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Marine Paleo Animal Fest, Day 3

saratogachalkMonday was a goniopholid crocodilian. Tuesday was mosasaurs, the largest of the marine predators. For day 3, we’re going to the other end of the scale.

What is a picture of a rock outcrop doing here? This is a picture of the Saratoga Chalk, courtesy of the Arkansas Geological Survey. Look at it this way, and it is tons of chalk, the same that they used to make for blackboards when they used the real thing.

But look at it under a microscope and you open up an entirely new world. For chalk is not just a rock. It is a rock made of trillions of shells of microscopic organisms that live in the oceans.

Two kinds of microorganisms make up most of the chalk. The Saratoga is primarily noted for its abundance of foraminifera, (forams for short) one-celled organisms that form shells, or tests, out of minerals dissolved in the sea water. The ones that make up chalk and limestone form theirs out of calcium carbonate. It is unclear what they are related to, but one thing is clear. They have developed a huge diversity in their over 500 million years of existence.


Pacific forams. Smithsonian,  Pamela Haddock, University of South Florida

I find forams fascinating because of their wonderful diversity. Here is another picture posted on the blog “Letters from Gondwana.” The article is a nice description of forams if you want more information on them.


The other group that is commonly found in chalk is called the coccolithophores. These are very tiny, once-celled plants found in the ocean and make up one of the largest groups of phytoplankton. They also make shells of calcium carbonate, but instead of a shell like the forams, they create their home with a few dozen intricately formed scales.

The coccolithophore Gephyrocapsa oceanica. Wikipedia.Gephyrocapsa_oceanica_color.jpg

When the cells die, the scales scatter and become tiny grains of calcium carbonate which, when piled up on the ocean floor with all the other debris from the oceans, can form those particles of chalk that you used to clean off the blackboard.

Both of these groups prefer shallow, warm seas. Go to the Bahamas or the Persian Gulf and you will get an idea of the environments that are admirably suited to making modern day chalk, as well as getting a good idea of what Arkansas was like 100 million years ago.



Day 2 of marine paleo-animals: Mosasaurs

Continuing our celebration of marine animals of the Cretaceous found in Arkansas, here is a picture of a mosasaur. It is from the Dallas (Perot) Museum of Nature and Science. They have a great display of several different mosasaurs. You can also see one on display at the natural history museum located at the University of Texas at Austin.


Heath mosasaur, Dallas Museum of Nature and Science

Heath mosasaur, Dallas Museum of Nature and Science

Mosasaurs were the apex predators of their time, which was in the Late Cretaceous. Tyrannosaurs may have ruled the land, but mosasaurs ruled the seas. The first mosasaurs appeared in the early Cretaceous, but by the end, they dominated the oceans. Unfortunately for them, they only had a 20 million year or so run at the top before the mass extinction at the end of the Mesozoic Era wiped them out along with the dinosaurs.

Mosasaur in UT-Austin museum

Mosasaur in UT-Austin museum

Mosasaurs were not related to dinosaurs, other than also being reptiles. They were most closely related to the group of lizards that include the monitor lizards, such as the Nile monitor and Komodo Dragon. They were fast predators with a powerful tail to move them through the water. Mosasaurs were so adapted to the water that they bore live young and were not able to walk on land, although they did still have to surface for air like every other reptile. Recent research has found they were endothermic (warm-blooded), unlike their competitors, giving them an edge by allowing them to sustain higher activity levels. It also meant they had to eat more often, making it necessary for them to be effective hunters. Research has also indicated they were countershaded, with a lighter belly than the back, much like many sharks of today. They had a varied diet, with some species specializing in different prey, so over the whole group, they pretty much ate everything in the ocean.

Mosasaur bones have been found in many places throughout southwest Arkansas, which was covered by the Western Interior Sea during the Cretaceous. Two species have thus far been recognized. Platecarpus was fairly small, only 4-5 meters (13-16 feet), but were noted for some exceptionally preserved fossils that retained the impressions of a tail fluke, allowing paleontologists for the first time to see what their tails looked like. The other species is Mosasaurus itself, a huge predator that reached lengths of 15-18 meters (50-60 feet).



Sharks! Welcome Back to School

Welcome back to the new school year. Some of you will be excited to be back, seeing old friends, making new ones, and learning new things. Some of you will be sad to see summer end. Many of you will be doing both at once. Others of you of course aren’t in school and don’t care about it, but if you are here, you are nevertheless interested in learning cool new stuff. So it is a time for a celebration of the natural world.

Shark Week is a big summer event on the Discover Channel. It is probably their biggest viewer draw all year. Who doesn’t like learning about sharks and seeing them in all their awe-inspiring glory? Additionally, if one is keeping up with the weather, southern Louisiana is currently being deluged, with Baton Rouge and surrounding areas practically getting washed away.

So I thought this would be a good time for Paleoaerie to hold its own version of Shark Week. I can’t do a series of tv specials, so I am going to extend my Paleo Shark week over two full weeks. All this week I will be putting up short posts on marine creatures that swam in the oceans of southern Arkansas during the Cretaceous. Every day will be a new post on something that would make your swim…interesting. Next week will truly be Paleo Shark Week. Every day next week will be highlighting a different shark that would be swimming in the Cretaceous waters of southern Arkansas.

To kick things off, I will start with this creature.


This is a crocodylomorph, meaning that it is in the same group that includes crocodiles and alligators. Specifically, it is a member of the family Goniopholididae. Species in this group were, at least superficially, similar to modern crocodilians. They were semi-aquatic hunters living in marsh and swamp lands. They wouldn’t look out of place with the modern alligators swimming around Arkansas today, except that they probably couldn’t compete effectively with alligators, who are better adapted for the lifestyle than they were. They lived throughout much of the Mesozoic, from the early Jurassic to the Late Cretaceous, when the more modern forms replaced them.

Goniopholids are what is known as mesosuchians, which means “middle crocodiles”. Mesosuchians, as the name suggests, were more derived than the earliest crocodyliforms, such as the protosuchians, although less derived than modern-day crocodilians. Mesosuchians is not a formal name, but an informal and decidedly paraphyletic (i.e. not a valid cladistic grouping because it leaves out some descendants) name to designate those crocodyliform species showing the early characteristics and those that show the characteristics of the modern crocodilians. Here is a phylogenetic tree put out by Chris Brochu in 2001, showing the general relationships within the crocodylomorphs. The names on the left side of the long main line include everything from that point on, e.g. Crocodymorpha includes “sphenosuchians” and everything below it, but not the Aetosauria and above. Mesosuchians plus Eusuchia (which does include all modern groups) can correctly be called Mesoeucrocodylia, but that hardly helps us specify the group.



Simosuchus, Royal Ontario Museum.  Photo by Gordon E. Robertson.


Mesosuchians include a wide variety of animals with a large number of species. They include terrestrial  animals like the carnivorous boar croc Kaprosuchus and the herbivorous Simosuchus, as well as the more typical semi-aquatic pholidosaurs, which include the super croc Sarcosuchus, one of the largest crocodylomorphs ever, reaching almost 40 feet.

Sarcosuchus may not have been quite as big as Deinosuchus though. Deinosuchus was an alligatoroid (within the larger alligator family, but not a modern alligator), which potentially reached upwards of 40 feet, but may have been heavier set. Sarcosuchus lived in the early Cretaceous at the same time as Goniopholis in Arkansas, but lived in Africa and South America. Deinosuchus, on the other hand, lived int he Late Cretaceous right here in Arkansas. While we have no bones to prove this, we do know they lived in Texas and Mississippi, as well as many other places in the United States. The environment would have been suitable for them, so there is no reason to think they did not live here as well.

2002-01-16 15.40.23

Sarcosuchus life size model “attacking” my family.


Real, Replica, or Fake

One question I get asked a lot when I show fossils to people is “Is it real or fake?” It is a question that always irks me because it seems very few people understand that this is an entirely wrong question.

People like to categorize things into binary bins. Is it black or white? Republican or Democrat? Is it raining or not? Do you accept science or religion? Of course, none of these questions make any sense as an either/or question. Just like real or fake, all of these questions miss the fact that there is more to it than one or the other. All of them can only be correctly answered if one is cognizant of the other variations. So today, I am going to introduce to you a more nuanced view of whether or not the fossils you see in museums are real or not.

Real fossils need little explanation. They are the actual fossil material. Whether or not it is actual bone or shell being preserved, a bone that has been replaced with minerals, a natural mold, or other some such style of preservation, they are real.


This is a real plesiosaur vertebra found in (or thereabouts) Sevier County, Arkansas.

Real in this case does not mean it is remains of the actual organism, although it can be. Bone, shell, leaves, and other tissues can be preserved indefinitely under the right conditions. Usually however, they are replaced with minerals or remain only as impressions in the sediment. In any case, these are all real fossils. They are the original fossil found, dug up, and brought back to the institution or person to whom it belongs.

Replicas  are casts or molds made from the actual fossil. They are made to look as close as possible to the original fossil. These are made so that the original can be protected while the copy is shown to many more people than could see the original. Use of replicas allows copies to be put in the hands of many people all over the world. In many instances, the original is too fragile or heavy to safely transport.


This is a cast of a real apatosaur bone. The original would be far too heavy and fragile to haul around to classrooms all the time.

The important point about replicas is that they are not fakes. They are duplicates of a real fossil. In some cases, they can be even better than the real thing. After decades of handling, the original fossils can get worn or broken, with details once present no longer visible.


Photo of the Berlin Archaeopteryx taken by Dr. Dave Hone. This fossil used to have, among other things, feathers on the legs, which were removed during too extensive preparation.

Fakes, on the other hand, represent something that is not only not real, but never existed. Many fakes are designed to deceive and so are often called forgeries. The difference between what many people think of as forgeries and what we are talking about here is that forgeries are usually designed to trick people into thinking they are the real thing. A replica, if presented as the real thing, would be considered a forgery. However, in paleontology, most things described as forgeries are in reality fakes designed to deceive people into thinking a fiction is real. Fakes are never acceptable in museums unless explicitly labeled to indicate that they are fantasies. The Piltdown Man is an example of a fake. It was made with the express purpose of making people think it was real, when in fact it was created from bits of human and animal bones that were altered to make them look like they belonged to the same primitive human.

Archaeoraptor was another fake. This one adds a wrinkle in the topic though. Archaeoraptor was made by gluing pieces of different fossils together. The individual pieces were real, but the resulting chimera was a fake.


Archaeoraptor. The picture on the right shows the various pieces. See the hyperlink for the full story.

As Archaeoraptor shows, fakes don’t have to be unreal to be fictional. There are lots of fakes that are real fossils put together in intentionally misleading ways. In the case of Archaeoraptor, they were simply trying to make the fossils more spectacular so they could sell them for a higher price. Others are done to discredit scientists or simply as pranks for fun.


Surgeon’s photo of “Nessie”

Of course, there are plenty of fakes that are made up out of whole cloth. Numerous “human” footprints found with dinosaur tracks are nothing more than carvings designed to trick gullible people. I have personally seen several in which the tool markings were clearly visible. The most famous picture of the Loch Ness Monster, known as the surgeon’s photo, was a fake.


A supposedly human footprint stepped on by a dinosaur track. Neither human nor dinosaur tracks look like this in reality. This is a clear fake being passed off as evidence of creationism by Carl Baugh.

So remember, when you are going to a museum or looking at fossils from a paleontologist, you may be looking at real fossils or replicas. But you will never be looking at fakes. They may not be the original fossils, but they are not trying to mislead you or lie to you, which is what fakes are trying to do. If you really want to see fakes, try here or here. And please, don’t insult your local paleontologist by saying they are showing you fakes when all they are doing is showing you replicas of real fossils that you might otherwise never be able to see.

Fossil Monday, A New Segment

Here is a new fossil for you to identify. I haven’t put up anything like it before, so you can rule out any of the usual candidates. I will put up the answer next Monday unless some early bird beats me to it. Good luck.


Fossil Friday: Stuck on the Rocky Shores

So were you able to identify our fossil this week?


This if Figure 5 from the only real publication on Arkansas fossil barnacles. I posted an articles on barnacles once before, but time grew short and I neglected to mention specifically the Arkansas ones, an egregious error on a website devoted to Arkansas fossils. So I am now correcting that with this post.

As I mentioned in the last post, barnacles are crustaceans and have been around since the Cambrian Period. They can be found throughout much of the Northwest half of the state, basically anywhere not carved out by the Mississippi river. However, other than some miscellaneous purported barnacles borings on clam shells and the like in the Ozarks and Ouachitas, there is not really any published literature on the subject.

For published information, if you really want to know about barnacles, you need to talk to Victor Zullo at the University of North Carolina, Ernest E. Russell of Mississippi State University, or Frederic Mellon. Sadly, you will find that difficult as they are all now deceased, leaving the field of Arkansas cirriped studies completely wide open to the prospective student.

In 1987, the trio published a paper detailing two new species of barnacles found in a quarry in Hot Springs County, Arkansas. The first barnacle was identified as being in the suborder Brachylepadomorpha and was named Brachylepas americana. They listed this as important as being “quite possibly the richest single accumulation of brachylepadomorph material ever encountered.” They also suggest that because of its similarity to other species in Europe that there was “unrestricted communication between these widely separated geographic regions during late Campanian time.”


Another thing I found interesting about these barnacles is where they were found. Thousands of these fossils were found in a gravel within the Brownstone Formation, dated to the Late Cretaceous, and deposited in a littoral environment. This is a high energy, near shore environment. The living representatives of this group, though, are only found near hydrothermal vents.

The other barnacle they discuss and the one which is shown in Figure 5 above is Virgiscalpellium gabbi and a subspecies V. gabbi apertus. These are only known from nine specimens however, unlike the thousands of B. americana. This seems to be a much less common species throughout its range than other barnacles.

Along with the barnacles, the trio mention the Brownstone Formation is rich in fossils of other types, including, the oyster Exogyra ponderosa, several gastropods, a sponge, brachiopod, serpelid worm, bryozoans, nannoplankton, and the odd vertebrate, such as mosasaurs, sharks, and skates.

Zullo, Victor A., Russell, Ernest E., and Mellen, Frederic F. 1987. Brachylepas Woodward and Virgiscalpellium Withers (Cirripedia) from the Upper Cretaceous of Arkansas. Journal of Paleontology. Vol. 61(1):101-111.

The Griffin and the Dinosaur

The Griffin and the Dinosaur by Marc Aronson review summary: Get it. put it in your library collections. It has science, history, sociology, and documents the efforts of the researcher so people can see how ideas are put together, all in an easy to read, accessible format. There is even a free online education guide, with classroom activities matched to sixth grade common core standards. Highly recommended for elementary and middle school libraries. To see why, read the full review below.

The Griffin and the Dinosaur: How Adrienne Mayor Discovered a Fascinating Link Between Myth and Science.

by Marc Aronson with Adrienne Mayor. Illustrated by Chris Muller

griffinanddinosaurPublication Date: 2014

National Geographic Society. ISBN: 978-1-4263-1108-6 (trade hardback) 978-1-4263-1109-3 (reinforced library binding) Available from Bound to Stay Bound Books

ATOS level: 7.4, AR quiz availability: reading practice, 1.0 AR points

Recommended: Grades 4-8

If you are looking for a book about dinosaurs or myths, get another book. But if you are looking for a book about how myths are made and how dinosaurs play into that, this is a great book. The story here is one of cultural interpretations of the natural world. Before people knew about dinosaurs, they found their bones and tried to explain them as best they could according to their worldview. This book tells of the search by one woman to unravel the origins of myths with the hypothesis that they began as most stories do, with a kernel of truth.

Adrienne Mayor has written two influential books, called The First Fossil Hunters and Fossil Legends of the First Americans, in which she lays out all her evidence to support the idea of dinosaur bones being the kernel of truth upon which some of the myths from the ancient Greeks and Romans and the native Americans were built. However, these books together run almost 900 pages, which, while interesting to the serious student, are a bit out of reach for the casual reader. The Griffin and the Dinosaur makes an excellent introduction to this work that is accessible for anyone who can read beyond the basic learning to read books.


Illustration by Chris Muller

Marc Aronson has written several books for children and young adults, mostly relating history in a way that people will actually read. The writing is clear, easy to follow, and relatable enough to keep most readers engaged. The book is illustrated with numerous photos of archaeological artifacts, historical photos and drawings, and the occasional dinosaur. There are too few dinosaurs for my taste, especially for a book with the word dinosaur in the title, but the book is focused on the history and myth interpretations, not dinosaurs. The photos are supplemented with illustrations by Chris Muller, which add to the feel of the book, connecting the bones to the imagination.

The book is split into eight chapters, each only a few pages long. The first chapter, “Prairie Girl”, describes Adrienne Mayor’s childhood and her developing interest in nature and ancient myths. The second chapter, “The Sound of Heat’, finds Adrienne in Athens studying ancient Greek manuscripts in Athens. I’m not too fond of this particular chapter. In a chapter only three pages long, two pages are taken up mostly describing the conditions of the library in which she studied. Only on the third page does Aronson talk about griffins and Mayor’s question about what kind of fossil animal might have inspired it. The last paragraph of the chapter tells of her discovery of the “monster of Samos”.


Illustration by Chris Muller

“Sketching Griffins”, the third chapter, describes her discovery of ancient bronze griffins on Samos, but only giraffe bones for the monster, which could not have inspired the myth. It does answer a question I have long wondered. How did an obviously wingless dinosaur become the winged griffin? The answer to that lies in the very earliest depictions of griffins, which did not have wings. The wings were added later as the myth of the griffin grew and became more fanciful. The other thing I like in this chapter is the discussion of search images. When people have an idea in their head of what something should look like, it aids them in identifying it quickly, but it blinds them to possibilities outside that image.

Chapter four deals with Adrienne changing her search image by more study of the development of the griffin myth through history as well as any connections others had made, which led her to the work of Othenio Abel, who had asserted the cyclopean myths came from mammoth skeletons.

Chapter five continues her search for the historical origins of the griffin tale. During this time, she discovers Triceratops, which she thought might be the kernel of truth behind the myth. This is a nice chapter because it shows that even big, embarrassing mistakes does not mean that one should give up. They merely teach you what you need to learn next.


Illustration by Chris Muller

“The Secrets of the Flaming Cliffs”, chapter six finally introduces Adrienne to Protoceratops, a small, beaked dinosaur that was found associated with eggs in a nest. It had a small frill and a long scapula, or shoulder blade, which could have been mistaken for a potential wing support. At least, it could if someone didn’t know very much about anatomy, which includes most people.

The last two chapters deal with the publication of her work and her continuing research into other myths and legends. It ends with a reference back to expanding our search images to find the truth behind the stories.

The book ends with few nice addendums. There is a map of the world showing where things mentioned in the text were found. There is a page of suggestions for further reading, which include her other books, books for younger readers, and online resources. A combined glossary and index covers the more challenging and interesting words. The book wraps up with a page about Marc Aronson and how the book came about.

So to sum up, there is precious little dinosaur and a whole lot of griffin in this book. But it does a wonderful job of depicting a personal story about how dinosaurs have played a role in the development of our cultural beliefs. It also serves as a reminder that we should not dismiss stories as pure fantasy. Strip away the fantastical and you may find something real underneath.




Questions from Students

A couple of weeks ago, I visited Dodd Elementary in Little Rock. After I left, the students wanted more information and sent me several questions. I thought, rather than respond to them individually, I would post the answers here.

Did saber-toothed tigers live at the same time as mammoths in the Ice Age? How old are mammoths?

Yes, they did! They even lived together in Arkansas during the Ice Ages, along with the more commonly found mastodons (which were like the mammoths, but a bit smaller (about the size of modern elephants) and were more adapted for forests than the grassy plains preferred by the mammoths.

What most people refer to as the Ice Age was in fact a series of almost a dozen times in which the glaciers expanded to cover much more land than they do now. This period lasted from about a million years ago to 11-12,000 years ago during what is called the Pleistocene Epoch.

There were actually many different species of saber-toothed cats. The most commonly known is one called Smilodon, which lived between 2,500.000  years ago to about 10-12,000 years ago.

The first mammoths appeared around 6,000,000 years ago, but the Woolly mammoths and the Columbian mammoths (the type that lived in Arkansas), first appeared about 400,000 years ago. They came south from Canada into the United States about 100,000 years ago. While they died out in North America almost 12,000 years ago, there were a few that lived on Wrangel Island near Russia until less than 5,000 years ago.

I wanted to know if cavemen were alive because didn’t the dinosaurs eat them?

All the dinosaurs (except birds) died out over 65,000,000 years ago, but the first humans only appeared around 200,000 years ago. So humans and dinosaurs were separated by an enormous amount of time and never lived together. Humans did live alongside the mammoths and saber-toothed cats during the Ice Ages, though. Humans killed and ate mammoths and humans and saber-toothed cats killed each other (we don’t know if humans ate the saber-toothed cats, but we’re pretty sure they ate us).

How old is coral?

Coral is very, very, old. The first corals appeared over 500,000,000 years ago. However, none of these early types of coral still exist. They all went extinct (died out) and were replaced by types of coral that evolved (descended) from them. The modern corals that you can see today first appeared in the Triassic Period roughly 200,000,000 years ago (the first dinosaurs appeared about 240,000,000 years ago).

How big is a T. rex egg?

No one knows! No T. rex eggs have ever been found. We can guess they were up to a foot long and up to five inches wide, but that is just a guess based on what we know of eggs that have been found from its distant relatives. What we do know is that T. rex babies were a lot smaller than the adults would have been no bigger than a small turkey.

How long is a sea spider?

fossil_focus_pycno_4Sea spiders, or pycnogonids (pic-no-go-nids), can grow up to 25 cm (10″). They can be found in the southern oceans today. Fossils of sea spiders are rare, but have been found as far back as the Cambrian Period almost 500,000,000 years ago. Even though they look something like spiders, while they are arthropods like spiders, they are not really spiders and occupy their own group within the arthropods. They are very strange animals, with most of their organs in their legs.

Eurypterus-remipes-LI think you may have been referring to a different animal though, the sea scorpions, which was part of the fossil collection we saw in class. Even though they are called scorpions, they are not true scorpions, although they are related to them. These animals, called eurypterids (your-ip-tur-ids), were mostly no more than 30 cm (12″), but could get almost 2.5 meters (8′), making them the biggest arthropods ever known. The earliest fossils we have found were dated at 467,000,000 years, but they may have first appeared over 500,000,000 years ago. They died out at the end of the Permian Period just over 250,000,000 years ago, along with most of the life on the planet at the time.

What is the shortest sea dinosaur?

While there were sea-going reptiles, there were no sea-going dinosaurs that we know of. The closest that we know of right now were the spinosaurs, which spent much of its time wading in relatively shallow water. These dinosaurs were huge, some of them approaching 15 m (50′) or more, with the smallest ones only a modest 8 m (26′).

Of the sea-going reptiles, the most common ones were the dolphin-shaped ichthyosaurs (ick-the-o-sores), the lizards called mosasaurs (literally lizard, they evolved from monitor lizards like the Komodo dragon),  the generally short-necked and big-headed pliosaurs (ply-o-sores), and the long-necked plesiosaurs (please-e-o-sores, for the purists, plesiosaur can also refer to both pliosaurs and the more traditional plesiosaurs because the larger group containing pliosaurs and plesiosaurs is named after the plesiosaurs. yes, it is a bit confusing). And of course we can’t forget the sea-going crocodiles called metriorhynchids (met-re-o-rine-kids).

The smallest ichthyosaur, or “fish-lizard” named Cartorhynchus (cart-0-rine-cuss) was less than 0.5 m (15″) long. it was also the oldest known one at almost 250,000,000 years old. You may notice that the picture below says the smallest was 70 cm, but an even smaller one was found.


Dallasaurus (“Dallas lizard”), the earliest known mosasaur, was also the smallest mosasaur at no more than 1 m (3′).

The smallest plesiosaur was just over 1 m (3′).

Thalassiodracon, or “sea dragon”,  probably the smallest known and most primitive pliosaur, was 1.5-2 m (5-6.5′), so slightly bigger than its relatives, the plesiosaurs. All of the marine (sea-going) crocodilians were more than 2 m (6 ‘) and would have eaten the others, so we can rule them out for shortest marine reptile from the Mesozoic Era during the age of dinosaurs.

There is another group of marine reptiles that was also common during the Mesozoic, although they are not so widely known. The thallatosaurs, which literally means “ocean lizard” were as small as 1 m (3′). Finally, there was a sea turtle-like group called placodonts, of which the smallest were just under 1 m (3′).

Notice that most of them all start off at roughly 1 m, except for the ichthyosaurs, which started off at less than half of that, so the winner for shortest sea reptile of the dinosaur age is the ichthyosaur named Cartorhynchus.

What is the longest sea dinosaur?

The undisputed king of the marine reptiles was the ichthyosaur named Shonosaurus, also known as Shastasaurus, which reached 23 meters (75 feet).


Still not the largest known individual of the species.

jurassicworld mosasaur

Jurassic World mosasaur, still not as big as Shonisasaurus

The longest mosasaur is, coincidentally, Mosasaurus itself, potentially reaching lengths of 18 meters (59 feet), so not as big as Shonosaurus. This animal used to live in Arkansas. According to the most official statements, the mosasaur in Jurassic World was 22 meters (72 feet), so bigger than the real ones, but not by a terribly large degree, and still smaller than Shonisaurus.

The longest pliosaur was no more than 18 meters (59 feet), while the longest plesiosaur was no more than 15 meters (49 feet), so none of them come close.


How did they breathe underwater?

It does seem like animals who live in the sea should be able to breathe underwater, doesn’t it? But the aquatic (a fancy word for living in the water) reptiles didn’t. Like all reptiles, they had to come up to the surface to breathe. This is true for any reptile that swims in the ocean, including sea turtles and marine iguanas. The same is true for their distant relatives, the birds. Penguins have to breathe air, even though they can dive deep. It is also true for all mammals, such as whales and dolphins. So how do they dive underwater and stay underwater for so long? They hold their breath, just like we do when we swim. Only they are much better at it than we are and can hold their breathe for a long time.

What is the longest land dinosaur?

That is an excellent question. The problem is that we have no fully complete skeletons of the largest dinosaurs, so we have to estimate their sizes from the bones we have.


As you can see on the chart above, there are several dinosaurs that are similar sized. Diplodocus and Supersaurus got up to 33.5 meters (110 feet). Argentinosaurus got upwards of 35 meters (115 feet) or more. Bruhathkayosaurus (Bru-hath-kay-o-sore-us) was possibly around this size as well, but the fossil material is too little to get a good estimate and what we had has disappeared. However, the American Museum of Natural History in New York has recently put on display the largest dinosaur ever displayed and possibly the largest dinosaur ever known at over 37 meters (122 feet).It doesn’t even have a name yet and is just called the AMNH titanosaur. Of course, the biggest dinosaur ever found is so little known that it has become almost mythical. Amphicoelias has been estimated to have been  as long as 58 meters (190 feet). Unfortunately, all that was found of this animal was a few bones, including a vertebra that stood 2.7 meters (8.9 feet) tall. The bones were very fragile, in very poor condition, and were preserved in mudstone, which crumbled easily. All of the fossils vanished (possibly crumbled away and swept out), so all we have left is a few drawings and measurements of the bones.

How big was Apatosaurus?

According to the fossils we have, Apatosaurus typically got around 22 meters (72 feet), but could have gotten as long as 27.5 meters (90 feet). Weight is a very difficult thing to estimate for many reasons, but most estimates place an adult Apatosaurus somewhere between 20-40 tons (40,000-80,000 pounds, 18000-36000 kg), or about the weight of 4-8 adult elephants.


Illustratration by Darren Pepper,

What is the shortest land dinosaur? What is the smallest dinosaur?


Illustration by Matthew Martyniuk. 1.8 m human, Yi qi (green), Epidexteryx hui (orange), Scansoriopteryx heilmanni (red)

That depends on what you consider a dinosaur. Anchiornis was estimated to be 34 cm (13″) long, but was a young adult, so probably got at least 38 cm (15″). But some consider Anchiornis to be an avialan, the earliest group of birds. Parvicursor is the smallest known adult dinosaur that is definitely not a bird according to some people, at 39 cm. Epidextipteryx was only 44 cm (17″) if you include the tail feathers, but only 25 cm(10″) if you don’t include them. However, Scansoriopteryx, also known as Epidendrosaurus, was only about 16 cm (6″), but we only have young ones that would have grown larger, but we don’t know how much larger. Epidextipteryx and Scansoriopteryx may look like birds, but were actually in a different group of dinosaurs. If you consider modern birds, the bee hummingbird takes the prize as the smallest known dinosaur at less than 6 cm (2.5″) and weighing less than 2 grams, just over the weight of a single penny.

But if you are talking about shortest, meaning how tall they stood, that is harder to work out because it would depend on how they stood, but none of these animals would have stood taller than 20cm (8″) at most.

For comparison, these dinosaurs were about the size of a common crow or perhaps even smaller.

Can an 8 feet tall person be as tall as a dinosaur?

A person standing 8 feet tall would be taller than a lot of dinosaurs. A baby just learning to walk would be bigger than some dinosaurs. If we include modern birds, which are also dinosaurs, there are some dinosaurs that a new born baby could hold in their hands (the bee hummingbird is less than 2.5″ long and more than an inch of that is taken up by the beak and tail feathers).

When did the dinosaurs live? When were they born?


Nyasaurus, illustration by Mark Witton

The earliest known dinosaur is Nyasaurus, which was found in rocks thought to be 243,000,000 million years old during the Triassic Period, the first part of the Mesozoic Era. There is some uncertainty if this was an actual dinosaur, so if it wasn’t, that would make dinosaurs like Herrerosaurus and Eorapter (both of which looked similar to Nyasaurus) the oldest dinosaurs at about 230,000,000 years old.

When did the dinosaurs die?

Everything that most people call dinosaurs died out at the end of the Cretaceous Period, the third part of the Mesozoic Era, about 65,500,000 years ago. However, they didn’t all die out. One small group of dinosaurs survived, which are the birds. Today, birds are the most diverse group of terrestrial vertebrates (animals with a backbone living on land), so dinosaurs are alive and thriving.

How long did the dinosaurs live?

Dinosaurs were on earth for a very long time. From their beginnings over 240 million years ago to the end of the Cretaceous Period, they lived for around 175,000,000 years. If you include the birds, they have lived for over 240,000,000 years and are still going strong.

If you are talking about individual dinosaurs, they have varied lifespans. Just as you can find mammals that live no more than a year or so to mammals like us that can live over a hundred years old (the oldest known person lived to 122), you can find dinosaurs that lived like that. Some species of hummingbirds only live a few years, so we can expect that some other dinosaurs may have only lived a few years as well. The giant, long-necked sauropods were adults by their teens and may have lived as long or longer than we do. We reall

How old are T. rexes?

If you mean how long ago did they live, Tyrannosaurus rex lived at the very end of the Cretaceous Period, the last period of the Mesozoic Era, 68,000,000-65,500,000 years ago. If you wanted to know how old an individual T. rex could get, They did most of their growing when they were between 14-18 years old, reaching maturity between 16-18 years old. But they didn’t live long after that. All of them that we know of died before they were 30. Of course, whether or not they could have lived longer than that, we don’t know, but that is the ages of the fossils that we have.

How did the dinosaurs die?

Most of the dinosaurs died out at the end of the Cretaceous Period about 65,500,000 years ago when two major events happened. The first was eruption of one of the largest volcanic events in the history of the Earth. The volcanoes that formed the Deccan Traps in India were so massive, the rocks from the lava put out by these volcanoes are over 6000 feet deep. These eruptions happened over tens of thousands of years, maybe even millions of years.

But that wasn’t the worst thing. An asteroid hit in Mexico at the same time as the volcanic eruptions were taking place. It was estimated to be about 10 kilometers (6 miles) across and left a crater more than 100 miles across. Remnants of the crater can still be seen in Chicxulub, Mexico. If all the nuclear bombs in the world were exploded at the same time, it would not be as powerful as the impact of that asteroid.

Did some animals live after the volcano and meteor?

Amazingly enough, yes. If they had not, we would not be here. Every form of animal suffered heavy losses, but most did not die out completely. One small group of dinosaurs survived, which became the birds. A lot of mammals died out, but a lot also survived. Amphibians and crocodilians did reasonably well. Anything small, able to take shelter, and lie dormant (like squirrels hibernating in the winter) to conserve their energy and ride out the tough times did ok. In the oceans, anything large, needing a lot of food, or having shells had a hard time.All the large sea-going reptiles died out. Virtually all the shelled cephalopods (squid relatives) went extinct, but their unshelled relatives survived. Tiny organisms called plankton that lived in the ocean and made their shells out of calcium carbonate died out and were replaced by types that used silicon for shells. During the Cretaceous, the ones with carbonate shells were so common, when they died, their shells piled up and became huge layers of chalk, forming what became the famous White Cliffs of Dover in England and the chalk beds in southwestern Arkansas, among other places. But they almost all died out during the volcano and meteor impact and never became nearly as abundant ever again. The reason for this is because the asteroid and volcanoes released so much carbon dioxide and sulfur into the air that was soaked up by the oceans that the oceans became very acidic and lost a lot of oxygen. So anim

Of course, insects of all sorts survived, as did a variety of invertebrate animals like snails, clams, starfish and the like. But all of them took severe losses, especially those that were specialized to eat only certain plants or animals. One that had a more varied diet managed to survive.

How was it there? Was it dusty or cold there?

During the Mesozoic Era, the time of the dinosaurs, it was, in general, warmer than it is now and the temperature differences between seasons were not as extreme as today. The north and south poles were not permanently frozen over during this time like they are now. But much like today, there were all types of weather and environments. It was hot and dry in some places, it snowed in other places. There were swamps and prairies, forests, deserts, almost any environment you can think of existed then. The only environment you might not find would be glaciers, but you could probably even find them near the tops of mountains at times. Of course, they didn’t exist in the same place on earth and there were different dinosaurs that lived in different areas.

Also remember that the Mesozoic covered an immense span of time, so the earth changed during this time.

Why didn’t the dinosaurs need to fly?

Some dinosaurs did fly, but most didn’t. Most animals today don’t fly either. I expect most animals would if they could, but it takes a lot of changes to evolve the ability to fly. As animals evolve, they can’t decide they are going to develop flight. Small changes will appear in individuals from time to time and if those changes are helpful (or at least not harmful), then they get passed on and can spread through the population. To develop flight, a large number of changes have to happen, so only a few types of animals have evolved in the right way to develop flight. Once they did though, it was very effective, which we can tell by looking at the large number of birds and insects and even bats that can fly.

Is it true that fish had sting rays?

Southern-stingray-dorsal-viewThere are some fish called stingrays and they do indeed have venomous spines on the tail, which can be painful and occasionally deadly if they sting someone. They only use them in self defense though, so they won’t hurt anyone unless they feel threatened.

Stingrays are common today and can be seen in many aquariums. But they are also found as fossils and have been around for millions of years. We have even found fossils of stingrays in Arkansas. They do not have bones like we do, but we do find lots of their teeth, which look like flat rectangles. They use these flat teeth for crushing shells of clams and other animals.

What was the tiny thing at the bottom of the smart board?

I’m sorry, I don’t know what you are referring to. Was it on the timeline? Please let me know and we can figure it out.

How many bones have you found?

I have found lots of shells and crinoids. I have found a handful of shark teeth. But I haven’t found too many bones. When I was on a dig in Argentina, I did find a pelvis (hip bones) of a sauropod (the giant, long-necked dinosaurs). I also found part of a skeleton of an archosauromorph (the ancestors of crocodiles and dinosaurs). When I worked in Wyoming and Colorado, I found several fossil turtle shells and part of the horn of what may have been a uintathere or some similar animal (rhino-like mammals with knobby horns and bumps on their heads). I also found several tiny bones of rat-sized mammals. I don’t know what they were, but I remember one place where the bones looked like turquoise (a greenish-blue gemstone).

What I would really like to find would be a dinosaur in southwestern Arkansas, although the skull of a mosasaur or elasmosaurus would be a close second. There are opportunities for finding fossils in most of the state, so keep looking and let me know if you find something!

Holiday Fun in Arkadelphia

Wow. I can not believe that I have not posted anything here since Halloween. My New Year’s Resolution is to not let that happen again. I have no excuses. But as was said on the Syfy show The Expanse, “We can not change the things we’ve done, but we can all change the things we do next.”

For this post, I want to relate the trip I took to Arkadelphia just before the Christmas holidays to visit the Goza Middle School on the invitation of one of their science teachers, Trent Smith. That trip will benefit many people in the future, and it also provided a chance to see some Arkansas geology and paleontology that may prove interesting to fossil enthusiasts.

The fossils that started this off. Picture by Trent Smith

The fossils that started this off. Picture by Trent Smith

This all started with an email I got from Trent Smith, who had found some fossils he wanted help identifying. After looking at the attached photo, I tentatively identified most of them as specimens of Exogyra ponderosa, a common oyster from the Cretaceous Period. There also appeared to be a goniatite ammonoid, a Cretaceous Period cephalopod, or squid relative. I could not be sure just from looking at the pictures, so I offered coming down to take a look at them in person. Trent was amenable to that and after a few emails back and forth, we arranged to not only look at his fossils, but talk to his eighth grade science class while I was there. It turned out that the school was interested in me talking to multiple classes, which all told was about 160 students. They suggested I could either give one talk to all of them at once, or I could do multiple talks to individual classes. I much prefer the smaller groups where people can get a more hands on experience with the fossils and have more opportunity for students to ask questions, so I opted to give several talks. I wound up giving seven talks, with two of the talks to combined classes. So I had the opportunity to speak with a lot of students.

When I got there, Trent helped me bring in my boxes and took me to his room to start setting up. Goza Middle School students are fortunate to have great science teachers who are passionate about science and education. Trent’s classroom fossil collection was by far the largest fossil collection I have ever seen in a public school classroom. They have a good variety of most of the invertebrate fossils that can be found in Arkansas. They also had a fabulous nautiloid ammonoid 4″ across or more. I had a shell of a modern Nautilus, a genus of the only extant ammonoids, so the students were able to compare a modern version with one over 70 million years old.

For each class, I gave a short introduction to the fossils that can be found in the state, which is much more diverse than most people realize. I also gave them a quick demonstration of the immense expanse of time we were discussing. I have a timeline that stretches eighteen feet and covers 600 million years. People are usually suitably impressed with that timeline, but when I tell them how much space our civilization represents on the timeline, they are stunned. At that scale, all of human recorded civilization is approximately the width of one human hair. Afterwards, we let the students look at the fossils I brought and ask questions. The students were more reluctant to get out of their seats and approach the front table than the younger kids I usually talk to, which I found interesting and speaks to how quickly we train our students to sit and listen without interaction. But once they got over their training, they enjoyed being able to handle the fossils and examine them close up. The students were uniformly polite and well behaved and were a pleasure to talk with. Midway through, the teachers treated me to a tasty potluck lunch.

My new favorite shirt

My new favorite shirt

If everything was left at that, it would have been a great trip and I would be happy to return, but they really went above and beyond. In addition to lunch and a small donation (I have generally not asked for payment for classroom visits in the past and as a result, getting paid for it almost never happens, but getting paid means I can go to more classes so is greatly appreciated), they provided me with even more. They gave me my first two Paleoaerie shirts, which they designed and they did a fantastic job. On the front of both shirts is a dinosaur foot that looks like the foot of Arkansaurus, the only dinosaur bones ever found in the state, and my name, Dr. Daniel. On the back of one shirt, it has the dinosaur foot with the words PALEONTOLOGY above it and DIGGING UP KNOWLEDGE below it. On the back of the second shirt, it says PALEOAERIE.ORG followed by my three statements of what guides my efforts: The universe is endlessly amazing, knowledge is useful only when it is shared, and you can’t really know something unless you understand how and why we think we know it. The shirts are going to be my uniform for future talks.

Exogyra ponderosa (Cretaceous oysters) collected in Arkadelphia by Trent Smith.

Exogyra ponderosa (Cretaceous oysters) collected in Arkadelphia by Trent Smith.

After school was over, Trent showed me a spot he has collected fossils from on Wp Malone Road, just west of I-30. According to the Arkansas Geological Survey’s geologic map of the Arkadelphia quadrangle, the area is listed as being in the Nacatah Sand, an Upper Cretaceous formation consisting of a mix of unconsolidated sediments deposited in a nearshore marine environment. However, the marl, a limey clay, we found in the creek looked more like it came from the Marlbrook Marl, a formation that lies underneath the Nacatah and separated from it by the Saratoga Chalk formation. The Saratoga Chalk is not thick in this area, so it is quite easy to go from the Nacatah to the Marlbrook in a very short distance. In this particular locale, the Marlbrook is close by and it is likely that what we found was washed downstream to where we found it. As I recall, Trent mentioned that fossils were more common the farther upstream one went, which would support this idea. The Marlbrook Marl, when fresh, is a blue-gray lime clay, or marl, laid down in nearshore, shallow marine environments, just like the Nacatah Sand, but without the sand contribution. The upper part of the Marlbrook is also famous for being extremely fossiliferous and this site was no exception. I initially attempted to collect what I found, but very quickly realized there were so many shells that it was impossible to carry them all. The great majority of what we found were shells of Exogyra ponderosa, but the numbers would have allowed us to quickly fill a crate with specimens. We also found a few snail shells (of what type I am not sure) and a terebratulid brachiopod, but the numbers of everything else did not begin to compare with the shells of Exogyra. On other trips, Trent collected numerous Exogyra shells and gave me two boxes full of shells. Thanks to him, I will be able to supply many Arkansas classrooms with actual Arkansas Cretaceous fossils.

Collection locality. Marlbrook (outlined teal-colored area) is upstream just west of collecting site.

Collection locality. Marlbrook (outlined teal-colored area) is upstream just west of collecting site. Click to enlarge.

Poorly preserved snails and clams. Little orignal material remains, leaving only the internal molds.

Poorly preserved snails and clams. Little orignal material remains, leaving only the internal molds.

This area is a nice place to collect. As long as one is on public land (or with the permission of the land owner), you can collect any of the invertebrates you want, so you can feel free to collect Exogyra shells here. But the Marlbrook also contains more than just oysters, brachiopods, and snails. It has also yielded mosasaurs and even the occasional elasmosaur. There is even the possibility that a dinosaur was washed out to sea and could be found there. So if you collect in this area and find some bones, give me a call.

Many thanks to Trent Smith and the whole of Goza Middle School, not just for your hospitality, but for living the statement of Dr. Scott the Paleontologist on Dinosaur Train: “Get outside, get into nature, and make your own discoveries.”

The Perfect Fossil for Halloween, At Least In Name

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?

Ohio Historical Society

Ohio Historical Society

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.

Tundra muskox. Wikipedia.

Tundra muskox. Wikipedia.

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 bombifrons. Candadian Museum of Nature

Bootherium bombifrons. Candadian Museum of Nature

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.