García-Ramos, J. C.; Mángano, M. G.; Piñuela, L.; Buatois, L. A.; Rodríguez-Tovar, F. J. (2014). The ichnogenus Tubotomaculum: an enigmatic pellet-filled structure from Upper Cretaceous to Miocene deep-marine deposits of southern Spain. Journal of Paleontology. 88(6): 1189-1198.