THEANATOMICALRECORD262:369–379(2001) EndocastofSambungmacan3(Sm3): ANewHomoerectusFromIndonesia DOUGLASC.BROADFIELD,1,2*RALPHL.HOLLOWAY,3 KENNETHMOWBRAY,4 ADAMSILVERS,5 MICHAELS.YUAN,3 1,2 ANDSAMUELMA´ RQUEZ 1DepartmentofCellBiologyandAnatomy,MountSinaiSchoolofMedicine,NewYork 2NewYorkConsortiuminEvolutionaryPrimatology,DepartmentofAnthropology, TheGraduateSchool,CUNY,NewYork 3DepartmentofAnthropology,ColumbiaUniversity,NewYork 4DepartmentofAnthropology,AmericanMuseumofNaturalHistory,NewYork 5DepartmentofRadiology,MountSinaiSchoolofMedicine,NewYork ABSTRACT Anewfossilcalvaria,Sambungmacan3(Sm3),describedinNewFossil HominidCalvariaFromIndonesia—Sambungmacan3byMa´rquezetal.,this volume,yieldsoneofthemostadvancedandcompleteendocastsyetrecovered fromJava.Thiscommunicationprovidesathoroughinterpretationofthe externalanatomicallandmarksobservableonSm3.Usingcomputertomog- raphy(CT)andtraditionalmorphologicalmeasurements,ourcomparative paleoneurologicalanalysesshowthatwhileSm3hasamosaicoffeaturesthat aresimilartobothIndonesianandChineseH.erectus,italsopossessessignif- icantcharactersreminiscentoflaterhominins.Theseincludeagreaterdegree ofasymmetrycharacterizedbyapossibleleft-occipital,right-frontalpetalial pattern,left-rightvolumetriccerebralasymmetry,andmarkedasymmetryin Broca’scap.Moreover,thefrontallobeoffersamorerounded,shortenedap- pearanceincontrasttotheflat,elongatedappearanceofotherIndonesian fossils(e.g.,Sangiran17).Anotheruniquetraitisexhibitedinthetransverse planewherethewidestbreadthofSm3occursmoresuperiorlythaninother IndonesianH.erectus.Thus,theendocastofSm3presentsauniquemorphol- ogynotseenpreviouslyinthehomininfossilrecord.Whilethestrongmodern humancharacteristicsinthisendocastmaynotrepresentaparticularances- try,theydoallowustorecognizeanewdimensionoftheremarkablevariation inIndonesianHomoerectus.AnatRec262:369–379,2001. ©2001Wiley-Liss,Inc. Keywords:brainevolution;humanevolution;Broca’scap;com- putertomography;petalia Indonesiahasbeenthesiteofthelongestcontinuous IndescribingtheendocastofTrinil2(H.erectusI), occupationbyanyhomininspecies.ThediscoveryofHomo Tilney(1927)positionedH.erectusfarabovegorillabut erectusbyEugeneDuboisin1891nearTrinil,Javabegan belowmodernhumans.Withoneofthemoredetailed anewchapterforhumanevolutionoutsideofAfrica.Since thattimeseveralfossilshavebeenunearthedinIndonesia datingfrom1.8MYAto53,000yearsago.Ourunder- standing,however,ofIndonesianH.erectusiscloudedby Correspondenceto:DouglasC.Broadfield,NewYorkConsor- anincompletefossilrecord,andtheunrelentingIndone- tiuminEvolutionaryPrimatology,DepartmentofAnthropology, siangeologywhichhasyieldedfewstratigraphiccertain- TheGraduateSchool,CUNY,NewYork,NY10036.Fax:(212) ties.Thishasledresearcherstoinferthebehaviorsof 860-1174.E-mail:[email protected] IndonesianH.erectusfromthemorphologicalfeaturesof Grantsponsor:NSF;Grantnumber:SBR9528100. thefossilsandfromthebrainendocaststhatcanbede- Received12June2000;Accepted20December2000 rivedfromthemorecompletecrania. Publishedonline28February2001 ©2001WILEY-LISS,INC. 370 BROADFIELD ET AL. endocast descriptions of that time, he considered the fron- (Fig. 1). While the neurocranium is almost complete in Sm tal lobe of H. erectus to be well developed. In addition, 3, portions of the basicranium from the posterior-most Tilney regarded the morphology of the inferior frontal lobe aspect of the foramen magnum to the rostrum of the as evidence that H. erectus “had learned to speak—to frontal lobes are missing. The third inferior frontal region communicate in verbal language” (Tilney, 1927). Tilney’s is present and ends infero-medially. Hence, the frontal enthusiasm for the mental capacity of H. erectus in Indo- rostrum and the orbital portion of the frontal lobe were nesia was not echoed by others of the time. Albeit Wei- reconstructed. The sphenoid contribution to the base of denreich (1937) considered Indonesian H. erectus to pos- the calvaria is missing, and thus the temporal poles are sess more advanced features in its endocast than Chinese lacking in Sm 3. Both poles and the midline basicerebral H. erectus, he stopped short of granting H. erectus lan- structures, representing the hypophyseal fossa were re- guage capabilities. Dubois (1933), H. erectus’s discoverer, constructed. Posteriorly, most of the area representing the apparently took a different view, agreeing with the de- petrous portions of the temporal bones are present, while scription of Black (1932) that H. erectus from China was those corresponding to the basiocciput, including the cli- more advanced in its endocast features than from Java. vus, foramen magnum, and the jugular portion of the A more recent set of studies by Holloway (1980, 1981a) occipital bone, are missing and have been reconstructed revisited the endocranial evidence for H. erectus from In- (Fig. 1). Compared to other Indonesian endocasts (Hollo- donesia. These revised endocranial capacities and new way 1980, 1981a) Sm 3 is remarkably complete. In addi- measurements dismissed most of the gyral and sulcal tion there is no apparent distortion to the skull.1 interpretation attempted in early descriptions (e.g., Kap- pers, 1929; Kappers and Bouman, 1939). In addition, Hol- Volume Determinations loway’s observations of a left-occipital, right-frontal pet- Volume measurements were made independently for alial pattern, and a well-developed inferior frontal region the two endocasts reconstructions. Measurements were for Indonesian H. erectus, indicated possible cognitive lat- done by water displacement (Holloway, 1980). First, each eralization (Holloway, 1980, 1981a; LeMay, 1976). Despite endocast was submersed in water for a period of several the revised endocranial estimates and morphological ob- minutes to ensure that any air trapped in the endocast servations of Indonesian H. erectus, one problem which was removed. A 3,500cc beaker, fitted with a specially has plagued the early Indonesian sample is a high degree designed overflow spout, was filled to overflow and allowed of incompleteness. A new fossil calvaria, Sambungmacan to drain. Next, the endocast was slowly lowered into the 3 (Sm 3), from near the village of Poloyo, described by beaker. As the endocast was lowered the resultant runoff Ma´rquez et al. (2001), yields one of the most complete was collected in another pre-weighed beaker and subse- endocasts from Indonesia. The present communication quently weighed. This method gives an immediate volume provides a thorough interpretation of the anatomical land- because the specific gravity of water is 1. Five determina- marks observable on Sm 3 and a comparative analysis tions were made for each of the endocasts and the average with other Indonesian endocasts. was calculated. MATERIALS AND METHODS Measurements and Indices The interior of the Sm 3 calvaria was cleaned of all While linear measurements may be of limited use in matrix in preparation for making a silicone rubber endo- endocasts (Holloway 1981b), chord and arc measurements cast. To prevent the rubber from adhering to the interior were taken to provide quantification of the overall shape surface, a separator was applied. Current casting methods configuration of the endocast. Chord and arc measure- use silicone rubbers instead of latex. Silicone compounds ments for length (frontal pole to occipital pole), maximum are preferred, because they give excellent detail reproduc- width and depth from the vertex to the most inferior tion with high tear strength for long lasting molds and less portions of the temporal lobes in the midsagittal plane, shrinkage, and do not require vulcanization at elevated bregma-lambda, bregma-asterion, and biasterionic breadth temperatures as does latex rubber. The silicone rubber were taken to the nearest 0.1mm on digital images using chosen for casting Sm 3 was Rhodorsil silicone rubber SigmaScan Pro (SPSS Scientific). Arc measurements were (RTV-585, Rhone-Poulenc), a premium grade silicone performed using a flexible fiberglass tape on the actual mold-making material that cures at room temperature to endocast. The indices and ratios derived from these mea- form a tough flexible rubber. Because the base of the skull surements were compared to those calculated for other is missing in Sm 3 the silicone rubber was applied in Indonesian H. erectus endocasts, Pan, Gorilla, Australo- layers on the fossil endocranium to give the greatest pithecus (Sts 5), and modern Homo sapiens. amount of detail. Layers were applied to the interior of the skull with a brush in a swirling motion. Each layer was Computer Tomography Scans allowed to cure, and a total of four layers were applied. Two endocast molds were made using this technique. CT scans of the endocasts of Sm 3, Trinil 2 (H. erectus I), Comparative measurements between the endocast and Sangiran 2 (H. erectus II), Sangiran 12 (H. erectus VII), endocranium show shrinkage of less than 1mm. and Zhoukoudian Locus E (Sinanthropus III) were per- Restoration of the endocast to its most likely original formed in order to obtain approximate volume estimates volume involved reconstructing only the base of the endo- of each hemisphere minus the cerebellum (Fig. 2). CT cast, as there was no noticeable distortion in the calvaria. scans were done at Mount Sinai Hospital/NYU Health Lips produced from silicone rubber extending over the surface of the broken edges of the calvaria were trimmed, and the missing portions were reconstructed using non- drying modeling clay (Klean Klay). Two of the authors 1See Marquez et al., preceding this article, for a full description (DCB and