Lingyuan’s Dinosaur with a Meal Still Inside

Inside the outline of one small dinosaur skeleton lies a second kind of evidence: bones from mammals it had eaten. The dinosaur is Huadanosaurus sinensis, formally named in 2025 from the Yixian Formation at Dawangzhangzi in Lingyuan, within the Chaoyang region of Liaoning.

Its holotype, the specimen that anchors the scientific name, is IVPP V 14202. A published photograph and drawing identify mammalian remains in the abdominal region. The meal remains can be studied in direct association with the skeleton that defines the species.

The research institution’s account identifies remains of a eutriconodont and a eutherian, two different mammalian groups. The relatively complete eutriconodont skeleton supported the interpretation that it had been swallowed whole.

Huadanosaurus also had robust teeth and jaws. Combining those anatomical features with the meal, the researchers inferred an ability to capture small prey actively. The contents provide direct evidence of consumption; the manner of capture is a reconstruction from several clues. The teeth, jaws and preserved prey thus contribute different kinds of evidence to the reconstruction.

The 2025 paper, by Rui Qiu and colleagues, introduced Huadanosaurus alongside another dinosaur, Sinosauropteryx lingyuanensis. The specimens had been discovered years earlier, in 2000 and 2004. A new scientific name can therefore represent a new understanding of an old collection rather than a fossil lifted from the ground that season.

The team compared anatomy and evolutionary relationships among several small theropods. Their proposed differences in hunting strategy replace the vague category of small carnivorous dinosaur with animals that may have used their heads, jaws and limbs in different ways.

The fossil belongs to the Early Cretaceous, around 125 million years ago. It puts mammals and a non-avian dinosaur into one documented feeding relationship. Its stomach contents record one episode of consumption within the wider Jehol ecosystem.

The researchers placed that meal alongside anatomical comparisons with related small predators. Differences in jaws, skulls and limbs suggested that animals living in the same regional environments could exploit prey in different ways, adding ecological detail to their reconstructed evolutionary relationships.