Open Paleo

Mirischia

Naish et al., 2004 my-RIS-kee-uh

From Latin 'mirus' (wonderful) and the Latinized plural of Greek 'ischion' (hip joint); meaning 'wonderful hips' or 'wonderful ischia', referring to the unusual ischia

121.4–113.2 million years ago Aptian, Early Cretaceous
Early Cretaceous stages

Mirischia is an extinct genus of coelurosaurian theropod dinosaur from the Albian stage (Early Cretaceous Period) of northeastern Brazil.

Under dispute

The placement of Mirischia is highly unstable. It was originally described as a compsognathid (Naish and colleagues, 2004); Dal Sasso and Maganuco (2011) recovered it as a basal coelurosaur outside Compsognathidae; Qiu and colleagues (2025) placed it in Sinosauropterygidae; and Delcourt and colleagues (2025), in their preferred implied-weights analysis, recovered it among the earliest-branching Maniraptoromorpha with Tanycolagreus and Santanaraptor. Given the conflict and the incomplete holotype, it is placed conservatively at Coelurosauria incertae sedis.

Diagnosis

  1. Pubic peduncle of ilium with concave cranial surface
  2. Pubic boot with no cranial expansion and 32% total length of pubis
  3. Pedicular fossae located craniodorsal to neural canal on caudal dorsal vertebra
  4. Neural spines between 63% and 67% longer at distal tips than at bases
  5. Ventral surface of sacral centra bearing shallow median depressions at either end

Species

Mirischia asymmetrica Naish et al., 2004

Type species

From Latin 'asymmetrica' meaning 'asymmetrical', referring to the fact that the left ischium of the specimen differs from the right.

Holotype
SMNK 2349 PAL , Staatliches Museum für Naturkunde Karlsruhe
Material
Nearly complete pelvis (both ossa pubis, both ischia, parts of both ilia), partial dorsal vertebra, four sacral vertebral centra, several gastralia, proximal parts of both femora, proximal tibia and fibula. Gut contents preserved.
Horizon
upper Romualdo Formation, Aptian, Early Cretaceous , 121.4–113.2 million years ago
Locality
Araripina region, Pernambuco, Brazil

References

  1. Naish, D.; Martill, D. M.; Frey, E. (2004). Ecology, Systematics and Biogeographical Relationships of Dinosaurs, Including a New Theropod, from the Santana Formation (?Albian, Early Cretaceous) of Brazil. Historical Biology 16(2-4): 57-70. Informa UK Limited. doi:10.1080/08912960410001674200 naish2004a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026c
  4. Qiu, R.; Wang, X.; Jiang, S.; Meng, J.; Zhou, Z. (2025). Two new compsognathid-like theropods show diversified predation strategies in theropod dinosaurs. National Science Review 12(5). Oxford University Press (OUP). doi:10.1093/nsr/nwaf068

    Placed Mirischia within Sinosauropterygidae in their compsognathid-theropod phylogeny.

    qiu2025a
  5. Delcourt, D.; Grillo, O. N.; Hendrickx, C.; Kellermann, M.; Langer, M. C. (2025). The coelurosaur theropods of the Romualdo formation, early Cretaceous (Aptian) of Brazil: Santanaraptor placidus meets Mirischia asymmetrica. The Anatomical Record ar.70085. Wiley. doi:10.1002/ar.70085

    Recovered Mirischia among earliest-branching Maniraptoromorpha with Tanycolagreus and Santanaraptor.

    delcourt2025a
  6. Dal Sasso, C.; Maganuco, S. (2011). Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous of Italy — osteology, ontogenetic assessment, phylogeny, soft tissue anatomy, taphonomy and palaeobiology. Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano 37(1): 1-281.

    Recovered Mirischia as a basal coelurosaur outside Compsognathidae.

    dalsasso2011a