Evidence of Eusocial Insects from the Hettangian/Sinemurian Jurassic of China?

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

Authors:

1. Lida Xing (a, b)
2. Eric M. Roberts (c)
3. Jerald D. Harris (d)
4. Murray K. Gingras (e)
5. Hao Ran (f)
6. Jianping Zhang (a)
7. Xing Xu (g)
8. Michael E. Burns(b)
9. Zhiming Dong (g)

Affiliations:

a. School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China

b. Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, Alberta T6G 2E9, Canada

c. School of Earth and Environmental Science, James Cook University, Townsville, Qld 4811, Australia

d. Physical Sciences Department, Dixie State College, 225 South 700 East, St. George, Utah 84770, USA

e. Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada

f. Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin 541004, China

g. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China

Abstract:

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. Taotieichnus 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.