Photo: Courtesy of Xing Lida

A research team led by Xing Lida from the China University of Geosciences (Beijing), in collaboration with co-authors from Spain, Brazil, South Korea, and Australia, has made notable progress in classifying Cretaceous sauropod tracks.

The sauropod tracks, found in Gajin-ri, Jinseong-myeon, Jinju, South Gyeongsang Province, South Korea, were named Gyeongsangsauropus pentadactylus. This marks Gyeongsangsauropus as the first sauropod ichnogenus identified in South Korea, with its unique morphology shedding new light on the posture and gait of sauropods.

The research findings have been published in the monograph Vertebrate Ichnology: The Fossil Record of Prehistoric Behavior.

Gyeongsangnam-do, in South Gyeongsang Province, has long been a significant area for dinosaur research in South Korea. Regarding the sauropod skeletal record, a study in 2016 reported on an Early Cretaceous somphospondylan (Dinosauria: Titanosauriformes) from Haedong-gun, featuring partial cervical and dorsal vertebrae. Since 2006, Korean researchers have documented over 4,000 dinosaur tracks in Goseong County, South Gyeongsang Province, cementing its status as one of the world's most important sites for dinosaur footprints.

In 2012, South Korean Jeong Yul Kim and co-authors described a new sauropod ichnospecies, Brontopodus pentadactylus, under the widely distributed ichnogenus Brontopodus, from the Haman Formation at the Gazin site in South Gyeongsang Province. The fossil-bearing strata are dated to between 113 and 94 million years ago. The Brontopodus pentadactylus tracks are well-preserved, with clear digit traces, and provide an invaluable sample of sauropod track morphology.

A recent study re-examines this ichnospecies by conducting a detailed comparison with various sauropod track records. The research group suggests that the features of Brontopodus pentadactylus, including the rotation angle of manus tracks, differ significantly from those of other Brontopodus ichnospecies. Consequently, this ichnospecies has been reclassified into the new ichnogenus Gyeongsangsauropus.

This study identifies the distinctive characteristics of medium-sized sauropod tracks (approximately 40-50 cm in length), including manus tracks with five short, blunt digits, with digits III-V being nearly identical in length and width. The manus tracks are noticeably outward rotated from the midline of the trackway.

The trackway parameters of Gyeongsangsauropus pentadactylus include an average stride length of 150 cm and a distance between manus and pes tracks of 50-80 cm. The hip height of the Gyeongsangsauropus pentadactylus trackmakers, estimated from footprint length, is approximately 2-2.9 meters.

The establishment of the ichnogenus Gyeongsangsauropus provides important scientific evidence for studying the locomotion and ecological adaptations of sauropods. The findings suggest that different groups of sauropods may have exhibited significant diversity in their postures and gaits, Xing said.

According to Xing, further research is crucial to gain a deeper understanding of sauropod evolution and their ecological roles within the paleoenvironment.