Rich, T.H., Kear, B.P., Sinclair, R., Chinnery, B., Carpenter, K., McHugh, M.L. & Vickers-Rich, P., 2014. Serendipaceratops arthurcclarkei Rich & Vickers-Rich, 2003 is an Australian Early Cretaceous ceratopsian. Alcheringa 38, 456–479. ISSN 0311-5518.Serendipaceratops arthurcclarkei is one of Australia’s most enigmatic dinosaur taxa. Based on a single ulna recovered from Early Cretaceous high-latitude deposits in southeastern Australia, the fossil was originally classified as a neoceratopsian, but subsequently reassigned to Genasauria indet. because of comparisons with atypical thyreophorans. However, a morphometric and structural re-examination of the holotype indicates that it is proportionally distinguishable among dinosaurians and, indeed, manifests decisive statistical compatibility with ceratopsians. Statistical assessment similarly yields a synapomorphy that places the taxon robustly within Ceratopsia. Most certainly, identification of a unique differential character state combination renders S. arthurcclarkei as valid. Its affinity with ceratopsians concurs with proliferating records of other Laurasian dinosaur lineages from the Southern Hemisphere, and may reflect ancient Pangaean dispersals into or out of Gondwana.Thomas H. Rich [trich@museum.vic.gov.au], Museum Victoria, PO Box 666, Melbourne, Victoria 3001, Australia; Benjamin P. Kear [benjamin.kear@geo.uu.se], Palaeobiology Programme, Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden; Robert Sinclair [sinclair@oist.jp], Mathematical Biology Unit, Okinawa Institute of Science and Technology, Tancha, Onna-son, Okinawa 904-0495, Japan; Brenda Chinnery [bjca@mail.utexas.edu], School of Biological Sciences, University of Texas, 1 University Station A5400, Austin, TX 78712, USA; Ken Carpenter [ken.carpenter@usu.edu], Prehistoric Museum, Utah State University-Eastern, 155 East Main, Price, UT 84501, USA; Mary L. McHugh [mmchugh@nu.edu], National University, 3678 Aero Court, San Diego, CA 92123, USA; Patricia Vickers-Rich [pat.rich@sci.monash.edu.au], School of Geosciences, PO Box 28, Monash University, Victoria 3800, Australia. Received 18.10.2013; revised 2.2.2014; accepted 7.2.2014.