Proc. Natl. Acad. Sci. USA Vol. 88, pp. 9082-9086, October 1991 Evolution Phylogenetic and functional affinities of Babakotia (Primates), a fossil lemur from northern Madagascar (Palaeopropithecidae/primate evolution/postcranium) WILLIAM L. JUNGERSt, LAURIE R. GODFREYt, ELWYN L. SIMONS§, PRITHUJIT S. CHATRATH§, AND BERTHE RAKOTOSAMIMANANA$ tDepartment of Anatomical Sciences, State University of New York, Stony Brook, NY 117948081; tDepartment of Anthropology, University of Massachusetts, Amherst, MA 01003; §Department of Biological Anatomy and Anthropology and Primate Center, Duke University, Durham, NC 27705; and IService de Paldontologie, Universit6 d'Antananarivo, Antananarivo, Madagascar Contributed by Elwyn L. Simons, July 2, 1991 ABSTRACT Recent paleontological expeditions to the An- Craniodental Anatomy and Tooth Shape karana range of northern Madagascar have recovered the partial remains offour individuals ofa newly recognized extinct With an estimated body mass ofjust over 15 kg, Babakotia lemur, Babakoda radofia. Craniodental and postcranial ma- is a medium-sized indroid somewhat larger than the largest terial serve to identify Babakota as a member of the palae- living indrid (Indri) but similar in size to several of the opropithecids (also including the extinct genera Palaeopropith- smallest extinct lemurs, Mesopropithecus and Pachylemur ecus, Archaeoindris, and Mesopropithecus). Living indrids (4). A detailed description of the maxillary dentition of form the sister group to this fossil lade. The postcranial Babakotia exists (2), but several important features merit anatomy indicates thatBabakotia was a medium-sized (=15 kg) mention here (Fig. 1 compares the type maxilla ofBabakotia indroid whose inferred positional behaviors were primarily to that of Mesopropithecus). Babakotia maxillae can be slow climbing and hanging. Although it is probable that a distinguished readily from other indroids by their possession leaping component typified the ancestral positional repertoire of more laterally compressed and mesiodistally elongated of all Malagasy lemurs, the mosaic nature of the locomotor postcanine teeth (with especially elongated upper premolars skeleton of Babakota further suggests that vertical dcimbing and third molar), a prominent mesial projection of the crown and hang-feeding rather than ricochetal leaping were primitive of the upper anterior premolar beyond the cervix, and for indrids and palaeopropithecids and that the dramatic incipient bilophodonty of the second molar. The palate also adaptations of the living indrids the diver- appears elongate, narrow, and squared off mesially. In this saltatory postdate last respect, Babakotia exhibits a condition more fully de- gence of these two lineages. veloped in Palaeopropithecus and Archaeoindris. As in most indroids, the root ofthe zygoma begins between the first and Babakotia radofilai is the first new genus of extinct "sub- second maxillary molars. The type specimen possesses a fossil" lemur to be discovered in Madagascar since 1909 (1, very prominent malar tubercle that is anteriorly situated 2). All of the fossil remains of this genus recovered to date (opposite the distal moiety of the first molar); in this last were found in Antsiroandoha cave in the Ankarana Range of respect Babakotia is more similar to Palaeopropithecus than northern Madagascar (3). Field seasons from 1988 to 1990 to either extant indrids or Mesopropithecus. have yielded parts of four individuals, including the type A few additional characteristics ally Babakotia generally specimen at Antananarivo University (UA/LPV-8713; upper with the palaeopropithecids and indrids but not specifically jaw plus postcranial fragments), another maxillary fragment with any one species. The central upper incisors are larger [Duke University Primate Center (DUPC) 9144], numerous than the lateral and separated by a small gap; the cheek teeth parts of a subadult (DUPC 9116), including craniodental are laterally compressed, the premolars more so than the fragments and many postcrania, and additional fragmentary molars; the premolar series is about two-thirds as long as the postcrania (DUPC 9921). The dental formula 2*1*2*3 and molar series; M2 is squarer than Ml and possesses more maxillary dental morphology clearly ally Babakotia with the transversely aligned mesial and distal pairs of cusps; M3 is indroid superfamily of Malagasy primates and more specifi- smaller than M1 and M2. cally with indrids (Avahi, Propithecus, and Indri) and palae- Similarity in overall tooth shape in Babakotia and all other and Me- indroids [except for the newly recognized Propithecus tat- opropithecids (Palaeopropithecus, Archaeoindris, tersalli (5)] was assessed by distance measures and clustering sopropithecus) as opposed to archaeolemurids (Archaeole- methods. We first created buccolingual/mesiodistal ratios for mur and Hadropithecus) (2). However, analysis of cranial each tooth from the canine to last molar in all living and and dental characters alone has proven to be inconclusive extinct indroids; the P2 of the three-premolared archaeole- regarding the more precise affinities ofBabakotia within the murids was omitted to facilitate interspecific comparisons. indrid-palaeopropithecid group. We believe that the postcra- Following standardization to Z scores to weight each ratio nial evidence presented here serves to clarify the issue of equally, mean shape variables for each species were used to phylogenetic affinities and offers an opportunity to assess the compute average taxonomic distances among taxa, and this locomotor adaptation of this new genus. Taken together, the 13 x 13 matrix was summarized using six different clustering available information gleaned from the fossil remains of algorithms (6, 7): UPGMA, WPGMA, single linkage, com- Babakotia leads us to offer a new phylogeny for indroid plete linkage, and (3-flexible with B equal to 0.25 and 0.50. primates and an alternative hypothesis for the evolution of Most clustering methods did an excellentjob ofcapturing the locomotion and skeletal design. distance structure as reflected in cophenetic correlations The publication costs ofthis article were defrayed in part by page charge Abbreviations: DUPC, Duke University Primate Centers; UA/LPV, payment. This article must therefore be hereby marked "advertisement" Universit6 d'Antananarivo/Laboratoire de Paltontologie des Ver- in accordance with 18 U.S.C. §1734 solely to indicate this fact. tebres. 9082 Downloaded by guest on October 1, 2021 Evolution: Jungers et al. Proc. Natl. Acad. Sci. USA 88 (1991) 9083 FIG. 1. Comparison (not to scale) ofthe maxillary dentition ofthe type specimen ofB. radofilai (UA/LPV-8713; Upper) to Mesopropithecus globiceps (Laboratoire d'Anatomie Comparee, Paris; Lower). The postcanine tooth row ofBabakotia is 45 mm long; that ofthe Mesopropithecus specimen is 31 mm long. Note the relatively long and narrow premolars of Babakotia. around 0.9. Fig. 2 presents the strict consensus phenogram the axial skeleton (two partial lumbar vertebrae, one cervical (Fig. 2A) of all six methods along with the UPGMA (Fig. 2B) vertebra, and one caudal vertebra), parts of the upper ex- and p(0.5)-flexible (Fig. 2C) solutions. The strict consensus tremity (medial portion of the right clavicle, most of the left phenogram underscores the distinctiveness of the archaeole- ulna, distal third of the left radius, most of the left carpus, a murids, which have relatively short and broad teeth. The complete right fourth metacarpal, a fragmentary left fourth second major cluster unites all other indroids, which have metatarsal, a left pollical proximal phalanx, and distal parts relatively longer and narrower postcanine teeth. Within this of two proximal phalanges) and parts of the lower extremity latter group, the extant indrids share enough similarity in (the distal end of the right femur, part of the left femoral tooth shape to form their own cluster regardless of method diaphysis, a portion ofthe right greater trochanter, left fibular used (as do Avahi and Indri within this cluster). The two head and shaft fragments, a virtually complete right calca- species of Mesopropithecus also always cluster together as neus, and the distal half of one metatarsal). The 1990 field do the large-bodied species of the Palaeopropithecus- season added other fragmentary shafts and right proximal Archaeoindris group. The findings most relevant to the issues femur (DUPC 9921) to the inventory of postcranial remains. at hand are that Babakotia eitherjoins the nonarchaeolemu- Detailed descriptions of these remains will be presented rid cluster as its last member (e.g., UPGMA algorithm; Fig. elsewhere, but their implications for function and phylogeny 2B) or links to Mesopropithecus (e.g., the P-flexible algo- serve as our focus here. Fig. 3 illustrates part of this post- rithm; Fig. 2C). The former phenogram emphasizes the cranial sample. unique narrowing and elongation of the premolars and third Four regions of the locomotor skeleton are sufficiently molar in Babakotia (and it also allies Mesopropithecus with complete to permit a multivariate assessment of the morpho- Palaeopropithecus-Archaeoindris), whereas the latter re- logical affinities of Babakotia: proximal ulna, proximal fe- flects the position of Mesopropithecus as the minimum link mur, distal femur, and lumbar vertebra. To broaden the to Babakotia. In sum, although Babakotia is most similar in taxonomic and adaptive base of our comparisons, we con- overall tooth shape to Mesopropithecus,