Novel insect traces on a dinosaur skeleton from the Lower Jurassic Lufeng Formation of China

Dense networks of burrow-like traces on the surfaces of bones are preserved on a partial skeleton of a prosauropod dinosaur (cf. Yunnanosaurus) from the Lower Jurassic Lufeng Formation in Yunnan, China. The traces, which gently meander across and, in places, shallowly excavate the surfaces of several axial and appendicular skeletal elements (total cumulative length over 29 m) consist of simple burrows, Y-shaped branches, overlapping intersections, and chambers. This unusual network is morphologically most similar to foraging traces of eusocial insects, particularly termites. Comparisons of known continental ichnofossils, demonstrate the novelty of this trace, which thus pertains to a new ichnotaxon, Taotieichnus orientalis ichnogen. et ichnosp. nov. T. orientalis most closely resembles subaerial foraging galleries constructed of mud or carton (saliva and faecal material mixed with soil or partially digested wood particles) and produced by a range of subterranean termites. Periodic, possibly seasonal, use of carrion as a nutrient source, and the construction of carton foraging galleries over decomposing vertebrate carcasses, is a known, but little documented, dietary supplement for some xylophagus, neotropical termite species. These Early Jurassic traces constitute the earliest evidence of eusocial insect foraging behavior, and suggest that a possible adaptive radiation of stem- or crown-group termites as foragers—or, at least, opportunistic decomposers—of animal carcasses had already occurred by the Early Jurassic.