Parrot Beaks, Graveyard
Photo by Jeff Wilson
Assembled like a puzzle from more than 20 pieces that lay on the side of a hill, the skull of a psittacosaur emerges, the rest safely protected in a jacket.
Parrot-beaked Dinosaurs
Most dinosaurs have long snouts, whether they eat plants or meat. Think of Tyrannosaurus or the horned Triceratops. There is always a snout of good length. But there is one group of extremely short-snouted, plant-eating dinosaurs that populated the Asian continent for millions of years during the Cretaceous. They are the parrot-beaked dinosaurs-the psittacosaurs. They have the shortest snout of any dinosaur, which gives the skull a parrot-like profile. Their nose opening is small and positioned high on the snout, and their beaks are anchored by special bones-above the rostral bone, and below the predentary. They were consummate herbivores-ate nothing but plants. They walked normally on two legs but clearly could reach the ground with their three-fingered hand. They were good runners but would have set no speed records for dinosaurs. In general, they were extremely successful in Asia anout 100 million years ago.
The parrot-beaked dinosaur Psittacosaurus from Outer Mongolia is the standard species for comparison.
Skull puzzle
White pieces of bone drew Jeff to the very top of a butte, where he saw the edges of a skull diving below the surface. It was a strange short skull. He recognized it instantly as belonging to a parrot-beaked psittacosaur. He spotted pieces that included the unusual pair of special bill bones, the predentary and rostral bones. But there were so many pieces, perhaps all that would remain intact is the part still in the ground.
That was how the pieces arrived back in the library at Camp I. First Jeff fit the lower jaw together. Then the race was on. It was clear that this was a paleontological puzzle. Erosion over many years had washed the front margin of the skull and the lower jaws down the hill. Could we reverse that breakdown? Paul and Dave joined the effort. Critical in this endeavor is how careful Jeff was when he first found the skull. Did he look for all of the pieces?
After a few hours and with nearly all of the bones glued back into place, the anterior margin of a psittacosaur skull lay on the lab table to our amazement. It had a relatively long skull that is shaped a lot like its cousin from Outer Mongolia, Psittacosaurus mongoliensis.
Stomach stones
Psittacosaurs are most common in the Early Cretaceous of Asia, about 135 to 110 million years ago. Paul led the team to rock suspected to be of this age. We thought we would give the area a closer look.
“I think it could be good. Looks like the bones are going in. Plus there is this bone-I don’t know-I have never seen anything like it,” remarked Fabrice. He had found a psitacosaur skeleton all right. As we gathered around to work on the skeleton, the strange bone was found to be connected to a small skull-it was the lateral horn of a psittacosaur! This small skull is quite a bit shorter in its proportions, almost round, than Psittacosaurus mongoliensis. We were terribly thrilled to realize that we had in hand a complete skull of this unusual plant-eater.
Photo by Fabrice Moreau
The big discovery of the day, a complete skull of a psittacosaur, garners everyone’s interest in the field.
As Paul edged around the skeleton, he chipped a layer of mud off, revealing a cluster of polished stones. He knew in an instant what it was-the “stomach stones” or gastroliths of the psittacosaur. There were more than a dozen, possibly more than two dozen. Paul had worked on Psittacosaurus mongoliensis for many years and knew that finding as many as 40 or more of these gastroliths in a single skeleton is not unusual.
How do you tell a gastrolith from a common pebble. Actually it can be quite difficult! We had the huge advantage that the matrix around the skeleton was fine-grained mud. In other words, the gastroliths really stuck out.
Photo by Fabrice Moreau
Rounded and polished from grinding, the “stomach stones” or gastroliths of Fabrice’s psittacosaur lay under the skeleton.
Desert Graveyard
It may come as a surprise for some to realize that a dinosaur skeleton is composed of the same basic set of bones as that of a camel. By studying the bones of many different animals, paleontologists come to appreciate how subtle changes in design, size, shape or number translate into basic adaptations. The camel, for example, has a number of specializations. It nis plants by clamping a sharp set of incisors in the lower jaw against a hard pad at the front end of the upper jaw. We examine dinosaur teeth and the margins of the bones of their jaws for similar features – wear facets on tooth crowns, attachment surfaces for horny bills.
Dinosaurian descendants
Some animals we might find in a desert, however, are closer to dinosaurs than others. Birds we now know, are dinosaurian descendants – “living dinosaurs” you might say. . Their skeletons are remarkably similar to those of Cretaceous raptors, like the dromaeosaur Deinonychus. For a dinosaur specialist – and there are several on the team – a well-preserved bird skeleton would be great to have for comparisons. But they are so fragile, they rarely survive for long.
With its horny bill in place and its bony eye ring still in its eye socket. the skull of a vulture makes a superb study specimen.
Paul was the lucky one. A large vulture, with wing bones as long as a human forelimb bones crashed into the side of a hill and was partially buried in sand. A predator ran off with the skull an part of the neck, which Paul found a couple of hundred yards away. The skeleton was amazingly complete – what a treasure for the comparative anatomist!
Tales from the dead
Paul needed only the faintest odor in the wind to recognize immediately the smell of death. He turned into the wind toward the unseen body, laughing as to how much like a vulture he had become. Soon it came into view. He was careful to walk out of the path of the wind, lest the smell become overpowering.
Tanned by wind and sand, the skin of this Bactrian camel mummy looks like metal sheeting, draped over its ribcage.
It was a Bactrian camel that died several months ago. Its skin, tanned by the wind and sand, looked more like sheet metal, draped over its ribcage. Its neck was drawn back to its head, with a wooden nose post still in place in its dried muzzle. A spider scurried under the carcass, where beetles and other insects gathered in harmony for a feast that would last several months.
This posture – an animal laying on its side with legs flexed and neck drawn back – is known as the “death pose.” Most relatively complete dinosaur skeletons are buried in a similar pose, because the same factors were at work after death. An animal dies and falls over; the carcass bloats as gasses emerge from the rotting flesh; the carcass collapses as the flesh is eaten away; the legs flex and the neck is drawn back as the strong tendons and ligaments shorten under the sun.
Deserts are superb graveyards, and that wasn’t the only body the team would find. “Wow! Is that a great carcass or what?,” crooned David, who arrived first at the scene. Three Mongolians watched in the distance, doubtless puzzled by our fascination in their dried, two-humped comrade.
Caught in death as if taking its last gasp, a Bactrian camel skeleton is discovered by the team.
As the team closed in, the carcass took form. The skull rested, jaws open, at the end of an arched neck. The forelimbs had been pulled away and dismembered. Ribs were strewn about. The legs were cocked. Dried skin draped the pelvic girdle. It was a study in taphonomy, that branch of science that studies how animals and plants die and become fossilized.
“Classic. Don’t move anything until I get some photos for my class,” announced David. “Look, see how the front limbs, not attached by anything but muscles, have been pulled away, how the skin over the ribcage burst after the carcass bloated with gases, and how the tendons over here dried in the sun and caused the neck to arch.”
We have spent weeks excavating 100-million-year old death scenes. It is fantastic to look at death just a few months old and imagine what the dinosaurs we dug up would have been like when they died millions of years ago. What an incredible smell that would have been!
Camp 1 Breakdown
You suddenly realize how much stuff was carried into the desert for Inner Mongolia 2001 when its time to break it all down. Ever try to lift a monster generator onto a truck bed? It’s a demanding job for seven. All of the fossils and gear were loaded onto a single flatbed truck.
Poles muscled by seven crew members helped lift the heavy generator onto the bed of a truck, as the team disassembled Camp I.
Relocating camp made all of us reflect on how good we had it at Camp I compared to many of our previous expedition experiences. Hot water, cooked meals, and all of the cold bottled water you could drink-wow! One of the advantages of working in proximity of an army base is that we could piggy-back on their supply runs. That ensured a constant supply of milk, eggs, and vegetables. In honor of our successful work, our friendship, and our basketball rivalry, the army invited us to dinner on our last evening.
With a portrait of Mao overlooking, the team celebtrates the end of the work in the Suhongtu region with the local army unit.
On the Road Again
We pulled out in the morning light, our vehicle caravan headed to the far western reaches of Inner Mongolia. Our destination, Mazongshan, meaning “horse mane mountain,” after the long, low series of peaks along its spine. This is about as far away from anything as it is possible to get. A full eight hundred miles west of Hohhot, the Mazongshan area would be a more difficult place to work, a place where a forgotten supply means you do without it.
The road coursed right along the border with Outer Mongolia and then skirted the edge of a great sand field to the south in the Alashan Desert. This desert is virtually impassable, so the ancient Silk Routes passed to either side of it as well. The sand that does accumulate is shoveled away by road crews, the only humans we encountered along the way.
On lonely desert roads, sometimes the only folks you see are road crews, keeping the sand at bay.
At the halfway point, we found ourselves in a small town called Ejin Qi. The broad river bottom coursing to the side of town was wet. Trees were everywhere. We noticed the trees especially, after driving a couple hundred miles without them. Ejin Qi is blessed with river water passing north to a now dry lake in the desert. It was Children’s Day, so the park was filled with youngsters enjoying themselves. We were enjoying the trip immensely. Thoughts about what fossils we might discover in our next Camp were not far from our minds.
In the desert town of Ejin Qi, a little girl smiles broadly while having fun in the park on Children’s Day.