Largest Cretaceous lizard track assemblage, new morphotypes and longest trackways comprise diverse components of an exceptional Korean Konservat-Lagerstätten ichnofauna

Abstract

A newly discovered assemblage of lizard tracks from the Lower Cretaceous Jinju Formation (Sindong Group, Gyeongsang Basin) Korea is the largest yet reported from the Cretaceous. It consists of at least 95 tracks comprising five trackways, including a meter-long trackway (T1) with 50 footprints assigned to the new ichnotaxon Neosauroides innovatus ichnosp. nov. Two other trackways (T2 and T3) are designated N. innovatus paratypes characterized by strong heteropody, relatively wide trackways and small narrow manus tracks. These morphological characteristics distinguish Neosauroides innovatus from the previously reported lizard trackways Sauripes hadongensis from the Hasandong Formation and Neosauroides koreaensis from the Haman Formation, both also from the Gyeongsang Basin. These three lizard track assemblages from the Korean Cretaceous constitute the entire global lizard track record for this period. The Mesozoic record of lizard tracksites is more localized than the lizard body fossil record. This limited distribution suggests bias in the track record and the fossil record more generally. However, due to deposition of fine-grained substrates, suitable for high definition track registration, the Jinju Formation is increasingly well known as an ichnological window on small tetrapod activity and based on diversity, abundance and high-quality preservation, is regarded as an exceptional Konservat-Lagerstätten.

The first possible choristoderan trackway from the Lower Cretaceous Daegu Formation of South Korea and its implications on choristoderan locomotion

“…Besides, amphibians have pentadactyl pes with rounded tips of digits, generally without claw marks 18 . Interestingly, “typical” lizard trackways are characterized by strong heteropody with pentadactyl manus and pes imprints such as Sauripes 19 and Neosauroides 20 , 21 . However, even lizards that swim do not have webbing between toes 22 .…”

14th Symposium on Mesozoic Terrestrial Ecosystems and Biota

“…Among known ichnotaxa those representing small frogs, lizards, diminutive dinosaurs and mammals were previously considered rare. However, the characterization of the ichnofauna as a Konservat-Lagerstätten is based, in part, on the excellent preservation of small tetrapod tracks at many sites and many levels at each site (Kim et al, 2019a). Although only one frog tracksite had been reported prior to 2022 (Kim et al, 2019b), a newly-discovered site, named Sindang-ri, with hundreds of frog tracks including clear trackways at multiple levels was recently discovered and given the popular label the "Frog Footprint Forum" site.…”

Lower cretaceous avian-dominated, theropod, thyreophoran, pterosaur and turtle track assemblages from the Tugulu Group, Xinjiang, China: ichnotaxonomy and palaeoecology

“…Similar records also occur in the Cretaceous strata of China, South Korea and America. For example, the recently opened (November 2019) Jinju Pterosaur Tracks Museum, Jinju City Korea, celebrates the large number of pterosaur tracks recovered from the Lower Cretaceous lacustrine deposits of the Jinju Formation (Kim et al, 2016(Kim et al, , 2019. Early Cretaceous pterosaur tracks are also known from terrestrial, lacustrine deposits in the Hekou Formation of Gansu Province (Zhang et al, 2006), the Jiaguan Formation of Chongqing Municipality in China (Xing et al, 2013e).…”