Qi Qi

Newly discovered theropod footprints are described from collapsed rock blocks derived from the Lower Cretaceous Guantou Formation at the Shangantian tracksite in Dongyang City, Zhejiang Province, eastern China. The specimens are preserved in at least 18 natural molds on a single siltstone slab. The footprint assemblage is composed of minute-sized tridactyl tracks with lengths ranging between 6.8 cm and 8.8 cm. Morphologically, these tracks exhibit a relatively wide divarication angle between digits II and IV, a low length/width ratio, weak mesaxony, and a prominent, elongate metatarsophalangeal pad associated with digit IV aligned along the long axis of digit III. Based on these diagnostic traits, the new tracks are tentatively assigned to Jialingpus isp. The reduced mesaxony and incomplete expression of the medial metatarsophalangeal area behind digit II represent morphometric and preservation-driven variations characteristic of Cretaceous Jialingpus material. Kinematic estimates from three distinct single-step trackways indicate that the trackmakers were moving at slow walking speeds of 0.4–0.8 m/s (1.4–2.9 km/h). This discovery enriches the mid-Cretaceous dinosaur track diversity in Zhejiang Province and provides important ichnological insights into the evolution and morphometric variation of Jialingpus across the Jurassic–Cretaceous boundary.

The Sichuan Basin is a pivotal region for understanding the transition and evolution of Jurassic–Cretaceous dinosaur faunas in China. Despite a rich skeletal record, the quadrupedal track record from the Penglaizhen Formation remains scarce. This study reports a new sauropod tracksite discovered near Zhoujiagou in the Shuangliu District of Chengdu, Sichuan Province. The tracks occur within the upper strata of the Lower Cretaceous Penglaizhen Formation. The tracksite preserves at least three tracks constituting a possible trackway. These medium-sized impressions are characterized by a sub-circular morphology, a weak heteropody, and a potential wide-gauge trackway pattern. Based on these morphological attributes, the tracks are preliminarily referred to the Brontopodus morphotype. This discovery fills a critical gap in the sauropod ichnological record of the Penglaizhen Formation and provides evidence suggesting that mamenchisaurid dinosaurs, or their functional equivalents, persisted in the Sichuan Basin into the Early Cretaceous.