Standing in the midst of the Hall of Birds are two mounted Chinese dinosaur skeletons from the Sichuan Basin: A two-footed meat eater named Yangchuanosaurus and a four-footed plant eater named Tuojiangosaurus. Both lived in the Late Jurassic period 150 million years ago. Both were found in the Shaximiao rock formation of purplish-red mudstones in present day Sichuan Province.
Yangchuanosaurus magnus means the large lizard of Yangchuan, China, where it was discovered by farmers in 1985.
It was fossilized in the mudstone rock lying on its side nearly intact, which is very unusual. Yangchuanosaurus was an active carnivore, weighing about 2 tons, closely related to Allosaurus of western US and Canada. It is thought to have been trapped in soft mud while it was hunting along the shore of a lake.
Note the body ridges on top of its skull. These may have supported colorful crests used in display.
Tuojiangosaurus multispinus means the many spined lizard of the Tuojiang River, near where it was found as an almost complete skeleton in the Wujiaba Quarry, near Zigong, in the mid 1970’s.
Weighing in at 1.5 tons, Tuojiangosaurus was a heavy-bodied, small headed stegosaur, closely related to the American Stegosaurus found in the Morrison formation of Colorado, Utah and Wyoming. It lived in the broad floodplain of the Sichuan valley with its many lakes and meandering muddy rivers. It had a beak and weak, spoon-shaped teeth with which it cropped ferns, cycad leaves and other low plants. These were swallowed almost whole and ground up for digestion by its crop.
The many plates of bone standing up along its backbone were apparently not for defense, but served a cooling and heating function, depending which way the animal stood with respect to the sun and breeze. For defense Tuojiangosaurus had shoulder spikes and wicked tail spikes that could swing sideways into an attacking predator like Yangchuanosaurus.
There were three types of dinosaur feeders: carnivores that ate meat, omnivores that ate meat and vegetation, and herbivores that ate plants.
Carnivorous dinosaurs like Yangchuanosaurus had sharp, recurved teeth serrated like steak knives to bite off chunks of meat that were swallowed whole. They evolved robust skulls, jaws, and head and neck musculature enabling them to attack and devour tough, heavy animals. Carnivorous dinosaurs had two large, powerful back legs upon which they ran and two smaller front arms with claws for holding onto prey. Deinonychus and Velociraptor were small, lean, carnivores with unusual large sickle-shaped slashing claws on each foot. They are thought to have been like wolves, hunting in packs, bringing down much larger plant eating dinosaurs by combined attack.
Compsognathus was a rooster sized carnivore that probably ate insects and small mammals. Other small bird-like dinosaurs with beaks may have been omnivores, feeding on plants and small animals, like modern crows do.
There is fossil evidence that carnivorous dinosaurs had a bird-like sense of sight and a keen sense of smell, which leads some paleontologists to think some were scavengers of dead animals. Most present day carnivores will also eat carrion (dead rotting meat).
Herbivorous dinosaurs had more diverse feeding methods than carnivores. Scientists try to figure out what these herbivores ate based on plant fossils found with the dinosaurs. As the ecology of the Late Jurassic emerges, we learn that there were no flowering plants, no fruits and nuts, and no grasses. The main plant groups were cycads, ferns, horsetails, ginkgoes, and conifers.
The near-ground feeders such as Tuojiangosaurus nipped the softer horsetails and fern leaves using their horny beaks. They also had evolved cheeks to keep the food from falling out of their mouths. Many of the herbivores had weak teeth. Food was swallowed rough, but was then masticated by a muscular crop before passing on to the stomach. Dinosaurs swallowed stones to help the crop grind up tough leaves and twigs. These highly polished stones are called gastroliths and those from large sauropods could be softball-sized.
Large sauropods like Mamenchisaurus had long necks that enabled them to eat higher vegetation. They had small heads and simple peg-like teeth that were used to strip needles and twigs off conifer branches.
Were all dinosaurs big?
No, but you might think so because there are more fossils of large dinosaur bones than small ones. This is because small bones are more likely to be lost to scavengers and to weathering than large bones. Paleontologists think that there were many more small to medium dinosaurs than large ones, but their remains rarely fossilized.
Are the skeletons of Yangchuanosaurus and Tuojiangosaurus real bone?
No, they are casts made from the real fossil bones saved for scientific study in China.
How smart were dinosaurs?
The only thing we have to go on is the generally small brain size with respect to body size, compared to mammals. We look to the birds, which are quite intelligent and display complex behavior. If birds are dinosaurs, then perhaps these dinosaurs had bird-like intelligence of a slightly lesser degree.
Did people ever meet dinosaurs?
Not the Mesozoic ones. They died out 65 million years ago. If birds are indeed small feathered dinosaurs, then we see and hear them every day.
Did dinosaurs make noises?
Dinosaurs probably vocalized in some way to announce territory or keep the heard together. Parasaurolophus has a prominent tube-like crest which looks like a sounding organ of deep bass tones.
What should a Paleontologist know?
In order to draw parallels between living and fossil organisms, paleontologists need extensive training in zoology, botany, and geology. They need a knowledge of fieldwork, which includes interpreting sediments, searching for fossils and then digging them up. This usually is done while camping in rough conditions in remote areas. They need to know how to prepare fossil specimens in the lab, to identify them and to care for a fossil collection in a museum or university. They need computer skills to analyze fossils. They need good writing skills in order to write reports and papers on their work.
Who discovered the first dinosaurs?
The Chinese dragon may actually be based on fossil bones of theropod dinosaurs, like Yangchuanosaurus, seen thousands of years ago in the rocks of places like the Sichuan Basin in China. Primitive bushmen in Africa knew about dinosaur tracks. In Europe, William Buckland of Oxford, England collected and named large fossil reptile bones Megalosaurus (Large Lizard) in 1824. That was followed the same year by discovery of Iguanodon teeth by Mary and Gideon Mantell of Sussex. In 1841, Sir Richard Owen named these large fossil reptilian animals “dinosaurs” (terrible lizards). In 1858 Joseph Leidy described the first American dinosaur, Hadrosaurus foulkii, a duck-billed dinosaur, from the Cretaceous marl pits of Haddonfield New Jersey. This dinosaur is displayed in the Academy of Natural Sciences, Philadelphia.
Were dinosaurs warm-blooded?
The answer is not simple or clear. Most living reptiles we know are cold-blooded; they depend on sun or warm air to heat them up and they retreat into shadow or water to cool off. The fast growth and active lifestyle of many bipedal dinosaurs favors warm-bloodedness. Birds are warm-blooded, so why not the dinosaurs that gave rise to them? The large sauropods were so massive that warming up and cooling off must have happened very slowly, furthermore, the large mass of fermenting plant material in their guts would tend to warm them so they may have not needed to be warm-blooded.
Parasaurolophus (pronounced: par-ah-saw-ROL-oh-fus)
Name: Parasaurolophus walkeri
Scientific classification: Family: Hadrosauridae
Range: Western North America
This painted cast is the head of a Parasaurolophus, a duck-billed dinosaur that lived during the late Cretaceous period, about 76-65 million years ago. Parasaurolophus is classified in the order Ornithischia, which means it was herbivorous (plant-eating) and had bird-like hips.
Parasaurolophus moved on two legs and was relatively fast. It probably walked on all fours to forage for food and may also have spent some of its time in water. Parasaurolophus had keen eyesight and hearing, but it lacked natural defenses such as claws and sharp teeth. Parasaurolophus grew to be 12 m (40 ft) long and 2.8 m (8 ft) tall at the hips. It weighed about 2,000 kg (2 tons).
How do we know what it looked like?
We know what these animals liked like by studying the parts that became fossilized. This usually means just the bones and teeth. Sometimes, scientists find fossilized skin impressions or semi-hard body parts such as tendons. From the clues about the animal’s body and from what we know about animals living today, scientists can construct a fairly accurate picture of a dinosaur’s body positioning, how it moved, and possibly how it behaved.
Why is its head that shape?
The long, bony crest on the top of its skull is hollow. The nostrils at the front of its snout went up through the crest and back down to form long tubes.
Parasaurolophus may have pushed air through these tubes to produce a foghorn-like sound. These sounds may have been used to signal danger or as part of courtship displays.
Parasaurolophus also had a notch on its back, right where the crest would touch when the animal leaned its head backwards
Name: Argentinosaurus huinculensis
Scientific classification: Family: Titanosauridae
Range: South America
This is a cast of a fossil vertebra (backbone) from Argentinosaurus huinculensis, one of the largest dinosaurs discovered based on scientific collections. It was part of a long line of vertebrae that supported the dinosaur and protected the spinal cord.
The name Argentinosaurus means “Argentine Lizard,” named for where it was discovered. The fossils were excavated from the Huincul formation in Patagonia, Argentina. Argentinosaurus belonged to the titanosaur family; giant armor-plated herbivores that have been found on every continent except Australia, but grew to enormous proportions in South America. It lived during the Cretaceous Period, 90 million years ago, when most of South America was an island cut off from the rest of the continent.
Scientists have not found the skull, neck, or tail of Argentinosaurus, but they have been able to determine its approximate size and features based on other fairly complete skeletons of related species, such as the titanosaur Saltasaurus, and the well-known sauropods Apatosaurus and Diplodocus. Argentinosaurus weighed over 70 metric tons (154,000 lbs) and was as long as three school buses, approximately 30-35 m (98-115 ft). Its food was most likely the conifers, cycads, and tree ferns that dominated the landscape.
Paleontologists have found Argentina to be one of several hotbeds for new species of dinosaurs. This was once a lush tropical landscape that was home to gentle giants and terrifying predators. The largest described carnivore, Giganotosaurus, was unearthed in the Patagonian desert not far from where Argentinosaurus was found. There are many sites currently being excavated and most likely, many more new species of dinosaurs waiting to be discovered.
Name: Tyrannosaurus rex
Scientific classification: Family: tyrannosauridae
Range: Western North America
Tyrannosaurus rex was one of the largest meat-eating dinosaurs that ever roamed the Earth. Fossil evidence shows that this carnivore lived across the western part of North America from Alberta, Canada to southwest Texas. T. rex fossils date from the late Cretaceous period, approximately 67-65 million years ago. The name Tyrannosaurus means “tyrant lizard,” and rex means “king.”
T. rex grew to be an estimated 13 m (43 ft) long and 4 m (13 f) tall at the hips, weighing up to 6,800 kg ( 7 tons). The massive skull can measure up to 1.5 m (5 ft) in length. Pointed, curved, and serrated teeth indicate that T. rex was a carnivore. Like all dinosaurs, it could replace old broken teeth, which is why some teeth are much shorter than others.
As is typical of many dinosaurs, the skull of T. rex had many large openings. These provided surfaces for attachment of powerful jaw muscles and passages for nerves and blood vessels, and they are thought to have reduced the weight of the skull. The eyes of T. rex were more forward facing than in other carnivorous dinosaurs, suggesting that they had binocular vision. The olfactory bulb of the brain was well developed, indicating a good sense of smell.rex could walk quickly at speeds between 16 to 32 km/h (10 to 20 mph). Powerful hind legs suggest the dinosaur was capable of chasing and capturing prey, but it also may have scavenged. T. rex had powerful but short fore-arms with only two fingers, which are thought to have been used to help grab and hold prey. Despite its large size, T. rex had a fairly small brain that was smaller than that of a human.
While we have learned much about how T. rex lived by studying fossils, some things may never be known, such as its color, what sounds it made, and the extent of its behavior.
The Delaware Museum of Natural History’s Dinosaur Gallery showcases the only dinosaurs on permanent display in the state. The towering dinosaur skeletons, Tuojiangosaurus and Yangchuanosaurus, represent Asian relatives of the familiar North American dinosaurs, Stegosaurus and Allosaurus, respectively. A Parasaurolophus head and Archaeopteryx are also on display. The Dinosaur Gallery includes the Science in Action Lab, where volunteers share specimens and answer questions. The Dino Den is a cozy spot for storytime, live animal presentations and getting an up-close view of the dinosaurs.