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Leyesaurus, Early JurassicBalde de Leyes Formation, Argentina · named 2011
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Leyesaurus

"Leyes lizard"

Lived
201 to 175 million years ago, Early Jurassic
Group
Early sauropodomorphs, Massospondylidae
Found in
Argentina
Named by
Apaldetti et al. 2011

Where its fossils were found

The evidence

Today

1 find

190 million years ago

Map: C. R. Scotese, PALEOMAP

Habitat

It lived in northwestern Argentina, where streams spread sand and gravel into broad fans of sediment.

Field notes

About Leyesaurus

What it was like

Leyesaurus was a plant eater from the long-necked line that later produced the giant sauropods, a relative of Massospondylus. It is known from a skull, neck bones and parts of the limbs.

Its world

It lived in what is now northwestern Argentina. Its fossils come from the Balde de Leyes Formation, whose age is tentatively placed in the Early Jurassic rather than firmly established.

How it was found

Apaldetti and colleagues named Leyesaurus in 2011, from a single find. Its name honors the family who found it.

Field gallery

More views of Leyesaurus

Scenes reconstructed from the available fossil evidence.

Leyesaurus in its habitat, photo 1

1 of 3

The evidence

The science behind Leyesaurus

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

From its own fossils

  • A partial skeleton preserves the skull and jaws, neck vertebrae, two tail vertebrae, damaged parts of the shoulder and upper arm, parts of the hips, the lower end of a fibula and part of the left foot.
  • Its neck vertebrae are especially long, and the outer faces of its upper teeth bulge outward.
  • The skull is short and low. The bones were found scattered, and are treated as one animal because they lay close together, none is repeated and they match in size.

Borrowed from relatives

  • Missing parts of the body, limbs and tail are restored by comparison with its close relative Adeopapposaurus.

Still unknown

  • The shape and size of its nostrils. The bones over the top of the snout are missing.
  • Exactly which foot bones it preserved. A bone once described as a distinctive foot bone was later identified as the lower end of the fibula, a slender bone of the lower leg.
  • Its skin covering, its color and how its body changed as it grew.

Discovery timeline

  1. 2009Close relativeMartínez
  2. 2011Named itApaldetti et al.
  3. 2018Family treeMarsh & Rowe
  4. 2025RedescriptionPeyre de Fabrègues et al.

Key papers

The research behind what we know of Leyesaurus

Close relatives

Other members of Massospondylidae

Sources: Wikidata