compared to our 37 C) and dropped to 27-28 at night when it was inactive, although it could drop to as low as 4.7 C and still get up and have normal activity during the day. This variability not only allows it to use less energy, but it also allows it to tolerate temperatures as high as 42 C. Starting the day cold allows it to absorb more heat during the day without overheating. And it is not just its temperature that it allows to vary. The echidna can vary its metabolic rate while still maintaining its normal activity levels. Of course, when it needs a stable body temperature, like for instance, when it is incubating an egg, it can do that too.
All told, the echidna is a pretty amazing animal. It is also about as close as we are going to get in a living animal to see what our mammalian forebears were like in the early years of mammalian existence.
The natural world can be a very strange place. WTF evolution?! is a great site that takes a humorous look at some of nature’s weird turns. Today I am going to celebrate some of nature’s curiosities by playing a game. Some animals are so weird they look like combinations of other animals. For instance, the platypus is often said to look like a cross between a duck and a beaver. I will provide a fictional cross between a set of animals. See if you can guess what real animal it might be. Then come back later to see what animal it is and description of what makes it such a curious animal.
For today’s cross, what might you get if you cross a kiwi (the bird, not the fruit) with an anteater and a hedgehog? I will give you a hint. It is an extant animal, so you can rule out any fossil animals.