The Smallest Dinosaur Tracks in the World: Occurrences and Significance of Minisauripus from East Asia.

We review the status of the distinctive ichnogenus Minisauripus based on more than 80 well-preserved tracks comprising a minimum of 50 trackways from two localities in China and five in Korea. The tracks, attributed to theropod dinosaurs, have been assigned to two ichnospecies, M. chuanzhuensis and M. zhenshounani, based on Chinese specimens. Until recently, the known range of foot lengths was 1.5–6.0 cm, indicating a diminutive track-making species. However, newly discovered Minisauripus tracks from the Haman Formation in the Changseon region of Korea are as short as 1.0 cm. Most remarkably, a few, provisionally also labeled cf. Minisauripus, are reported as large as 16–20 cm, potentially adding unprecedented new data to the previous record. The larger tracks suggest that all the small tracks pertain to juveniles and not a small, distinct species as previously inferred. Tracks with foot lengths of only ∼1 cm suggest that individuals hatched from very small eggs. The fact that such tracks are abundant in fine-grained, lake-margin facies argues for the importance of suitable preservational conditions in recording the activity of small trackmakers. Thus, inferences about dinosaur population structure, growth rates, and other biological and ecological phenomena, based on the absence of small dinosaur tracks, should be made with caution. [ABSTRACT FROM AUTHOR]