The Dinosaur That Existed Before “Dinosaur” Was a Word

Plateosaurus was named in 1837. Richard Owen invented the word “dinosaur” in 1842. For five years, Plateosaurus existed as a scientific genus without belonging to any named group, because the group didn’t have a name yet. It is one of the oldest, best-understood, and most scientifically important early dinosaurs, and most people have never heard of it.

Plat-ee-oh-SAWR-us — “plat-ee-oh-SAWR-us”

Fast Facts

Field	Info
Time period	Late Triassic, around 214–204 million years ago — among the very first large dinosaurs, roughly 150 million years before T. rex
Fossils found	Germany, Switzerland, France, Greenland — over 100 specimens known
Length	16–33 feet — but with extraordinary variation between individuals (see Fun Facts)
Weight	600 kg to 4,000 kg — same species, wildly different sizes
Diet	Plants — ferns, conifers, cycads; probably selective browsing
Speed	Moderate bipedal runner — obligate biped, not able to walk on all fours despite earlier assumptions

Fun Facts

Adults of the same species varied in size more than almost any other dinosaur.

Most dinosaur species have a fairly consistent adult size. Plateosaurus did not. Fully grown adults ranged from 4.8 metres to 10 metres long — and from 600 kg to 4,000 kg in weight. That’s the same species, at the same life stage, ranging from the size of a large horse to the size of a small elephant. This extraordinary variation — called developmental plasticity — appears to have been driven by environmental conditions. This variation may reflect developmental plasticity, with growth strongly influenced by environmental conditions. It may have been an adaptation that allowed Plateosaurus to survive fluctuating conditions without going extinct.

It was named five years before “dinosaur” was a word

Hermann von Meyer described Plateosaurus in 1837. Richard Owen coined “Dinosauria” in 1842, and when he did, he used three genera to define the group: Megalosaurus, Iguanodon, and Hylaeosaurus. Plateosaurus wasn’t included because, at the time, it was poorly known and hard to categorise. It predated its own taxonomic home by five years.

Dozens of individuals died in the same mud traps, repeatedly.

The three main Plateosaurus fossil sites — Trossingen and Halberstadt in Germany, and Frick in Switzerland — were all ancient mud mires. Plateosaurus appears to have been repeatedly drawn to these boggy areas, possibly to feed on plants growing there, and got stuck. The larger and heavier the individual, the harder it was to escape. The Frick site in Switzerland may extend for over a kilometre and a half, potentially containing hundreds of individuals. It is one of the richest dinosaur sites in Europe.

It was obligately bipedal — its arms genuinely could not walk.

For much of the 20th century, Plateosaurus was reconstructed as a quadruped or facultative biped — sometimes on two legs, sometimes four. Detailed biomechanical analysis in the 2000s and 2010s showed this was wrong. The wrist anatomy of Plateosaurus physically prevented it from placing its hands flat on the ground in a walking posture. It was a full-time biped. All those old reconstructions with it on all fours are incorrect.

It may have been warm-blooded in an unusual way.

A landmark 2005 study of Plateosaurus bone histology found something strange: the growth rings in its bones look like those of a warm-blooded animal, but the growth pattern — adjusting pace based on conditions — looks like cold-blooded behaviour. It may have had a genuinely intermediate metabolism, or one that had features of both strategies. This finding matters because Plateosaurus is early enough in dinosaur evolution that understanding its physiology helps explain how warm-bloodedness developed across the group.

One of the best-studied early dinosaurs in the world

With over 100 specimens, including many near-complete skeletons, Plateosaurus is better represented in the fossil record than almost any other Triassic dinosaur. It is the reference point against which other early sauropodomorphs are measured and the standard-bearer for understanding what the very first large dinosaurs looked like.

It had large claws on its hands — possibly used for feeding and defence

The three grasping fingers on each hand bore substantial claws. These may have been used to hook branches and pull vegetation down to feeding height, and may also have served in defence against the predators of the time — early theropods and other Triassic carnivores considerably smaller than Plateosaurus itself.

Did You Know — Was It an Ancestor of the Giant Sauropods?

For a long time, Plateosaurus was presented as a direct ancestor of animals like Diplodocus and Apatosaurus — the prototype from which the great long-necked giants evolved. Modern cladistic analysis has complicated this picture.

Plateosaurus was a basal sauropodomorph — an early member of the broader group that eventually produced sauropods — but it is not considered a direct ancestor of any specific sauropod lineage. It was very likely more of an early branching relative than a true precursor. The broad body plan it shared with later sauropods — long neck, small head, upright posture, herbivorous teeth — reflects a common heritage, not a direct line of descent. It is a cousin, not a grandfather.

Myths & Movie Moments

It walked on all fours.

For most of the 20th century, museum mounts and illustrations showed Plateosaurus as a quadruped or semi-quadruped. This is now definitely wrong. The anatomy of the wrist and forelimb makes quadrupedal walking impossible. Some older museum mounts still show the outdated posture — a living record of how science has changed.

It was a slow, primitive, transitional animal.

Plateosaurus is sometimes presented as a clumsy stepping stone between earlier small dinosaurs and the great sauropods. It was actually a highly successful, widespread animal that dominated European ecosystems for millions of years, was probably warm-blooded, and had sophisticated adaptations for its environment. “Primitive” relative to later dinosaurs doesn’t mean poorly adapted to its own time.

It was the direct ancestor of Diplodocus and friends

The ancestral relationship between Plateosaurus and true sauropods is more complicated than the classic “prosauropod → sauropod” sequence suggested. Plateosaurus was in the right part of the family tree, but the lineage leading to Jurassic giants diverged in ways that don’t trace directly back to Plateosaurus specifically.

What If It Appeared Today?

A Plateosaurus appearing in the temperate forests and farmland of modern Germany or Switzerland would find a dramatically different world from the hot, arid, semi-tropical landscape it evolved in. Whether modern vegetation — flowering plants, grasses, broad-leafed deciduous trees — would suit its digestive system is genuinely uncertain.

At up to 4 tons and 10 metres, a large individual would very probably have few if any natural predators. It would very likely strip considerable vegetation from any area it moved through. Its grasping clawed hands would probably be effective at pulling branches down to feeding height.

The most interesting consequence: it’s reasonable to think a site like the Swiss Mittelland — where the Frick fossil beds lie — would see Plateosaurus drawn to any boggy or soft-ground areas, possibly with fatal results, just as it was 210 million years ago.

Could You Keep One as a Pet?

Size: Ranges from large-horse to small-elephant within the same species. You might get lucky. You probably wouldn’t.

Diet: Tough Triassic plants — ferns, conifers, cycads. Modern plant compatibility is uncertain, but its grinding teeth and grasping hands suggest it was reasonably adaptable at finding and processing vegetation.

Temperament: Probably not aggressive toward things it didn’t consider food. But claws substantial enough to pull down conifer branches would cause considerable accidental damage to soft furnishings, fences, and people.

The specific problem: Its arms couldn’t touch the ground in a walking position. This means every interaction would be conducted from an upright bipedal stance, with grasping clawed hands at approximately shoulder height. Affectionate or curious behaviour would be structurally eventful.

Modern equivalent: A large, inquisitive, plant-eating bipedal lizard the size of a horse that hooks things with its hands.

Verdict: 🟡 Chaotic — Absolutely chaotic. Even the smaller ones would be a terrible idea.

Final Thought

Plateosaurus walked the earth when the continents were still joined, when Europe was a desert crossed by rivers, and when dinosaurs were still newcomers — untested, uncertain, not yet the rulers of anything. One of the most abundant large animals of its era. Over 100 of its skeletons have been pulled from European rock, and scientists are still learning from them. The mud that killed so many of them preserved something remarkable: not just bones, but a window into how the very first age of dinosaurs actually worked.