Open Paleo

Herrerasaurus

Reig, 1963 he-RER-a-SAWR-us

Named for Victorino Herrera, the Argentine rancher who discovered the first specimen in 1958, combined with Greek 'sauros' meaning 'lizard', meaning 'Herrera's lizard'.

237.0–227.3 million years ago Carnian, Late Triassic
Late Triassic stages

Herrerasaurus is likely a genus of saurischian dinosaur from the Late Triassic period. Measuring 6 m (20 ft) long and weighing around 350 kg (770 lb), this genus was one of the earliest dinosaurs from the fossil record. Its name means "Herrera's lizard", after the rancher who discovered the first specimen in 1958 in South America. All known fossils of this carnivore have been discovered in the Ischigualasto Formation of Carnian age (late Triassic according to the ICS, dated to 231.4 million years ago) in northwestern Argentina. The type species, Herrerasaurus ischigualastensis, was described by Osvaldo Reig in 1963 and is the only species assigned to the genus. Ischisaurus and Frenguellisaurus are synonyms.

Diagnosis

  1. Robust, high premaxilla with three teeth; tall maxilla with eight teeth
  2. Dentary with twelve teeth; mandibular symphysis strong and taller than alveolar ramus
  3. Sacrum with three vertebrae
  4. Short, tall ilium with very robust anterior spine; pubis nearly perpendicular to vertebral axis with expanded distal 'foot' similar to Antrodemus
  5. Gracile femur slightly curved in S-form with clear greater trochanter and distinct aliform fourth trochanter in upper 2/5 of bone
  6. Robust tibia shorter than femur (tibia/femur index: 87); wide astragalus without ascending process; very small calcaneum
  7. Central metatarsals more elongate than typical for size (3rd Mt./femur index: 45)

Species

Herrerasaurus ischigualastensis Reig, 1963

Type species

Named for the Ischigualasto Formation of Argentina, where all known fossils were discovered.

Holotype
PVL 2566 , Colección de Paleontologia de Vertebrados de la Fundación Instituto Miguel Lillo
Material
Partial skeleton
Horizon
lower Ischigualasto Formation, Carnian, Late Triassic , 237.0–227.3 million years ago
Locality
a few kilometers east-southeast of Aguada de la Peña, San Juan, Argentina Reig (1963) places the holotype by bearing from Aguada de la Peña and names no site. A referred specimen comes from Valle Pintado, which is also the type locality of Panphagia and Chromogisaurus.

Synonyms of the genus

Name Type Reason
Frenguellisaurus junior subjective Material is now considered indistinguishable from Herrerasaurus.
Ischisaurus junior subjective Now interpreted as juvenile material of Herrerasaurus.

Notable specimens

  • PVSJ 407

    División de Paleontología de Vertebrados del Museo de Ciencias Naturales y Universidad Nacional de San Juan pathology

    Referred Herrerasaurus skull bearing a pit in a skull bone and two pits on the splenial, attributed to a bite. Surrounding bone is swollen and porous, indicating a short-lived non-lethal infection, likely sustained in a fight with another Herrerasaurus.

    Sereno & Novas (1993)

References

  1. Reig, O. A. (1963). La presencia de dinosaurios saurisquios en los "Estratos de Ischigualasto" (Mesotriasico Superior) de las provincias de San Juan y La Rioja (República Argentina) [The presence of saurischian dinosaurs in the "Ischigualasto beds" (upper Middle Triassic) of San Juan and La Rioja Provinces (Argentine Republic)]. Ameghiniana 3(1): 3-20. reig1963a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Illustrated by E. Viola.

    jones2026c
  3. Sereno, P. C.; Novas, F. E. (1993). The skull and neck of the basal theropod Herrerasaurus ischigualastensis. Journal of Vertebrate Paleontology 13(4): 451-476. doi:10.1080/02724634.1994.10011525

    Source of the hip height estimate.

    sereno1993b