About Bob

The Museum’s Curator of Paleontology, world-renowned Dr. Robert T. Bakker (or, as some call him, Bob) is the leader of the handful of iconoclastic paleontologists who rewrote the book on dinosaurs three decades ago. Along with other noted paleontologists, Bakker has changed the image of dinosaurs from slow-moving, slow-witted, cold-blooded creatures to — at least in some cases — warm-blooded giants well-equipped to dominate the Earth for 200 million years. Dr. Bakker can be found all over the globe, notably leading the Museum’s paleontology field program.

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.

Bakker blogs: Indiana Dipsy & the Temple of More Room — A fascinating tail of surprise

Here’s the poster (as I see it) for the latest episode in the long-running Indiana Jones franchise, with Harrison Ford playing Diplodocus playing Indiana Jones.

Before you object to its realism, Harrison is not too old; our Dipsy will be, after all, 148  million, 345 thousand and 77 years old on a Thursday in November.

Dipsy Goes Down: Dr. Bakker blogs about our Diplodocus de-installation

Indiana Dippy Thwarts a Gang of Cut-Throat allosaurs
along the Red Fork of the Powder River.

Actually, the art is from Dr. Bob’s favorite book from the fourth grade, So Long Ago, by E. Boyd Smith, published 70 years ago. According to the book, the great whip-fighter is supposed to be a Brontosaurus, but our Diplodocus would be very similar, just skinnier around the middle. So Long Ago is hard to find but worth the effort.

For his role as the Professor-Dipsy, Ford will have to be fitted with a prosthetic neck (his is short by nine vertebrae) and we will have to insert an animatronic bull whip to his derrière, in classic Diplodocus style. We’ll have to contact his agent, but we’re sure he won’t mind.

Opening scene: The tortuous canyons around Hole in the Wall, Wyoming, where the Red Fork of the Powder River cuts steep gorges and box canyons that confuse lawmen and tourists. Jones is investigating rumors of a cache of antique gold coins stolen by Butch Cassidy and the Sundance Kid. Their gang stopped the Union Pacific Railroad Express train, blew open the safe, and absconded with the relics, plus cash. (That really did happen.)

We see Indiana Dipsy following the miscreants’ trail up the dry wash. Meanwhile, hiding in the rocks a hundred feet above are the scaly heads of allosaur outlaws, who lick their thin lizard-lips in anticipation of an ambush. “This’ll be easy…” they think as they evaluate the weapons carried by the Dipsy. “Weak jaws, wussy thin teeth…he can’t bite back.”

“Whooop whooop!”  Down they come, a dozen hardened criminals, armed with saw-edged knives in their mouths. It looks like Indy-Dipsy can’t possibly escape.

“Wwwwwwwwffffffffft  WHAM!” Our hero lashes out with his whip tail, catching the nearest brigand around the throat. “Yank-thud”: The would-be bushwhacker gets toppled. Now our Indiana Dipsy clambers up the canyon wall, deftly hopping from one boulder to another.

“Haha!” He yells derisively, “You thought you had me cornered. Bet you didn’t know that I was born right here in Hole in the Wall!”

The tail sweeps right and left. Up and down. Desperado-allosaurs get flipped and tossed, smacked along their muzzles, tumbled under boulders and rolled down by the dancing Diplodocus.

“I grew up here. I know every niche and cavern. I played with the young Sheriff Bill Utterback all over these rocks!”

***

Gripping, right?  And, as they say in Hollywood, “Based on a true story.” Our very own HMNS Diplodocus did, in fact, come from the Red Fork of the Powder River, from an outcrop of red and green mudstone just a stone’s throw away from Hole in the Wall. Plus, the Red Fork Dipsy was a champion tail-fighter who could whip a score of opponents all at once. His trainer in tail-martial arts was W. H. Utterback from the Carnegie Museum in Pittsburgh.

Bill Utterback — The “Redoubtable Utterback” as he was known back then, was already a famous Frontier Dino-Hunter when he penetrated the badlands of the Red Fork in 1902 and 1903. He had scored an entirely new kind of long-necked dinosaurian monster at Canon City, Colorado, the site of the new Federal Penitentiary. Canon City and Boulder had fought over who was going to get the state university and who was going to get the prison. (Boulder lost.)

Utterback’s Canon City finds became Haplocanthosaurus, an herbivore with anatomical features that contrast with those of Dipsies . Haplos have stubby, thin tails and very long front legs, resemblances to the ginormous Brachiosaurus. Go to the Cleveland Museum to see an excellent Haplo — one of eleven great reasons to visit that city. (The Rock n’ Roll Hall of Fame is reason #7.)

Haplos were part of the “Bite-Back” group of long-necked vegetarians, a clan that includes the very common camarasaurs. Jaw muscles were large, by herbivore standards, and the front teeth were immense. These were no timid dinosaurian Bambis. They could crunch down on unwary carnivores. It’s very interesting that the Bite-Back species had much stronger jaws than did Dipsies, but far weaker tails.

Here’s an angry camarasaur running down a terrified baby allosaur.

Dipsy Goes Down: Dr. Bakker blogs about our Diplodocus de-installation

Though Haplos were intriguing to scholars, the real star of the Jurassic at the time was Diplodocus and its kin, creatures with weak muzzles, extraordinarily elongated necks and rumps of massive construction. The Pittsburgh crew had already scored a pair of fine Diplodocus along Sheep Creek, Wyoming, in the 1890’s. The New York museum got a super rump and tail from Como Bluff, Wyoming about the same time.

Here’s the New York view of Dipsy: Note that the beast is standing tripod-fashion, using the mightily muscled tail as the center leg. Why is the lab guy hitting the dino with a chisel?  I haven’t a clue.

Note where the tail meets the ground:

Dipsy Goes Down: Dr. Bakker blogs about our Diplodocus de-installation

***

New York became the center of Dipsy-ology when, beginning in 1899, they exhumed a half-dozen skeletons at Bone Cabin Quarry just north of Como.

So, when Utterback arrived at Hole in the Wall in ’02, an entire posse of Diplodocus had been dug up at a half dozen spots. Skulls, necks, shoulders, torsos, rumps, feet were well represented. Andrew Carnegie, who footed the bill for the  Pittsburgh expeditions, was immensely pleased with the results. The bone-hunters honored their benefactor by naming the Pittsburgh species Diplodocus carnegiei, which became the most famous Dipsy species, a status it still retains today. Dipsy-specialists felt self-satisfied too. They were sure they understood every compartment of the Diplodocus body form.

They were wrong.

Dipsy tails were the problem, but no one suspected that there was a caudal flaw in all the reconstructions. Dipsy tails were powerful near the hips and then tapered down to a blunt point, in the manner of a croc tail, or so everybody thought. That’s the way all the plaster copies of Carnegie’s Dipsy were mounted in Berlin, in London, in Vienna, and many other spots.

Check out this gorgeous anatomical drawing of the New York Dipsy: Note how the artist showed the termination of the tail. The diagram fibs a bit — New York crews had not actually found the final tail vertebra.

Dipsy Goes Down: Dr. Bakker blogs about our Diplodocus de-installation

Then came Utterback. He explored Hole in the Wall and found our Dipsy, a rather delicate-looking individual. Excellent portions of neck, torso, limbs — and tail. This skeleton would be named Diplodocus hayi and would eventually come to Houston. The base of the tail was standard Diplodocus: thick where it attached to the hips, thinning down until it reached where it should stop, according to all the brightest and best among Jurassic dino-thinks. But it didn’t stop! The Hole in the Wall Dippy tail kept going and going and getting thinner and thinner and losing all the normal prongs of bones for joints and muscles that normal vertebrae have. At about vertebra number 40, counting from the hips, the tail bones became so thin they looked like nunchucks, those rods of wood martial-arts fellows like to swing around. The nunchucks then continued for another 20 vertebrae or more. When Utterback got to the last vertebrae preserved in the series, he was sure there had been more in the living animal, because dino tails end in a short half-vert, with a pointy rear end. Utterback’s tail terminated in another long nunchuck that must have connected with at least one more, to mark the extreme finality of the caudal organ.

Look at this fine anatomical diagram of Utterback’s tail tip. The entire intact Dipsy tail was longer than the neck and body put together. The last 30 feet of tail looked like an enormous bull-whip.

Dipsy Goes Down: Dr. Bakker blogs about our Diplodocus de-installation

Dipsy Goes Down: Dr. Bakker blogs about our Diplodocus de-installation

Even the veteran Carnegie Museum folks were flummoxed by this, although there had been hints of a nunchuck-tail one English Jurassic dino. Utterback’s discovery forced all the museums to re-boot their tail diagrams.  Inside museum drawers from old digs they found nunchucks that had been mingled with Diplodocus bones. The scientists just hadn’t paid enough attention to these strange bones. New excavations in Utah backed up Utterback. Skeletons of Dipsies and their close kin, the apatosaurs, revealed complete tails. Every one had the same arrangement seen in the Hole in the Wall specimen. Clearly all the Dipsy tails in all the exhibits and textbooks had to be changed. In a few years, it was clear that Dipsies were not alone in carrying the multiple nunchuck device. Apatosaurus and Brontosaurus*, extra-massive fellows with the same basic proportions of Diplodocus, were equipped with the super-whip too.

There still was one more major correction that needed to be made in how the tail was restored. The Carnegie folks made the tail droop down  from the hips, like this:

Dipsy Goes Down: Dr. Bakker blogs about our Diplodocus de-installation

The droopy reconstruction forced the tail to lie along the ground for most of its length. Problem: trackways proved that Dipsy-type dinos moved in big herds. Wouldn’t the tails get stepped on?  At the Smithsonian, dino-sleuth C. W. Gilmore scrutinized the joint where tail met the hips. The droopy arrangement had to be wrong, way wrong, because the joint on the back of the hips didn’t match the joint on the front of the tail. When he rearranged the bones correctly in his Dipsy, Gilmore was delighted to see that the tail didn’t droop at all. Instead the tail rose up and out from the hips and then made a long, slow descent. The widely arching tail made much more anatomical sense — and it looked infinitely cooler.

Clearly the whip-tailed dinos carried their tail high off the ground, where it wouldn’t be stepped on and where it was ready to lash out. And here is the elegant result: the Dipsy at Denver, re-mounted a la Gilmore. Now the tail didn’t drag.

Dipsy Goes Down: Dr. Bakker blogs about our Diplodocus de-installation

Your Curator, Dr. Bob, wrote his first scientific paper as a geeky undergrad on how Dipsy tails never dragged.

The whip-tailed giants of the Jurassic were obviously designed for some serious martial arts, nunchuck-wise. The long thin bones in the tail tip would have been surrounded by a sheath of flexible skin and ligaments. When the huge muscles in the tail-base twitched, the lightweight tail tip would go slashing at high speed. Estimates go to 700 mph and beyond. You could hear the Dipsy tail cracking like a whip. As a weapon, it was unique among dinosaurs. Only Dipsies and the related families used multi-nunchucks to trip their enemies and lash their foes. Whip-tails were most diverse in the Late Jurassic, but some survived into the next Period, the Cretaceous. The very last whip-tail was the magnificent Alamosaurus of the Late Cretaceous. The Perot Museum in Dallas has a fine reconstructed skeleton, tail held high.

You can see a bunch of whip-tailed dinos on display all over the world. But remember, it all started with our Houston Dipsy and the careful digging of Bill Utterback. Which is the best whip-tail display? OURS! Because the tail is actually whipping around, coiled on the right, ready to swing fast to the left.

*There’s a lot of confusion about these two genera, Apatosaurus and Brontosaurus. Most dino-scholars put the Bronto species into the genus Apatosaurus. Your Curator, Dr. B., and Matt Mossbrucker, the Director of the Morrison Museum in Morrison, Colorado, are studying new specimens of giant whip-tails from the Jurassic; we’re giving a paper at the big Geological Society of America conference in late October. Our conclusions: The species Brontosaurus excelsus and Apatosaurus ajax were related but turn out to be far more distinct than we had thought. It has not escaped our notice that these new specimens might force us to re-appraise the status of Brontosaurus.

Bakker blogs: Why Dimetrodons had interclavicles — and Uma Thurman doesn’t

HUZZAH! We have the missing bone: the largest unit in the Dimetrodon skeleton, the one bony element we never hoped to find! We thought weʼd have to sculpt a fake one, but now we have the real thing — the INTERCLAVICLE.

Whatʼs that you say? Never heard of an interclavicle? Its common name is the breast-plate. Most of our ancient Permian critters, both reptile and amphibian, have breast-plates.

breastplateNo,not like that.

Our Dimetrodon wasnʼt armored on his chest like Bugs Bunny playing the Valkyrie in “Whatʼs Opera Doc.” The true breast-plate was a long, narrow, strong beam of bone that was fixed to the chest along the midline. Itʼs got a long “stem” in back, and an expanded “bowl” up front. The interclavicle is so named because it was attached to the big collar bones, also known as clavicles. Hereʼs a view of our new find, plus a diagram of how the clavicles and interclavicle attach to each other and to the shoulder blades:

diagramThe diagram is drawn as if the entire shoulder were flattened by a bulldozer so all the
bones are in one plane. Weʼve color-coded the bones so
the osteologically challenged
donʼt get frightened.

volunteer diagram

Our new specimen is held by the volunteer who found it.

To understand the architectural implications of the interclavicle, we must decide on our favorite role played by Uma Thurman. (We just love her — we even have a bone bed named “Uma”). We are impressed with Uma as “Ulla”, the Swedish femme fatale/housekeeper/tidying-upper in The Producers, but our choice would be Mia, the gangster girlfriend in Pulp Fiction.

Mia explains the interclavicle in the famous scene where she is stabbed in the heart with a huge syringe wielded by John Travoltaʼs character, who is trying to resuscitate her after an unfortunate mix-up in recreational prescriptions.

Travolta illustrates an emergency procedure: the needle must be thrust hard through the human breast-bone and into the cardiac cavity to jump-start the heart.

(Note: Do not try this at home. Ever. Not even with the pet gerbil.)

Mia does regain consciousness, with the syringe still sticking out of her breast-bone. (The technical name for her breast-bone is sternum.)

But let’s get to the osteological point. The breast-bone, aka sternum, is NOT the same as the breast-plate, aka interclavicle. Our human breast bone is part of our rib-cage. Itʼs in the middle of our chest and ties the right and left side of our ribs together. Itʼs made from rather soft bone material (so you can, in fact, get a needle through). The turkey breast-bone is the same unit, a sternum, but is much bigger and harder.

Next Thanksgiving, poke around with your fork to see how the birdʼs ribs attach to the sternum.

But back to Ms. Thurmanʼs sternum. Scrutinize this diagram; it shows Umaʼs skeleton:

uma skeleton

Examine the rib cage and breast-bone. Note the collar bones (clavicles). They are slender, graceful bones with swivel joints where they attach to the sternum.

Iʼll give you a minute.

Got it? Now repeat after me: “Sternum ties ribs together; clavicles are slender and have swivel joints.”

Okay. Now look at this chest, from a close kin of Dimetrodon. The clavicles are wide bones, much, much broader than ours. See the interclavicle? Itʼs not attached to the ribs. It lies under the sternum and has a stiff overlapping joint with the clavicles. The entire clavicle/interclavicle apparatus makes an extraordinarily strong, T-shaped apparatus, a rigid support for the shoulders.

shoulder blade

In the Dʼdon clan, the interclavicle is immensely long, far longer than the thigh. If you probe around your own chest you will, I guarantee, not find an interclavicle.

Hereʼs what our chest would look like if we did have one and a set of broad clavicles to match. (If you do find an interclavicle on yourself, call the 800 number at the bottom of the blog).

human interclavicle

We primates donʼt have an interclavicle or wide clavicles attached stiffly to the interclavicle. Neither do cats, dogs, horses, goats, guinea pigs, elephants, ʻpossums, raccoons, dolphins, aye-ayes or numbats (Google those last two). No normal mammal has an interclavicle today. We lost them in the Late Jurassic, about 150 million years ago.

So, what did the interclavicle/clavicle unit do in Dimetrodon, et al? Two things.

One, it helped armor the chest. Since it was dense, hard bone, the interclavicle plus clavicles protected heart and lungs from blows delivered by an opponent. In other words, the bones acted as a chest-protector. And that means all members of a Permian baseball team would be outfitted to play catcher (think about it).

Two, it was the attachment for the biggest muscle in the front limb, the pectoralis. Dimetrodon and its friends and relations were all really buff. The pecs were huge. We know that from the bump of bone on the upper arm, the “delto-pectoral crest”, where the pecs attached. Feel the inside of your armpit. The muscle here is the pectoralis. If you were a Dʼdon, the pecs would be four times thicker.

Our new, perfect Dimetrodon interclavicle shows clearly where the pecs attached all along the “stem.” By the way, the buff pecs explain why this bone gets chewed to bits by scavengers nearly every time. The interclavicle is so meaty that it is the first place to bite if you are hungry. Check out this sketch of a Dʼdon relativeʼs chest.

ddon chest

A couple of final points and inquiries. There are very few mammal species alive now who have interclavicle/clavicle apparatus like a Dimetrodonʼs. Who are they? Why is their motherhood so weird? They give us a clue about why most of us Mammalia have lost the bone.

Homework: Move your left shoulder blade up and down and around, as you feel your left collar bone with your right hand. Could Dimetrodon do that? Massage a cat or dog while they are relaxed. See how the shoulder blade moves? Could a Dʼdon or its relatives do that? Ride a horse. Feel the shoulder blade move. Is such mobility possible in an early Permian reptile? Now do you have a notion about why we advanced mammals lost the stiff interclavicle/clavicle arrangement?

Lastly and more importantly, what if Uma Thurmanʼs characterʼs Mia were equipped with a proper Dʼdon interclavicle composed of hard, dense bone? She would not have been resuscitated. The needle would have broken off.

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.