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.  

Get a LIFE: Happy (almost) 60th anniversary to the magazine that launched a thousand dino geeks

Some people like to tell me, “Dr. Bob, get a life!”

I did, 60 years ago. Here I am re-reading my battered copy of the magazine that got me hooked on paleontology.

Celebrating Life!
Happy anniversary to the LIFE magazine that created … me!

Sept. 7, 1953 was the publication date of the greatest, most momentous article on fossils and the history of life. LIFE issued its glorious “The World We Live In” series with a cover story about the prehistoric safari. Stegosaurus and Brontosaurus loomed large on the opening page. There were trilobites too, full-page photos, and scenes from the Texas Red Beds. Then came Triassic dinos, Jurassic dinos, Cretaceous dinos, and the ocean-going reptiles who filled the warm tropical seas of the Mesozoic. There were evolutionary opportunists, the conquering furballs of the Paleocene Epoch, who rushed with Darwinian speed to fill the voids left by dinosaur extinction. Prominent furry mammals included the the famous “Saber-toothed Vegans”, six-horned Uintatheres, followed by Killer Warthogs like our mounted skeleton of Archaeotherium. Finally, the LIFE story reached a crescendo with the Ice Age behemoths: mastodons, mammoths and saber-toothed cats.

But what hooked my fourth-grade mind wasnʼt merely the monster parade of weird and wondrous beasts. It was the story. LIFE writer Lincoln Barnett explained how chromosomes and habitats cooperated in manufacturing new species. How we could see desert lizards evolving right now in Americaʼs Southwest. And how Birds of Paradise exemplified the power of sexual selection to transform bodies and behavior.

The fossil history became even more wonderful because we could understand what shaped the successive waves of creatures who swept across land and sea, dominated the ecosystems, and then suffered catastrophic die-offs to make room for the next surge of evolution. Barnettʼs prose was graceful and riveting (he wrote an award-winning biography of Einstein for kids). Many other budding scientists owe their careers to Barnett and to Life.

We should never underestimate the extraordinary power of fine science journalism. As a 9-year-old, I read and re-read that LIFE magazine in my Granddadʼs solarium. Then I said to myself, “Wow, thatʼs the best story I ever read. Best story I could imagine.” At dinner, I announced to my startled parents, “Iʼm gonna grow up to be a paleontologist and dig up the history of the world!”

After a polite pause, Mom remarked “Thatʼs nice dear … itʼs a phase and youʼll outgrow it.”

(She still says that.)

Celebrating Life!
Hereʼs an unapologetic plug to buy this issue of LIFE. We see here a scene
from the middle of the narrative. A Late Jurassic Allosaurus is feeding on
the rump of a brontosaur. The painting is by Rudy Zallinger and was based
on the skeletons at New York — the museum there dug a brontosaur with
severe tooth marks on the bones, bites that matched the jaws of an
allosaur dug from the same strata not far away.

Do check your used book stores for this issue of LIFE. They are out there, but delicate since the paper is hi-acid. The paleo-issue was bound together with other special LIFE numbers on nature as a hard-cover, “The World We Live In.” There was a kidsʼ edition of the book, too, and a Golden Book version of the fossil story.

Paleo-powered pictures for everyone on Sept. 24: Bakker’s back with a big book of dinosaurs

Our esteemed curator of paleontology, Dr. Robert T. Bakker, is back in town and on campus at HMNS Tuesday, Sept. 24 for a very special book signing and lecture.

Coinciding with the release of his brand new picture book, The Big Golden Book of Dinosaurs, Dr. Bakker will lead a lecture in the Giant Screen Theatre, to be followed by a book-signing session at the Museum Store.

From the Google

Among the topics to be addressed during the lecture with Dr. Bakker’s inimitable enthusiasm are: Was T. rex a slow-footed stumble-bum? (No!) Were tyrannosaurs devoid of any gentle, nurturing gestures? (No way!) Were gigantic meat-eating dinos ticklish? (You bet!) Could you out-run an angry charging triceratopsine? (Don’t even try.)

Kid-friendly dino activities will be available throughout the Grand Hall prior to the lecture, beginning at 5 p.m. For more information or to book your tickets in advance, click here!

Why all the Shark Week mania over megalodon? Why two other sharks blow it out of the water

With all the fuss over megalodon lately (including the Discovery Channel’s doubled-down non-apology), we decided to give some attention to a couple of grossly unappreciated other prehistoric sharks. Great whites are great and all, and megalodon is a marvelous monstrosity, but there are two other prehistoric shark species that really blow everything else out of the water.

We get that megalodon is mega-huge, and it’s thrilling to ruminate over an extra-large, extra-hungry version of today’s Great White. But what about sharks with scissors for jaws? Or a buzz-saw mouth full of teeth?

It’s not science fiction. Here are two prehistoric sharks that we think should be in the running for their own Shark Week special:

Edestus

There were several species of this scissor-jawed prehistoric shark, the largest of which — Edestus giganteus — could rival the size of a modern Great White. But instead of regular shark teeth (which are pretty scary as is), Edestus had a mouth that cut like giant scissors.

“When you say ‘shark,’ the first thing that pops in your head is teeth,” says Associate Curator of Paleontology David Temple. “Sharks have had similar kinds of teeth, but there were some weird evolutionary offshoots where the teeth don’t look like we imagine them now. Instead of the rows and rows of teeth that we expect the mouth, Edestus’ mouth looked more like a modern dolphin’s, and its teeth were more like shearing scissors.”

Image courtesy wikimedia

Edestus wound up with its unusual, protruding shears (pictured above and reenacted here) because it did not shed its worn teeth like a modern shark would. Instead, new teeth continued to grow outward until its two rows of single-file teeth protruded out past its mouth.

Helicoprion

Also called the whorl shark, the Helicoprion is notable for its bizarre toothy set-up. Like Edestus, instead of shedding its old, worn teeth, Helicoprion retained them, adding new teeth in a single row in a spiral formation (imagine the growth pattern of the world’s longest fingernails, and you’ll get the idea.)

For years, Helicoprion’s remains confused scientists and an accurate body outline eluded researchers:

Photo courtesy Scientific American
The many faces of Helicoprion, courtesy of Ray Troll for Scientific American.

Recently, though, a report published in Biology Letters offered new insight into the shark’s unusual jaw. Instead of protruding past the lower jaw and coiling beneath the chin, as was once thought, or existing completely externally as some sort of defensive structure, scientists now believe that the shark — which had no teeth at all in its upper jaw — housed its “whorl” of teeth inside its lower jaw. To kill soft-bodied prey, it sliced upward like a buzz-saw, using this vertical spiral of teeth to push food back into its throat.

courtesy WikiMedia

A “whorl” of Helicoprion teeth

“Two of my fantasy acquisitions to the museum are paleozoic sharks,” Temple says of these often underappreciated freaks of the sea.

What say you: Should Discovery Channel devote a special to these super-special sharks?