Sivapithecus Is East and Dryopithecus Is West, and Never the Twain Shall Meet DAVID R
Total Page：16
File Type：pdf, Size：1020Kb
ANTHROPOLOGICAL SCIENCE Vol. 113, 53–64, 2005 Sivapithecus is east and Dryopithecus is west, and never the twain shall meet DAVID R. BEGUN1* 1Department of Anthropology, University of Toronto, Toronto, Ontario, M5S 3G3, Canada Received 26 June 2003; accepted 7 March 2004 Abstract Sivapithecus and Dryopithecus are well-described Miocene hominids (great apes and humans), both known since the 19th century. Over the years these genera have been combined into one (Dryopithecus) or separated up to the subfamily level. Each have been dismissed as interesting side branches, hailed as direct ancestors, or recognized as sister clades to one or more clade of extant hom- inid. Here I argue that they are each stem taxa of the two living hominid clades Ponginae and Homi- ninae. A famous poem by Rudyard Kipling tells the tale of a British and Afghan soldier whose differences (in ethnicity) obscure their similarities (in character). The relationship between Sivapithe- cus and Dryopithecus is similar. On the one hand, Sivapithecus is restricted to South Asia, has thickly enameled molars, robust jaws, and superficially baboon-like forelimbs; Dryopithecus is European, has thinly enameled molars and gracile jaws, with suspensory forelimbs. On the other hand, both are great apes, both had suspensory adaptations, large brains, and delayed development, and both are closely related to living hominids. Recognition of the likely relations of Sivapithecus and Dryopithecus pro- vides insight into the causes, timing, and paleobiogeography of crown hominid origins. Key words: hominid origins, Asia, Europe, climate change Introduction [reviewed recently by Harrison (2002) and Ward and Duren (2002)] it seemed less likely to many researchers that Eur- “Sivapithecus is east and Dryopithecus is west, and never asian fossil hominoids could be directly related to living the twain shall meet, Till climates change, forests shrink, taxa, though many continued to believe that Sivapithecus (or and hominids retreat. Alas, today they are neither east nor Ramapithecus) in particular had a specific relationship to west, on the continents of their birth, Since hominids moved humans (see Appendix for a classification of the Miocene South of Cancer from opposite ends of the earth” (shame- hominoids discussed here). lessly modified from Rudyard Kipling’s “The Ballad of East In the modern era most researchers now agree that Dryo- and West”, The One Volume Kipling Authorized, Double- pithecus and Sivapithecus are great apes, but there is dis- day, Doran & Company, Garden City, New York, 1928). agreement on their relations to living taxa. Most researchers Dryopithecus was first described in 1856 from fossils conclude that Sivapithecus is a sister clade to Pongo. A few found in the foothills of the French Pyrenees, three years researchers, focusing primarily on differences between before Darwin’s publication of “On the Origin of Species” Pongo and Sivapithecus in postcranial anatomy, but also in (Lartet, 1856). Lartet and most subsequent workers in the part on gnathic differences, have suggested that the fossil 19th century recognized the great ape affinities of this fossil taxon is either a stem great ape or a stem hominoid, without taxon, and a number noted the resemblances of Dryopithe- a direct relationship to Pongo (e.g. Benefit and McCrossin, cus to African apes (e.g. Gaudry, 1890). Sivapithecus was 1995; Pilbeam, 1997). In my view the case for a Pongo– first definitively described by Lydekker (1879), from fossils Sivapithecus clade, reviewed briefly below, is considerably from the Potwar Plateau of present day Pakistan, though he stronger. The relations of Dryopithecus are even less well originally named the taxon Paleopithecus [noting that Pale- agreed upon. A number of researchers also feel that Dryop- opithecus is preoccupied, Pilgrim (1910) introduced the ithecus is a stem hominid (Andrews, 1992) or hominoid nomen Sivapithecus]. Again, a number of researchers, (Benefit and McCrossin, 1995; Pilbeam, 1997). Others see including Lydekker, noted particular similarities to orangu- Dryopithecus as a member of a very diverse Pongo clade tans. Kelley (2002) and Begun (2002) review the history of that includes most Eurasian hominids, including Ouranop- these and other Eurasian hominoid discoveries. To make a ithecus and Oreopithecus (Moyà-Solà and Köhler, 1993). long story short, once hominoids were recovered in Africa Finally, some researchers view Dryopithecus as a member of the African ape and human clade, along with Ouranopithe- * Corresponding author. e-mail: [email protected] cus, though these researchers disagree on the precise rela- phone: 1-416-978-8850; fax: 1-416-978-3217 tions among African apes and humans (e.g. de Bonis and Published online 30 September 2004 Koufos, 1993, 1997; Koufos, 1995; Begun et al., 1997; in J-STAGE (www.jstage.jst.go.jp) DOI: 10.1537/ase.04S008 Begun, 2001, 2002). I will argue here that most of the mor- © 2004 The Anthropological Society of Nippon 53 54 D.R. BEGUN ANTHROPOLOGICAL SCIENCE phological evidence of Dryopithecus and Ouranopithecus (McCrossin et al., 1998; Ishida et al., 2004)], none show any points to a sister clade relationship to African apes and indication of any type of below-branch quadrupedalism as in humans. extant and late Miocene hominoids. Both hypotheses of specific phylogenetic links between The principle distinguishing feature of the ‘griphopiths’ is Asian great apes on the one hand and Afro-European great their robust gnathic morphology, and this is probably related apes on the other are also consistent with proposed phyloge- to a novel adaptation to exploit a wider range of food types netic relations and paleobiogeographic patterns among other in the slightly more seasonal environments of the middle Miocene to recent Eurasian and African mammals. They are Miocene of Eurasia (Heizmann and Begun, 2001). Ample also consistent with most estimates of divergence dates from evidence exists to indicate that the climate changes that molecular data and suggested patterns of dispersal caused by would lead eventually to the disappearance of tropical and changing ecological settings. The combined evidence of subtropical ecological settings in most of Eurasia were morphology, functional anatomy, phylogeny (morphology already under way at the beginning of the middle Miocene and molecular), climate change, and paleobiogeography (see below). provide the basis for a model of modern hominid origins. Eurasian Hominid Diversity Eurasian Hominid Origins It is intriguing that the ‘griphopiths’ have a European, Current evidence suggests that Eurasian hominids and Asian, and African distribution, and it is tempting to con- middle Miocene African hominoids derive from one or more clude that this represents the initial separation of both Eur- members of a group (probably paraphyletic) loosely referred asian great ape clades and the African ape clade (Figure 1). to here as the ‘griphopiths’. This includes Griphopithecus However there is no evidence for this. Griphopithecus from Europe and Turkey, and Equatorius (or Griphopithe- alpani does not share any derived character with any late cus), Nacholapithecus and Kenyapithecus from Kenya. The Miocene hominid, despite tentative suggestions to the con- cf. Griphopithecus from Engelswies, Germany and Gripho- trary (e.g. Alpagut et al., 1990). Similarly, Equatorius, Ken- pithecus alpani from Paşalar and Çandır, Turkey are appar- yapithecus, and Nacholapithecus do not share specific ently the oldest ‘griphopiths’, though some uncertainty synapomorphies with great apes, again despite a few claims persists with regard to the age of the Turkish samples. Ger- to the contrary (e.g. McCrossin et al., 1998; Ishida et al., man and Turkish Griphopithecus is currently estimated to be 2004). While the nasoalveolar clivus of Nacholapithecus has ~16–16.5 Ma (Heizmann and Begun, 2001; Begun et al., been interpreted as elongated and overlapping with the max- 2003). African and Slovakian ‘griphopiths’ are younger, at illary palatine process, resulting as well in some reduction of ~15 Ma (Steininger, 1999; Ward et al., 1999). African the incisive foramina, other similarities to great apes are ‘griphopiths’ may have evolved from Eurasian Griphopithe- lacking. These premaxillary similarities are more parsimoni- cus, though the fossil record of middle Miocene hominoids ously interpreted as homoplasies possibly related to the in Africa is very poor and the possibility that in situ ances- enlarged anterior dentition of Nacholapithecus, apparently tors existed cannot be dismissed. ‘Griphopiths’ from all also shared by Afropithecus (Ishida et al., 2004). All of these three continents are united by a suite of derived characters taxa are best viewed as broadly ancestral to all hominids. that distinguish them from early Miocene hominoids such as Because the ‘griphopiths’ are distributed widely both geo- Proconsul, including large, thickly enameled molars with graphically and temporally, it is not clear exactly when and low cusps and restricted dentine penetrance, some reduction where the two main clades of living hominids evolved (Fig- in cingulum development and frequency, robust jaws, and ure 1). However, by ~12.5 Ma both are established in their certain modifications to the upper incisors. They are distin- respective regions, Sivapithecus in Chinji Formation depos- guished from Afropithecus in lacking the autapomorphic its in the Potwar plateau and Dryopithecus from St. Gaudens features of the anterior dentition,