Open Paleo

Lepidus

Nesbitt & Ezcurra, 2015 LEH-pee-doos /ˈlɛpɪdəs/

Latin for 'fascinating' or 'charming'.

237.0–205.7 million years ago Carnian–Norian, Late Triassic
Late Triassic stages

Lepidus is a genus of extinct theropod from the Upper Triassic of the United States. It lived in the Otis Chalk localities of the Dockum Group in Texas, from 231 to 223 million years ago.

Under dispute

Lepidus praecisio is recovered deeply within Coelophysidae as sister to Coelophysis by some analyses (Ezcurra, 2017; Ezcurra and colleagues, 2020) but as a basal neotheropod outside Coelophysoidea, among the successive sister taxa of Neotheropoda, by others (Nesbitt and Ezcurra, 2015, in their combined analysis; Martínez and colleagues, 2025).

Diagnosis

  1. Well-developed posterior pyramidal process on astragalus delimiting posterolateral tibial facet (autapomorphy)
  2. Fused astragalus and calcaneum
  3. Low anterior ascending process of astragalus
  4. Mediolaterally compressed calcaneum
  5. Proximodistally extended ridge on posteromedial tibia surface
  6. Distinct scar on anterior distal tibia surface

Species

Lepidus praecisio Nesbitt & Ezcurra, 2015

Type species

From Latin 'praecisio' meaning 'fragment' or 'scrap'.

Holotype
TMM 41936-1.3 , Texas Memorial Museum, Austin, Texas, USA (used for collections now housed in the Vertebrate Paleontology Collections at the Jackson School Museum of Earth History, Austin, Texas, USA), now called the Texas Science and Natural History Museum
Material
Articulated distal ends of left tibia and fibula and left astragalocalcaneum
Horizon
Dockum Group, Carnian–Norian, Late Triassic , 237.0–205.7 million years ago
Locality
Dockum Site 7 General, Texas, United States Nesbitt and Ezcurra (2015) give the horizon only as "Otis Chalk area, Dockum Group" and call its correlation unresolved. Lehman and Chatterjee (2005) map the Otis Chalk strata in the upper Cooper Canyon Formation, while Lovelace and colleagues (2025) place Lepidus "from the Colorado City Formation (lower Dockum Group)" by correlation.

References

  1. Nesbitt, S.; Ezcurra, M. (2015). The early fossil record of dinosaurs in North America: A new neotheropod from the base of the Upper Triassic Dockum Group of Texas. Acta Palaeontologica Polonica 60. Polska Akademia Nauk Instytut Paleobiologii (Institute of Paleobiology, Polish Academy of Sciences). doi:10.4202/app.00143.2014 nesbitt2015a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates.

    jones2026c
  3. Ezcurra, M. D. (2017). A New Early Coelophysoid Neotheropod from the Late Triassic of Northwestern Argentina. Ameghiniana 54(5): 506. Asociacion Paleontologica Argentina. doi:10.5710/amgh.04.08.2017.3100

    Recovered Lepidus deep within Coelophysidae as sister to Coelophysis.

    ezcurra2017a
  4. Ezcurra, M. D.; Butler, R. J.; Maidment, S. C. R.; Sansom, I. J.; Meade, L. E.; Radley, J. D. (2020). A revision of the early neotheropod genus Sarcosaurus from the Early Jurassic (Hettangian-Sinemurian) of central England. Zoological Journal of the Linnean Society 191: 113-149. Oxford University Press (OUP). doi:10.1093/zoolinnean/zlaa054

    Coelophysoid revision recovering Lepidus outside Coelophysoidea as a basal neotheropod.

    ezcurra2020a
  5. Martínez, R. N.; Colombi, C. E.; Ezcurra, M. D.; Abelín, D. O.; Cerda, I.; Alcober, O. A. (2025). A Carnian theropod with unexpectedly derived features during the first dinosaur radiation. Nature Ecology & Evolution 9(12): 2238-2247. Springer Science and Business Media LLC. doi:10.1038/s41559-025-02868-4

    New Carnian theropod analysis bearing on Lepidus's basal neotheropod placement.

    martínez2025a
  6. Lovelace, D. M.; Kufner, A. M.; Fitch, A. J.; Curry Rogers, K.; Schmitz, M.; Schwartz, D. M.; LeClair-Diaz, A.; St.Clair, L.; Mann, J.; Teran, R. (2025). Rethinking dinosaur origins: oldest known equatorial dinosaur-bearing assemblage (mid-late Carnian Popo Agie FM, Wyoming, USA). Zoological Journal of the Linnean Society 203(1): zlae153. Oxford University Press. doi:10.1093/zoolinnean/zlae153

    Names the unit at the Otis Chalk localities as the Colorado City Formation, within the lower Dockum Group.

    lovelace2025a
  7. Lehman, T.; Chatterjee, S. (2005). Depositional setting and vertebrate biostratigraphy of the Triassic Dockum Group of Texas.

    Maps the Otis Chalk strata within the upper part of the Cooper Canyon Formation.

    lehman2005a