I abide in a goodly museum,
Frequented by sages profound
’Tis a kind of strange mausoleum
Where the beast that have vanished abound
There’s a bird of the ages Triassic
With his antediluvian beak
And many a reptile Jurassic,
And many a monster antique.
—MAY KENDALL, BALLAD OF THE ICHTHYOSAURUS, 1887
THE TRIASSIC TRIAD
Most of the earliest discoveries of dinosaurs took place in England in the 1820s and 1830s, but other European countries soon began to make their own mark on paleontology. By the mid-1800s, Germany jumped to the forefront in vertebrate paleontology. Germany had a long tradition of scholarship and research, and Germans are famous for their work ethic, respect for scholars and teachers, and dedication to being the best in a subject. Much of the early foundations of geology were laid by Abraham Gottlob Werner in the Freiburg Mining Academy in the late 1700s, and German scientists had been among the pioneers of fossil collecting since the 1600s.
One of the breakthroughs described a series of beds older than the Jurassic rocks first recognized and named by the German philosopher, explorer, and naturalist Alexander von Humboldt. He officially described the first Jurassic rocks and coined the name “Jurassic” in 1795. By 1831, German geologist Friedrich von Alberti identified a threefold succession of rocks lying beneath the typical Jurassic limestones and shales full of ammonites that was widespread across Germany and Switzerland. The lowest unit was a distinctive sandstone called the Bunter, or Buntsandstein. Above it was a limestone full of fossil shells known as the Muschelkalk (clam chalk) for its abundant fossil shells. At the top was a series of typically red sandstones and shales called the Keuper. This threefold pattern was so consistent and widespread over Central Europe that von Alberti called it the “Triassic” (“tri-” for “three”).
Soon geologists were studying the German Triassic in greater detail, and they discovered that it had fossils much more primitive than those found in the overlying Jurassic. Naturally this included dinosaurs as well. The Keuper, in particular, consisted of ancient river, lake, and floodplain deposits of Late Triassic age, and in some places it was rich in gypsum and salt from ancient dry lakebeds. River and floodplain deposits are perfect for the preservation of land plants and animals, and indeed a number of different fossil conifers had been found there. Primitive reptile fossils, some of the earliest tiny fossil mammal teeth, as well as the huge flat-bodied crocodile-shaped amphibian Mastodonsaurus (once called Labyrinthodon) were also found there.
In 1834, about a decade after the naming of Megalosaurus and Iguanodon, a local doctor, Johann Friedrich Engelhardt, discovered some vertebrae and giant leg bones in the reddish shales of the Keuper in Heroldsburg, near Nuremberg, Germany. Three years later the specimens reached the noted paleontologist Christian Erich Hermann von Meyer. Today von Meyer is famous as the first paleontologist to describe and name Archaeopteryx from the Solnhofen Limestone, as well as the Solnhofen pterosaurs including Rhamphorhynchus and Pterodactylus, but he also worked on many different kinds of fossils, especially the reptiles and amphibians of the Permian and Triassic beds of Germany. He was one of the earliest scientists to recognize in 1832 that the large land reptiles of the Mesozoic were a distinct group, and in 1845 he named the “Pachypodes” or “Pachypoda” (“heavy foot” in Greek) for the previously published Iguanodon and Megalosaurus. Luckily for history, Owen had coined the name Dinosauria in 1842. If von Meyer’s name had been earlier, kids today would be talking about and marveling at pachypods instead of dinosaurs!
Figure 6.1
Plateosaurus: (A) complete articulated skeleton in the Eberhard-Karls-Universität Tübingen; (B) reconstruction of Plateosaurus in life. ([A] Courtesy of Wikimedia Commons; [B] courtesy of N. Tamura)
Von Meyer published his description of the specimens in 1837 and gave them the name Plateosaurus engelhardti (figure 6.1). The original type material consisted of about 45 bone fragments, of which half are now lost. The species name honors the discoverer, but the translation of the generic name is controversial. The suffix “-saurus” is clearly Greek for “lizard” or “reptile,” but von Meyer did not explain what he meant by the prefix “plateo-.” Various scientists since then have decided he meant “broad” or “flat” or even “paddle.” With that publication, Plateosaurus became only the fifth dinosaur to be named that is still considered valid today (the first four were the British dinosaurs discussed in chapters 1–3). Although it was named five years before Owen named the Dinosauria in 1842, Owen did not mention it because it was too incomplete to say much about it other than that it was a large reptile.
DER SCHWÄBISCHER LINDWURM
Unlike most of the early British dinosaurs, which were based on incomplete material and have never been found as a complete skeleton, Plateosaurus was remarkably common in the Late Triassic. In fact, Plateosaurus has been found in about 50 localities running along the Triassic outcrops in central and southern Germany and in Switzerland and eastern France. Many of these localities produced multiple nearly complete articulated skeletons, so the anatomy of Plateosaurus is very well known. Only the huge assemblage of Iguanodon from Bernissart, Belgium, comes close to the sample size of Plateosaurus specimens among the earliest named dinosaurs.
One of the best localities is near Halberstadt in the Saxony-Anhalt district of northeastern Germany. Found in a clay pit and excavated between 1910 and 1930, this locality produced between 39 and 50 skeletons in a remarkable state of completeness and preservation. Along with them were two skeletons of one of the earliest known turtles, called Proganochelys. Most of this material was described in 1914 by Otto Jaekel (just as World War I began to disrupt scientific research) and ended up at the Museum für Naturkunde in Berlin. Sadly, Allied bombers destroyed several specimens during World War II, but the Berlin Archaeopteryx and the huge dinosaurs from Tendaguru, including Giraffatitan, were not destroyed (see chapter 9). It is impossible to recover additional specimens because the Halberstadt quarry is now covered by a housing development.
The largest Plateosaurus locality by far is Trossingen, near the Black Forest of Württemberg in southern Germany, south of all the previous finds. This locality was worked first by Eberhard Fraas in 1911–1912, then by Friedrich von Huene from 1921–1923 after World War I ended, and finally by Reinhold Seemann in 1932. Trossigen has produced 35 partial or complete skeletons and fragments of another 70 individuals, which is one of the largest samples of a single population of dinosaurs ever discovered. Plateosaurus was so large that paleontologist Friedrich von Quenstedt nicknamed it the “Schwäbischer Lindwurm” after the legendary worm-like dragon of Norse and German mythology called the “lindwurm.” Sadly, some of the Trossigen specimens were also destroyed during World War II when Allied bombs destroyed the former Naturaliensammlung in Stuttgart (today, the Naturkunde Stuttgart). A recent study of the material by Dr. Rainer Schoch of the Stuttgart Museum has shown that the most important specimens survived the bombing. The Stuttgart Museum has a spectacular modern exhibit with a room of fossils for each Mesozoic time period. The Late Triassic display has the skeleton of Mastodonsaurus and other Keuper fossils and also features skeletons and restorations of Plateosaurus.
The third large assemblage of Plateosaurus came from a clay pit in Frick, Switzerland. First collected in 1976, the skeletons are deformed by the tectonic processes that bent the rocks as the Alps rose up. Nevertheless, numerous skeletons are complete and articulated, just as in Trossigen and Halberstadt.
By far most of the important work on Plateosaurus was done by Friedrich von Huene (figure 6.2). Born in 1875, von Huene (baptismal name: Friedrich Richard Baron Hoyningen) was one of Germany’s greatest paleontologists of the first half of the twentieth century. He spent his entire career at Tübingen but never held a post higher than curator because he had no interest in administration. He was a tireless worker, and his major accomplishments include describing the tiny primitive dinosaur relative Saltopus from the Upper Triassic of Elgin, Scotland, in 1910 (see chapter 5), and the enormous titanosaurian sauropod Antarctosaurus from the Upper Cretaceous of Argentina in 1929. Over his prolific career he published on many other fossil reptiles, including pterosaurs, the little aquatic Permian reptile Mesosaurus, the Late Triassic predator Prestosuchus from Brazil, and many extinct relatives of mammals and primitive amphibians as well. He holds the distinction of naming and describing more dinosaur species still valid today than anybody except for Othniel Charles Marsh.
Figure 6.2
Friedrich von Huene as a young man. (Courtesy of Wikimedia Commons)
Von Huene’s greatest work, however, was probably his long-term studies of Plateosaurus. Before he began, little was known of the dinosaur other than von Meyer’s fragmentary type specimens. From the fragments, no one could tell whether it was related to the predatory theropod dinosaurs such as Megalosaurus or to the herbivorous dinosaurs or to something else. It was just a large dinosaur by Triassic standards, but otherwise it remained a mystery. Von Huene began studying the original type specimens from Heroldsburg and found that the museum collections of Plateosaurus were mixed together with what he believed to be a large predator related to Prestosuchus, called Teratosaurus. Most of the Plateosaurus reconstructions of that time falsely mixed the predatory skull with sharp recurved teeth of Teratosaurus with the huge body and broad hips of Plateosaurus, making it an incongruous hodgepodge of a predator and a herbivore. When the Trossingen specimens came into his lab, he had excellent material to work with and fully described the entire skeleton of Plateosaurus, demonstrating that it was a large-bodied herbivorous dinosaur. In fact, it was then the largest dinosaur of its time (the Late Triassic). He showed that it had a deep, narrow, boxlike skull with eyes facing sideways, which was good for spotting predators around you. Plateosaurus had conical fang-like teeth in the front and thick, bluntly serrated leaf-shaped teeth in the jaw suitable for shredding vegetation (mainly ferns, cycads, and conifers) that formed the Late Triassic forests. The sharp teeth in front have led some paleontologists to suggest that Plateosaurus was not a strict herbivore and may have been omnivorous. Its low jaw joint gave it the leverage for a powerful bite, so it could crush even the toughest vegetation. With its large size and long neck, it could reach high vegetation that no other animal at the time could access.
It had rather small but robust front limbs for its size, relative to the long hind limbs, so it was clearly bipedal. Jaekel originally thought that Plateosaurus sprawled on all fours in a quadrupedal gait, but later he argued that they hopped like kangaroos. However, von Huene showed that the wrist and hand are configured so they cannot rotate and place the palms or the tips of the fingers down (if it had walked on its finger tips as it does on its toes). So he argued that these animals could not walk on all fours. More recently, studies of the hands show that they could not pronate (rotate until they were palms down). This completely rules out their putting their palms flat on the ground, as von Huene had originally argued. In fact, some of the skeletal mounts had switched the two lower arm bones (radius and ulna) in order to bend the wrist and make their palms lie flat on the ground. Instead, Plateosaurus hands had large recurved claws on them, which could have been used for tearing down plant branches, digging up roots, or for defense against predators (such as the early Dilophosaurus relative Liliensternus from the same beds, which von Huene also described).
Von Huene also followed the conventional belief of his time that dinosaurs were just big sprawling lizard-like creatures, so they were shown in a kangaroo-like pose, resting on their tail. They had to put an awkward bend in the tail of the mounted skeletons to allow it to bend where it touched the ground. We now know that Plateosaurus was like most advanced bipedal dinosaurs that hold their body parallel to the ground and their tail out straight behind (see figure 6.1). The large rib cage and the broad hip bones suggest that Plateosaurus was quite barrel-chested, which is consistent with having a large complex gut for fermenting and digesting tough fibrous leaves.
Most important of all, von Huene realized that Plateosaurus had many features that foreshadowed the huge sauropods that were being discovered in North America and elsewhere: a simple narrow skull with peg-like teeth for stripping and crushing leaves, a relatively long neck, a long tail, and a large trunk for digesting plants. In 1932, he created a new group, the Prosauropoda, for the primitive dinosaurs that were ancestral to the great sauropod giants that evolved later in the Jurassic. A number of related species have since been found in other Triassic beds around the world, but Plateosaurus is still the largest, most complete, and best known of them. And he named a bigger group, the Sauropodomorpha, to include both Prosauropoda and Sauropoda. This group is still in use today, although Prosauropoda is now considered a taxonomic wastebasket for all primitive sauropods that are not members of the advanced groups of sauropods.
Von Huene went beyond the pure description and anatomical analysis with which most paleontologists contented themselves. He was also fascinated with the way the Trossigen Plateosaurus were fossilized and their burial positions. Thus von Huene was a pioneer in the young field of taphonomy: the study of what happens to the bodies of living animals after death. Both Jaekel and Fraas had argued that the skeletons had been mired in a mud hole, trapped, and starved to death. Von Huene noticed that the skeletons were fully preserved in their death poses, suggesting that they had slumped down in their bellies as they died, with their limbs folded beneath them (figure 6.3). Their necks were curved sideways and backward, which is common in many animals when their nuchal ligament (the long elastic band down the back of the neck that holds the head and neck up) contracts after death and pulls the neck back. Von Huene looked at the dry lake deposits of gypsum and salt and the sandstones from the Keuper sandstones and argued that many of them had died crossing a dry desert region, possibly on some migration to better food sources and water. He argued that they were trapped in the mud next to watering holes when they were too weak to move further on their migration. This interpretation is no longer considered plausible; later workers have argued that the skeletons were buried in a rapidly moving mudflow or have come back to the idea that they were mired in thick mud pools. The fact that only the heavy adults are trapped, and the lighter juveniles and the lighter predators are missing, seems to support this. Whatever the final verdict, von Huene can be considered not only one of Germany’s greatest vertebrate paleontologists but also one of the pioneers of taphonomy.
Figure 6.3
Top view of the articulated skeleton of Plateosaurus in its death position, with the legs folded beneath it and the neck curved back and sideways (the skull is missing). This specimen is one of many from Trossingen and is on display in the Staatliches Museum für Naturkunde Stuttgart. (Courtesy of Wikimedia Commons)
PLATEOSAURUS TODAY
Since von Huene’s time (he died in 1969 at the ripe old age of 94), much additional work has been done on Plateosaurus. Thanks to the large number of skeletons from several quarries, paleontologists can assess variation within a single population, which is impossible for 95 percent of dinosaurs because most are known from only a few specimens (and often partial specimens at that). The first striking thing is the incredible variability of adult body sizes. By looking at adult bones only (bones where the cap, or epiphysis, is fully fused to the shaft, which happens when the bone stops growing), adults ranged between 4.8 and 10 meters (16 and 33 feet) long and weighed between 600 and 4,000 kilograms (1,300 and 8,800 pounds).
Studies show that many bones are hollow or spongy inside, a feature that many later and bigger dinosaurs used to reduce the weight of their bones in their necks, backbone, and tail. The size of the lungs can be estimated because it is possible to move the ribs in and out to their minimum and maximum extent and estimate the change in ribcage volume. From this analysis, it seems that Plateosaurus breathed about 20 liters of air each time it inhaled (for a 700 kilogram dinosaur), or about 29 milliliters per kilogram of air. This ratio is typical of birds, but not of mammals.
Many studies have pointed out that Plateosaurus was one of the largest dinosaurs to walk fully on the tips of its long toes (digitigrade). However, it does not have the extreme elongation of the ankle and toe bones, nor the bony features of the ankle, that would allow it to be a very fast runner. Instead, paleontologists think Plateosaurus was a moderately fast runner, certainly fast enough with its large size and stride length to outrun most predators (most of which were smaller in the Triassic).
Studies of the growth lines in the limb bones of Plateosaurus show it had a typical sauropod growth pattern: rapid growth as a juvenile to reach a large enough size to be safe from predators, then slow but steady growth as it reached adulthood. By contrast, birds and mammals grow quickly as juveniles, then stop growing when they reach adulthood. Some paleontologists argue that Plateosaurus was endothermic (regulated its internal temperature as mammals and birds do, by burning its food to generate metabolic body heat).
This is interesting because when sauropods became huge their gigantic mass and relatively small surface area relative to their huge volume meant they probably had to abandon endothermy. Instead, large sauropods are thought to have used their huge bulk and limited surface area to resist changes in body temperature, so they heated up slowly in the day and cooled down slowly in the night (but see discussion in chapter 17). For this reason, they did not need the expensive endothermic system of burning their food to generate metabolic body heat (a strategy called inertial homeothermy, or gigantothermy). The contrast between bigger sauropods and their ancestor Plateosaurus shows how these physiological strategies can change, even within a lineage.
The growth lines in the bones also allow us to determine the age of a specimen. Some individuals reached adult size at 12 years, others were still growing at 20 years, and one reached the age of 28 years. It is possible that they lived longer because all the specimens apparently died in accidents, and none reached old age. There is a remarkable absence of juveniles in the assemblage, suggesting that the death trap that mired them tended to trap only the heavier adults and did not entrap the lightweight juveniles (and their small predators).
Finally, comparing the size of the eye socket with living animals suggests that Plateosaurus was active both during the day and at night, so it was not strictly diurnal or nocturnal. It may have become active in late afternoon as the temperatures cooled, and then took a midday siesta to avoid the noon heat after being up all night.
Plateosaurus was the first of the sauropod relatives to be discovered and is still the best known and best sampled. However, prosauropods were widespread in Upper Triassic and Lower Jurassic beds all over the supercontinent of Pangea, although most of these fossils are incomplete. Other members of the Plateosaurus family include Plateosauravus and Euskelosaurus from Africa, Jaklapallisaurus from India, Unaysaurus from Brazil, Yimenosaurus from China, and Ruehleia from Germany. The other branch of prosauropods are related to Massospondylus, originally described by Richard Owen in 1854 from fossils found in Lower Jurassic beds of southern Africa. Close relatives of Massospondylus include Prahdania from India, Coloradisaurus from Argentina, Lufengosaurus from China, and Glacialisaurus from Antarctica. Another branch is the Riojasauridae, including Riojasaurus from Argentina and Eucnemesaurus from South Africa. The third group is related to Anchisaurus, known from the Lower Jurassic beds of Connecticut. Other primitive sauropods include the Chinese Yunnanosaurus and Jingshanosaurus, and Melanorosaurus from South Africa. The more advanced giant sauropod dinosaurs of the later Jurassic and Cretaceous are most closely related to the anchisaurine branch.
So from the original fragments of Plateosaurus found in 1837 as the fifth known dinosaur, there was a big evolutionary radiation of similar-looking prosauropods on nearly every part of Pangea, from Europe to eastern North America, to China and India, to South America, Africa, and even Antarctica. These early bipedal long-necks were eventually replaced by the radiation of advanced sauropods with gigantic bodies and extremely long necks and tails, and they were never able to walk on two legs again.
FOR FURTHER READING
Barrett, Paul M. “Prosauropod Dinosaurs and Iguanas: Speculations on the Diets of Extinct Reptiles.” In Evolution of Herbivory in Terrestrial Vertebrates: Perspectives from the Fossil Record, ed. Hans-Dieter Sues, 42–78. Cambridge: Cambridge University Press, 2000.
Barrett, Paul M., and David J. Batten, eds. Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs. Oxford: Blackwell, 2007.
Colbert, Edwin. Men and Dinosaurs: The Search in the Field and in the Laboratory. New York: Dutton, 1968.
Curry Rogers, Kristina, and Jeffrey Wilson. The Sauropods: Evolution and Biology. Berkeley: University of California Press, 2005.
Farlow, James, and M. K. Brett-Surman, eds. The Complete Dinosaur. Bloomington: Indiana University Press, 1999.
Fastovsky, David, and David Weishampel. Dinosaurs: A Concise Natural History, 3rd ed. Cambridge: Cambridge University Press, 2016.
Galton, Peter M., and Paul Upchurch. “Prosauropoda.” In The Dinosauria, 2nd ed., ed. David B. Weishampel, Peter Dodson, and Halszka Osmólska, 232–258. Berkeley: University of California Press, 2004.
Hallett, Mark, and Mathew J. Wedel. The Sauropod Dinosaurs: Life in the Age of Giants. Baltimore: Johns Hopkins University Press, 2016.
Holtz, Thomas R., Jr. Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. New York: Random House, 2011.
Mallison, Heinrich. “The Digital Plateosaurus I: Body Mass, Mass Distribution, and Posture Assessed Using CAD and CAE on a Digitally Mounted Complete Skeleton.” Palaeontologia Electronica 13, no. 2 (2010): 8A.
Naish, Darren. The Great Dinosaur Discoveries. Berkeley: University of California Press, 2009.
Naish, Darren, and Paul M. Barrett. Dinosaurs: How They Lived and Evolved. Washington, D.C.: Smithsonian Books, 2016.
Remes, Kristian, Carole T. Gee, and P. Martin Sander. Biology of the Sauropod Dinosaurs: Understanding the Life of Giants. Bloomington: Indiana University Press, 2011.
Spaulding, David A. E. Dinosaur Hunters: Eccentric Amateurs and Obsessed Professionals. Rocklin, Calif.: Prima, 1993.
Wedel, Mathew J. “What Pneumaticity Tells Us About ‘Prosauropods,’ and Vice Versa.” In Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs, ed. Paul M. Barrett and David J. Batten, 207–222. Oxford: Blackwell, 2007.