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Plateosaurus
Fossil range: Upper Triassic, 216–199 Ma
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Mounted skeleton of P. engelhardti (almost complete specimen AMNH 6810 from Trossingen, Germany)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Infraorder: Prosauropoda
Family: Plateosauridae
Genus: Plateosaurus
von Meyer, 1837
Species
  • P. engelhardti von Meyer, 1837 (type)
  • P. gracilis Yates, 2007
Synonyms
  • Zanclodon Plieninger, 1846
  • Dimodosaurus Pidancet & Chopard, 1862
  • Gresslyosaurus Rütimeyer, 1856
  • Pachysaurops von Huene, 1961
  • Pachysaurus von Huene, 1907-1908
  • Pachysauriscus Kuhn, 1959
  • Sellosaurus von Huene, 1907-1908

Plateosaurus (meaning 'flat lizard') is a genus of plateosaurid prosauropod dinosaur that lived during the Late Triassic period, around 216 to 199 million years ago in what is now Central and Northern Europe. The latest research recognizes two species: the type species P. engelhardti from the late Norian and Rhaetian, and P. gracilis from the lower Norian, although others have been assigned in the past, and there is no broad consensus on the species taxonomy of plateosaurid dinosaurs. Similarly, there are a plethora of synonyms at the genus level.

Discovered in 1834 by Engelhardt and described three years later by von Meyer, Plateosaurus was the fifth dinosaur genus to be named that today is still considered valid. However, it was not one of the three genera originally used by Owen in 1842 to define Dinosauria, because at the time it was poorly known and difficult to identify as a dinosaur. Plateosaurus is among the best known dinosaurs, with over 100 skeletons found, some of them nearly complete. Plateosaurus was a bipedal herbivore with a small skull on a long, mobile neck, sharp but plump plant-crushing teeth, powerful hind limbs, and a grasping hand with a large thumb claw possibly used for defence and feeding. Unusually for a dinosaurs, Plateosaurus showed strong developmental plasticity: fully grown individuals were between 4.8 and 10 metres (16 and 33 ft) long and weighed between 600 to 4,000 kilograms (1,300 to 8,800 lb). Commonly, the animals lived for 10 to 25 years.

Despite the plethora and excellent quality of the fossil material, Plateosaurus was for a long time one of the most misunderstood dinosaurs. Some researchers proposed theories that conflicted with geological and palaeontological evidence, but have become the paradigm of public opinion. Since 1980 the taxonomy and taphonomy, and since 2000 the biomechanics and palaeobiology of Plateosaurus have been re-studied in detail, totally altering the interpretation of the animal's posture and behaviour.

Contents

Description

Size comparison between P. engelhardti and a human.

The type species of Plateosaurus, P. engelhardti, was one of the largest dinosaurs of its time. Adult individuals reached 4.8 to 10 metres (16 to 33 ft) in length.[1] Average individuals had a mass of around 600 to 4,000 kilograms (1,300 to 8,800 lb).[2] A member of a group of early herbivores known as prosauropods, Plateosaurus was larger and more powerfully built than most similar animals such as Anchisaurus, but not as stocky as typical quadrupedal prosauropods such as Riojasaurus. The second, older species, P. gracilis (formerly named Sellosaurus gracilis), was somewhat smaller, with a total length of 4 to 5 metres (13 to 16 ft).[3] Plateosaurus had the typical body shape of a herbivorous bipedal dinosaur: a small skull, a long and flexible neck composed of ten cervical vertebrae, a stocky body and a long, mobile tail composed of at least forty caudal vertebrae. The center of mass was located just in front of the hips, so that a slightly flexed pose of the hind limbs was sufficient to create balance over the hind feet alone.

P. engelhardti skull cast, Royal Ontario Museum

The skull of Plateosaurus was deeper than that of most prosauropods, although still small and narrow compared to the size of its body. As in almost all archosaurs, it had five sets of fenestrae (skull openings): the naris and orbit, two temporal fenestrae (a lateral infratemporal fenestra and dorsal supratemporal fenestra) at the back of the skull and an antorbital fenestra between the eye and nose. The snout carried many small, leaf-shaped, socketed teeth in both the upper and lower jaw, five to six on the premaxilla, twenty four to thirty on the maxilla, and twenty one to twenty eight on the dentary. The teeth had serrated, leaf-shaped crowns suitable for crushing plant material. The low position of the jaw joint gave the chewing muscles great leverage, so that Plateosaurus could deliver a powerful bite. These features suggest that it fed exclusively on plants.[4] Plateosaurus may have had narrow cheek pouches, which kept food from spilling out when it ate. Its eyes were directed to the sides, rather than the front, providing all-round vision to watch for predators. Some fossil skeletons have preserved sclerotic rings.

Restoration of two P. engelhardti

The ribs of Plateosaurus were connected to the dorsal vertebrae with a hinge joint, as in all saurischian dinosaurs, and its lung volume has been estimated at ~20 l, or 29 ml/kg bodyweight,[5] which is a typical value for birds, but not for mammals.[6] This indicates that Plateosaurus probably had an avian-style flow-through lung. The tail of Plateosaurus was typically dinosaurian, with high mobility. Plateosaurus had a low limb length ratio, with the fore limbs less than half as long as the hind limbs. The former were roughly as long as those of a human, and similarly proportioned, but much stronger. However, their motion range was limited, so that the animal could only reach objects under and just in front and to the sides of the anterior body. Together with the great difference in limb length, this limit made quadrupedal walking impractical. The hand had three strong grasping fingers, of which the thumb was able to partly oppose the others, and a weakly developed fourth finger. The fifth finger was very small, but angled strongly against the others, and fully opposed the thumb. Fingers 1 through 4 had claws; that of the thumb was disproportionately large. Altogether, the forelimb was a powerful grasping tool, able to project significant force on objects up to the size of a branch or strong root. The hind limb shows adaptations to a cursorial mode of life, such as a lengthened metatarsus and a digitigrade posture. Overall, it is long in comparison to the trunk length, as opposed to quadrupedal forms such as Riojasaurus.

Discovery and history

In 1834, physician Johann Friedrich Engelhardt discovered some vertebrae and leg bones at Heroldsberg near Nuremberg, Germany. Three years later German palaeontologist Hermann von Meyer designated them as the type specimen of a new genus, Plateosaurus.[7] Since then, remains of far over 100 individuals of Plateosaurus have been discovered.

Between the 1910s and 1930s, excavations in a clay pit at Saxony-Anhalt dug up between 39 and 50 skeletons that belonged to Plateosaurus, Liliensternus and Halticosaurus. Some of this material was assigned to P. longiceps, a species today considered a junior synonym of P. engelhardti and described by palaeontologist Otto Jaekel in 1914.[8] Most of the material found its way to the Museum für Naturkunde in Berlin, and part of it was destroyed during World War II. The Halberstadt quarry today is covered by a housing development.

P. engelhardti, collection number F 33 of the Staatliches Museum für Naturkunde Stuttgart, Germany, in dorsal view. The skeleton was kept in articulation as found at Trossingen (Germany) by Seemann in 1933. It has the typical folded hind limbs of most Plateosaurus finds. Unusually, the anterior body is not twisted to one side.

The second major German locality with Plateosaurus finds, a quarry in Trossingen in the Black Forest, was worked repeatedly in the 20th century. Between 1911 and 1932, excavations during six field seasons lead by German palaeontologists Eberhard Fraas (1911-1912), Friedrich von Huene (1921-23)[9][10] and finally Reinhold Seemann (1932) revealed a total of 35 complete or partially complete skeletons of Plateosaurus, as well as fragmentary remains of approximately 70 more individuals.[11] The Trossingen material that survived World War II today can mainly be found at the Staatliches Museum für Naturkunde Stuttgart (SMNS) in Stuttgart and the museum of the Institute for Geosciences of the Eberhardt-Karls-University Tübingen, but because von Huene's excavations were co-sponsored by the American Museum of Natural History in New York, some material, including a nearly complete and well preserved individual, was transferred to the United States. As of 2009, the Trossingen locality is occasionally worked by the Staatliches Museum für Naturkunde Stuttgart.

P. engelhardti, collection number MSF 23 of the Sauriermuseum Frick, Switzerland, in dorsal view. This is the most complete Plateosaurus skeleton from Frick.

The Plateosaurus skeletons in a clay pit of the Tonwerke Keller AG in Frick, Switzerland, were first noticed in 1976. Since then, whenever quarry operations touched the fossiliferous layer, new material was found, indicating that the lagerstätte is extensive. While the bones are often significantly deformed, Frick yields skeletons comparable in completeness and position to those of Trossingen and Halberstadt.[12] In August 2007, another nearly complete skeleton was found in the clay pit, while more bones were discovered by an amateur palaeontologists on the Frickberg, a hill on the other side of the valley. Martin Sander, palaeontologist at the University of Bonn, Germany, indicated that the fossiliferous area could extend for 1.5 kilometers, making it the most extensive fossil site in Europe. Ben Pabst, the leader of the 2007 and earlier Frick excavations, estimates that the site contains one dinosaur per 100 square meters.

Overall, material assigned to Plateosaurus has been found at over 50 localities in Germany (mainly along the Neckar and Pegnitz river valleys), Switzerland (Frick) and France.[11] In 1997, workers of an oil platform of the Snorre oilfield located at the northern end of the North Sea, were drilling through sandstone for oil exploration when in a drill core extracted from 2,256 meters below the seafloor they stumbled upon a fossil they believed to be plant material. In 2003, the specimen was sent to Jørn Harald Hurum, palaeontologist at the University of Oslo for study. Martin Sander and Nicole Klein, palaeontologists of the University of Bonn, analyzed the bone microstructure and concluded that the rock preserved fibrous bone tissue from a crushed knucklebone belonging to Plateosaurus,[13] making it the first dinosaur found in Norway and the deepest in the world.[14] Plateosaurus material was also found in Greenland.[15]

Classification and type material

 Plateosauria 
 Plateosauridae 

Unaysaurus



Plateosaurus




 Massopoda (to sauropods) 



Basal sauropodomorph phylogeny simplified after Yates, 2007.[16] This is only one of many proposed cladograms for basal sauropodomorphs. Some researchers do not agree that plateosaurs were the direct ancestors of sauropods

Plateosaurus was the first prosauropod to be described, and is the type genus of the family Plateosauridae, to which gives its name. Initially, when the genus was poorly known, it was only included in Sauria, with the possibility of being some kind of reptile.[7] In 1845, von Meyer created the group Pachypodes (now unused) to include Plateosaurus, Iguanodon, Megalosaurus and Hylaeosaurus.[17] However, Dinosauria (technically the same as Pachypodes) already existed, and had priority. Plateosauridae was proposed by Othniel Charles Marsh in 1895 within Theropoda.[18] Years later, it was moved to Prosauropoda by Huene,[9] and was accepted by most authors.[19][20] For many years the clade only included Plateosaurus, but later two more genera were considered to belong to it: Sellosaurus[21] and possibly Unaysaurus.[22] Of these, Sellosaurus is probably a junior synonym of Plateosaurus.[3]

The type series of Plateosaurus engelhardti included "roughly 45 bones".[23] However, of these nearly half are lost today. The remaining material is kept in the Institute for Paleontology of the University of Erlangen-Nürnberg, Germany. From it, Markus Moser in 2003 selected a lectotype, a partial sacrum. The type locality is not known for certain, but Moser attempted to infer it from previous publications and the color and preservation of the bones, concluding that the material probably stems from the "Buchenbühl", roughly 2 kilometres (1.2 mi) south of Heroldsberg near Nürnberg, Bavaria, Germany.[24]

The type specimen of Plateosaurus gracilis, an incomplete postcranium, is kept at the Staatliches Museum für Naturkunde Stuttgart, Germany. The type locality is Heslach, a suburb of Stuttgart, Germany.[3]

Etymology

The etymology of the name Plateosaurus is not clear. The original description contains no information, and various authors have offer differing interpretations. The first explanation was offered by Agassiz, who listed Greek platy/πλατη (Paddel, Rudder; Agassiz translates as Latin pala = spade) and sauros/σαυρος (lizard).[25] Agassiz consequently renamed the genus Platysaurus,[26] probably from Greek platys/πλατυς (broad, flat, broad-shouldered),[24] creating an invalid junior synonym. This derivation was copied by later authors, so that Plateosaurus is often translated as "broad lizard" or "flat lizard". However, as pointed out by Moser,[24] von Meyer compared Plateosaurus to decidedly non-flat animals, namely large terrestrial extant mammals.[7] Often, platys/πλατυς is also supposed to have been intended as a reference to the laterally flattened teeth of Plateosaurus,[27] which is impossible because the teeth were unknown at the time of description. Moser suggests a better alternative, Ancient Greek plateia/πλατεια (broad way), which corresponds better to the stem of Plateosaurus, which clearly is "plate-", and not "platy-". Thus, the name should be translated as "broadway lizard"[24] or even "wide gauge lizard".

Taxonomy

Valid species

  • Plateosaurus engelhardti
  • Plateosaurus gracilis
Restoration of P. gracilis, formerly known as Sellosaurus

The taxonomic history of Plateosaurus is complex and confusing. As of 2009, only two species are accepted as valid,[3][24] the type species P. engelhardti and the older P. gracilis, previously referred to as its own genus Sellosaurus. Galton showed clearly that all cranial material from Trossingen, Halberstadt and Frick pertains to one species. Markus Moser performed the most extensive and detailed investigation of all plateosaurid material from Germany and Switzerland, concluding that the Trossingen material stems from the same species as the type material.[24] Sellosaurus is also seen as a synonym, but Moser does not state clearly whether he considers S. gracilis to be identical to P. engelhardti. Palaeontologist Adam Yates of the University of the Witwatersrand casts further doubt on the generic separation, and includes the type material, but not all assigned finds of Sellosaurus gracilis, to Plateosaurus as P. gracilis.[3] Previously, Huene had already concluded this in 1926,[9] but other researchers did not follow.

Invalid species

All named species of Plateosaurus except P. gracilis have turned out to be junior synonyms of the type species or invalid names. Huene[28] practically erected a new species and sometimes a new genus for each relatively complete find from Trossingen (three species of Pachysaurus and seven of Plateosaurus) and Halberstadt (one species of Gressylosaurus and eight of Plateosaurus).[12] Later, he collapsed several of these species, but remained convinced that more than one genus and more than one species of Plateosaurus was present in both localities. Jaekel also believed that the Halberstadt material included several plateosaurid dinosaurs, as well as non-plateosaurid prosauropods.[8] Systematic research by Peter Galton drastically reduced the number of genera and species. Galton synonomized all cranial material,[4][29][30] and described differences between the syntypes of P. engelhardti and the Trossingen material, which he referred to P. longiceps.[31] Galton recognized P. trossingensis, P. fraasianus and P. integer to be identical to P. longiceps.[32] Markus Moser, however, showed clearly that P. longiceps is itself a junior synonym of P. engelhardti.[24] Furthermore, a variety of species in other genera were created for material belonging to P. engelhardti, including Dimodosaurus poligniensis, Gresslyosaurus robustus, Gresslyosaurus torgeri, Pachysaurus ajax, Pachysaurus giganteus, Pachysaurus magnus and Pachysaurus wetzelianus.[24]

Plateosaurus engelhardti (previously P. quenstedti) skull and neck at the Museum für Naturkunde, Berlin

However, it must be noted that there is much prosauropod material from the Germany Knollenmergel in museum collections, most of it labeled as Plateosaurus, that does not belong to the type species, and possibly not to Plateosaurus at all. Some of this material is not diagnostic; other material has been recognized to be different, but was never sufficiently described.[8]

Dubious material

Several prosauropod species are considered to be nomina nuda ('naked names') or nomina dubia ('doubtful names') due to their fragmentary nature and poor preservation. For example, Teratosaurus trossingensis von Huene 1908 is known from only a partial right hind limb, and may belong to practically any Triassic prosauropod.[3]

Taphonomy

The taphonomy of the three main Plateosaurus sites Trossingen, Halberstadt (both in Germany) and Frick (Switzerland) is unusual in several ways.[12] All three sites are nearly monospecific assemblages, meaning that they contain only one species. This is highly unusual, and requires very special circumstances to explain. However, shed teeth of theropods have been found at all three sites, as well as remains of Proganochelys, an early turtle. All sites yielded almost complete and partial skeletons of Plateosaurus, as well as isolated bones. The partial skeletons tend to include the hind limbs and hips, while parts of the anterior body and neck are rarely found in isolation. The animals were all adults or sub-adults; no juveniles or hatchlings are known. Complete skeletons and large skeleton parts that include the hind limbs all rest right side up, as do the turtles. Also, they are mostly well articulated, and the hind limbs are three-dimensionally preserved in a zig-zag posture, with the feet often much deeper in the sediment than the hips.[12]

Earlier interpretations

In the first published discussion of the Trossingen Plateosaurus finds, Fraas suggested that only miring in mud allowed the preservation of the single complete skeleton then known.[33] Similarly, Jaekel interpreted the Halberstadt finds as animals that waded too deep into swamps, became mired and drowned.[8] He interpreted partial remains as having been transported into the deposit by water, and strongly refuted a catastrophic accumulation. In contrast, von Huene interpreted the sediment as aeolian deposits, with the weakest animals, mostly juveniles, succumbing to the harsh conditions in the desert and sinking into the mud of ephemeral water holes.[10] He argued that the completeness of many finds indicated that transport did not happen, and saw partial individuals and isolated bones as results of weathering and trampling. Seemann developed a different scenario, in which Plateosaurus herds congregated on large water holes, and some herd members got pushed in. Light animals managed to get free, heavy ones got stuck and died.[34]

A different school of thought developed almost half a century later, with Weishampel suggesting that the skeletons from the lower layers stemmed from a herd that died catastrophically in a mudflow, while those in the upper layers accumulated over time. Weishampel explained the curious monospecific assemblage by theorizing that Plateosaurus were common during this period.[11] This theory was erroneously attributed to Seemann in a popular account of the plateosaurs in the collection of the Institute and Museum for Geology and Paleontology, University of Tübingen,[35] and has since become the standard explanation on most internet sites and in popular books on dinosaurs. Rieber proposed a more elaborate scenario, which included the animals dying of thirst or starvation, and being concentrated by mudflows.[36]

Current interpretation

A detailed re-assessment of the taphonomy by palaeontologist Martin Sander of the University of Bonn, Germany, found that the mud-miring hypothesis first suggested by Fraas[33] is true: animals above a certain body weight sank into the mud, which was further liquidified by their attempts to free themselves. This scenario, similar to that proposed for the famous Rancho La Brea Tar Pits, is the only one explaining all taphonomic data. The degree of completeness of the carcasses was not influenced by transport, which is obvious from the lack of indications for transport before burial, but rather by how much the dead animals were scavenged. Juveniles of Plateosaurus and other taxa of herbivores were too light to sink into the mud, or managed to extract themselves, and were thus not preserved. Similarly, the scavenging theropods were not trapped due to their lower body weights, combined with a proportionally larger footprint. There is no indication of herding, nor of catastrophic burial of such a herd, or catastrophic accumulation of animals that previously died isolated elsewhere.

Palaeobiology

Posture and gait

Example of a P. engelhardti cast (of specimen SMNS13200) mounted in the outdated quadrupedal pose, Staatliches Museum für Naturkunde Stuttgart (Museum am Löwentor)

Practically any imaginable posture has been suggested for Plateosaurus in the scientific literature at some point in time. von Huene assumed digitigrade bipedality with erect hind limbs for the animals he excavated at Trossingen, with the backbone held at a steep angle at least during rapid locomotion.[9][37] In contrast, the main investigator of the Halberstadt material, Jaekel, initially concluded that the animals walked like lizards, i.e. quadrupedally with a sprawling limb position, plantigrade, and laterally undulating the body.[38] Only a year later, Jaekel instead favoured a clumsy, kangaroo-like hopping,[39] a change of heart for which he was mocked by German zoologist Gustav Tornier,[40] who interpreted the shape of the articulation surfaces in the hip and shoulder as typically reptilian. Fraas, the first excavator of the Trossingen lagerstätte, also favoured a reptilian posture.[33][41] One of the most absurd publications on this topic was written by Müller-Stoll, who listed a number of characters required for an erect limb posture that Plateosaurus supposedly lacked, concluding that the lizard-like reconstructions were correct.[42] However, most of these adaptations are actually present in Plateosaurus.[2][5]

Cast of a P. engelhardti skeleton mounted in the correct bipedal fashion, Natural History Museum of Milan

From 1980 on, an increased understanding of dinosaur biomechanics and studies by palaeontologists Christian and Preuschoft on the resistance to bending of the back of Plateosaurus[43][44] lead to widespread acceptance of an erect, digitigrade limb posture and a roughly horizontal position of the back.[24][35][45][46 ][47][48] Many researchers were of the opinion that Plateosaurus could use both quadrupedal gaits (for slow speeds) and bipedal gaits (for rapid locomotion),[43][44][45][47] while Wellnhofer insisted that the tail curved strongly downward, making a bipedal posture impossible.[48] However, Moser showed that the tail was in fact straight.[24]

This consensus was shattered by two detailed studies of the fore limbs of Plateosaurus by Bonnan and Senter (2007) and Mallison (in press), which both clearly showed that Plateosaurus was incapable of pronating its hands.[5][49][50] The pronated position in some museum mounts had been achieved by exchanging the position of radius and ulna in the elbow. Plateosaurus was an obligate digitigrade biped. Further indicators for a purely bipedal mode of locomotion are the great difference in limb length (the hind limb is roughly twice as long as the forelimb), the very limited motion range of the forelimb, and the fact that the center of mass rests squarely over the hind limbs.[2][5][50]

Plateosaurus shows a number of cursorial adaptations, including an erect hind limb posture, a relatively long lower leg, an elongated metatarsus and a digitigrade foot posture.[2] However, in contrast to mammalian cursors, the moment arms of the limb extending muscles are short, especially in the ankle, where a distinct, moment arm-increasing tuber on the calcaneum is missing.[9] This means that in contrast to running mammals, the animal probably did not use gaits with aerial, unsupported phases. Instead, Plateosaurus must have increased speed by using higher stride frequencies, created by rapid and powerful limb retraction. Reliance on limb retraction instead of extension is typical for non-avian dinosaurs.[51]

Feeding and diet

P. engelhardti skull in semi profile

Important cranial characteristics (such as jaw articulation) of most prosauropods are closer to those of herbivorous reptiles than those of carnivorous ones, and the shape of the tooth crown is similar to those of modern herbivorous or omnivorous iguanas. The maximum width of the crown was greater than that of the root, resulting in a cutting edge similar to those of extant herbivorous or omnivorous reptiles.[46 ] Paul Barrett proposed that prosauropods supplemented their herbivorous diets with small prey or carrion.[52] The old, widely cited idea that large dinosaurs, including Plateosaurus, swallowed gastroliths (gizzard stones) to digest food because of their relatively limited ability to deal with food orally has been refuted by a study on gastrolith abdunance, weight, and surface structure in fossils compared to alligators and ostriches by Oliver Wings.[53][54]

Growth and metabolism

Similar to all non-avian dinosaurs studied to date, Plateosaurus grew in a pattern that is dissimilar to both extant mammals and other dinosaurs. In the closely related sauropods with their typical dinosaurian physiology, growth was initially rapid, continued somewhat slower well beyond sexual maturity, but was determinate, i.e. the animals stopped growing at a maximum size.[55] Mammals grow rapidly, but sexual maturity falls typically at the end of the rapid growth phase. In both groups, the final size is relatively constant, with humans atypically variable. Extant reptiles show a sauropod-like growth pattern, with initially faster growth, then a reduction in growth rate after sexual maturity, and almost, but not fully, stop growing at old age. However, their initial growth rate is much lower than in mammals, birds and dinosaurs. The reptilian growth rate is also very variable, so that individuals of the same age may have very different sizes, and final size also varies significantly. In extant animals, this growth pattern is linked to behavioural thermoregulation and a low metabolic rate (i.e. ectothermy), and is called developmental plasticity.[1]

Plateosaurus followed a trajectory similar to sauropods, but varied growth rate and final size as seen in extant reptiles, probably in response to environmental factors such as food availability. Some individuals were fully grown at only 4.8 metres (16 ft) total length, while others reached 10 metres (33 ft). However, the bone microstructure indicates rapid growth, as in sauropods and extant mammals, which indicates endothermy. Plateosaurus apparently represents an early stage in the development of endothermy, in which endothermy was decoupled from developmental plasticity. This hypothesis is based on a detailed study of Plateosaurus long bone histology conducted by Martin Sander and Nicole Klein of the University of Bonn, Germany.[1]

Long bone histology also allows estimating the age a specific individual reached. Sander and Klein found that some individuals were fully grown at 12 years of age, others were still slowly growing at 20 years, and one individual was still rapidly growing at 18 years. The oldest individual found was 27 years and still growing; most individuals were between 12 and 20 years old.[1] Due to the absence of individuals smaller than 4.8 meters long, it is not possible to deduce a complete ontogenetic series for Plateosaurus, or determine the growth rate of animals under 10 years of age.

Plateosaurus on exhibition

Mounted P. engelhardti cast with incorrectly pronated hands, Museo del Jurásico de Asturias

Publicly exhibited skeletons or skeleton parts or life-sized models of Plateosaurus can be found in the following institutions and locations: In Germany:

  • Bayrische Staatssammlung für Paläontologie und Geologie, Munich [3]
  • one mounted skeletal cast. This mount has disarticulated lower arms, creating enforced pronation.
  • GPIT 1: nearly complete individual, mounted in bipedal pose with horizontal back. Minor errors only.
  • GPIT 2: nearly complete composite skeleton, anterior half and posterior half each from one individual. Mounted in a bipedal running pose. The back is incorrectly angled steeply.
  • various partial skeletons in position as found at the feet of the two mounts
  • Staatliches Museum für Naturkunde Stuttgart, Stuttgart [4]
  • SMNS F33 [5], articulated individual lacking the skull and tail. One of the best preserved finds in the world.
  • "Sellosaurus" gracilis hind limb and partial sacrum.
  • Mounted cast of SMNS13200 [6], a nearly complete individual. Previously part of a group of casts mounted in different poses, this quadrupedal version is the sole remaining mount since the museum's exhibition re-design in 2007. Significant errors: the ribcage is flat oval instead of high oval, the limbs sprawl, enforced pronation through disarticulated lower arm.[2][5]
  • Several life-sized reconstructions. Pre-2007 models with massive errors of proportion, new models with minor inaccuracies. Some in impossible quadrupedal pose.
  • Nearly complete individual, mounted in plantigrade, kangaroo-like position.
Mounted P. engelhardti cast in the Museum for Natural Science in Kassel, with radius and ulna switched around
  • Cast of SMNS 13200 in tripodal pose. Formerly exhibited at the Staatliches Museum für Naturkunde Stuttgart, this mount has an impossible curvature of the back, sprawling limbs, incorrectly aligned ribs and metatarsals, and misplaced radii and ulnae.
  • [10] Articulated skull and neck.

In Switzerland:

  • Sauriermuseum Frick, Frick
  • MSF 23 [11], nearly complete individual from Frick, in position as found.
  • several partial skeletons
  • mounted cast in quadrupedal pose.

In the US:

Front view of the AMNH P. engelhardti specimen
  • AMNH 6810, nearly complete individual from Trossingen, mounted in bipedal pose.
  • nearly complete composite individual from Trossingen.[56]

Popular culture

Like this full sized model in Germany, Plateosaurus is often erroneously shown walking quadrupedally in popular depictions

Plateosaurus has frequently been featured in various forms of media. In the opening sequence of The Land Before Time II: The Great Valley Adventure, Plateosaurus was featured briefly. Plateosaurus was also featured briefly in the first episode ("New Blood") of the BBC television series Walking with Dinosaurs, to illustrate the success of dinosaurs. Plateosaurus has also had a few appearances in European BD. A huge and apparently carnivorous Plateosaurus attacks Dr. Mortimer in Le Piège diabolique, while a similarly gigantic (but herbivorous and dimwitted) Plateosaurus inadvertently causes havoc in Le voyageur du Mésozoïque.

References

  1. ^ a b c d Sander, M. and Klein, N. (2005). "Developmental plasticity in the life history of a prosauropod dinosaur". Science 310:1800-1802. doi:10.1126/science.1120125
  2. ^ a b c d e Mallison, H. (accepted). "The digital Plateosaurus I: body mass, mass distribution and posture assessed using CAD and CAE on a digitally mounted complete skeleton". Palaeontologia Electronica
  3. ^ a b c d e f Yates, A.M. (2003). "Species taxonomy of the sauropodomorph dinosaurs from the Löwenstein Formation (Norian, Late Triassic) of Germany". Palaeontology 46(2):317-337.
  4. ^ a b Galton, P.M. (1984). "Cranial anatomy of the prosauropod dinosaur Plateosaurus from the Knollenmergel (Middle Keuper, Upper Triassic) of Germany. I. Two complete skulls from Trossingen/Württ. With comments on the diet". Geologica et Palaeontologica 18:139-171.
  5. ^ a b c d e Mallison, H. (in review). "The digital Plateosaurus II: an assessment of the range of motion of the limbs and vertebral column and of previous reconstructions using a digital skeletal mount". Acta Palaeontologica Polonica
  6. ^ Frappell, P.B., Hinds, D.S. and Boggs, D.F. (2001). "Scaling of respiratory variables and the breathing pattern in birds: an allometric and phylogenetic approach". Physiological and Biochemical Zoology 74(1):75–89
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External links


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Plateosaurus engelhardti

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Reptilia
Subclassis: Diapsida
Infraclassis: Archosauromorpha
Divisio: Archosauria
Subsectio: Ornithodira
Superordo: Dinosauria
Ordo: Saurischia
Taxon: Eusaurischia
Subordo: Sauropodomorpha
Infraordo: Prosauropoda
Superfamilia: Plateosauria
Familia: Plateosauridae
Genus: Plateosaurus
Species: P. engelhardti - P. longiceps

Name

Plateosaurus Meyer, 1837

Vernacular Name

日本語: プラテオサウルス
中文: 板龍

Simple English

Plateosaurus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Superorder: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Infraorder: Prosauropoda
Family: Plateosauridae
Genus: Plateosaurus
Meyer, 1837

Plateosaurus (meaning 'flat lizard') is a genus of plateosaurid prosauropod dinosaur that lived during the Norian and Rhaetian stages of the Late Triassic Period, around 216 to 199 million years ago in what is now Europe. The Plateosaurus was the fist long-necked plant eater in the Triassic Period. An adult Plateosaurus can weigh up to 1,500 pounds and 27 feet long. They use both hands to pull leaves off trees, but since they have weak teeth, they use their sharp thumb claws to defense themselves against predators.








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