A Tale of Two Compys: What Jurassic Park got right — and wrong — about dino anatomy

Bakker - Dino Geek JP 1

A piece of unapproved Ivy League art. Title: Podokesaurus holyokensis, Triassic/Jurassic Dinosaur, on the head of Michelangelo’s David. Material: Collage of Xerox images, clipped by scissors, Scotch taped together.  Date: March, 1964.  Artist: Robert Thomas Bakker, Yale freshman.

OMG I was such a dino-geek in college.

I had other interests — I was enraptured by sculpture and took the fabled freshman History of Art course. The collage shown here was taped together during the lectures on the Renaissance renewal of anatomically correct human form made famous by Greek sculptors. Last month, I found the collage in an old notebook, in the garage, under my copy of American Battleships, a Design History. (That’s for a future blog on the U.S.S. Texas.)

The tiny dinosaur is Podokesaurusat the time, one of two famous bantam-weight predators of the Late Triassic and earliest Jurassic, the first chapters in dinosaur history. I knew the critter well because it was dug from the red beds of the Great Triassic/Jurassic Valley. Those fossil-rich sandstones and shales filled a rift valley that extended from Nova Scotia to the Carolinas. The rift was as big as the East African Rift we see today.

Smack dab in the middle of the Triassic/Jurassic Valley was New Jersey, where I grew up. Not far north from my house were the Palisades and Granton Quarry, where Triassic flying reptiles had been discovered, plus long-snouted phytosaurs like our HMNS Smilosuchus, plus dino footprints.

The reason I applied to Yale was mostly because it had a museum chock full of red beds specimens. When I visited in 1963, Yale had a cast of the podokesaur skeleton on display — sadly, the original was destroyed by fire 50 years previously. Next to the cast was a lively life-sized sculpture, done by the Yale curator Richard Swann Lull.

“Nifty!” I thought. “Art and paleontology combined! This is the place for me.” The Yale museum was super hospitable to freshmen. I got a job cleaning a Triassic red beds skull — not a dino, but a bizarre plant-eating reptile, woodchuck-sized, with spikes coming out of the head like a tricked-out horned toad. These fellows must have lived in colonies. A bunch were dug from a small area in New Jersey. Podokesaurs surely chased these prickly morsels.

Late Triassic, New Jersey. A colony of vegetarian Hypsognathus emerges from their burrow. Maybe they had been hiding from podokesaurs, Maybe they had been watching Jersey favorite “The Sopranos” on HBO. Texas was host to a similar reptile. Extra points if you can find it in our Triassic mural.

Late Triassic, New Jersey. A colony of vegetarian Hypsognathus emerges from its burrow. Maybe they had been hiding from podokesaurs. Maybe they had been watching Jersey favorite The Sopranos on HBO. Texas was host to a similar reptile. Extra points if you can find it in our Triassic mural.

Freshman year also introduced me to the tradition of the “mixer” — parties where Yalies and young women from nearby colleges co-mingled. At a Mt. Holyoke mixer, I got an earful from female geology students who were steamed, justifiably, about gender bias. Old fogey Yale profs grumbled that “girls can’t lift heavy rocks [...] can’t do serious fossil work.” Podokesaurus was a counterargument. It was discovered in 1910 by none other than Dr. Mignon Talbot, who was chair of the geology department. Talbot did her Yale Ph.D. on sea-lilies, crinoids, relatives of starfish that were abundant in Devonian rocks of New York State (we have some fab Jurassic crinoids in our hall). Dr. Talbot went on to become president of the college.

The Wikipedia portrait of Dr. Talbot. The label must’ve been written by a Yale Professor.

The Wikipedia portrait of Dr. Talbot. The label must’ve been written by a Yale professor.

Even though, as college president, she out-ranked most of the Yale faculty of her time, they insisted on calling her “Miss Talbot instead ofDr. Talbot. Yeesh. In 1965, the Yale director of graduate studies told me “Bob, we shouldn’t give Ph.D.s to girls … they’ll just get married and have babies.” Double yeesh!

But he didn’t know how famous her dinosaur would yet become! Dr. Talbot’s dinosaur influenced Jurassic Park — yes, that little novel (series) turned super-franchise

In the article naming the beast, she noted that a similar-sized dino had just been excavated from the Late Triassic of Germany. It would be christened Pro-compsognathus” in belief that the renowned Compsognathus of the Late Jurassic might be a descendant (it isn’t). 

Since the one and only skeleton of the pro-compy is missing key parts, Dr. Talbot’s graceful Podokesaurus was used to fill in the blanks and give a general portrait of the fox-sized predators of the Late Triassic. Talbot’s creature gained more fame when it became the inspiration for an entire family, the Podokesauridae.

Later in the twentieth century more species were added to the podoke clan, including Coelophysis from New Mexico. The New York museums scored a mass grave of Coelophysis in the 1940s and 1950s: dozens of skeletons from adults two yards long to babies as small as Podokesaurus and Procompsognathus. 

Proud members of the Family Podokesauridae. Coeolphysis grew to seven feet long. Check out the pubis in these guys!!

Proud members of the Family Podokesauridae. Coeolphysis grew to seven feet long. Check out the pubis in these guys!

IMPORTANT WARNING! The Jurassic Park franchise uses two names for tiny Triassic dinos: “pro-compy” and “compy”. There might be confusion among the dino-laity.

The true Compsognathus is Late Jurassic, with kin in the Early Cretaceous, and it doesn’t have podoke family values. As we’ll see in a bit, Crichton clearly meant his tiny carnivores to be classic Late Triassic/Early Jurassic carnivores — and that means podokesaurs.

The podokes had a near-monopoly in the meat-eating role in the Late Triassic/Early Jurassic. They were not only small and mid-sized carnivores, equivalent to kit foxes, coyotes and wolves, but they became the movers and shakers in the apex predator role. Big species attained lengths of 22 feet and weights approaching a ton — bigger than the biggest land meat-eaters today (grizzly and polar bears). All podoke species had that graceful build of Dr. Talbot’s Podokesaurus: supple neck, long torso, and outstandingly elongated tail.

And, for those of you who are pelvis-literate, you’ll notice another design feature: The pubis bone was outstanding in the forward slant and length.

Podoke attack! A ten-foot long podokesaur predator menaces the thin-necked herbivore Anchisaurus. Early Jurassic, Massachussetts, somewhere near Amherst College. 

Podoke attack! A 10-foot long podokesaur predator menaces the thin-necked herbivore Anchisaurus. Early Jurassic, Massachussetts, somewhere near Amherst College.

For Jurassic Park fans, Procompsognathus rings a bell. In Michael Crichton’s novel, the first dino we get to know is tweensey (but deadly) — a species identified as a pro-compy. These blood-thirsty characters are fond of jumping into perambulators and biting the faces of juvenile humans. They move in gangs. Crichton was dead-on here. Tracks from the Triassic/Jurassic do document podoke-packs, small carnivores cavorting in groups.

Podoke dance floor? Slab of shale with a dozen small predators cavorting. 

Podoke dance floor? Slab of shale with a dozen small predators cavorting.

In the Jurassic Park movie, the pro-compys are unstoppable nasties who confront the gifted character actor, Wayne Knight (Newman) of Seinfeld fame. (Knight’s best known for portraying portly and disreputable men, but we should remember that he was a dashing romantic lead in Third Rock from the Sun.)

In Jurassic Park, Knight’s character learns a lesson — the hard way. At first, he insults the pro-compys and tries to scare them away. Then they flash their threat-collars, a device cribbed from the Australian Frilled-Lizard. Then they hurl loogies of what seems to be venomous schmaltz. Nice scene. Scary.

However, dino-nerds: watch out. There are no bones in the lizard collar so preservation in a skeleton would be unlikely. Plus, threat collars are unknown among the many dinos now represented by fossils with skin. 

Plus, plus, no dino could spit. Spitting requires complex lip and face muscles of the sort a trombonist must have (didja know I was first-trombonist in the school band?). Reptiles can’t spit, birds can’t spit. Fossil dino faces show that the big, complicated lips just weren’t there.

Spitting cobras cheat. They don’t really spit. They have mouth muscles that squeeze the poison gland so the venom comes squirting out through the hollow fangs. Clever, but not a genuine spit.

Crichton used his dinos carefully. He fills Jurassic Park and Lost World novels with a lovely time-safari through the Mesozoic. He begins with the pro-compy, from the earliest slice of dino-time, about 210 million years ago. The long-necked brachiosaurs and stegos filled out the later Jurassic, some 145 million years ago. You could add a true Compsognathus here if you like. For the Early Cretaceous, 110 million years ago, we are given Deinonychus antirrhopus (labeled Velociraptor but actually Deinonychus). Triceratops, T. rex and the advanced ostrich-dinos fill out the last slice of Cretaceous, the Lancian Age, 66 million years ago. You can teach an entire paleo course with this fine selection of fossils. 

Remember, in the books and movies the label “pro-compy” and “compy” is synonymous with the podokesaurs. Crichton did not intend his Triassic dino to be a Compsognathus, the Late Jurassic animal quite different in body plan from the podokesaurs. Here’s where dilophosaurs come in.

Dilophosaurus, sensu stricto, is a Southwest Early Jurassic apex meat-eater — a big brother of Coelophysis and Podokesaurus. The first specimens were announced by the Berkeley museum in the 1950s. Size: near maximum for the podoke family, nearly 2,000 pounds soaking wet. Our Chinese colleagues excavated a super diloph of the same body mass. In each and every bony bump, the dilophosaur is built to the same basic plan used for Coelophysis, et al. Big difference, besides size, is the side-by-side bone crests on the head.

The Berkeley diloph. Black-n-white foto shows first restoration of head without crests. Color snapshot shows the crests added. Michelangelo’s David in for scale. Do note that this is a biggish predatory dino. 

The Berkeley diloph. Black and white photo shows first restoration of head without crests. Color snapshot shows the crests added. Michelangelo’s David in for scale. Do note that this is a biggish predatory dino.

In the books, Crichton does not describe any head ornaments for his pro-compys. The movie, on the other hand, gives the little fellows side-by-side crests, perfect miniatures of what true dilophs have. I go to screenings of the JP franchise every chance I get (“JP” is what we insiders call Jurassic Park). When I saw the 3D version on the HMNS Giant Screen, I was treated to massive vibrations that punctuated the scary parts. 

“Dilophosaurus … DILOPHOSAURUS!” shouted the five-year-old sitting behind me. He was kicking the back of my seat with unconstrained enthusiasm. Can’t blame the kid. He had his plastic diloph in his lap, evidently a cherished pet and quite accurate in most anatomical details (neck and ankle too long, too skinny). The extreme close-ups of the pro-compy head on the screen did look diloph-y. But … the size was as wrong as wrong can be and still stay within the podoke family.

Plastic dilophosaur, by Safari Ltd. About nine bucks at the museum gift shop, with your member discount.

Plastic dilophosaur, by Safari Ltd. About $9 at the Museum Store, with your member discount.

I was tempted to turn around and issue a correction: “Hey kid, that dino is a hundred times too small …” But I restrained myself. I estimated that the leader of the movie pro-compy pack was no more than 15 pounds, Boston Terrier-sized. With head crests, size matters. Small podokes don’t have much in the way of cranial protuberances. All the big crests are on big heads attached to big bodies.

Want to be a podkesaur? You must get a nose-notch. Coelophysis here has one.

Want to be a podokesaur? You must get a nose-notch. Coelophysis here has one.

And … there was something more, something missing from the schnoz in the movie compy. “No nose notch …” I said to myself. “Those guys in the movie have no nose notch … so … they aren’t members of the Family Podokesauridae!”

Notches below the hole for the nostril are a big deal in dinos and dino-kin. Land Croc-oids of the Triassic, second cousins of dinosaurs, usually are notched. But strong notches are rare amongst the carnivorous dinosaurians. T. rex is notch-less. So is Allosaurus and all the myriad raptors, from Micro-raptor to Meso-raptor to Mega-raptor. The bona fide Compsognthus is notch-less. The podoke family is the most consistently notched. Enjoy my own diagram of the Harvard skull from Coelophysis above. Please stare at the nose. There’s a notch here. Dilophosaurus has an even more emphatic notch.

No notch = no podokesaurid. Simple as that.

What about that long, slanty pubis, another hallmark of the podoke family? Study the movie dino as long as you like. You will find no unambiguous evidence of long, slanty pubic bones. None.

My conclusion: the movie artists did a great job with the pro-compys. They cobbled together a frightening chimaera from a bunch of critters, some lizards, some small meat-eating dinos, some big ones. These little dinos are the most imaginative, most mixed-up of all the JP creations. So enjoy them! But you cannot use the movie pro-compys to teach a lesson in dilophosaurs or any dilophosaur kin. The movie “compy/pro-compy” is NOT a crested podokesaur.

* Recently, some paleontologists have insisted using the name Family Coelophysidae to replace Podokesauridae, because we have so many skeletons of Coelophysis. These folks are well-meaning but, ahem, I am a Yalie and so I am sworn to defend the honor of Mt. Holyoke College and all its faculty and graduates. And its presidents. And its dinosaurs.

But here’s the Hitch: Who really discovered that dinosaurs had feathers?

I grew up in the 1950s and 1960s reading books about the dinosaur “orthodoxy.” According to this traditional view, the dinos died out at the end of the Cretaceous because their beloved swamps dried up and the air became too cool. But the new conditions were perfect for us quick-thinking Mammalia, so we took over, along with the other hot-blooded class, feathered birds. That was the Official Scientific View until the 1970s.

Whew! It’s hard to believe that four decades ago paleontology could be so very, very wrong.

Us versus Them. The smart hot-blooded mammal Didelphodon defies a rex. The furball is saying “Just wait till yer swamps freeze....”

Us versus Them. The smart hot-blooded mammal Didelphodon defies a
rex. The furball is saying “Just wait till yer swamps freeze…”

Today we know that Tyrannosaurus rex was not a big lizard. It was the 10,000-pound roadrunner from hell, clothed in fine feathers. Tyrannosaurs and other dino-clans ranged far north and far south and survived icy winters just fine. We mammals were kept small all through Mesozoic times because the dinos, on average, were faster on their feet, quicker in their jaws, and had better hearts and lungs. Dinos won the roles of top predator and top herbivore fair and square. The humiliating truth is that we mammals are the class that won by default, taking over only because some external event removed our dinosaurian overlords.

Face the facts friends: we are furry carpet-baggers.

Question: Who first discovered that dinosaurs were part of the hot-blooded bird family tree?

Was it Dr. Bob Bakker, your faithful curator? Aww, nice of you to ask, but the original hot-blooded-dino guy was long before my time.

How ‘bout Yale’s John Ostrom, who dug up the raptor Deinonychus in 1964 and linked raptor-dinos to the early bird Archaeopteryx?

No, he wasn’t the first. (Oddly, John fought the idea that Deinonychus had feathers.)

Was the first dino-bird chap Thomas Henry Huxley, the pugnacious defender of Darwin in the late 1860s and 1870s? Huxley, who coined the term “agnostic,” was a favorite of my advisor at Harvard, Stephen J. Gould. Huxley did point out that hips and shoulders of dinos were very bird-like, and so were feet. Therefore, Huxley argued, some sort of dinosaur-oid was the ultimate ancestor of the bird class.

But no again. Huxley was not the first to see bird-ness in the dinosaurs.

T. H. Huxley, as portrayed in Punch. Among his many jobs, Huxley served on the Board of Fisheries.

T. H. Huxley, as portrayed in Punch. Among his many jobs, Huxley
served on the Board of Fisheries.

Got your notebook ready? Here comes the answer, and it makes most museum-goers raise an eyebrow.

The true discoverer of feathered dinos was… the Reverend Edward Hitchcock, State Geologist of Massachusetts, Professor at Amherst College, philosopher and Congregationalist pastor. Hitchcock figured out that dinos were a subclass of birds as early as 1838 — four years before the term “dinosauria” was invented!

First Director, Massachusetts Geological Society, Edward Hitchcock. His wry sense of humor and boundless joy in science is evident.

First Director of the Massachusetts Geological Society, Edward Hitchcock. His
wry sense of humor and boundless joy in science is evident.

How many skeletons did Hitchcock dig up? None. Not a one. But surely his lab got many well-preserved parts of dinos, right? Nope. Only after he retired did a partial skeleton show up, blown to bits by gunpowder used to excavate a well. Hitchcock came to the fundamental truth about dinosaurs entirely from fossil trackways.

Across the pond at Oxford, Hitchcock’s colleague, the Reverend William Buckland did dig hundreds of Jurassic and Cretaceous bones and some pretty good skeletons. The Oxford fossils inspired Buckland’s student, Richard Owen, to come up with the name “dinosaur” in 1842.

Sad to say, neither Buckland nor Owen realized that their restorations of dino skeletons were, in today’s parlance, “bass ackwards” — they put a huge bone in the shoulder, giving the critters a clumsy muscle-bound look in the forequarters. They didn’t realize that their “shoulder” was really part of the hips. Hitch*, on the other hand, without a single well-preserved osseous specimen, scrutinized the footprints and got dinos correct, fore and aft.

What a guy.

“Bass Ackward” dinosaur in the 1820‘s--1860’s. The restoration done under Richard Owen, with gigantically distorted forelimbs and flat feet. Painting by Luis Ray from our “Big Golden Book of Dinosaurs”.

“Bass ackward” dinosaur in the 1820s-1860s. The restoration done
under Richard Owen, with gigantically distorted forelimbs and flat feet.
Painting by Luis Rey from our Big Golden Book of Dinosaurs.

Hitchcock and Buckland were members of the “Pious Paleontologists,” thoughtful scholars of the early 1800s who took the record of the rocks and the record of Scripture seriously. Hitch was persuaded that earth history, written in pages of shale and sandstone, would make everybody better, more intelligent citizens. He wrote a delightful book for his Congregationalist flock,The Religion of Geology probably the finest rumination of how rocks and fossils can be integrated with piety.

Hitch won the reputation as an inspiring lecturer at Amherst. Emily Dickinson, among many others, was enraptured by the stories of prehistoric New England and how the past had shaped the woodlands and gardens of the present day.

When Hitch took over the Geological Survey, the Connecticut Valley was already famous for red Jurassic rocks. Quarries were dug for paving stones, excellent for walkways, and massive sandstone blocks, ideal for constructing “brownstone” homes, college dorms and courthouses. (Alas, as coal-fired furnaces became common, acid rain ate into the Triassic-Jurassic sandstones and many brownstone monuments began crumbling in the mid-20th Century.)

Hitch and his crew found petrified remains in these beds: some fern-like fronds, stems of horsetail reeds, bits of fish and a magnificent bug, the larva of some ferocious water insect. The red rocks had petrified weather, too: some surfaces had the delicate pattern of raindrops. Others showed deep cracks produced by prolonged drying.

But the most abundant remains were tracks, thousands of them. Some of the littlest footprints were made by flat-footed, lizard-oid critters with long, supple toes in fore and hind paws. Much more common, and often of giant size, were tracks made by somebody very different — mystery animals who grew as big as elephants and shared a common body plan that kept Hitchcock’s powers of deduction busy for his entire career. It was a great quest — he was on the trail of the creatures who ruled the Jurassic world on land.

Giant mystery tracks exposed along a county road in Massachusetts, with the local farmers using the one-horsepower field vehicle to visit the site.

Giant mystery tracks exposed along a county road in Massachusetts, with
the local farmers using the one-horsepower field vehicle to visit the site.

Hitch pondered the prints made by the mystery toes. Almost two centuries before Microsoft and Apple, Hitchcock began a digital revolution, inventing new methods of deciphering the details of paws. He and his son scoured libraries for anatomical details of the class Amphibia, the class Reptilia, and the hot-blooded classes, the Mammalia and Aves. Then they ran digital experiments, chasing all manner of animals across muddy fields — including barefoot boys with cheeks of tan — so they could draw the arrangement of toes.

All this research gave the Reverend Hitchcock more insight into the animal sole than anyone had obtained before. Step by step, Hitch filled a dossier of clues that would lead him to a final identification.

Bakker - Hitch Bird Dino pt1 6

Barefoot boy track as drawn in Hitchcock’s great monograph. Little dots are raindrop impressions. Hitch found drop marks on rock slabs with the mystery monster tracks. There was no evidence, pro or con, that the boy or the monsters carried slingshots, a la Bart Simpson.

First Clue: Bipeds. Nearly all the mystery tracks, even the biggest, were made by animals walking on their hind legs alone. That was unlike the locomotion of most lizards and mammals. And unlike the way dinosaurs were restored — with huge shoulders.

Second Clue: Toe-walkers, not flat-foots. Usually there was not a trace of the heel so it must have been held high off the ground. That eliminated dinosaurs because the dinos were flat-footed — so said the brightest and best of Europe’s bone-sleuths.

Bakker - Hitch Bird Dino pt1 7

Third Clue: Long Achilles tendons. This clue was the biggie. Over 99 percent of the tracks showed nothing of the ankle and nothing of the front paw, because the mystery beasts were strict toe-walkers. But in a precious few fossils, the tracks captured the mystery animal as it squatted down on all fours to drink or sniff the earth. Marvelous. The entire backside of the ankle was pressed into the mud — the Achilles tendon wasn’t wide and flat like a lizard’s. It was gracefully elongated and slender. The front paws were tiny, five-fingered and carried short, sharp claws. Maybe there was a mark left by a stumpy tail — the track wasn’t clear on this point.

Hitchcock’s mind raced. What prehistoric monsters had ankles and front feet built that way? Not mammoths or rhinos. Those giant hairy beasts always had front feet wider than the hind, and the ankle was always short. Well then, what about frog-oids? The hopping amphibians did have long, powerful hind limbs, strong calf muscles and small hands. The thought of multi-ton froggies stomping over the Jurassic meadows was … well, weird. And exciting.

If not frogg-oids, mebbe … bandicoot-oids? Australia was famous for “low-class” mammals, the marsupials, which on average were smaller in the brain than antelope, deer and other “normal” mammalians. Kangaroos and bandicoots had enlarged rear legs with super-strong calf tendons — plus little hands. Therefore, Hitchcock had to take seriously the idea of Massachusetts being overrun by Jurassic bandicoots bouncing about, as big as bull African elephants.

The Usual Suspects: Giant prehistoric beasts who might have made the tracks.

The Usual Suspects: Giant prehistoric beasts who might have made the
tracks.

And then there was the original suggestion made about 1800 by farmers who dug tracks on their land: Maybe it was Noah’s raven. The Flood Story in Genesis says Noah released a raven from the ark to test the depth of the water. The raven didn’t come back, so Noah concluded that some bare land had appeared. The Noah reference was a joke, an i.d. offered with a chuckle. But, indeed, to the un-trained eye, the Jurassic mystery tracks did have an avian gestalt …

… and Hitchcock could feel that he was getting close to the final answer. He needed just one more new type of CSI analysis, a quantitative sole-searching that would finger the culprit and reveal, once and for all, the identity of the Jurassic rulers.

Hitchcock’s Digital Data Base -- one page of the great monograph of 1858. Paleo-podiatry would enable the Reverend to solve the mystery of the Jurassic tracks.

Hitchcock’s Digital Data Base: one page of the great monograph of
1858. Paleo-podiatry would enable the Reverend to solve the mystery of the Jurassic tracks.

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!

How To Stuff Your Archaeopteryx For Thanksgiving

Serves 1/20th of a person.

You must become pubis-savvy to understand Archaeopteryx. The pubic bone commands the guts – and gut evolution was huge in bird origins.

1) Check out an allosaur, a typical big meat-eating dinosaur. Note that the pubic bone points down. This position limits the size of the guts because the intestines must stop in front of the pubis.

2) Check out a chicken, a typical modern bird. The pubis has been pulled way back so it points backwards. Now the guts can expand all the way to the rear of the bird.*

3) Now examine Archaeopteryx. If it were a typical bird with a big gut, the pubis should point backward. It doesn’t. It points down, like in an allosaur.

4) So……Archaeopteryx was a gut-less wonder, compared to a modern bird. The space for the intestines was still small. It couldn’t digest food as fast as a modern bird can and it couldn’t digest tough food items.

5) Modern-style bird guts didn’t evolve until the Cretaceous.

* that’s why we can stuff a bird with so much stuffing on Thanksgiving.

How To Get Your T.rex to Perch on Your Finger
Evolution of the Back-Grabber Toe in Birds

Here is our Archaeopteryx hind foot. Note that it’s got a “back-grabber toe,” an inner toe that points inwards and a little backwards.

Modern birds usually have an even bigger back-grabber toe that points further backwards. This inner toe lets the bird grab a branch or a finger and hold on.

(The toe is equivalent to our human big toe).

The other three toes in Archaeopteryx point forward and attach to three long ankle bones that are bound together tightly by ligaments. The inner toe has just a stub of an ankle bone.

Anchisaurus

Look at a primitive dinosaur, like Anchisaurus. No back-grabber. Instead the inner toe is thick and long and points forward. The toes attach to four long ankle bones that are loose and can spread.

Here’s the key step:

Meat-eating dinosaurs evolved an inner toe that pointed inwards – like a bird’s. Its ankle bone is a stub – just like a bird’s.

The three main toes have ankle bones tightly bound together – like birds’.

Raptor-type dinosaurs were even more bird-like, with thin, long ankle bones.

Archaeopteryx evolved from a raptor-type dinosaur by enlargement of the inner toe.