HYPOTHESES OF HIPPOPOTAMID ORIGINS 31 THE MYTH OF THE HIPPO-LIKE ANTHRACOTHERE: THE ETERNAL PROBLEM OF HOMOLOGY AND CONVERGENCE Martin PICKFORD Collège de France, and Département Histoire de la Terre, UMR 5143 du CNRS, Case postale 38, 57 rue Cuvier, 75005, Paris. e-mail:
[email protected] Pickford, M. 2008. The myth of the hippo-like anthracothere: The eternal problem of homology and convergence. [El mito de la similitud entre antracoterios e hipopótamos: el eterno problema entre homología y convergencia.] Revista Española de Paleontología, 23 (1), 31-90. ISSN 0213-6937. ABSTRACT The notion that anthracotheres had hippo-like body proportions, locomotion and lifestyles has been in the lit- erature for so long, and has been repeated so many times, that it has taken on the aura of unquestionable truth. However, right from the beginning of studies into hippo-anthracothere relationships over a century and a half ago, observations were made that revealed the existence of fundamental differences in dental, cranial and post- cranial anatomy in the two groups. From 1836 to 1991 two skeletal characters (a descending plate at the angle of the mandible, and raised orbits) have overshadowed all others in suggesting close relationships between hippos and a single anthracothere genus (Merycopotamus) later to be joined by a second genus, Libycosaurus, in 1991 for the descending angle, and 2003 for the raised orbits (Lihoreau, 2003; Pickford, 1991). Close examination of these structures reveals that they are not homologous in the two groups, yet they have played an inordinately stubborn role in interpretations of the relationships between them, featuring in papers as recently as 2005.