Bone chip-filled burrows associated with bored dinosaur bone in floodplainpaleosols of the Cretaceous Hasandong Formation, Korea

Borings in dinosaur bone, which are intimately associated with subjacent bu rrows filled with bone chips, are recognized from a Lower Cretaceous floodp lain vertic-calcic paleosol. Dapyeongri, Korea. The bored bone is an in sit u weathered scapula of herbivore. The borings are ubiquitous within and on scapula, and have diverse orientations. They are mostly solitary with diame ters from a few millimeters to 1 cm. The bone chip-filled burrows have simi lar diameters to those of borings and occur sporadically just below (within 10 cm downwards) the scapula. Some burrows are isolated and some are clust ered. Burrow direction is also variable, and some burrows are intertwined, forming networks. The bone borings and related bone chip-filled burrows pos t-dated bone weathering processes such as cracking, fracturing, brecciation , and disintegration, which indicates that Dapyeongri bone borers preferred to feed upon dried skeleton. Dermestid beetles are the most likely organis m for Dapyeongri bone borers and burrowers, considering that it is the most common carrion insect inhabiting vertebrate carcasses in dry decay stage. These bone borings and bone chip-filled burrows provide evidence that derme stid beetles played an important role as the last scavengers of dinosaur ca rcasses during the Early Cretaceous. Such scavenging by carrion insects und er dry climate may have impacted negatively the dinosaur fossil preservatio n in Cretaceous deposits. The behavior of Dapyeongri bone borers/burrowers is compared with that of dung beetles documented from the Upper Cretaceous Two Medicine Formation [Chin and Gill, Palaios 11 (1996) 280-287]. which ca che subterranean burrows with organic matter transported from the surface. These unique trace fossils thus provide additional evidence for understandi ng Cretaceous trophic interaction between dinosaurs and insects. (C) 2000 E lsevier Science B.V. All rights reserved.