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Segisaurus

Camp, 1936 SAYG-ee-SAWR-us

Named after Tsegi Canyon, Arizona, where the only known specimen was discovered, combined with Greek sauros, "lizard" — means "Tsegi Canyon lizard"

192.9–174.7 million years ago Pliensbachian–Toarcian, Early Jurassic
Early Jurassic stages

Segisaurus is a genus of small coelophysid theropod dinosaur, that measured approximately 1 meter (3.3 feet) in length. The only known specimen was discovered in early Jurassic strata in Tsegi Canyon, Arizona, for which it was named. Segisaurus is the only dinosaur to have ever been excavated from the area.

Diagnosis

  1. Well-developed clavicle retained (persistent clavicle unique among known coelurosaurs at time of description)
  2. Incompletely enclosed pubic fenestra (obturator notch rather than fully enclosed foramen)
  3. Completely enclosed ischial fenestra (not seen in other dinosaurs)
  4. Solid vertebral centra and solid limb bones (fibula with only slight marrow cavity; tibia and centra fully solid)
  5. Midcaudal vertebrae bearing a supplementary anterior neural spine in addition to the principal spine
  6. Hind foot with vestigial first and fifth digits; forefoot third digit slender and compressed, lying closely parallel to and nearly equal in length to second digit

Species

Segisaurus halli Camp, 1936

Type species

Named in honor of Ansel Hall, a colleague of the describer Charles Camp.

Holotype
UCMP 32101 , University of California Museum of Paleontology
Material
Partial skeleton: shoulder girdle, anterior dorsal and caudal vertebrae, left humerus, partial left radius/ulna and manus, ribs, parasternum, sacrum, pelvis, complete left hind limb and foot, and parts of the right hind limb
Horizon
Navajo Sandstone Formation, Pliensbachian–Toarcian, Early Jurassic , 192.9–174.7 million years ago
Locality
UCMP locality V338, Arizona, United States

References

  1. Camp, C. L. (1936). A new type of bipedal dinosaur from the Navajo Sandstone of Arizona. University of California Publications in Geological Sciences 24(2): 39-56. camp1936a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026c