The Process - Discovery to Display

Though the Permian period did have large predators - like the 600-pound Dimetrodon and the 8-foot Eryops - it was dominated by small creatures, with small bones (called microfossils). Here, teachers and volunteers on the museum's team look for fossils that might lead to an excavation site.

Is this anything special?

Fossils look a lot like rocks - because that's what they are. Over millions of years, the materials that make up an organic bone are replaced with the minerals that surround the bone as it is buried - eventually resulting in a bone-shaped rock. Which means that looking for fossils on the surface takes a little bit of training.

As it turned out, this is pretty special - as they dug beneath the surface, the team discovered an associated Dimetrodon skeleton, including parts of a skull, backbone, legs and several of the spines that supported the impressive back-fin this species is known for.

Here local Seymour teacher Kimberly Beck starts the painstaking and delicate process of uncovering a fossil. Tools like paintbrushes are useful in clearing dirt away without damaging the fossil itself, which can often be quite brittle. Eventually, a sealant may be used to stabilize the fossil before it is removed.

A team member examines a find using a jeweler's scope to discover whether it is a fossil, and if so, what kind.

The team uses GPS navigation tools to map the locations of fossil beds they have found. This way, they can determine the geologic layer each site rests in as well as its relation to the other sites.

Here, team members Chris Flis and Johnny Castillo dig around an articulated Dimetrodon spine. They are looking for evidence of additional fossil remains. If more remains are found, the area of excavation will widen. If not, they will continue preparing the spine to be "jacketed" with plaster before it is removed from the site.

The original spine has been jacketed with plaster to stabilize it, as the team continues to excavate around it. Several vertebrae and other Dimetrodon bones continue to be discovered at this site, raising hopes that it may contain an entire associated Dimetrodon.

The team has completely excavated this layer. The next step will be to dig underneath the plaster jackets, flip them, plaster the bottom to seal the casing and remove them from the site. Then, the jackets will be taken to the museum for further preparation and study.

Dr. Bakker begins to dig beneath one of the jackets, in order to start the process of removal, and discovers yet another fossil.

After the jacket is completed, Johnny Castillo and Chris Flis take it out of the site, to be transported back to the Museum.

Back at the Museum, Dr. Bakker works with volunteers and visitors to continue excavating fossils from the contents of one of the plaster jackets brought from the site in Seymour. Earlier on this day, a young boy found an unidentified claw in the matrix. Could it be a new species?

Once a fossil has been completely freed from the dirt and other material that surround it, it's ready to be put on display. This Dimetrodon hip fossil (found by teacher David Henderson) is currently on display at the Houston Museum of Natural Science.

Neal Immega, Volunteer Team Member

Neal Immega became a geologist the day his dad brought home a big box of rocks from Big Bend National Park. "I thought they were so cool - and that they each had a story to tell." Since then, Neal has become a passionate professional geologist and master docent at the Houston Museum of Natural Science.

He loves to collect fossils, since "this is Texas - there aren't any minerals to be found here!" His favorite fossils are crinoids, incredibly complex creatures that are difficult to collect, "A real challenge."

He specializes in leading tours and docent training for geology-related exhibits at the Museum, including the Wiess Energy Hall and the current Lucy's Legacy exhibition. He's completed extensive field work, and leads geology field trips for the Houston Geological Society, the Houston Gem and Mineral Society as well as HMNS.

He received his bachelors degree in geology ftom Texas A&M and his Ph.D. in geochemistry from the University of Indiana. He worked in geochemistry for Shell Oil for 30 years, but says that "I have much more fun being a volunteer for the Museum."

Captorhinus

Not everyone can be the giant of their era - and this diminutive reptile is proof. The biggest Captorhinus was only about a foot long; runts topped out at about 7 inches.

This field sketch of a Captorhinus shows it much closer to a Dimetrodon that it would have wanted to be, in order to illustrate its small size. (c) Robert T. Bakker

In addition to being teensy, the Captorhinus was also extremely primitive. As Dr. Bakker describes it, "If you started as a Captorhinus, you could end up evolving into just about anything." This species is close to the base of almost every modern species' family tree.

If you saw one today, it would look like a chunky lizard with a pointy snout. It also had two complete rows of teeth, for cracking and eating something small and hard, like snails or millipedes.

The HMNS team have found dozens of Captorhinus fossils at the site, including vertebrae, ribs, legs and several examples that are almost complete skeletons. Shed Dimetrodon teeth have been found with these fossils, proving yet another species had a reason to run when the Texas Finback lumbered on the scene.

Trimerorhachis

It would be a good idea to write this down, because I'm definitely not going to be able to spell it twice - Trimerorhachis is an amphibian that looks just like a modern mudpuppy, except that it comes equipped for battle. We think of frogs and salamanders as having soft skin, but this species is covered in bony armor.

As it turns out, nearly all of the amphibians found in the Texas Red Beds are similarly battle-ready, covered everywhere with armor. As Dr. Bakker puts it, "You could hit them repeatedly with a hammer and not slow them down." Why? What did they need this protection for? And what made modern amphibians get rid of it?

Fossils from this species are surprisingly rare at the dig teams' site, though they have found pieces of a skull at the main site.

Diadectes: Giant Amphibian

At 10 feet long, Diadectes was a formidable amphibian. It was also one of the first known plant-eating vertebrates - meaning that despite his impressive size and heavy bones, it was still Dimetrodon food.

Diadectes was strong - perhaps the strongest species of the time. It had shortened jaws and blunt teeth for grinding plants - but it also had shovel-shaped incisors, an example of which is shown above, found at the Seymour site. In addition, its wide, strong claws would have used for digging - to hide, or to look for roots to eat during the dry season.

Fossils from this species have been surprisingly rare in the main fossil bed the team is working on - only one or two examples per thousand. This is a mystery, as Diadectes would have been the main prey for Dimetrodon. The site is littered with Dimetrodon remains - so if not Diadectes, what was it eating?

A field sketch of Diadectes. (c) Robert T. Bakker.

That Daffy Edaphosaurus

Warmly called "Daffy" by many who study this species, Edaphosaurus looks like a Dimetrodon with a weight problem - which seems unfair, since this species was a vegan. The original vegan, in fact - along with Diadectes, Daffys were the first species to eat plants on land, striking fear in the hearts of conifers everywhere.

Field sketch of Edaphosaurus. (c) Robert T. Bakker

Daffys had a tiny head on a huge body, with legs that are also much shorter than its cousin, the Permian king of the food chain.

That massive body needed a lot of water, and the team has found bits and pieces - such as big vertebra and leg fossils - of this species near the lakebeds on their site. Surprisingly, they've also found a site that may have a nearly complete Daffy - in a dry bed. (The redder the sediment, the drier the local climate; also, amphibian species can't live without constant access to water, so their presence indicates water in the environment.)

What was our Daffy doing so far from water? This week, the team will continue digging this dry site and looking for more clues.

Eryops - Permian Jaws

Eryops was the Permian Jaws - a seven to eight foot chunky amphibian, covered with armor, and with a head like an alligator, including the dangerous, strong jaws. Despite Dimetrodon's place as king of the Permian food chain, a smart one wouldn't go too close to the water's edge. Eryops could take out a juvenile Dimetrodon, no problem, and even a mature Dimetrodon might find himself on the business end of a row of razor sharp teeth. Kind of like Godzilla vs. King Kong.

Eryops was the top water-based predator of the time, and would have eaten anything in and around the water's edge. If not for later Triassic amphibians, he would have bragging rights for largest amphibian ever. As a cold-blooded amphibian, he would have grown slowly and lived to terrify fish and other aquatic species for a very long time - perhaps 100 years. In Seymour, the team has found fragments of Eryops skull and jawbone.

Lysorophian attacks!

The mighty Dimetrodon was the biggest, scariest, most massive thing to walk the Permian, the size of a modern-day tiger. But what teeny-tiny little creatures scurried around between its toes?

Look at any environment today, and you'll see that most things are small - like the hundreds of species of frogs that inhabit the rainforest or the hundreds of thousands of species of beetles living all around the world. And while it's easy to be wowed by the biggest and the meanest - it's often the smallest of the small that have the most to tell us about what life was like when they were alive.

Though the small critters have the advantage of numbers - it's the big guys that are most likely to stick around long enough to get fossilized. Small bodies are easy prey for scavengers and tiny skeletons often don't have what it takes to survive the elements long enough to be buried and preserved.

And so our knowledge is skewed to the super-sized - the Megalodons and Titanosaurs. But the pint-sized are much more sensitive to their environment - like the frogs or salamanders of today - and can tell us much more about conditions in a given era.

For this reason, the HMNS dig team has been thrilled to find many fossilized Lysorophians - which grew to only about a foot long - at the site.

(c) Robert T. Bakker

Though small, this species was armed to the teeth:

"The jaw bones were thick for such a little animal and carried strong, slightly curved fangs...Most astonishing was the body form...The torso went on and on and on. And on, a total of nearly a hundred vertebrae, so the distance from neck to hips was thirty times the head length. The ribs were long, curved and of exceptional thickness and strength. In other words, the design was emphatically like a chunky snake’s."

Though they resemble thick-bodied vipers, Lyserophians are in fact amphibians - evident from four stout bones in their throats that supported gills, something no reptile ever has. And they used this as a weapon, too:

"Gill slits aren’t just for breathing in the water. They’re for hydraulic ambushes."

In theory, the Lysorophian would have explosively widened it's mouth, sucking in water and prey, clamped the jaws shut to impale the prey, and then sent the water rushing out of the gills. In addition:

"The jawbones of lysorophians were stouter than what most amphibians have today, so the killing bite must have been stronger...Plus – the immense strength of the ribcage could have pinned prey within the body coils."

Permian small(er) fry had much to fear from the Lysorophian. But what, in turn, killed them in such numbers in the Texas Red Beds? Hundreds have been found, each of similar size, and all curled into a ball, with the head tucked between the torso.

As it turns out, drought doesn't care how strong your jaws are. And in the Late Carboniferous-Early Permian, the world was hit with one of the greatest killing-drought cycles of all time. As an amphibian, Lysorophian needed water - and lots of it. To survive the drought, it learned to hibernate.

"The rainy season would mean a flush of greenery and prey everywhere. Lysorophians ate their fill and grew fast, courted mates and reproduced. Then, when drought returned, the entire generation went down into their burrows together...The Amphiuma of today’s ponds curl around their eggs to keep them moist and safe. Maybe the bomb-shelters of the Sleeping Serpents were maternity wards."

On the HMNS site in Seymour, the team has found five complete skeletons, in the same grouped pattern. The team has also found Gnathorhiza (Permian Lungfish) - also burrowers - nearby. Dr. Bakker theorizes that "Perhaps they were waiting for spring rains that never came." Like the amphibians of today, they are important environmental indicators - whenever a large number are found together, you know that something happened to kill them off.

(Quotes and information excerpted from The Sleeping Serpents of the Texas Redbeds by Dr. Robert T. Bakker.)

Secodontosaurus: The "Fox-Faced Finback"

When first discovered in the 1880s, Secodontosaurus was a petrified enigma. The slender muzzle meant its bite would have been a quick snap – perfect for small, hard-to-get prey. But the body was huge, almost 250 pounds, and the low, massive forequarters could perform heavy work.

This new species could also easily be confused with the Dimetrodon - both have four stubby limbs and tall fins on their backs. However, it had an unusually narrow skull - hence the nickname "Fox-Faced Finback" - which was probably used for some kind of adapted feeding strategy, like burrowing.

(c) Robert T. Bakker

And, instead of the Dimetrodon's enlarged killing fangs, Secodontosaurus had a long row of small teeth, each sharp-edged like a little knife blade.

This species is also much more rare than Dimetrodon, fossils of which are all over the Texas Red Beds. The last fossil of Secodontosaurus found there was unearthed in 1936.

That is, until dig team member and teacher Nancy Lauletta Bowen discovered a piece of one in 2006. This is the first Secodontosaurus fossil found in 70 years, and it's the first excavated with modern, CSI methods - which means that much more diverse information has been preserved about this fossil than any other of its kind.

Lauletta Bowen and Dr. Bakker point to her Secodontosaurus find. Detailed image below.

Seymouria, our hometown favorite

In case you haven't guessed it already, Seymouria is our hometown favorite because this species was discovered near and named after Seymour, TX - the town situated closest to the fossil beds that made Texas Dimetrodon Central.

Seymouria was small, about two feet long, with many razor-sharp teeth in its triangular head as well as legs that were both longer and stronger than the first amphibians - meaning that it could live in water and on land. In fact, some scientists can't agree whether Seymouria was a land-loving reptile or a water-addict of the amphibian class. The consensus seems to be that this species marks the evolutionary transition between the two.

This scientific conundrum is found almost exclusively in the Red Beds of Texas - yet another reason to keep digging for more evidence.

Multiple Seymouria are often found curled up together, meaning that they might have been burrowers. The team has found Seymouria vertebrae and leg bone fossils at the main site, and an almost complete backbone from one individual at another site, that looks so strong "You could probably stand on it," according to Dr. Bakker.

Diplocaulus, aka "Boomerang Head"

The weirdest species the team has found in the Red Beds is the “Boomerang Head,” or, as it's officially known, the species Diplocaulus, meaning "two tailed," a reference to its double-spined tail bones.

It has an extrememly odd-looking body, with a flattened body and legs. The head, however, is pulled out to the sides in the shape of a boomerang - so extremely that by adulthood, the head could be 4 to 6 times wider than it was long. It was armor plated as well, with extremely strong jaws.

Some scientists contend that this shape may have helped Diplocaulus glide through the water - but the flattened lower body could not have contained the muscles of a strong swimmer. It's much more likely that this was an ambush predator, who waited unseen on the bottom of a murky river until unwary prey came along.

It's also possible that the skull served as a defensive mechanism - in which Diplocaulus may have used the points of its head as sideways horns to punch with - or as an aid for mating. Since Diplocaulus' eyes were on the top of its head, finding and impressing a mate by sight would be near impossible. So, a larger skull makes a love connection much more likely.

In any case, it's hard to imagine a predator - even the mighty Dimetrodon - swallowing this easily.

(c) Robert T. Bakker

After Dimetrodon, Diplocaulus fossils are the next most common find at the team's site. They've found pieces of skull - which has a unique shiny, pitted surface that feels very much like it came from a living thing - everywhere they look. They've also found leg fossils and pieces of backbone that show how incredibly strong this species was - perhaps the strongest example of sideways locomotion that's ever evolved.

A piece of Diplocaulus skull discovered at the HMNS site.

Texas Red-Beds: World's Largest Dimetrodon Cemetary

The Texas Red Beds are the finest, most gloriously complete fossil record of a critical threshold in evolution: The Dawn of the Land Ecosystem. The fossil record at this location shows us the rise of the first top predator the world had ever seen on land - as well as the many species it hunted.

Kimberly Beck looks closely for tiny fossils that might lead to a new excavation site.

But we didn't always know what we know now. The discovery of the Texas Red Beds came late in the history of paleontological science. Dinosaurs, Pterodactyls and Woolly Mammoths were all found far earlier. But there was the immense slice of time, labeled the Paleozoic Era - which begins with the Cambrian roughly 540 mya and ends with the Permian, about 250 mya - with almost no fossil record. Museum cases had only a few bones from Russia.

All that changed when Philadelphia paleontologist E.D. Cope discovered fossils in the Texas Red Beds in 1877. Not one or two or a dozen pieces - thousands of bones. Scores of species. Complete skulls, nearly every tooth in place. Entire feet, every toe perfect. Torsos and shoulders, hips and tails.

Chris Flis and Johnny Castillo prepare a Dimetrodon spine to be removed from the site.

About 80% of the big vertebrates (defined as having a body weight 100 pounds or more) found in the region were reptiles. The most formidable were carnivores growing up to 400 pounds, as heavy as a modern-day tiger - what would eventually be called Dimetrodon. It soon became the most well-known of all Red Beds' new species, and it ruled over a land ecosystem full of primitive reptiles.

Now, as in Cope's era, the Red Beds are a harsh environment- unfailingly hot and dry, with ground water in the summer that's a nasty brew of alkali and pink mud, heated to the temperature of afternoon tea. So much calcium is dissolved in the water that a few weeks camping out could give you kidney stones.

Since the Cope's discovery, dozens of scholars have braved the elements to dig into the Red Beds of Texas, and their efforts have given us 95% of all known fossils from the Paleozoic era - including many, like Seymouria, that are known almost exclusively from Texas Red Beds sites. Fossils found here continue to serve as the standard for the rest of the world.

A new discovery in the Texas Red Beds.

(Information excerpted from Texas Redbeds Revolution, by Dr. Robert T. Bakker.)

Xenacanthus: Permian Oddball

Xenacanthus was an oddball shark, even for a prehistoric species. It was shaped like an eel, with a nasty poisonous spine sticking straight out of the top of it's head. Since it lacked the well-known speed; large, fearsome teeth; and seemingly endless jaw capacity of modern sharks, it's comforting to know the poor guy had at least this one way to defend itself from the big, bad Dimetrodon, the Godzilla of the Permian world.

(c) Robert T. Bakker

Xenacanthus was found exclusively in freshwater environments - like the swampy shallows of North Texas 290 mya, but also all over the world, in places like Europe, Australia, South America and North America - such as the Museum's site near Seymour. It would have slithered through these ancient waters like an underwater snake, using a fin that ran along its back from head to tail.

This Permian oddball was part of an evolutionary line of sharks that first appeared in the Devonian, proliferated like mad through the Carboniferous and Lower Permian periods before taking a final bow towards the end of the Triassic. 220 million years in all - not bad.

Field sketch of Xenacanthus with Diplocaulus - possible prey? (c) Robert T. Bakker

By nature sharks don't make good fossils - most of their bodies are soft cartilage, which decays before the necessary processes can take place. However, Xenacanthus jaws and braincases were hard bone, meaning that we can recover more of this species that most other sharks. In Seymour, the team has found pieces of these, along with lots of Xenacanthus teeth and poison spines. Also in the area - shed teeth and coprolite from Dimetrodon, meaning this wasn't a site Xenacanthus came to relax.

Xenacanthus vs. Dimetrodon: a battle of epic proportions

"Imagine you’re the star of the Red Beds, a big, bull Dimetrodon. You’re just lounging around the edge of a wide lake, on a sultry hot day near the present-day town of Seymour, Texas. Time: 285 million years ago.

A stream of ripples is coming towards you, like a low-speed torpedo just below the surface. You’re reptilian brain is intrigued….you take a few steps closer…

Worried? Nope. You’re the biggest, baddest predator in the ecosystem. A quarter ton of taut muscle and bone. All your neighbors on land fear you. Your saw-edged fangs can bite through any reptile’s hide. You’re the fastest thing on four legs – you have limbs longer and quicker than anyone your size.

Suddenly, the lake erupts in an explosion of fins and fangs. Great gleaming shark teeth slash through the spray..."

Dr. Bakker holds a Dimetrodon humerus found at the site to illustrate its location in this species' body.

Like a scene from the Jaws: The Pre(history)quel, Dr. Bakker describes a scene we might have witnessed in Seymour, had we been there almost 300 million years ago. Dimetrodon fangs meet the sharp teeth of a Xenacanthus, a species of prehistoric shark that's completely unlike the species we know today.

To begin with, they don't have a dorsal fin - so the situation described above would have been missing the obligatory Spielberg-ian music.

"Complete Xena skeletons from Germany show a most un-sharkey profile. The body has no pointy dorsal fin at all. Instead, there’s a low, continuous fin extending from the back of the head all the way to the tip of the tail (with a slight notch over the bum). No shark alive today has that fin design."

No forked tail fin.

"The tail is long and muscular and strong but hasn’t a hint of a fork – the tail just gets thinner and thinner towards the rear and finally ends in a point. Xenas couldn’t generate the thrusts needed to accelerate into a great, long burst of speed, white-shark fashion."

No giant teeth.

"Xenacanth teeth weren’t great, huge saw-edged fangs. The xenacanth chompers were tiny. Each one had two thin, sharp cusps, sticking up at and angle, plus an even smaller cusp between the two main cusps. That dental design is not for chopping up big victims. It’s for snagging small fry."

Field drawing of Xenacanthus with Diplocaulus, a freshwater neighbor. (c) Robert T. Bakker.

Doesn't sound very threatening. So what makes Xenacanthus a shark?

"The skeleton around the brain says so. Braincase elements are the most complicated sector of the whole skeleton, because there are dozens of muscles, nerves, arteries, veins and joints. And each major division of fish has its own way of designing a braincase. Take apart the braincase and put it back together. It’s built like a shark."

So was Xenacanthus a Dimetrodon-slayer? Based on the evidence found by the team in Seymour, the answer is an emphatic no.

"We find giant, saw-edged shed teeth all around the Xenacanth corpses in Seymour, and elsewhere in the same general layers. The biggest shed teeth are mighty daggers, fifty millimeters tall, reinforced with a central pillar of enamel and dentine, and sharp-edged front and back. A tooth like that could kill any xenacanth shark. The ballistic evidence is overwhelming – these shed teeth are the “bullets” left at the crime scene by the shark-eater."

So, despite today's sharks' reputation as super-predators, Xenacanthus had a reason to be scared.

(c) Robert T. Bakker

"Shed Dimetrodon teeth are everywhere, including all the spots where shark skulls and spines are dug. The CSI evidence is undisputable – finbacks ate sharks, including big sharks."

But Xenacanths were by no means defenseless. They had a potent weapon to fight back.

"The Xenacanth head spine is huge...at the tip, the spine is smooth and ultra-sharp, so it would penetrate easily into the mouth of any predator foolish enough to grab the shark by the front end. It probably wasn’t a passive weapon. It has a strong, moveable joint with the head, so muscles and ligaments could have pivoted the spine around."

Plus, the spine was poisonous. Back to the battle:

"Our big bull Dimetrodon is watching a Xenacanth, as it zips out to grab its prey. The big finback isn’t shark-wise. His hunting instinct kicks in. He can’t resist the temptation – The quarter ton reptile leaps with jaws wide open. He bites down hard to inflict the killing bite. A searing pain penetrates the Dimetrodon’s mouth. It’s like being stabbed with a red-hot poker.

The finback staggers backward out of the water, rubbing his face into the soft red mud – the goop soothes the pain just a little bit. It will be a week before the swelling goes down.

Next time he will treat Xena with respect."

(Quotes excerpted from Xena - Warrior Shark Princess, a Red-Beds Surprise, by Dr. Robert. T. Bakker.)

Dimetrodon: NOT a dinosaur

Despite constantly being lumped in with T. rex and stegosaurus in the world of plastic dinosaurs - Dimetrodon was actually the top pre-dinosaur predator. Actually, it was the only predator around before the dinosaurs showed up - the first king of the food chain, and the first evidence we have of the formation of a land ecosystem.

This species ruled in the Permian Period – the time just before dinosaurs showed up that ended with history’s most massive known extinction. Discoveries from this period help answer the question “Where did dinosaurs come from?”

Dimetrodon were 7 to 14 feet long, weighed up to 600 pounds and had 4-foot tall fins on their backs. According to Dr. Bakker, you would not want to meet one in a dark alley – “If they were alive, they would look upon you as a food item.”

(c) Robert T. Bakker

Fearsome they may be, but few extinct species are as important than Dimetrodon – its existence represents a key step in earth history. Dimetrodon dominated its world, the largest meat-eater that had ever evolved up to the time. It was strong enough to kill any other land animal.

When Dimetrodon ruled, lizards hadn’t evolved yet, nor turtles, nor snakes. There weren’t any crocodiles, gators, frogs, salamanders, or even flowers. The only plants around were ferns, horsetails or other primitive conifer with dull green leaves.

Dimetrodon femur found by the team in Seymour, TX. Additional objects present for scale.

In fact, it's so old that Dimetrodon has a special spot in human evolution. The Texas Finback is located very close to the base of the mammalian family tree that includes all ‘possums, dogs, and cats, monkeys, apes and humans. So…you can put a portrait of the Texas Finback up on the mantel, next to Grandma and Grandpa.

This plaster jacket covers and protects an associated Dimetrodon skeleton found by the team in Seymour, TX. It has since been removed from the site and taken to the Museum for study.

"Where's the beef?"

There's a mystery paleontologists have been puzzling over for decades that's pretty well summed up by everyone's favorite Wendy's ad.

Dimetrodon vertebrae found at HMNS site; additional object present for scale.

The Permian Red Beds in North Texas have turned up hundreds of Dimetrodons - the top predator of the era - but only a few fossils of the plant eaters they would have munched on. Without evidence of enough meat for this species to survive, how did they flourish for so long?

Dimetrodon ribs found by HMNS team.

In other words, Where's the beef?

About 50 years ago, E.C. Ulson, UCLA, hypothesized that Dimetrodons didn't eat plant eaters very often - because they were eating sharks.

Xenacanthus sharks of the era were unlike anything we've seen today. While the front of this prehistoric shark resembles modern species, it's back was shaped like an eel, and it had a long, poisonous spine coming out of its head. Most importantly, these were freshwater sharks that lived in the shallow, swamp-like habitat that was also populated by Dimetrodon 290 million years ago.

Evidence found by the HMNS paleo dig team supports this theory. For example, the team has found lots of Xenacathus teeth and poison spines at the site - but comparatively few examples of Xenacanthus coprolite (or shark poop). If the teeth were lost in the act of eating something, there would be coprolite around to prove it. Instead, the team has found lots of chewed-up shark skull.

An example of coprolite found at the site.

Something was eating the Xenacanthus at this site. Dimetrodon is the only species in the same weight class.

So, mystery solved?

Regarding image use and copyright

The HMNS paleontology dig team is thrilled to bring you as many pictures as we can of what's happening this week in Seymour.

Please note that all drawings, illustrations and diagrams posted to this blog are (c) Robert T. Bakker. Educators are encouraged to download these images for use in their classrooms under the Fair Use guidelines of the U.S. Copyright Office.

All other photos and images are (c) Houston Museum of Natural Science.

Erin Blatzer, blog editor

Erin is a science geek with a communications degree that lucked into the world's best job - which is mainly composed of talking, writing and now, blogging about the amazing variety of cool stuff that happens at The Houston Museum of Natural Science every day.

She's twice narrowly escaped heat stoke while digging with the team in Seymour - and loved every minute. She also has experience handling snakes, eating bugs, transporting chickens, frogs and other live animals, and generally discovering how many fascinating stories there are to tell about the fine people she works with. She's excited to have the chance to help the team share their story with you this week, and hopes you'll visit the blog often to catch up on their exploits.

Chris Flis, Museum Team Member

Officially, Chris Flis is a site manager for The Woodlands Xploration Station, a satellite facility of The Houston Museum of Natural Science that houses more than 10 dinosaurs, an impressive collection of giant minerals, live bugs and much more - and he's a paleontologist at heart. He's been traveling to remote areas to find fossils since he was a kid, and has had the pleasure of digging into ancient history in Ireland, Nova Scotia, and England. His current research includes identifying and cataloging Eocene marine species present in fossil-bearing areas near College Station. With the Museum, he's dug extensively in Seymour, along with other pre-historic sites in Texas, as well as Kansas and the Morrison Formation in Wyoming. He's also an enthusiastic fossil photographer and many of his photos are featured in this blog.

Johnny Castillo, Volunteer Team Member

Johnny Castillo is a long-time volunteer with the Museum's paleontology department. He has dug mammalian fossils in Nebraska, spent three dig seasons working with the Museum on a Triceratops, and this is his fourth time digging with the team in Seymour. He's also dug in Stone City and High Island.

"I was no different than any other kid, I guess. The top three things I wanted to do was dig for dinosaurs, go into Egyptology - I thought it would be really neat to go to Egypt and dig for treasure - or drive an ice cream truck. Getting to eat all the ice cream you want - that's a big thing for a kid."

This week, Johnny is working on removing a plaster jacket full of Dimetrodon fin spines and vertebrae from the site, and looking for the bones that could be underneath.

Kimberly Beck, Teacher Team Member

"Every rock has a story to tell!"

Kimberly Beck is the Chemistry and Integrated Physics and Chemistry teacher at Seymour High School in Seymour, TX. She first worked with the HMNS dig program in 2007 as part of the Museum's field program for educators, in which teachers work on a real dig site in order to bring that experience and enthusiasm - as well as real fossils - back into their classrooms.

But let's let her tell it:

"I have been learning alongside the Museum's team ever since my first dig last summer. Now, I dig on the Brazos River in Knox County every chance I get and have found everything from Permian arthropod tracks to Pleistocene mammoth tusk. I love working outdoors in the dirt and am fascinated with the natural history, anatomy and physiology, and investigative nature that comes with studying fossils. Every rock has a story to tell!"

Students from Beck's class will visit the team on site this week, and you'll hear all about their experiences digging fossils right here.

Beck earned a Biology Degree from Texas Woman’s University, with a traineeship with NASA at Kennedy Space Center in Cape Canaveral, Florida.

David Temple, Associate Curator of Paleontology

Associate Curator of Paleontology David Temple likes to say he's also the unofficial head of the Museum's "Department of Mysteries" - meaning that he's our Renaissance Man, the go-to guy when you've got a weird bug, strange goo, unusual fossil, mysterious substance or other generally unknown object you'd like to know what to do with.

Now in his 16th year at the Museum, David organizes the Museum's field program in Seymour. With a background in archaeology, he started here as a part-time teacher and wandered into paleontology by accident. David brings his background in archaeology to the process of digging for fossils - in which the entire context of surrounding each find is catalogued. He also has a passion for photography, and many of the images you will see on this site are David Temple Originals.

David is ready for all your paleontology questions. As well as your questions on bug cooking, squamates, space rocks, or almost anything else.

Dr. Bob Bakker, Curator of Paleontology

Dr. Robert T. Bakker is the leader of the handful of iconoclastic paleontologists who rewrote the book on dinosaurs three decades ago. Along with other noted paleontologists such as John Ostrom and Armand de Ricqules, Bakker has changed the image of dinosaurs from slow-moving, slow-witted, cold-blooded creatures to, in at least some cases, warm-blooded giants well equipped to dominate the Earth for 200 million years. Long before feathered fossils were found, Bakker contended that some dinosaurs were endowed with insulating feathers. New research continues to lend strong support to this view, no longer in the minority.

“I was fond of saying most of dinosaur science was wrong stuff, and that did offend a lot of people. Someone had to say dinosaurs had feathers,” said Bakker. “I want to put dinosaurs in context and in their chosen environment. I want you to be able to feel and think and smell what a Stegosaurus experienced. I want you to smell fresh fish on your teeth as a Ceratosaurus, then do this with the whole history of dinosaurs. Then I want you to finally understand how and why dinosaurs ruled.”

As curator of paleontology for the Houston Museum of Natural Science, Dr. Bakker has led the paleontology dig team in Seymour for the past two dig seasons, using a "CSI"-based approach, (for example, fossilized teeth uncovered are the “bullets” that help the team identify the victims and the predators in an ancient ecosystem) in order to discover the relationships between and the behavior of the species that lived in North Texas 250 million years ago.

In addition to his work with the Houston Museum of Natural Science, Dr. Bakker is also the Director of the Morrison Natural History Museum in Colorado. He is also the author of many books on paleontology, including the groundbreaking 1986 book The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction. Bakker was among the advisors for the film Jurassic Park, and the character Dr. Robert Burke in the motion picture The Lost World: Jurassic Park is based on him.