that it was a small primitive bird with a relatively high skull, blunt rostrum and a slightly high premaxilla; that the antorbital fenestra was elliptical but not enlarged, the dentary was robust, the surangular was narrow and elongated, and the dentition is extremely well developed and acute; that there are over 50 extremely elongated caudals, constituting 60% of the body length, and the forelimb is extremely short with a short and thick humerus; the pubis was elongated and extremely inflated at its distal end and the ischium is broad; the hind limb was long and robust, the tibia is only slightly longer than the femur, the tarsals are separated, and the metatarsals are relatively robust with unfused proximal ends; the feathers are short, small, and uniform; many ornament the top of the skull, cervical, and dorsal regions, in addition to the dorsal and ventral caudal region. Palaeobiology Diet The specimen NIGP 127587 was preserved with the remains of a lizard in its gut region, indicating that small, fast-moving animals made up part of the diet of Sinosauropteryx prima. Numerous lizards of this type have been found in the same rocks as Sinosauropteryx. These lizards have been interpreted as most likely belonging to the genus Dalinghosaurus. Dalinghosaurus was probably a fast-running lizard adapted to living in open habitats, much like Sinosauropteryx itself. The possible Sinosauropteryx specimen GMV 2124 (Sinosauropteryx? sp.) was found with three mammal jaws in its gut region. Hurum, Luo, and Kielan-Jaworowska (2006) identified two of these jaws as belonging to Zhangheotherium and the third to Sinobaatar, showing that these two mammals were part of the animal's diet. Zhangheotherium is known to have had a spur on the ankle, like the modern platypus, which would indicate that Sinosauropteryx fed on possibly venomous mammals. Reproduction The same specimen of S. prima which had preserved a lizard in its stomach contents (NIGP 127587) also had several small eggs in its abdomen. Two eggs were preserved just in front of and above the pubic boot, and several more may lie underneath them on the slab. It is unlikely that they were eaten by the animal, as they are in the wrong part of the body cavity for the egg shells to have remained intact. It is more likely that they are unlaid eggs produced by the animal itself, proving the specimen to be a female. Each egg measured long by wide. The