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Between classes and school appearances, I have not had the time to write up as complete a description as I would like, so I will do a more complete description of the fossil later. But for now, did any of you think you saw crinoids in the face? If you did, you are correct! This photo was originally published on the Arkansas Geological Survey‘s blog. If you haven’t checked them out, I encourage you to do so.
Crinoids are perhaps the most common fossil found in Arkansas. They can be found in many of the Paleozoic rocks in northern Arkansas in the Ozarks and Ouachitas, although they are most common in the Mississippian age limestones of the Ozarks. All those white rocks along Highway 65 towards Leslie and Marshall are good candidates, although watch out for cars along the highway, please.
Crinoids are often called sea lilies because of their resemblance to plants, but they are actually animals that are related to sea urchins and starfish, so they are far more closely related to you than to any plant. Even though they lived in shallow marine environments during the Paleozoic Era, you can still find them today in deep water along what is called the continental slope. If you swim out into the deep water a long way away from shore and you get to the edge of the continent, you will see a cliff or steep slope descending all the way down to the abyss of the absolute bottom of the ocean. Congratulations, you have reached the continental slope and the last refuge of the crinoids.
It’s another Monday! You know what that means, right? The end of the weekend, an extra dose of coffee to get the day started, and a new fossil for Mystery Monday. Today’s fossil is a very common fossil in Arkansas. Some people think these fossils form a kind of spooky face. Bonus points if you can say where the picture came from. Once I tell you what it is, you should check out all the other cool info they have.
On Monday, we posted this picture of an Arkansas fossil. Were you able to figure it out?
This is a fossil of Calamites (watch your spelling, we want to avoid any calamities). Calamites was a relative of the modern-day horsetails, Equisetum. But unlike today’s horsetails, which are generally only a meter or so in height (although some giant horsetails can grow up to 7 meters or more), Calamites grew up to 30 meters (100 feet).
Equiseta often grow clonally, spreading the rhizomes widely through the surrounding ground, forming large clumps of plants that are essentially the same plant, connected via their roots. Assuming Calamites did the same thing, it has been estimated “they may have been the largest organisms that ever lived.” This group of plants is unique in the incorporation of silica into their stems, giving rise to one of their common names being scouring rushes.
This group of plants first appeared in the late Devonian, but really had their heyday in the Carboniferous Period, although they died out soon after in the Permian. The Carboniferous is so named because most of the world’s coal was formed during this time. The reason for this is because of the difficulty in digesting plant matter. Cellulose, the primary ingredient in plant cell walls and what we call “dietary fiber.” Even today, other than fungi and some bacteria, there is precious little that can break it down. Lignin, the other main component of plant cells walls, otherwise known as “wood,” is even harder to break down.
The only thing that can really digest it is white rot fungi. Back then, there was little to nothing that could eat it. As a result, dead plant matter tended to sit around for a very long time, making it much more likely to accumulate and form coal. Once the enzymes needed to break down lignin evolved, white rot fungi found themselves with a hugely abundant food supply and acted like teenaged football players after a game at an all-you can-eat buffet. And thus ended the Carboniferous Period, in a massive bout of white rot.
Like modern horsetails, Calamites preferred wet soils around rivers and lakes, cropping up all over the world. While they avoided the standing water of the swamps, they flourished any place that regularly got wet, so levees and floodplains were good environments for them. There were no angiosperm trees at that time, what was there were forests of giant Calamites and ferns. Plants called lycopods, most commonly Lepidodendron, dominated the swamps along with the ferns, which were pretty ubiquitous.
Calamites’ modern counterparts are all herbaceous perennials, so Calamites is unique in the group for having a woody trunk. They form extensive underground rhizome networks, growing large clumps of clones from the rhizomes. The leaves form regularly spaced whorls around the stem, creating the horizontal lines breaking up the ridges running vertically up the trunk on Calamites. Inside, the xylem forms rays running from the exterior to the pith in the center. Oftentimes, the pith rots away, leaving a cavity that gets filled with sediment, forming an internal cast, or steinkern.
As a plant fossil, anyone can legally collect Calamites fossils as long as they are not on National Forest property (nothing is allowed to be collected in National Parks and Forests). Good places to look for Calamites would be among the Pennsylvanian (Late Carboniferous) rocks in the Quachitas and Ozarks. While Calamites may be found in rocks of Mississippian (Early Carboniferous) age, the rocks in Arkansas from that age are primarily marine. Good for finding sea shells, but land plants like Calamites are going to be rare, only there as a result of being washed in by a storm or some such. You will be much more likely to find them in rocks like the Atoka Formation on both sides of the Arkansas River Valley. Most of the Ozarks is Mississippian, but much of the Ouachitas is Pennsylvanian, so are much more likely to have them. You might find them in the Hartshorne sandstone (seen best capping Petit Jean Mountain), but plant fossils are rare and fragmentary. You would have better luck in the McAlester Formation overlying the Hartshorne. You can also try the Savanna and Boggy Formations, which are also of Pennsylvanian age.
It’s time for Mystery Monday! Here is a fossil that can be found in Arkansas, but is completely different from anything I’ve put up here before. Let’s see if you have the paleontological fiber needed to solve this puzzle, or do you lack the stomach for it?
It’s Friday again. Were you able to get the answer to Monday’s fossil?
The skull shown in the picture belonged to Arctodus simus, the giant, short-faced bear (the not-so-giant short-faced bear, A. pristinus, was smaller and lived in more southerly areas than A. simus). Arctodus lived in Arkansas and much of North America during the late Pleistocene, from less than 1 million years ago up to about 12,000 years ago, when most of the large North American Ice Age fauna went extinct. Arctodus was the North American version of the European cave bear, Ursus speleaous. While the European cave bear was a close relative of most modern bears, Arctodus was more distantly related, its only living relative being the spectacled bear, Tremarctos ornatus. It is sometimes considered possibly the largest terrestrial, mammalian carnivore that ever lived, standing over 3.5 m ( 11.5 ft) tall. Even on all fours, it was almost 2 m (6.5 f) at the shoulder. You would have to get at least 4.5 m (almost 15 ft) up a tree to avoid its reach, assuming it didn’t just tear the tree down or shake you out of the tree. It weighed in at a full ton and could run 40 mph (over 60kph). However, that is also the top range of modern Kodiak brown bears, otherwise known as Alaskan grizzly bears. In the wild, the bears don’t usually get over 1500 pounds (although they can), but the largest ever known was a bear in the Bismarck, ND zoo that weighed 2130 lbs at his death and previously weighed possibly close to 2400 lbs, although he was a very fat bear. There is another bear pelt on display at Space Farms Zoo and Museum in New Jersey that is claimed to be from a bear over 12 ft. tall and over 2,000 lbs, but those claims remain unverified are considered by most to be exaggerated. There is another bear that may have been even bigger. Arctotherium angustidens lived in South America about three million years ago and stood almost 3.5 m tall, so similar to Arctodus and the largest of extant bears, but was much more robust, weighing in the neighborhood of 3,500 lbs.
Arctodus is generally known for its long legs and short face. However, research in the past decade has indicated that its legs were neither longer than expected, nor was its face all that short. It was simply big. Like other bears, it is thought to be fairly solitary most of the time. Contrary to many depictions, it was not particularly adapted to running quickly, considering that modern grizzlies can run 30 mph. What may have made people think they were unusually fast is a combination of their size giving them long legs and tracks that have indicated they used a pacing gait, with the legs on the same side of the body moving in unison, rather than in opposition like most other animals. This sort of gait is typically used in animals with longer legs or at faster trots. Camels use it and dogs and cats, among others, do it when maintaining a trot before they break into more of a gallop. However, the pacing gait is not indicative of a fast-running animal, but of an animal that maintains a quick pace for long distances, it bespeaks of endurance, not speed.
Like most bears, Arctodus is thought to have been omnivorous, eating both plants and animals. There have been several hypotheses concerning its diet, from mostly scavenging to hypercarnivorism. It was certainly capable of bringing down large prey, although its limbs were not as flexible as most high level predators, nor were they particularly robust for their size, leading some to think they scavenged, although they would be hard-pressed to compete with giant vultures in scavenging and recent work indicates the tooth structure was not sufficient for chomping through bone. They may have been better suited for foraging plant material with their unusually flexible wrist giving them an almost semi-opposable thumb, much like pandas. This suggests possible tree-climbing to some workers, although Arctodus was a very large animal to be climbing trees. Besides, it typically lived in more open, grassland environments the majority of the time, so it is unlikely to have been adapted for tree-climbing.
They went extinct roughly 11,000 years ago, along with a large number of other large species. A reduction in rich food supplies is thought to have caused the extinction of the large herbivores. This would have placed a great deal of stress on the carnivores, causing increased competition. The dire wolves lost out to the modern grey wolves during this time, chiefly thought to be a result of the gray wolves being able to hunt and subsist on smaller and fewer prey than the larger dire wolves. This same reasoning would apply to Arctodus as well, which had to compete against both wolves and other bears, for a greater percentage of the share to fuel its larger body. On the other hand, evidence for this hypothesis has been lacking in analyses of tooth wear.
If you want to see more of Arctodus, make your way to the La Brea Tar Pits in Los Angeles. many bones of this bear have turned up from the tar and are on display at the Page Museum.
The weather forecast this week is for snow. So in going with the theme lately of Ice Age animals, I thought I would bring you another one for this week’s Mystery Monday fossil. This picture doesn’t have a scale, so I will just say this skull is bigger than yours (under the assumption that all my readers are Homo sapiens or within the same size range, my apologies to the exceptionally macrocephalic).
Our Mystery Monday fossil concerns a photo taken by the Arkansas Archaeological Society on one of their digs. I’m still trying to find when this was taken, but I know roughly where. Can you tell what it is they are uncovering?
On Monday I posted a picture of a tooth from an animal that is a famous California resident, although is not generally considered an Arkansan. Were you able to figure it out?
The tooth is a canine from a Smilodon, the saber-toothed tiger (although not actually related to tigers). Smilodon fossils have been found in a few caves in the Ozarks of northern Arkansas, most notably Hurricane River Cave and the Conard Fissure (the Conard Fissure was excavated by Barnum Brown for the American Museum of Natural History, who also did a lot of famous dinosaur digs for them in the Rockies) . Originally, they were described as having come from two different species of Smilodon: S. fatalis and S. floridensis. Smilodon fatalis, sometimes called S. californicus, is well-known from the La Brea Tar Pits in California, although has been found throughout much of North America and Pacific coastal areas of South America. Smilodon floridensis was known primarily from, unsurprisingly, Florida and neighboring states. However, these days most researchers view them all as the same species, so just Smilodon fatalis. There are two other recognized species. Smilodon populator lived in South America and was bigger, with a few hundred more pounds on S. fatalis. Smilodon gracilis was half the size of S. fatalis and lived earlier than either of the other species, and is considered by some to be ancestral to them.
Smilodon fatalis is the quintessential Ice Age predator. It appeared about 2.5 million years ago and only died out about 10-13,000 years ago, so it may have been possible that Smilodon preyed upon early humans, at least along the Pacific coastal areas. It was a big, burly cat weighing up to 600 lbs. with heavily muscled forelimbs. Of course, it is best-known for its 7” long, serrated canines, thus the name Smilodon, meaning “carving knife tooth”. Smilodons were part of a group known as Machairodontinae, a subfamily within Felidae known as the “dirk-toothed cats.” These long teeth necessitated a jaw that could swing extraordinarily wide. Smilodon was specialized for killing large prey, such as bison, horses, and young mammoths and mastodons. Much debate has centered on how it dispatched its prey, with depictions of a Smilodon burying its canines in the skull or eviscerating its prey. However, more recent studies have indicated the canines were too fragile to withstand such treatment or couldn’t get a sufficient bite to properly tear into the abdomen. It is thought instead that Smilodon used its powerful forelimbs to stun and restrain the prey until it could bring its canines into play with its powerful neck muscles to slash the throat and cut the major arteries, causing the animal to bleed out quickly. They were not fast runners, preferring to attack from ambush, staying hidden within the vegetation of the forests and bushlands it preferred to live in.
Youngsteadt J.O., 1980: A saber toothed cat smilodon floridanus from hurricane river cave northwest arkansas usa. Nss Bulletin: 8-14
B. Brown, The Conard Fissure, A Pleistocene Bone Deposit in Northern Arkansas…,Memoirs of the American Museum of Natural History, Vol IX, Part IV, February 1908.
Another week has gone by and so little done here. I started my Vertebrate paleontology class this week and if you think it takes a lot of work to take one, just imagine the amount of time it takes to design one.
So today, we announce the mystery fossil from Monday. Did you have any idea what it was? It stumped everyone on the Facebook page, so if you couldn’t figure it out, don’t feel bad. It was a hard one. These are not terribly uncommon fossils, but most people are completely unfamiliar with them, despite the fact that anyone who visits a public aquarium has seen its living relatives.
This is part of a tooth plate from a ray, most likely Aetobatus, the eagle ray. They are filter feeders eating plankton and have been around since the Miocene 20 million years ago. While none have been found in Arkansas that I know of, they have been found in pretty much every state around us, so I expect so collector out there somewhere has probably found some here. Check us out Monday for a new fossil!
UPDATE: I need to correct a mistake I made in this post. Eagle rays, like Aetobatis here, were and are not filter feeders. The large rays, like the Manta ray in the same family, are indeed filter feeders, the smaller rays, like Aetobatus and its close relative Myliobatis, another ray that lived in the area at the same time (as well as earlier in the Eocene over 40 million years ago), were durophagous, meaning they used their teeth to crush shelled prey, such as clams, crabs, and shrimp. The main part of the tooth brought to bear on the prey item is the flat, plate-like part.
For this picture and much more information on the current species of eagle rays, go to the Florida Museum of Natural History.
Last Friday I posted clues to a mystery fossil. The clues were 1) I lived in AR during the Mississippian Period roughly 330 million years ago and am a very common fossil to find here. 2) Many people think I’m a coral, but I’m not. 3) I am named after a famous Greek mathematician and inventor. Who, or more precisely, what am I? Allie Valtakis got the right answer as the bryozoan, Archimedes. Here is what the Arkansas Geological Survey says about it.
The Bryozoa grow attached to the sea-floor as do corals, but they differ significantly from corals in terms of soft-part anatomy. The bryozoans are exclusively colonial and fall into two broad groups, the lacy colonies and the twig-shaped colonies. Individual “houses” (zooeciums) lack the radial partitions found in corals, but they are divided transversely by partitions called diaphragms (Fossils of Arkansas). Bryozoans can also grow as incrustations on the shells of other organisms and are commonly associated with reef structures.
“Bryozoans are tiny colonial marine animals that are present in marine and fresh water today. They are sessile benthonic animals (fixed to seabed) that are filter feeders and prefer shallow seas, living fairly close to shore (neritic). One bryozoan called Archimedes (see picture below) is abundant in Mississippian age rocks in Arkansas and is so plentiful that one of the rock formations called the Pitkin Limestone was once referred to as the “Archimedes Limestone”. Generally, only small pieces of bryozoans that resemble “fronds” are preserved in Mississippian and Pennsylvanian age rocks in the Ozark Plateaus Region.
Freeman, Tom, 1966, Fossils of Arkansas: Arkansas Geological Commission
Bulletin 22, 53 p., 12 pls., 15 figs., 1 map.
Way to go, Allie!
Can you guess this week’s fossil? I will do things a bit differently this time. Unlike previous fossils, in which I told people on the Facebook page as soon as someone provided the correct answer, I will not reveal the answer until Friday, so you have plenty of time to give it a try. In addition to the picture (note the scale) below, I will provide one clue every day until Friday. Good luck!
Clue 1: It’s from the Cretaceous.
Clue 2: It’s modern day relatives are widely considered a delicacy.
Clue 3: This is no wilting lily. This creature is big and bold. It shows how twisted it is on the outside for all the world to see. Dude, that’s heavy.
Come back tomorrow for the answer! You can also find it on the Facebook page.
Walking with Dinosaurs 3D movie review
I went to see Walking With Dinosaurs 3D this weekend. My kids were interested in seeing the movie and I liked the BBC “Walking with Dinosaurs” TV mini-series, so we were all eagerly anticipating the movie. I had read a few reviews of the movie, some by paleo people, who said the dinosaurs were great, but the voices were terrible, which gave me pause, but it’s a BBC movie on dinosaurs, how bad could it be, right?
Sad to say, I have to agree with most of the reviewers. This movie may be much more enjoyable if you can’t hear it. To begin with, whatever expectations you may have, forget them. If you are going in expecting to see a big screen version of the BBC “Walking with Dinosaurs,” you will be disappointed by the cartoon voices and plot. If you are looking for light entertainment for little kids, you might be a bit surprised by the rather jarring breaks providing a subpar, documentary-style educational interlude which will kick everyone out of the story.
The film reminded me nothing so much as a cross between the BBC documentary-style series and The Land Before Time movie series, failing at both. I think the reason for this is because it seemed to clearly start off with the idea of it being a kid-friendly movie along the lines of the TV series, but some executive decided after it was made that it was not going to draw enough kids. So the movie was recut and really bad dialogue added to it instead of the normal narration one would expect in a nature documentary, along with completely superfluous modern scenes bookending the film, wasting the talents of otherwise fine actors. The voices were obviously added as an afterthought because the dinosaurs do not act like they are speaking. I could even occasionally hear the original dinosaurian bleating and honking in the background even as they are supposedly talking. The dialogue, as Brian Switek noted in his review, destroyed any emotion that may have been evoked by the scenes that were supposed to be emotionally powerful. What should have been poignant, heart-tugging scenes were drained of any impact by juvenile pratterings that never ceased. I found myself wishing for the dinosaurs to just shut up once in a while. As a result, it is a movie that may be enjoyable for a little kid, but eminently forgettable. Bambi was a much more riveting emotional experience, not to mention more educational about the lives of deer.
The story line was inconsistent with the idea of a nature documentary and a poor choice for a dinosaur movie. Whether or not the worst aspects of it were in the original script, I don’t know, but the final plot, while suitable for a cartoon Land Before Time, was wholly inappropriate for a nature “fauxmentary.” For a film that was supposedly educational, it pushed moral viewpoints which are only valid in human cultural environments and completely invalid in the natural world. The idea that intelligence and courage will overcome the thoughtless, testosterone-fueled belligerence of the larger alpha males is a noble sentiment and may work in a human context, but not in the depicted dinosaur society. Control of a herd of large herbivores that have evolved extravagant displays will never pass to the runt of a litter because he saves the herd in a time crisis due to his quick thinking. The plot line for the movie is far more appropriate to an after-school special involving actual, human children, not dinosaurs. As such, it completely destroys any educational effectiveness of the movie. The only education that remains is that dinosaurs lived in a snowy Alaska and that some dinosaurs had feathers, particularly the smaller theropod carnivores. I really like this aspect of the movie, but its authenticity in these aspects was completely undermined by the silliness of the rest of the movie.
To make it even more confusing in terms of genre plotting, the movie shows that females in the herd are dominated by the alpha male, but glosses over what that means in terms of sexual dominance. In a kid-based movie, this understandably only goes as far as hanging out with each other. In the natural world (and post-adolescent human worlds), as every adult in the audience will understand, it means the female submits to the alpha male’s sexual advances. In terms of a human kid’s movie, it sends very poor messages about the role of females in society. In terms of an educational nature show, it is intentionally misleading to spare the typical parental sensibilities of what is appropriate for kids to see.
In short, if you go to see this movie (which I would really recommend waiting until a rental, as it is not worth spending the price for a 3D movie), go expecting to see a mindless 80 minutes of passable, but forgettable, entertainment for children with no real educational value other than to say look, aren’t dinosaurs neat? Enjoy the graphics, ignore the rest.