Discovered in 1834 by Johann Friedrich Engelhardt and described three years later by Hermann von Meyer, Plateosaurus was the fifth named dinosaur genus that is still considered valid.

Plateosaurus was a bipedal herbivore with a small skull on a long, flexible neck, sharp but plump plant-crushing teeth, powerful hind limbs, short but muscular arms and grasping hands with large claws on three fingers, possibly used for defence and feeding.

Unusually for a dinosaur, Plateosaurus showed strong developmental plasticity: instead of having a fairly uniform adult size, fully grown individuals were between 4.8 and 10 metres (16 and 33 ft) long and weighed between 600 and 4,000 kilograms (1,300 and 8,800 lb).

[3] 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.

Luckily, however, a 2011 study by SMNS curator Rainer Schoch found that, at least from the finds of Seemann's 1932 excavation, "the scientifically most valuable material is still available".

[J] German geologist Hanns Bruno Geinitz in 1846 gave "(πλᾰτῠ́ς, breit)" [English: broad][K] as the origin of the name, with von Meyer's Latin spelling Plateosaurus evidently derived from the stem of πλᾰτέος (plateos), the genitive case of the masculine adjective platys in Ancient Greek.

[L] Agassiz consequently renamed the genus Platysaurus,[M] probably from Greek πλατυς (platys – "broad, flat, broad-shouldered"), creating an invalid junior synonym.

"[20] Von Meyer later gave the formal name Pachypodes or Pachypoda ("thick feet") to his second division of "Saurians with Limbs Similar to Heavy Land Mammalia", but the group was a synonym of Richard Owen's Dinosauria from 1842.

He repeatedly referred to its gigantic size ("Riesensaurus" = giant lizard) and massive limbs ("schwerfüssig"), comparing Plateosaurus to large modern land mammals, but did not describe any important features that fit the terms "flat" or "shaped like an oar.

"[P][19] Researcher Ben Creisler therefore concluded that "broad lizard" is the most suitable translation, and possibly was intended to emphasise the giant size of the animal, in particular its robust limb bones.

[28] The authors of that publication, palaeontologists Albert Prieto-Márquez and Mark A. Norell, refer the skull to P. erlenbergensis, a species erected in 1905 by Friedrich von Huene and regarded as a synonym of P. engelhardti by Markus Moser.

[6][37] The shoulder girdle was narrow (often misaligned in skeletal mounts and drawings),[37] with the clavicles (collar bones) touching at the body's midline,[6] as in other basal sauropodomorphs.

[2] In 1845, von Meyer created the group Pachypodes (a defunct junior synonym of Dinosauria) to include Plateosaurus, Iguanodon, Megalosaurus and Hylaeosaurus.

[1][13][51][52] Before the advent of cladistics in paleontology during the 1980s, with its emphasis on monophyletic groups (clades), Plateosauridae was defined loosely, as large, broad-footed, broad-handed forms with relatively heavy skulls, unlike the smaller "anchisaurids" and sauropod-like "melanorosaurids".

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).

[6][57] In contrast, Jaekel, the main investigator of the Halberstadt material, initially concluded that the animals walked quadrupedally, like lizards, with a sprawling limb position, plantigrade feet, and laterally undulating the body.

[58] Only a year later, Jaekel instead favoured a clumsy, kangaroo-like hopping,[36] a change of heart for which he was mocked by German zoologist Gustav Tornier,[59] who interpreted the shape of the articulation surfaces in the hip and shoulder as typically reptilian.

[60][61] Müller-Stoll listed a number of characters required for an erect limb posture that Plateosaurus supposedly lacked, concluding that the lizard-like reconstructions were correct.

[37][40][70] A recent study based on the cross-sectional geometry of long limb bones, comparisons with extant taxa and inference models also confirmed a bipedal posture and erect stance for Plateosaurus.

The maximum width of the crown was greater than that of the root for the teeth of most "prosauropods", including Plateosaurus; this results in a cutting edge similar to those of extant herbivorous or omnivorous reptiles.

In the closely related sauropods with their typical dinosaurian physiology, growth was initially rapid, continuing somewhat more slowly well beyond sexual maturity, but was determinate, i.e. the animals stopped growing at a maximum size.

Extant reptiles show a sauropod-like growth pattern, initially rapid, then slowing after sexual maturity, and almost, but not fully, stopping in old age.

In extant animals, this growth pattern is linked to behavioural thermoregulation and a low metabolic rate (i.e. ectothermy), and is called "developmental plasticity".

Plateosaurus followed a trajectory similar to sauropods, but with a varied growth rate and final size as seen in extant reptiles, probably in response to environmental factors such as food availability.

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.

Due to the absence of individuals smaller than 4.8 metres (16 ft) long, it is not possible to deduce a complete ontogenetic series for Plateosaurus or determine the growth rate of animals less than 10 years of age.

[44] Comparisons between the scleral rings and estimated orbit size of Plateosaurus and modern birds and reptiles suggest that it may have been cathemeral, active throughout the day and night, possibly avoiding the midday heat.

[3] 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.

[5] In contrast, von Huene interpreted the sediment as aeolian deposits, with the weakest animals, mostly subadults, succumbing to the harsh conditions in the desert and sinking into the mud of ephemeral water holes.

[81] 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[60] is true:[3] animals above a certain body weight sank into the mud, which was further liquefied by their attempts to free themselves.