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Herrerasaurus, Late TriassicIschigualasto Formation, Argentina · named 1963
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Herrerasaurus

heh-RARE-ah-SORE-us

"Herrera's lizard"

Lived
237 to 227 million years ago, Late Triassic
Length
about 4.5 m (15 ft)
Group
Early dinosaurs, Herrerasauridae
Found in
Argentina
Named by
Reig 1963

Size comparison

To scale

Where its fossils were found

The evidence

Today

11 finds

230 million years ago

Map: C. R. Scotese, PALEOMAP

Habitat

It lived on river floodplains with seasonal rainfall and vegetation that probably included conifers and ferns. Eoraptor, Panphagia and Eodromaeus lived in the Ischigualasto region.

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Field notes

About Herrerasaurus

What it was like

Herrerasaurus was one of the earliest known dinosaurs, a bipedal meat eater that grew to about 4.5 meters (15 feet) long. It had a long skull with sharp, curved teeth and strong hind legs built for fast movement.

Its hands had sharp claws for grabbing prey, and it probably hunted small reptiles and other early animals of its time. For years, scientists debated exactly where Herrerasaurus belonged on the family tree, and some early studies were not even sure it was a true dinosaur.

Its world

Herrerasaurus lived from about 237 to 227 million years ago, during the Late Triassic, in what is now Argentina. All known fossils come from the Ischigualasto Formation.

It shared its world with other early dinosaurs, including Eoraptor, Panphagia, and Eodromaeus, at a time when dinosaurs were still a small part of a world dominated by other kinds of reptiles.

How it was found

Reig named Herrerasaurus in 1963, based on fossils found in Argentina. Around 11 finds are now known, including a nearly complete skeleton that helped settle much of the early debate about its classification. Its closest relatives include Staurikosaurus and Sanjuansaurus, other early saurischian dinosaurs from South America.

Field gallery

More views of Herrerasaurus

Scenes reconstructed from the available fossil evidence.

Herrerasaurus in its habitat, photo 1

1 of 7

Lived alongside

Found in the same rock formations

A rock formation can hold fossils laid down millions of years apart, so not every animal here met Herrerasaurus.

The evidence

The science behind Herrerasaurus

Which parts of the picture come from its own bones, and which come from its relatives.

From its own fossils

  • A nearly complete skeleton shows a meat eater that walked on strong hindlegs and balanced its body with a long tail.
  • The long skull held curved, serrated teeth, and an extra joint allowed movement within the lower jaw.
  • Its hands had prominent grasping claws on the inner fingers and smaller outer fingers.

Borrowed from relatives

  • Most of the skeleton is known from its own bones.
  • Scaly skin and lips are inferred from comparisons with other early dinosaurs and their reptile relatives.

Still unknown

  • Its color and skin texture.
  • Which small herrerasaurid fossils belong to young Herrerasaurus.
  • Its exact position among the earliest branches of the dinosaur family tree.

Often drawn wrong

  • Its palms faced inward, rather than lying flat toward the ground.
  • Its tail balanced the body above the ground, rather than dragging behind an upright, kangaroo-like stance.

Discovery timeline

  1. 1963Named itReig
  2. 1992New findSereno & Novas
  3. 1994Full descriptionNovas
  4. 1994Full descriptionSereno
  5. 1994SkullSereno & Novas

Key papers

The research behind what we know of Herrerasaurus

Close relatives

Other members of Herrerasauridae

Sources: Wikidata