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.

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!

The Seymour Blob: Putting something in your head from the ground beneath your feet

As you may already know, the Houston Museum of Natural Science has long been digging up wonderful Permian fossils in Seymour, Texas. Curator of Paleontology Dr. Robert T. Bakker and his team of hot, tired and pink (from the dirt) volunteers have made major finds, but sometimes it’s the little things that count — like finding little amphibians, such as the boomerang-headed Diplocaulus and the snake-like Lysorophus, too.

lysorophus 2

The rock stars of the Seymour dig are people like Chris Flis, who finds bones everywhere. There are also geologists on the team, like Gretchen Sparks, who are interested in sedimentology (how the dirt got there) and who pick up interesting bits and wonder what they are.

This is a warty blob (that’s a technical term) that she found. It sort of looks like a bone or a burrow dug by something. I tested it and found that it is made of calcium carbonate.

CalichiSmall

To see more, I ground and polished the end. Now we can see that this is not a bone because it does not have a marrow cavity or bone lamellae. Warty surfaces like this are frequently found on the outsides of arthropod burrows because the animal lines the burrow with spit and sediments balls — but the warty parts of these structures are inside and on the exterior, so this is not a shrimp burrow.

The flowery appearance of the growth indicates that this is caliche, one of those sedimentary features that often get little attention.

Caliche is a hard-water deposit on steroids. Caliche forms in dry areas like North Texas when more water evaporates from the surface of the ground than falls as rain. Ground water dissolves minerals like calcium carbonate and gypsum from the soil and rock. When the water evaporates from the surface, these minerals are deposited in flowery growths called “efflorescences”.

The climate in Seymour is so dry that caliche is growing right now. During the Permian (about 250 million years ago), the climate must have been even dryer, because we find bands of caliche in the soil. Each band represents an ancient soil layer.

CalichiCloseupc Annotated

We can even tell the history of the caliche deposition. The interpretation is based on what covers what:

A.    White layer was deposited in a nearly flat crack in the dirt. Note the white flowers.
B.    The pink layer covers the white and has the same shape of flowers but contains more iron.
C.    Layer B was partially covered by darker pink laminations. The laminations indicate that crystal growth was much slower.
D.    The blob fractured and the dark red layer of sediment was deposited along with fragments of Layers A and B. This is a mini sedimentary dike.
E.    Since Layer D is made of sediment and not hard caliche, it shrank and cracked in the process of drying. This crack was filled with a quickly-deposited rind of fine grained white material followed by very slow growing clear crystals, making the darker band inside the white. This looks like an agate filling but is still carbonate.

Were all these layers deposited 250 million years ago? That actually would be easy to tell, because young carbonate has a carbon delta C13 signature well within the 50,000 year sensitivity range for the method. It just costs money to have the analysis done, and there are probably better uses for the resources right now – like having more specimens mounted!

I conclude that the warty bone-looking thing is really an inorganic crystallization of carbonate and possibly gypsum. Did you know you could learn so much from gravel?

Hittin’ the road with the HMNS Paleo crew!

BB describing boomerhead

I got the chance to travel from Houston to Seymour, TX and explore the Texas Redbeds in search of fossils with David and the HMNS Paleo Program. HMNS staff and volunteers have been making these trips for four years now. They have found several excellent specimens and brought them here to prepare for our new and improved Paleontology Hall. I’d had some experience looking at the bones and things that the crew had been bringing back to the Museum but this was my first experience actually in the field – and I was pretty excited!

Drawing of a Diplocaulus

The first morning we arrived at the site and looked around at a few different locations before settling down in the “pit” to dig. I got to spend a little time training my eyes to see fossilized bone, teeth, cartilage and coprolites among the rocks at the “spoil pile” which is a great experience because the ratio of fossils to rocks on the surface is such that you have a pretty good chance of closing your eyes and picking up a fossil! Then we moved over to learn the digging technique where fossils were a bit more hidden in the pit; it took a few minutes to get the hang of how to hold the tools and make sure that you are using enough force to move the dirt but not so much that you break a hidden bone. All and all it was really enjoyable first day at the site.

Over the next two days after Dr. Bakker arrived we visited several other sites on the property and I got a chance to work on excavating a dimetrodon spine, map some dig sites (here’s a fun school dig site mapping activity), learn about other findings like the diplocaulus or “boomerang head” skull we’re looking at in the photo above. I enjoyed the opportunity to work alongside the experts and learn about all of the preparation work that is required for each and every specimen that will be in the new Paleontology hall (coming soon!) here at the Houston Museum of Natural Science. I can’t wait to see everything on display in the new wing of the Museum – it’s going to be so exciting!

For more information about what fossils are found at the dig site in Seymour check out some of the entries on the Prehistoric CSI blog, you can also find some really awesome illustrations on that site to bring the animals to life!