Back to Seymour, Back in time: Part One

Far up in north Texas, past Ft. Worth and Wichita Falls, past the point where the flora turns from trees to shrubs, past a town with a funny name, Megargel, pop. 203, past a massive wind farm with tall white blades lording over thousands of acres of land, and then another, and another, lies the humble community of Seymour. Nestled in the Red River Valley near the southeastern corner of Oklahoma, the little city contains a high school (Go Panthers!), a couple of small hotels, a handful of fast food restaurants and steakhouses, several churches, and a tiny collection of historic prairie-style homes tucked behind Main Street. It’s the kind of town you live in not for the amenities, but for the rich soil and the open sky that stretches to the horizon, and the friendly rural folk, farmers and ranchers, who with their own hands have built it up from nothing.

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Wind turbines stand over fields of wheat on one of several wind farms outside Wichita Falls. Kelly Russo

On a weekend, you can enjoy a movie under the stars, take the family to the park, or hop in your SUV and explore the landscape. Nights open above like a planetarium, studded with a billion stars that would delight any gazer, and if you’re up for some night adventure, it’s a great time to search the dirt roads for nocturnal wildlife. But for all this, a trip to Seymour is incomplete without a visit to the pride of the city: the Whiteside Museum of Natural History.

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Seymour storefronts and cobblestone streets are a testament to this city’s history. Jason Schaefer

A recent addition to the rural landscape and a welcome diversion from daily life on the ranch in burning heat, the museum has blossomed into a local treasure in a single year. Under the direction of geologist and paleontologist Chris Flis, the once-dusty abandoned building that used to house a car dealership now contains excellent specimens of Permian-era fossils discovered less than 10 miles away in the Craddock bone bed, including the iconic Dimetrodon.

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Murals on the Whiteside Museum of Natural History provide a fascinating departure from the rural look of historical storefronts. Kelly Russo

With the help of paleo curators Dave Temple and Dr. Robert Bakker, The Houston Museum of Natural Science has obtained its Permian fossils from this site for the past 11 years. Flis began building the Whiteside collection from the Craddock and other local dig sites, and in the past year, to use Temple’s words, “He’s been busy.”

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A model Tyrannosaurus rex head at the Whiteside Museum of Natural History displays the contemporary conception of the dinosaur’s appearance. T. rex had pinfeathers on its head and jaw. We joked he looked a little like John Travolta. Kelly Russo

Racks of specimens jacketed in element-proof plaster-and-burlap casts line the back wall of the Whiteside, and in the fossil prep lab, the skeletons of Edaphosaurus, Diplocaulus, and Eryops line a long table as Flis categorizes the fragments to piece together whole prehistoric animals. These bones, about 280 million years old, represent a time in the fossil record when amphibians first exited the water and dragged themselves across land, eventually developing into early reptiles. And the Craddock bone bed is one of the richest cross-sections of this time period in the world.

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At the Whiteside Museum of Natural History, an open jacket of an Eryops skull, a Permian-era amphibian, displays the methods paleontologists use to prepare fossils. Jason Schaefer

Kelly and I visited Seymour, the Craddock and Whiteside the weekend of June 6 to gather information about our site and assist in the celebration of the Whiteside’s first anniversary. While the trip didn’t require any miles-long hike-ins through the backcountry, nor a tent and a sleeping bag since we “camped” in the Sagamar Hotel for four nights, the trip was nothing short of an adventure. We met the locals, played in the dirt, prospected for new fossils, and helped our paleontologists work on our active Dimetrodon digs. The work was sweltering and filthy, but the excitement of discovery, of putting hands on bone that hadn’t seen sunlight in hundreds of millions of years, holding history in the palm of your hand, was enough to keep us out in the heat, fueled by the magic of wonder.

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The spinal column and fin spines of an Edaphosaurus, a Permian-era land herbivore, line a long table in the fossil prep lab at the Whiteside Museum of Natural History. Kelly Russo

The first day, we didn’t know what we were getting ourselves into. To beat the heat, Temple prefers to rise early to eat breakfast around 6:45 a.m. at the local Maverick diner, where Seymour’s agriculturalists congregate for any combination of bacon, eggs, sausage, potatoes, and biscuits. Kelly doesn’t drink coffee, but I required about a half-gallon just to get the day started. I’m a late riser.

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Kelly (right), and educator and HMNS volunteer Shana Steinhardt, photograph a Texas horned lizard on the Craddock ranch near Seymour. Jason Schaefer

After the rich meal, plenty of calories to burn, our group caravaned off to the Craddock, a 4,400-acre ranch down a lonely county road. A dirt truck path carved through the mesquite and cedar brush was our only access to the dig site. Normally, we were told, the land is dry and brown, more a desert than a semi-arid valley, but following heavy rainfall two weeks prior from the same storm system that flooded Houston in May, the land was the greenest it had been in a decade. The rain caused an explosion of life, giving us five sightings of the Texas horned lizard, our state reptile, now listed as a threatened species due to its rapid decline in recent years.

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This Texas horned lizard, listed as threatened by the State of Texas, was one of five sightings that we had during the course of our trip. Jason Schaefer

But what’s good for the land ain’t so hot for digging fossils. On the way out to the site, Temple worried the mud would be too sticky for our company vehicles to push through, and even if we did, that the soil at the site might be too wet. Paleontologists depend on dry conditions to fleck away sedimentary rock with delicate tools. Wet ground means a difficult dig and sometimes the loss of specimens.

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Paleontologists and volunteers from the Houston Museum of Natural Science and Seymour locals gather at our dig site in the Craddock Bone Bed. Kelly Russo

Conditions weren’t as bad as we thought, however. The site was about as good as it could get in spite of the rain. We cleaned up some litter, tarpaulin fragments and other jacketing materials that had aged in the weather, and set to work removing a pile of scree that had fallen in the rains and partially covered our biggest jacket. You can dig with anything you can prod the ground with, breaking up the clay into dust like a toothpick cleaning teeth, but Temple prefers a bayonet with a modified pommel to stab the soil and unlock it with a quarter turn. Others used screwdrivers, dental picks, or awls. Dr. Bakker hadn’t yet joined us; he would come a day later.

Sissy

A regular sight on the Craddock, Donald Gayle Coltharpe, lease-holder for the Craddock ranch, carries his dog Sissy perched on his shoulder. Kelly Russo

We dug slowly, handful by handful, making sure no bone fragments were lost in the soil we collected in buckets and discarded over the side of a nearby ravine. That first day, with the help of volunteers Dr. Mitch Fruitstone and Shana Steinhardt, Kelly and I learned about the process of extracting bone from the dirt. Using whatever digging tool you choose, you enter the soil at a shallow angle, digging into the side of a hill rather than down until your pick hits solid rock. It’s easier than you’d think to notice the difference. Though the sediment has hardened with time, it crumbles away easily. Bone fragments and rock will not break apart unless struck with an implement, hence the ginger digging. The idea is to remove the dirt from the rock, not the rock from the dirt. Each significant sample that is discovered must have its depth in the soil and location relative to other fossils recorded to place it in the geological record.

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The plaster jacket we hoped to flip over the weekend and transport back to the museum was buried under a layer of sediment after heavy spring rains. Jason Schaefer

The goal of the day was to “flip the jacket,” that is, carve the dirt out from under a fossil-rich lump of sediment until it stands on a pedestal, then turn it upside-down to plaster the underside. When the specimen is completely jacketed, it’s ready for transportation. Contrary to what the movies may suggest, paleontologists do the painstaking final prep work for fossils not in the field, but in a controlled environment, a laboratory with fine, electric-powered implements.

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Using a replica bayonet as a digging tool, HMNS Paleontologist Dave Temple teaches me how to uncover the plaster jacket without harming it. Kelly Russo

The plaster field jacket is made of layers like papier mache. Diggers begin with a separation layer, usually aluminum foil, so the plaster doesn’t stick to the specimens, and then dip fragments of material like burlap or cotton into plaster of Paris that hardens in minutes. Once the specimen is completely covered and dry, it is marked for cataloging so paleontologists know what it contains and its upright orientation when they return to it days, weeks, months, or sometimes years later.

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A jacketed Dimetrodon rib specimen from a neighboring dig site illustrates both the layering and soil removal techniques paleontologists use to preserve the integrity of fossilized bones. Kelly Russo

By one in the afternoon, we broke for lunch and to tour a nearby longhorn ranch. We had dug no more than a foot into the soil around the jacket, and Temple was nearly bitten by a four-inch centipede, a common sight for this part of Texas, but it was a good start to the weekend, with much more adventure to come.

Author’s note: This is the first part in a series detailing the HMNS excursion to the Craddock Bone Bed.

Digging in the dirt: Getting to know the Dimetrodon of the Texas Permian Red Beds

I love my job. Not everyone can say that. My avocation and vocation are as two eyes with one sight (paraphrasing Robert Frost). Part of that job was taking a group of 15 patrons up to the Museum’s dig site outside Seymour, Texas. There, under the tutelage of Dr. Robert Bakker and David Temple, the group learned how to properly excavate bones of ancient animals —  in this case, Permian synapsids, amphibians, and fish.   

I got to go through a spoil pile (the pile of debris and castoff that others have thrown aside), and found several bits of our very early ancestors, the synapsid Dimetrodon.  I also worked on removing the overburden (the rock and dirt that is over a site we want to excavate), and found bits from a dorsal spine of a Xenacanthus, an ancient shark. It was the fulfillment of a childhood dream (as I child I played paleontologist rather than fireman and my first Deinonychus is still buried out back at my childhood home).

But I’m not the only one who dreamed of finding fossils in Texas.

Noted Swiss naturalist Jacob Boll came to Texas in 1869 to join La Reunion commune that is located in the current Reunion District of Dallas. (The Reunion Tower is named in honor of that small settlement.) La Reunion commune was responsible for the first brewery and butcher shop in the Dallas area. It also helped Dallas become the center for carriage and harness making.

Jacob Boll came over to set up high schools based in scientific inquiry. Through the late 1870s, he searched for fossils for Edward Drinker Cope, the noted “Bone Wars” paleontologist. Boll found over 30 new vertebrate species from the Permian period, which can be seen in the collections of the American Museum of Natural History.  Unfortunately, on his last trip, he was bitten by a rattlesnake, wrote some final letters to his family, composed a short poem in German, and died.  

In the Permian period, Texas was very different from today. Near Seymour, there were rivers and seasonal flood plains. However, even with this picture, there are still unexplained factors about the life of Dimetrodon — one being that there was not enough prey to sustain the population that we have found in the fossil record. While the Dimetrodon were making sushi out of Xenacanthus and chewing on some Trimerorhachis legs (like frog legs, only much shorter), there was not enough food to go around.

Now add to this case the curious fact that almost no Dimetrodon skeleton found has an intact tail. Anyone who has been to a good Cajun restaurant will know that the best meat on an alligator is the tail. And Dimetrodon would agree — hence the lack of tails.

But even this does not account for all the food necessary to keep all the predators alive.  Where is the missing food?

Dr. Bakker gave us a couple of hints as to what he thinks is the answer. 

 A few miles away from the site, there is an old Permian river basin where we find Edaphosaurus, a large Dimetrodon-like herbivore. Was it possible for Dimetrodon to walk a few miles, ambush an animal about its size, then walk back for a rest? This would provide food for the population.          

If you are interested in learning more about the Texas Red Beds, join us for our Fossil Recovery Class on May 20. You can go through some of our collection from the trip and learn about fossil collecting and identification techniques.

Click here for more information.  

Bakker blogs: Murder by hickey — or a dinner date with a meat head

We’ve been pondering  the problem of Dimetrodon-on-Dimetrodon violence. It’s a Red Beds tragedy; fin-back reptiles were nibbling each other’s brain bones and gouging each others’ cheeks.

But now, maybe, we have some evidence for the softer side of fin-backs: hickeys and love-bites.

Here’s a scientifically precise reconstruction of one fin-back smooching another on the back of the neck, sort of like the cover for a Permian romance novel: Fifty Shades of Red (Beds).

Murder by hickey: Dr. Bob explores another side of Dimetrodon-on-Dimetrodon violence in the latest Bakker blog

Neck-nibbling is quite the thing among living species of predators, both large and small. Cats do it. Go to Animal Planet and see male lions grabbing the lioness by the nape.  Or come visit our Seymour digs in north Texas and meet “Elton,” the male Mountain-Boomer Lizard. Male Mountain Boomers, aka “collared lizards,” are the brightest lizards in all of the Lone Star State.  Not “bright” as in “smart,” but as in wearing “fabulous iridescent blues and pinks and yellows in the mating season.” Elton stakes out a wide, flat area in our quarry where he struts his stuff, doing Marine-style push-ups to attract females and frighten away younger males. Every spring he succeeds in enticing a healthy female, almost as muscular and buff as he is.

Here’s a portrait of Elton, snapped by David Temple, Curator and Herpeto-photographer extraordinaire.

Murder by hickey: Dr. Bob explores another side of Dimetrodon-on-Dimetrodon violence in the latest Bakker blog

(Warning: If you keep Boomers in captivity, never have two males together in a small cage. They’ll beat the coprolites out of each other. The same warning often applies to keeping two curators together.)

Actual Boomer mating includes neck-grabbing. Elton has an extraordinarily wide forehead housing mighty jaw muscles, so the love-nibble has force behind it. If she’s willing, the female displays a hunkered-down posture and shows off her red dots. Therefore, when the female Boomer signals “Bite me!” it’s in fact a “Come hither!” message.

Here’s a fine snap of a female Boomer, from Mike Cong Wild Photography.

Murder by hickey: Dr. Bob explores another side of Dimetrodon-on-Dimetrodon violence in the latest Bakker blog

Elton does NOT view us humans as a higher species. He’ll race to where we’re digging under the shade of a tarp and give us the hairy eyeball, lizard-style, cocking his head right and left. Then out he goes to ascend his viewing stand, a foot-tall sandstone block 20 feet away.  I think he’s checking us out to make sure we are not competition for his favorite lizard-love.

Given such behavior by Elton, we expect that our 400-pound Dimetrodons engaged in some sort of gnathic-cervical love-grabbing. Do we have petrified evidence? You bet. Here’s a cervical vertebra number two, the big bone right behind the head. It belongs to a full grown  D. loomisi, a species nicknamed the “Keira Knightly Finback” because of the excessively long, slender neck. The arrow points to a bite — a  powerful nibble that actually removed a piece of bone.

Murder by hickey: Dr. Bob explores another side of Dimetrodon-on-Dimetrodon violence in the latest Bakker blog

But that’s a bit too big of an ouch. There would be thick muscles running from the vertebra to the back of the skull that flex the head up and down, side to side, and twist the head around. This bite would have gone right through the thick part of the muscles, leading to massive trauma, blood loss and death.

Murder by hickey!

Check out this diagram: On the right you’ll see some of the massive and meaty muscles that are located around the head and neck.

Murder by hickey: Dr. Bob explores another side of Dimetrodon-on-Dimetrodon violence in the latest Bakker blog

It was a sad day when we realized that our love nibble was instead hard evidence of cannibalism. But the head-neck bites also prove something elegant and marvelous about Dimetrodons. We mammals are, supposedly, the Highest Class. We have the most advanced, most efficient anatomical tools for cutting up our food and digesting it quickly. We are far better than the cold-blooded class Reptilia, or so the textbooks say.

Cold-blooded reptiles today do seem sloppy and inefficient. Nile crocodiles and komodo dragon lizards kill zebra, wildebeest and goats — but once their prey is dead, their table manners are primitive. The big reptiles bite their prey anywhere and everywhere, chomping down on bony snouts and chins where there’s not much meat.

Mammal top predators display far greater precision. The tiger examines his prey carefully before removing bite-sized pieces off the meaty zones. The rear teeth slice meat as efficiently as your neighborhood butcher making prosciutto.

You can do this experiment  at home: buy some delicious Texas beef jerky and present a big piece to your hungry dog (or your friend’s). The pup will position the jerky between its rear teeth and slice, slice, slice, GULP. The quick slicing action comes from special features of those rear teeth.

Scrutinize these photos of a wolverine. See the big rear teeth?  When the wolverine bites meat, the upper rear tooth slides against the lower tooth, and the teeth hone each other like metal shears. That’s why mammal meat-eaters can cut even tough meat and tendons swiftly.

Murder by hickey: Dr. Bob explores another side of Dimetrodon-on-Dimetrodon violence in the latest Bakker blog

Fossil predator lairs from the Age of Mammals show that these precision-slicers are old adaptations. When we excavate prey carcasses left by saber-toothed predators like Dinictis and Hoplophoneus (both on display in our new Morian Hall of Paleontology), we see bite marks on the skull bones where there was lots of meat — the rear of the skull, the brain case and the tops of neck vertebrae. The extinct mammals ate like the highly efficient carnivores in today’s world. Saber-toothed cats did not waste much time and energy gnawing bony, meat-poor zones of chin and snout. Neither did the extinct dog-like Hyenodon.

Our Dimetrodon was a very, very primitive reptile. In fact, in most ways, D’don was even more primitive than a crocodile or komodo dragon. One big deficiency was the set of meat-slicing teeth. Dimetrodons didn’t have the enlarged self-sharpening chompers. The upper rear teeth could not slide past the lowers in a honing action. Therefore, so the theory goes, a Dimetrodon would have been sloppy and slow and inefficient when dismembering big carcasses.

If D’dons were really as sloppy as crocs and komodo dragons, then we’d find bite marks all over skulls and necks. But if D’dons were careful and efficient, they would have left tooth marks concentrated on the meaty zones of heads and necks.

When we analyzed bite marks on all the necks and heads from our digs, I was flabbergasted. (Talk to anyone in the lab — Dr. Bob hardly ever gets gabberflasted.) Our supposedly primitive Dimetrodon did not bite a la lizard. Or a la crocodile. Or a la gator.  Bite marks were targeted with consummate precision. Little energy had been wasted gnawing at non-meaty parts. Bony snouts and chins were not chewed upon. Instead, the tooth marks had been concentrated on all the most meaty zones of the head and cervical region. Bites on the braincase are exactly where big, thick muscles attached. Bites on the cheek are where the jaw muscles attached. Bites on the neck are where the thickest cervical flesh was located.

I have new respect for the Texas Red Beds Dimetrodon. Whenever we unearth another D’don victim, I doff my hat in honor of its masticatory prowess.  Our modern mammal efficiency began a hundred million years earlier than we had thought. And now, when we do lunch at Smokey Bros Barbecue and we chew succulent brisket and bring a doggy-bag back to Skippy, we thank our fin-back ancestors.

Dumb as a rock? A lumpy bit of earth reveals a geological timeline in Seymour

Editor’s note: Today’s blog comes to us from paleontologist and field volunteer Neal Immega.

You all know by now that the museum has a dig in Seymour where we are finding fabulous Permian fossils, including the toothy Dimetrodon and the weird boomerang-headed salamander Diplocaulus. We don’t dig in just one place; lots of people go prospecting for new sites (or maybe they are just looking for a private spot to do their business).

A previous blog topic was on a weird lump that turned out to be a caliche ball. Today we have another lumpy rock to look at. This specimen was collected by geologist Gretchen Sparks, who brought it in just to plague me.  Let’s see just how much information we can squeeze out of it:

CrossBeds

At first glance, it’s just a rock showing cross-bedded sandstone with low-angled bedding, doubtless caused by water deposition in the Permian creek that crossed our digging area. This is pretty normal stuff. We see cross-bedding everywhere at the dig site, because the sandstone is durable and stands in relief.

But why is it lumpy? The bulge in this picture is not exactly standard:

Profile

It gets better. The rock is too heavy to be only quartz. A heavy, light-colored sandstone is likely to be cemented by barite (barium sulfate). Let’s cut the rock in half and polish the face.

cutLumpLabeledThis is turning out better than I expected. You can see a seam of barite cutting the nodule vertically in half. The sandstone shows horizontal layers which correspond to the cross-bedding.

What about the red-colored area? The area we are working in North Texas is called the Permian Red Beds because everything got oxidized from prolonged exposure to the atmosphere. It was a really dry time, and the critters stayed close to the Permian creek which deposited these sediments. It is good for us because the fossil remains are concentrated in a small area (our dig site is just about the size of a tennis court).

Let’s consider this possible sequence of events.

1.    250 million years ago, sandstone was deposited in a creek. It is all cross-bedded.

2.    The sand grains were likely coated with iron oxide and thus turned red.

3.    The sandstone was buried by maybe 1000-plus feet of additional rock.

4.    Shales deeper in the geological section were heated by the normal geothermal gradient to hundreds of degrees and adsorbed water was squeezed out, taking with it the barium that was also adsorbed (from the ocean) on to the clay surfaces. The water moved vertically along cracks in the rock.

5.    When the barium reached the rocks we are digging in, the barium precipitated because the pore water is very “hard” with dissolved gypsum. The barium reacts with the local sulfate, producing barium sulfate which is essentially insoluble in water. It is the ultimate “hard water” scum.

6.    The barite precipitated as the vertical seam and filled the pore space in the red rock.

7.    A whole lot of rock was eroded in the next 250 million years to bring us to the present and the rocks back to the surface.

8.    10 to 100-thousand years ago or so, North Texas was in an Ice Age, and it was really wet with lots of vegetation. Decomposing vegetation created a reducing environment which dissolved iron right out of the rock. Barite is very chemically resistant, and this lump could have been at the surface through part of the ice age. The iron could have partially leached out of the lump at that time. You can see that the leaching went deeper into the lump where there are horizontal fractures in the rock.

All this from a lump of rock. Thanks, Gretchen!