Open Paleo

Huadanosaurus

Qiu et al., 2025 hwah-dan-o-sor-us

From Chinese 'huadan' (the birthday of a great person or institution), commemorating several Chinese scientific anniversaries, and Greek 'sauros' (lizard).

125.8–121.4 million years ago Barremian, Early Cretaceous
Early Cretaceous stages

Huadanosaurus is an extinct genus of compsognathid-like coelurosaur from the Lower Cretaceous (Barremian) Dawangzhangzi bed of the Yixian Formation, Liaoning Province, China. The single species, Huadanosaurus sinensis, is known from an almost complete juvenile skeleton (IVPP V 14202) recovered from lacustrine deposits of the Jehol Biota; specimens of this species had previously been assigned to Sinosauropteryx prima before Qiu and colleagues (2025) erected the new genus. The holotype preserves stomach contents consisting of a eutriconodont mammal and a eutherian mammal, indicating active predation on small mammals.

Under dispute

Huadanosaurus was described by Qiu and colleagues (2025), who recovered it among the Jehol compsognathid-grade theropods that they grouped as Sinosauropterygidae, alongside Sinosauropteryx and Sinocalliopteryx. Its tyrannosauroid-like cranial features were interpreted as convergence rather than phylogenetic signal. It is placed in Compsognathidae in the family's traditional, broadly used sense; the Sinosauropterygidae hypothesis is reflected in the Compsognathidae clade dispute.

Diagnosis

  1. Large oval concavity between the anterior margin of the antorbital fossa and the maxilla.
  2. Large lacrimal recess on the lacrimal.
  3. U-shaped bifurcation at the posteroventral margin of the dentary.
  4. Fan-shaped neural spine on the axis.
  5. Coracoid strongly elongated lateromedially with an extended posteroventral process.
  6. Obturator process exceeding 70% of the total length of the ischial shaft.

Species

Huadanosaurus sinensis Qiu et al., 2025

Type species

From Latin 'sinensis' (Chinese), referring to the country of discovery.

Holotype
IVPP V14202 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Almost complete skeleton missing the feet and distal caudal vertebrae; juvenile based on unfused neurocentral sutures and scarred bone surfaces. Preserves mammalian stomach contents.
Horizon
Dawangzhangzi Member, Yixian Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
Dawangzhangzi, Lingyuan, Liaoning, China

References

  1. 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

    Erects Huadanosaurus for a juvenile skeleton from the Dawangzhangzi bed previously assigned to Sinosauropteryx prima. Holotype preserves eutriconodont + eutherian gut contents.

    qiu2025a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

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

    jones2026c