Whole-Hole Catalogue: The Horned Meat-eater Ceratosaurus

Here’s the skull and life portrait of the carnivorous dinosaur Ceratosaurus, from the Late Jurassic of Colorado, Wyoming and Utah.  It’s the only meat-eater with a tall, sharp-edged horn on its nose.

(And it’s my very favorite dino of all time – isn’t it just lovely?).

Check out the holes in the skull and the organs that fill the holes in life.

The nostril is no surprise, it’s the oval slit up front.

The eye is in the third big hole from the front.

The very big hole between nostril and eye is for the complex air chambers connected to the throat – birds have these chambers too.

The triangular hole behind the eye was filled with jaw muscle.

The eardrum was located far aft, behind the muscle hole, tucked under a little ledge made by the skull.

Who had a stronger bite, Ceratosaurus or Tyrannosaurus? Compare the size of the holes for jaw muscles……..

Interested in learning more about dinosaur skulls? Check out my previous blog.

Whole Hole Catalogue – How to be a Dino-Skull Sleuth

Last month we had a great question about what was inside a dinosaurs head. Today, we look at a dinosaur skull and answer “What are all those openings in the head for?”  Dino skulls do seem totally, wholly hole-y.

Check out our exploded Archosaurus head. The appearance in life is at the top – we don’t really know the color but this fellow had to hide in the bushes, so we painted him green. Archosaurs is INCREDIBLY important in dino evolution. He’s way ancient – from the latest Permian Period of Russia, about 248 million years ago.

The holes in the Archosaurus head are the clues to how it and its close kin were about to evolve into genuine dinosaurs. There weren’t any true dinosaurs in the Late Permian – that would come later, in the Late Triassic, about 220 million years ago. But the basic proto-dino head architecture had been fixed in Archosaurus.

Some holes are easy – the nostril is at the front. The eardrum was in a little notch at the back. The eyeball was in the big oval hole, second hole from the rear. Now for the good part…..

….there are two big holes for jaw muscles behind the eye, one low on the side, the other high up on the top. These jaw-muscle holes are temporal fenestrae – they mark a huge clan of critters that include lizards, snakes, crocs and dinosaurs. We mammals have only one hole on each side, low on the skull.

But wait, there’s more: between eye and nostril  in Archosaurus is a big aperture that you WON”T find in a mammal,  a lizard or a snake. It was packed with a special air-chamber connected to the throat and lungs. When Archosaurus breathed, air went around through these chambers, keeping the head cool.

Many Early Triassic creatures, descendants of Archosaurus, carried these holes, and so did early crocodilians. We call the snout-hole group “Ruling Reptiles” which in Latin is “Archosauria.” Archosaurs took over the land ecosystem during the Triassic, monopolizing the roles of large predator and large herbivore. There was something in that head design that gave Archosaurs a competitive edge.

Then came dinosaurs. All early dinos had the same blueprint – two muscle holes behind the head, one big air-chamber twixt nose and eye. Don’t take my word for it. Go to our galleries and find the holes in our T. rex. You’ll find the same layout in stegosaurs and raptors, duck-bills and ostrich dinos.

That’s the end of the first hole lesson. Do your homework. Find photos of dino skulls and label the openings.

Which raptor turned into the first bird?

We get so many great questions through our blog, and every now and then we can turn those responses into a blog post. One our readers favorite posts is “What would YOU ask a paleontologist?”

Last week we got this question from kght2:

“Do all birds come from a specific raptor, or do they come from different species of raptor that are cousins and not ancestors. I wonder this because while all birds are similar, they don’t seem to be any more similar than different raptors I have seen, and while this isn’t great information, I have heard of many raptors likely having some from for feathers. Primarily i wonder if the consensus is that all birds came from a single species, or that they came from a family of species instead, and this answer would also have implications that people should know for any species or family of species?”

Dr. Bakker, curator of paleontology here at the museum wrote this in response:

Another darn good question.

Archaeopteryx was the first bird, back in the Late Jurassic. It’s got the complicated arrangement of feathers on its arm to fly like a pheasant today does. All other birds evolved from Archaeopteryx or something very like it

Deinonychus (read my blog about Deinonychus) is a famous raptor-dinosaurs who look very close in their bones to Archaeopteryx. The tiny Microraptor from China is closer still.  Thanks to the dinosaur specimens from Laoning, China, we know that all the raptor-type dinosaurs had feathers. (T. rex had feathers too – the tyrannosaur clan were clothed in a full pelt of fine kiwi-style plumage.) But Deinonychus and all the Laoning feathered dinosaurs are from the Early Cretaceous – that’s too late to be an Archaeopteryx ancestor.

We need a Jurassic raptor to be our Archaeopteryx ancestor.

We now have a few specimens from the end of the Jurassic. These are advanced raptor-like dinosaurs with long arms built like Archaeopteryx.

So….we’re getting close to discovering the one, single raptor-dinosaur who evolved into the first bird. It had to be in the Mid or Late Jurassic.

If you have any questions you would like to ask any of our bloggers or curators, send us an email at blogadmin@hmns.org.

Interested in learning more about dino-birds? Make sure to check out our next exhibition, Archaeopteryx: Icon of Evolution, opening April 23, 2010.

Ankylosaurus at HMNS: 40 Year Mystery Solved

One of the oldest displays in the Houston Museum of Natural Science is our full scale recreation of the dinosaur Ankylosaurus.  This recreation of a late cretaceous herbivore was created by the Sinclair Oil Company for the exhibit “Sinclair Dinoland” which opened at the 1964-1965 Worlds Fair in New York. 

sinclair-articleDr. Barnum Brown acted as a consultant to world renowned zoological sculptor Louis Paul Jonas to create a paleontological menagerie of dinosaurs that would showcase the Dinosaurs of the Mesozoic.  This would be the end of Dr. Barnum Brown’s long paleontological career and association with Sinclair oil as he died shortly before the fair opened in 1964.

The dinosaurs were created at Louis Paul Jonas Studios and then transported to the fair grounds past New York City on a flat barge in a brilliant and surreal publicity stunt. You can hear the original audio from the Sinclair Dinoland exhibit labels from the 1964-65 Worlds Fair by clicking here.
In addition to carrying the Sinclair banner at national stops by train and flatbed trucks, the dinosaur sculptures were used by Sinclair in other advertising campaigns, such as this print ad featuring the Houston Ankylosaurus advertising the dinosaurs and the Dinoland exhibit. 

The Jonas Ankylosaurus around 1970

After the closing of the fair, the models toured the country on specially constructed flatbed trailers. Visiting Houston in 1966 and 1968, the nationwide tours attracted millions of visitors. One of the Houston visits was to Gulfgate Mall- the first shopping mall in the city. The second, was to HMNS. The Museum, newly expanded in 1969, had empty space and the popularity of these visits was not lost on HMNS.

By 1969 the tour had ended.  Sinclair Oil was being bought out by Atlantic Richfield and the famous Brontosaurus logo was mostly retired.  Smithsonian Institute had declined the offer of the collection. The dinosaur menagerie was put into storage.

The Sinclair Worlds Fair models as they appear now
taken recently on a HMNS Field trip.

Texas offered up a unique home.  Dinosaur Valley State Park, located along the Paluxy River near Glen Rose, was in its infancy. The park site contained scores of dinosaur tracks from the early cretaceous and initially it was thought that the entire collection would go to the newly created dinosaur themed state park. However, with the corporate take-over by Atlantic Richfield and competing interested parties, that deal fell through. The park became home for the Tyrannosaurus rex and the Brontosaurus, which can still be seen on display in the park. The remainder of the collection was distributed across the country.  These two models (seen left) originally had moving parts, the jaw opening and closing on the Tyrannosaurus and the neck moving on the Brontosaurus.  These simple motions thrilled the children of the 1960s and represented the first step in the creation of moving lifelike robotic dinosaurs such as the defunct Dinamation, and in 2008 the Toyota Center show Walking with Dinosaurs

So what is the Mystery?

Out of the collection, two dinosaurs are officially listed as whereabouts unknown. Thought by Worlds Fair Historians to be at the Cleveland Zoo and now listed as “lost,” the Ankylosaurus has been exhibited continuously at HMNS since 1970 when it was officially donated to HMNS by the President of Atlantic Richfield.  The Ornitholestes, however remains lost. The smallest of the Dinoland  sculptures at 6 feet long, this small dinosaur could easily be in some enthusiast’s living room, garage,  rock shop or pancake house anywhere in America.

How do you hide an elephant in a cherry tree? You paint his toenails red.

During the time the Sinclair Dinosaurs were touring the United States on flatbed trucks I thought this joke was very, very funny.  In a sense though, that is one reason the Ankylosaurus has remained “missing.” This is not for lack of looking or curiosity. Both the 1964-65 Worlds Fair and the Sinclair Dinoland exhibit have a substantial fan base today, and original souvenirs still sell for a premium.  

Cosmetic surgery is a popular trend now and to stay good looking the Worlds Fair Louis Paul Jonas’ Ankylosaurus had some work done- albeit not in plastic surgery but in fiberglass. So at the time when photographs of exhibits and artifacts were made available via the internet, the Jonas Ankylosaurus had a dramatic new paint job, a bellowing face lift and a dynamic repositioning of his derriere. The makeover also created a new formidable base featuring a large oak-like tree a not to mention a pack of harassing carnivorous Dromaeosaurs.  The missing Jonas Ankylosaurus commission has been hiding in plain sight in Houston Museum of Natural Science Paleo Hall for almost 40 years!

 The Jonas Dinosaur menagerie was conceived as being an outdoor exhibit, and after the fair and all the national tours, all but two of the sculptures in the collection ended up as open air exhibits. The Houston Ankylosaurus remained indoors and, though modified, it is perhaps the best preserved of the Sinclair Dinoland models.