Segisaurus
"Tsegi lizard"
- Lived
- 193 to 175 million years ago, Early Jurassic
- Diet
- Carnivore
- Length
- about 1.5 m (5 ft)
- Group
- Theropods, Coelophysidae
- Found in
- United States
- Named by
- Camp 1936
Size comparison
To scale
Scale in metersOutline: typical theropod shape
Where its fossils were found
The evidence
Today
185 million years ago
Habitat
Segisaurus lived among desert dunes preserved in the Navajo Sandstone. The plant eater Seitaad also lived in this desert region.
Field notes
About Segisaurus
What it was like
Segisaurus was a small, slender predator about 1.5 meters (5 feet) long, a relative of Coelophysis. It had long legs for running and probably hunted insects, lizards and other small animals. Its skeleton shows a wishbone, a bone shared with birds.
Its world
It lived in the Early Jurassic in what is now Arizona. Its bones come from the Navajo Sandstone, which formed as a vast desert of sand dunes. The small plant eater Seitaad lived in the same desert.
How it was found
Camp named Segisaurus in 1936 from one partial skeleton. It is named after the canyon where it was found.
Field gallery
More views of Segisaurus
Scenes reconstructed from the available fossil evidence.
1 of 3
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 Segisaurus.
The evidence
The science behind Segisaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- A partial skeleton preserves much of the trunk and limbs, including long legs and a slender shoulder blade.
- Its long bones are hollow, and a wishbone joins the shoulders.
- The preserved hand claws are strongly curved, while the foot claws have gentler curves.
Borrowed from relatives
- Coelophysis helps restore the missing head as a narrow, lightly built skull.
- Dilophosaurus supplies broader comparisons for missing parts of the hands and feet.
Still unknown
- The shape of its skull and neck.
- Its full finger arrangement and the shape of its innermost toe claw.
- Its skin covering, color and adult size.
Often drawn wrong
- A flap of skin along the neck appears in some older restorations, but it is speculative.
Discovery timeline
- 1936Named itCamp
- 2005RedescriptionCarrano, Hutchinson & Sampson
- 2010Same rocksSertich & Loewen
- 2024Close relativeBugos & McDavid
Key papers
The research behind what we know of Segisaurus
Named it
Named Segisaurus from a small partial skeleton found in the Navajo Sandstone of Arizona.
A new type of bipedal dinosaur from the Navajo Sandstone of Arizona. University of California Publications in Geological Sciences 24: 39-56
No link available
Redescription
Confirmed hollow bones and a wishbone, identified the skeleton as a subadult and reassessed its early theropod relationships.
New information onSegisaurus halli, a small theropod dinosaur from the Early Jurassic of Arizona. Journal of Vertebrate Paleontology 25: 835-849
Read the paper : New information onSegisaurus halli, a small theropod dinosaur from the Early Jurassic of Arizona (opens in a new tab)Same rocks
Described Seitaad, a plant eater from the same desert sandstone, whose skeleton was buried in a collapsed dune.
A New Basal Sauropodomorph Dinosaur from the Lower Jurassic Navajo Sandstone of Southern Utah. PLoS ONE 5: e9789
Read the paper : A New Basal Sauropodomorph Dinosaur from the Lower Jurassic Navajo Sandstone of Southern Utah (opens in a new tab)Close relative
Described young Coelophysis skulls, adding comparisons for the lightly built head missing from Segisaurus.
Juvenile skulls of Coelophysis bauri from Ghost Ranch, New Mexico. Acta Palaeontologica Polonica 69
Read the paper : Juvenile skulls of Coelophysis bauri from Ghost Ranch, New Mexico (opens in a new tab)
Close relatives
Other members of Coelophysidae
Sources: Wikidata