The lost holotype of Laiyangpus liui Young (1960) (Lower Cretaceous, Shandong Province, China) is found: Implications for trackmaker identification, ichnotaxonomy and interpretation of turtle tracks

The vertebrate track Laiyangpus liui, from the Lower Cretaceous of Shandong Province in China has been the subject of misunderstanding and misinterpretation since it was discovered and named in 1960, and reposited in the Institute of Vertebrate Paleontology and Paleoanthropology collections in Beijing. It was initially misinterpreted as evidence of a coelurosaurian (non-avian theropod) trackmaker supposedly showing evidence of tridactyl manus and tetradactyl pes. This discredited conclusion was influenced by erroneous 1930s interpretations in the European literature, of tracks later shown to be of turtle affinity. A half century later, when morphologically disparate avian and non-avian theropod tracks were reported from the type locality, it was suggested that the ichnites were most likely crocodilian swim tracks. However, at that date (2010), and for some time previously, the type specimen was believed lost, and in at least one instance the label Laiyangpus had been applied to quite different theropod track specimens in the collections. With the discovery of turtle swim tracks at several Lower Cretaceous sites in China, it was suspected, and later (2015) stated that the tracks were likely attributable to turtles. This, inference was confirmed when the holotype was rediscovered and examined in detail, revealing that Laiyangpus liui is sufficiently similar, morphologically, to Chelonipus to be considered a subjective senior synonym. We therefore propose transferring L. liui to Chelonipus liui, comb. nov. which is diagnostic of tracks attributable to turtles. (C) 2018 Elsevier Ltd. All rights reserved.