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TriassiccarnivoreFossil completeness: excellent

Tawa hallae

Pronunciation: TAH-wah HAL-eye

A lightly built Late Triassic theropod from Ghost Ranch, represented by several articulated skeletons that illuminate early dinosaur dispersal.

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Tawa hallae

The page URL and title are included automatically. Optional contact details are used only to discuss this report. Do not submit private information or precise sensitive fossil-site coordinates.

Last updated 26 July 2026

Side-view life reconstruction of Tawa hallaeArt by TotalDino · CC BY-SA 4.0

Field guide

Overview

Tawa hallae was an early theropod from the Late Triassic Chinle Formation of New Mexico. Multiple associated skeletons preserve nearly the entire body, including a delicate skull. Tawa combines primitive dinosaur features with traits seen in later theropods, making it important for understanding the earliest radiation of carnivorous dinosaurs. Its presence alongside other distantly related early dinosaurs at Ghost Ranch supports repeated dispersal into North America rather than a single local radiation.

Its fossils occur between approximately 215 and 213 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

Form and function

Anatomy

Tawa had a long, low skull with recurved serrated teeth, a flexible neck, grasping hands and long hind limbs. Air spaces invaded parts of the neck vertebrae, an early expression of the pneumatic system elaborated in later theropods and birds. Its lightly built skeleton and long tail supported agile bipedal movement.

  • Long, low skull with serrated recurved teeth
  • Lightly built bipedal skeleton
  • Grasping hands with curved claws
  • Early pneumatic openings in neck vertebrae
  • Long hind limbs and balancing tail
  • Mixture of primitive and derived theropod traits

Evolutionary position

Scientific classification

  1. 1Dinosauriaclade
  2. 2Saurischiaclade
  3. 3Theropodaclade
  4. 4Tawagenus
  5. 5Tawa hallaespecies

This simplified classification path shows one placement from Dinosauria to this species. Each step is clickable, and other analyses may support alternative relationships.

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Scale

Size comparison

Scientific record

Discovery and naming

A field team led by Alex Downs discovered the first Tawa material in the Hayden Quarry at Ghost Ranch in 2004. Continued excavation produced skeletons of several growth stages. Sterling Nesbitt and colleagues named Tawa hallae in Science in 2009. Tawa is the Hopi name for the Sun spirit, and the species honours Ruth Hall, founder of the Ghost Ranch Museum of Paleontology.

Discovery credit: Alex Downs, Ghost Ranch field crews.

Naming authors: Sterling J. Nesbitt, Nathan D. Smith, Randall B. Irmis and 3 coauthors.

Palaeoenvironment

Habitat and behaviour

The Chinle Formation at Ghost Ranch records river channels and seasonal floodplains in an increasingly arid interior of Pangaea. Tawa lived alongside coelophysoids, the unusual Daemonosaurus, crocodile-line archosaurs and other reptiles.

Tawa's teeth and grasping hands identify it as a small carnivore that probably hunted vertebrates and other manageable prey. Several individuals accumulated in the Hayden Quarry, but the burial assemblage does not establish social hunting or herd structure.

Worth knowing

Field notes

  • Its name comes from the Hopi Sun spirit Tawa.
  • Several skeletons represent different growth stages.
  • The holotype preserves most of the skull and skeleton.
  • Its anatomy helped support a South American origin followed by early dinosaur dispersal.

Fossil distribution

Fossil locations

Ghost Ranch, Hayden Quarry regionGhost Ranch, Hayden Quarry region, New Mexico, United States
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Ghost Ranch, Hayden Quarry region

New Mexico, United States

Chinle Formation

approximate site marker

Markers are deliberately approximate. They identify published fossil areas without exposing sensitive excavation coordinates.

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Fossil specimen record

Museums and research collections

Ruth Hall Museum of Paleontology

verified

Abiquiú, United States

Ghost Ranch interprets the Hayden Quarry discoveries and the early dinosaurs recovered from its Chinle Formation badlands.

Record type: castChecked 26 July 2026Institution website

A research repository is not necessarily a public exhibit. Loan and display status can change, so check with the institution before visiting.

Scientific uncertainty

  • Analyses agree that Tawa is an early theropod but differ in its precise position relative to coelophysoids.
  • The Hayden Quarry association does not prove that Tawa lived or hunted in groups.
  • Body mass is estimated from incomplete growth-stage samples.
  • Colour and external body covering remain unknown.

Evidence

References and sources

  1. 01
    The Paleobiology Database

    Open source
  2. 02
    A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs

    Sterling J. Nesbitt, Nathan D. Smith, Randall B. Irmis and 3 coauthors · Science 326(5959), 1530–1533 · 2009

    Open source
  3. 03
    Tawa hallae: early dinosaur evolution at Ghost Ranch

    U.S. National Science Foundation

    Open source