Submitted 25 October 2018Accepted 3 December 2018Published 14 January 2019

Corresponding authorTara R EdwardsTEdwardslatrobeeduau

Academic editorWilliam Jungers

Additional Information andDeclarations can be found onpage 17

DOI 107717peerj6202

Copyright2019 Edwards et al

Distributed underCreative Commons CC-BY 40

OPEN ACCESS

Combining legacy data with new droneand DGPS mapping to identify theprovenance of Plio-Pleistocene fossilsfrom Boltrsquos Farm Cradle of Humankind(South Africa)Tara R Edwards1 Brian J Armstrong1 Jessie Birkett-Rees2 Alexander FBlackwood1 Andy IR Herries13 Paul Penzo-Kajewski1 Robyn Pickering45 andJustin W Adams36

1The Australian Archaeomagnetism Laboratory Department of Archaeology and History La TrobeUniversity Melbourne Victoria Australia

2Centre for Ancient Cultures Faculty of Arts Monash University Clayton Melbourne Victoria Australia3Centre for Anthropological Research University of Johannesburg Johannesburg Gauteng South Africa4Department of Geological Science University of Cape Town Cape Town Western Cape South Africa5Human Evolution Research Institute University of Cape Town Cape Town Western Cape South Africa6Centre for Human Anatomy Education Department of Anatomy amp Developmental Biology BiomedicalDiscovery Institute Faculty of Medicine Nursing amp Health Sciences Monash University Clayton MelbourneVictoria Australia

ABSTRACTBoltrsquos Farm is a Plio-Pleistocene fossil site located within the southwestern cornerof the UNESCO Hominid Fossil Sites of South Africa World Heritage Site The siteis a complex of active caves and more than 20 palaeokarst deposits or pits manyof which were exposed through the action of lime mining in the early 20th centuryThe pits represent heavily eroded cave systems and as such associating the palaeocavesediments within and between the pits is difficult especially as little geochronologicaldata exists These pits and the associated lime minerrsquos rubble were first explored bypalaeoanthropologists in the late 1930s but as yet no hominin material has beenrecovered The first systematicmappingwas undertaken by Frank Peabody as part of theUniversity of California Africa Expedition (UCAE) in 1947ndash1948 A redrawn versionof the map was not published until 1991 by Basil Cooke and this has subsequently beenused and modified by recent researchers Renewed work in the 2000s used Cookersquosmap to try and relocate the original fossil deposits However Peabodyrsquos map does notinclude all the pits and caves and thus in some cases this was successful while in otherspreviously sampled pits were inadvertently given new names This was compoundedby the fact that new fossil bearing deposits were discovered in this new phase causingconfusion in associating the 1940s fossils with the deposits from which they originatedas well as associating them with the recently excavated material To address this wehave used a Geographic Information System (GIS) to compare Peabodyrsquos original mapwith subsequently publishedmaps This highlighted transcription errors betweenmapsmost notably the location of Pit 23 an important palaeontological deposit given therecovery of well-preserved primate crania (Parapapio Cercopithecoides) and partialskeletons of the extinct felid Dinofelis We conducted the first drone and Differential

How to cite this article Edwards TR Armstrong BJ Birkett-Rees J Blackwood AF Herries AIR Penzo-Kajewski P Pickering R AdamsJW 2019 Combining legacy data with new drone and DGPS mapping to identify the provenance of Plio-Pleistocene fossils from BoltrsquosFarm Cradle of Humankind (South Africa) PeerJ 7e6202 httpdoiorg107717peerj6202

Global Positioning System (DGPS) survey of Boltrsquos Farm Using legacy data high-resolution aerial imagery accurate DGPS survey and GIS we relocate the originalfossil deposits and propose a definitive and transparent naming strategy for BoltrsquosFarm based on the original UCAE Pit numbers We provide datum points and anew comprehensive georectified map to facilitate spatially accurate fossil collectionfor all future work Additionally we have collated recently published faunal data withhistoric fossil data to evaluate the biochronological potential of the various depositsThis suggests that the palaeocave deposits in different pits formed at different timeswith the occurrence of Equus in some pits implying ages of lt23 Ma whereas moreprimitive suids (Metridiochoerus) hint at a terminal Pliocene age for other depositsThis study highlights that Boltrsquos Farm contains rare South African terminal Pliocenefossil deposits and creates a framework for future studies of the deposits and previouslyexcavated material

Subjects Evolutionary Studies Paleontology Spatial and Geographic Information ScienceKeywords Equus GIS Dinofelis Legacy dataMetridiochoerus andrewsi Boltrsquos Farm PliocenePleistocene Palaeocave

INTRODUCTIONBoltrsquos Farm is the name given to a series of fossil bearing palaeocave remnants locatedsim15ndash30 km to the southwest of the early Pleistocene early hominin (Paranthropusrobustus early Homo and Australopithecus africanus) bearing sites of Swartkrans andSterkfontein and sim1 km south of the Rising Star Cave system (Homo naledi) (Bergeret al 2015 Dirks et al 2015) (Fig 1) Apart from the little explored archaeological andfossil bearing site of Goldsmithrsquos (Mokokwe 2007) 05 km to the south Boltrsquos Farm is themost southwestern fossil-bearing site in the Gauteng exposures of the Malmani dolomiteUNESCO Hominid Sites of South Africa World Heritage Site (colloquially referred to aslsquoThe Cradlersquo) The pits and caves that are now collectively referred to as Boltrsquos Farm occuron three properties the western Klinkerts property the eastern Greensleeves Property andthe northern Sterkfontein Quarry (Fig 2) The fossil site is named after Mr Billy Bolt theowner of the original farm that sat on the eastern Greensleeves property and SterkfonteinQuarry (known as Main Quarry) The western Klinkerts part of the site was owned by theClyde Trading Company (indicated on the original site map as the Amlors Ors Co SOMSF1 SF2)

As with the other caves in the area Boltrsquos Farm was heavily mined for speleothem(calcium carbonate from stalagmites stalactites and flowstones) in the terminal 19th andearly 20th centuries The speleothem was burnt in kilns to make lime for use in the goldextraction process Evidence for this is preserved as lime minerrsquos cottages and kilns thatsurvive at both the northeast and southeastern end of the Greensleeves Property (Fig 2)While discrete deposits existed mining revealed and created a series of pits and dumpsfrom which fossils were collected from the 1936 (Broom 1937) to the current projects(Pickford amp Gommery 2016)

Edwards et al (2019) PeerJ DOI 107717peerj6202 223

Figure 1 Location of the Cradle in South Africa (A) and Boltrsquos Farm within the Cradle (B) Elevationdata made available from Jarvis et al (2008)

Full-size DOI 107717peerj6202fig-1

The significance of Boltrsquos Farm lies both within this numerous extensive network ofpits that have yielded a diverse range of faunal material (SOM Text S1) and the suggestedPliocene ages for some of the specimens (Seacuteneacutegas amp Avery 1998 Gommery et al 2008a)Early mentions described Boltrsquos Farm as a single deposit (Cooke 1963) while later workrecognised the inherent complexity and published faunal data relating to specific pits (egDelson 1984 Cooke 1991 Cooke 1993) It is now generally accepted that the site consistsof deposits of various ages that formed either as part of the same cave system at differenttimes (Gommery et al 2012) or may represent the infill of several completely unconnectedcaves Although several publications have used biochronological correlations to suggestdepositional ages for specific pits at Boltrsquos Farm (eg Delson 1984 Seacuteneacutegas amp Avery 1998Reynolds 2007Gommery et al 2008a) no comprehensive review of the biochronologicallysensitive taxa has been attempted Recent Cradle-wide dating suggests some cave localitiesmay be younger than previously thought (Pickering et al 2018) which has particularimpact on biochronological interpretations of some Boltrsquos Farm pits forming within theearlier Pliocene (Seacuteneacutegas amp Avery 1998 Gommery Seacuteneacutegas amp Thackeray 2008b)

While the use of spatial aids eg geographic information system (GIS) remote sensingand photogrammetry for visualising landscapes has a strong history in archaeology(Gibbons 1991 Lock amp Stancic 1995 Birkenfeld Avery amp Horwitz 2015 De l Del la Torreet al 2015 Fernaacutendez-Lozano amp Gutieacuterrez-Alonso 2016 Jorayev et al 2016 DellrsquoUnto etal 2017) its application to palaeoanthropology and palaeontology has previously beenacknowledged as lagging (Conroy et al 2008 Anemone Conroy amp Emerson 2011) These

Edwards et al (2019) PeerJ DOI 107717peerj6202 323

Figure 2 New georectified map of Boltrsquos Farm from accurate DGPS survey Coordinate systemWGS1984 UTM35S

Full-size DOI 107717peerj6202fig-2

methods are wide reaching and can be applied on a landscape scale eg mapping andidentifying fossil bearing outcrops (Oheim 2007) mapping hominin migration routes(Holmes 2007) and reconstructing palaeoenvironments (Bailey Reynolds amp King 2011)GIS is also extremely valuable on a intra-site scale allowing not only for visualisation(Armstrong et al 2018) but analysis and reconstruction of bone and stone accumulations(Nigro et al 2003) While highly valuable these methods have yet to be applied toBoltrsquos Farm

In this contribution we chronicle the previous work carried out on the Boltrsquos Farm pitsfrom the 1930s to the present with a particular focus on the names and locations of thevarious deposits (Table 1) To this end we provide new spatial data and make availableaccurate survey control points for future use (SOM SF3) The aim of this is to reduce theconfusion regarding pit location and naming which are the result not only of staggeredresearch since the early 20th century but the intrinsically complex nature of the depositsacross the surface at Boltrsquos Farm We also present an overview of the previously described

Edwards et al (2019) PeerJ DOI 107717peerj6202 423

Table 1 Known locations across Boltrsquos Farm and various names within the literature sorted by source Coordinates from DGPS survey given in South African Gridand UTM

F Peabody (1947unpublisheddata)

UCMPLocality

Cooke (1991) Seacuteneacutegas et al(2002)

Thackeray etal (2008)

Zipfel ampBerger (2009)

Gommery etal (2012)

MonsonBrasil ampHlusko(2015)

Pickford ampGommery(2016)

Thispublication

SAHarte-beesthoek 94Lo27

UTM -35

Pit 1 (Kraal Pit) V67256V75133

Pit 1 Kraal Pit Pit 1 Kraal Pit Kraal Pit (Pit1)

Pit 1 Pit 1 (KraalPit)

Pit 1 Pit 1 minus71816550Y2880218092X

7120933995N571787823E

Pit 2 (Kiln Cave) V67257 Pit 2 Kiln Pit 2 H Cave H Cave (Pit2)

NA Pit 2 (KilnPit)

H Cave Pit 2 minus71808454Y2880137641X

7121014414N571779731E

Pit 3 (KB Cave) V67258V75132

Pit 3 KB Cave Pit 3 Cobra Cave KBCobraCave (Pit 3)

Cobra Cave Pit 3 (CobraCave)

Cobra Cave Pit 3 (Co-bra Cave)

minus71775725Y2880150923X

7121001137N571747015E

Pit 4 (GarageRavine)

V67259 Pit 4 GarageRavine Cave

Pit 4 GarageRavine Cave

GarageRavine Cave(Pit 4)

GarageRavine Cave

Pit 4 (GarageRavine Cave)

GarageRavine

Pit 4 minus71623214Y2880568009X

7120584218N571594565E

Pit 5 (SmithCave)

V67260V75139

Pit 5 SmithCave

Pit 5 Smith Cave-misidentified

Smith Cave(Pit 5)

Smith Cave Pit 5 (SmithyCave)

Aves Cave 4(listed as Pit13)

Pit 5 minus71692381Y2880228869X

7120923223N571663704E

Pit 6 (BaboonCave)

V67261 Pit 6 BaboonCave

Pit 6 Baboon Cave Baboon Cave(Pit 6)

Baboon Cave Pit 6 (BaboonCave)

Baboon Cave Pit 6 minus71196127Y2880661711X

7120490554N571167649E

Pit 7 (ElephantCave)

V67262 Pit 7 ElephantCave

Pit 7 Bridge Cave ElephantBridge Cave(Pit 7)

Bridge Cave Pit 7 (Ele-phant Cave)

Bridge Cave Pit 7 minus71348713Y2880563021X

7120589204N571320174E

Pit 8 V75269 Pit 8 NA Rodent Cave Rodent Cave(Pit 8)

Rodent Cave Pit 8 (RodentCave)

Aves Cave 2 Pit 8 minus71700181Y2880266450X

7120885656N571671501E

Pit 9 NA Pit 9 Pit 9 No name No name (Pit9)

NA NA Pit 9 NA minus71790951Y288019379X

7120958288N571762235E

BushmanOutcrop

NA Breccia out-crop

Breccia Out-crop

Breccia Out-crop

NA Milo A NA Milo A Milo minus7113198Y2880625805X

7120526445N571103527E

Pit 10 V67263 Pit 10 GreyBird Pit

NA Main Quarry Grey BirdPitMainQuarry (Pit10)

NA NA NA NA Destroyed ndashapprox loc -71810363Y2880123234X

7121028815N571781639E

Pit 11 NA Pit 11 Pit 11 U Cave NA (Pit 11) X Cave NA X Cave Pit 11 minus71569186Y2880320273X

7120831855N571540558E

Pit 12 NA Pit 12 Pit 12A No name No name (Pit12A)

Pit 12 (A) NA Pit 12 (A) Pit 12 minus71487209Y2880393871X

7120758287N571458614E

NA NA NA Pit 12B NA No Name (Pit12B)

Pit 12B NA Pit 12 b Pit 12B minus71377978Y2880444538X

7120707640N571349426E

Pit 13 NA Pit 13 Pit 13-Misidentified(Pit 5 wasmapped)

Arm Pit (Pit 13) NA NA Aves Cave 5 NA minus7168494606Y28802228518X

7120929237N571656272E

(continued on next page)

Edwards

etal(2019)PeerJDOI107717peerj6202

523

Table 1 (continued)F Peabody (1947unpublisheddata)

UCMPLocality

Cooke (1991) Seacuteneacutegas et al(2002)

Thackeray etal (2008)

Zipfel ampBerger (2009)

Gommery etal (2012)

MonsonBrasil ampHlusko(2015)

Pickford ampGommery(2016)

Thispublication

SAHarte-beesthoek 94Lo27

UTM -35

Pit 14 (Benchmark Pit)

V67264 Pit 14 Bench-mark Pit

Pit 14 BenchmarkPit

Bench MarkPit (Pit 14)

BenchmarkPit

Pit 14 Bench-mark Pit Lo-cation 10

Aves Cave 1 Pit 14 minus71680196Y2880248291X

7120903808N571651524E

Pit 15 V73105 Pit 15 Pit 15-Misidentified

Aves Cave Aves Cave(Pit 15)

Aves Pit 15 AvesLocation 11

Aves Cave 6 Pit 15 minus71671637Y2880262266X

7120889838N571642968E

Pit 16 (EquinePit)

V67265 Pit 16 EquinePit- cut offmap

NA NA NA Milo B NA Milo B Pit 16 minus71109010Y2880649901X

7120502359N571080566E

Pits 17ndash22 NA Not mapped NA NA NA NA NA NA NA NA NA

Pit 23 V4888 Pit 23 Tit HillPit

Pit 23-Misidentified

Tit Hill Pit -Misidentified

Tit Hill Pit(Pit 23)

Tit Hill Pit -Misidentified

Pit 23 TitHill Pit Loca-tion 13

Tit Hill Pit -Misidentified

Pit 23 (TitHill Pit)

minus71363419Y2880879361X

7120272991N571334874E

Tit Hill V67270 Old Dumps(Cooke 1991)

Femur Dump NA Femur Dump Pit 23 BoltsFarm DumpLocation 13

Femur Dump Tit Hill minus71326245Y2880884057X

7120268297N571297715E

Pit 24 NA NA NA NA NA NA NA NA NA No locationdata madeavailable

No locationdata madeavailable

Pit 25 (GazellePit)

V67267 Pit 25(Gazelle Pit)

NA NA NA NA NA NA NA No locationdata madeavailable

No locationdata madeavailable

NA V67268 NA NA NA NA NA New Cave NA NA No locationdata madeavailable

No locationdata madeavailable

NA V67269 NA NA NA NA NA Jackal Cave NA NA No locationdata madeavailable

No locationdata madeavailable

Edwards

etal(2019)PeerJDOI107717peerj6202

623

and undescribed faunal material reposited across US and South African institutions withthe aim of providing key biochronological ages for the Boltrsquos Farm deposits where possibleIn doing so we also provide the first basis for associating historic and more recentlydeveloped fossil samples excavated from these pits a critical step in reconciling the faunalrecord from across this prolific locality and allowing for more justified intra- and intersitefaunal taphonomic and palaeoecological analyses

REVIEW OF PREVIOUS EXCAVATIONS MAPPING ANDNOMENCLATURE AT BOLTrsquoS FARMThe first mentions of Boltrsquos Farm are by Broom (1937) but there is confusion as to thedefinite locality to which he is referring Broom (1937) and Broom (1939) used a numberof site location names no longer used today referring interchangeably to lsquoSterkfonteinFarmrsquo lsquoSterkfontein Cavesrsquo lsquoBoltrsquos Farmrsquo and lsquoBoltrsquos Workings at Sterkfonteinrsquo Inhis initial publications Broom (1937) and Broom (1939) described a number of novelcarnivores Leptailurus spelaeus (Family Felidae Order Carnivora figured in Broom (1939)but specimen not currently locatable) Crossarchus transvaalensis (Family HerpestidaeOrder Carnivora figured in Broom (1939) but specimen not currently locatable) andthe type specimen of the extinct hedgehog Atelerix major (Family Erinaceinae OrderEulipotyphla TM 1544 subsequently subsumed into Erinaceus (Atelerix) broomi perWerdelin amp Peigne 2010) These specimens are described as originating from lsquolsquoSterkfonteinin a cave about a mile south of that in which Australopithecus was foundrsquorsquo (Broom 1937pp 512) which fits the known location of what today is Boltrsquos Farm Broom (1939) furtherqualifies the location of these specimens as lsquolsquofound at Boltrsquos workings on Sterkfonteinrsquorsquo(Broom 1939 pp 333) alongside the description of the STS 130-299 specimenMachairodustransvaalensis (Family Felidae Order Carnivora) Broom continued to sample at BoltrsquosFarm until 1948 describing additional type specimens such as Felis shawi (BF 1555 FamilyFelidae Order Carnivora subsequently subsumed into Panthera leo Linnaeus 1758) andElephantulus antiquus (Family Macroscelididae Order Macroscelidae figured in Broom(1948) but specimen not currently locatable) as well as preserved remains of Phacochoerusmodestus (BF3-3355 Family Suidae Order Cetartiodactyla subsequently subsumed intoPhacochoerus antiquus Broom 1948 Adams et al 2015 see SOM Text S1) There has beenconsiderable confusion over the provenance of these early fossil specimens to what iscurrently defined as Boltrsquos Farm let alone specific pit deposits due to the ambiguity ofthese early reports that sadly likely cannot be addressed short of direct specimen sampling(eg Trueman et al 2005)

Between 1947 and 1948 the southern section of the University of California AfricaExpedition (UCAE) visited Boltrsquos Farm led by CL Camp and F E Peabody (Camp 1948)Their aimwas to gain further fossil evidence and geological context for the australopithecinespecimens described by Dart (1925) and Broom (1936) The UCAE undertook systematicsampling of fossiliferous calcified deposits across the Cradle including from several minerspits and rubble on Boltrsquos Farm While members of the UCAE did keep detailed fielddairies recording daily activities and discoveries it is often difficult to reconcile whether

Edwards et al (2019) PeerJ DOI 107717peerj6202 723

specimens were identified in situ or collected from minerrsquos rubble Further some localitieshave several rubble dumps nearby and subsequently it can be difficult to associate arubble dump with any one pit Attention was often paid to the matrix adhering to anyspecimens collected and attempts made to match this with sediment in a nearby localityFrank Peabody created the first known map of the site (SOM SF1 SF2 list of pits Table1) which was not published in its original form until recently (Monson Brasil amp Hlusko2015)mdashalthough used by Cooke (1991) to generate his map (see below) The expeditionamassed a significant collection of fossils from a range of sites now housed at the Universityof California Museum of Paleontology (UCMP) (Peabody 1954 Monson Brasil amp Hlusko2015) with some specimens repatriated to Evolutionary Studies Institute at the Universityof the Witwatersrand (Johannesburg) and the Ditsong National Museum of NaturalHistory (Pretoria) South Africa

Due to his sudden death in 1958 Peabody was unable to prepare a detailed report ofhis work at Boltrsquos Farm as he had done for Taung (Peabody 1954) Subsequently Cookevisited the UCMP in 1957ndash1958 (as well as in 1975 and 1983) to study the fossils recoveredby the expedition (Cooke 1991) Cooke (1991 p9) published a map lsquolsquoredrawn directlyrsquorsquofrom Peabodyrsquos survey map including pit numbers associated names and locality numbersfrom the UCAE (Pits 1ndash16 and 23ndash25)

The Palaeontological Expedition to South Africa (PESA) ran from 1996ndash1999 under thedirection of Senut and Pickford (Seacuteneacutegas amp Avery 1998) The project undertook furthercollections from fossil dumps and attempted to relocate all sites from the UCAE usingCookersquos (1991) map (Seacuteneacutegas et al 2002) While they were not able to identify all thesites with certainty the project did discover a new site Waypoint 160 (Seacuteneacutegas amp Avery1998) and microfauna from the deposits has been used to argue a terminal Miocene orearlier Pliocene age for the deposits (5ndash4 Ma Seacuteneacutegas amp Avery 1998 54ndash05 Ma Gommeryet al 2008a)

The HOPE (Human Origins and Past Environments) project a collaboration of Frenchand South African researchers based out of the Ditsong National Museum of NaturalHistory worked at the site from 2001 They attempted to align the UCAE lsquolocirsquo on Cookersquos(1991) map with those observed in the field (Seacuteneacutegas et al 2002 Thackeray et al 2008)From 2006 HOPE transformed into the HRU (HOPE Research Unit) conducting regularsurvey and excavations at Boltrsquos Farm As a result several previously undiscovered siteswere described (Gommery et al 2012) In order to expose the bone rich in situ brecciasdetailed excavation of several unstudied deposits (Pit 14 Brad Pit A amp B Milo A amp B) wereundertaken An updated map was presented in Thackeray et al (2008) which included there-identified deposits from Seacuteneacutegas et al (2002) and used names rather than the originalUCAE Pit numbers Pit 7 renamed Bridge Cave Pit 11 renamed X Cave Pit 14 (incorrectlylisted as Pit 15) is renamed Aves Cave and Pit 3 renamed Cobra Cave Locations for otherUCAE Pits such as Pit 2 (renamed H Cave) Pit 1 Pit 8 (named Rodent Cave) are alsosuggested Thackeray et al (2008) also map a number of lsquonewrsquo sites in addition toWaypoint160 and Alcelaphine Cave including Domrsquos Site Machine Cave X Cave and Y Cave

Gommery et al (2012) built on this research when describing another series of lsquonewrsquosites including a sequence north of Pit 23 called Brad Pit A-C a series west of Pit 6 called

Edwards et al (2019) PeerJ DOI 107717peerj6202 823

Milorsquos Pit A and B Brigitte Bones A and B and Carnivore Pit Further to the northwestanother new locality is designated Frankyrsquos Cave (Gommery et al 2012) Gommery et al(2014) present a simplified map of the Klinkerts property pits (excluding new localitiesBrigitte Bones Domrsquos and Brad Pit C)

Monson Brasil amp Hlusko (2015) attempted to clarify issues around the naming of pitsthrough a historical summary along with the accession of taxa from the previouslyunreported New Cave and Jackal Cave While the authors included a summary table withalternative names for the original pits recorded in 1947 sites since discovered or withmaterial not accessioned at UCMP (eg Waypoint 160) were not included

The history of staggered research at Boltrsquos Farm spanning eight decades has created anumber of issues regarding the consistency of naming practices across the site with somepits acquiring two names or being lsquodouble discoveredrsquo This paper aims to provide clarityand rectify these issues of misidentification Our intent is to create a transparent schemeadvocating for a return to the original naming practices of the site initiated by Camp andPeabody while also producing a new georectified map to assist in ongoing research at thesite (Fig 2)

METHODSField work was undertaken as part of South African Heritage Resource Agency Permit ID866 Ref No 922330032

Aerial imagery site survey and GISHigh-resolution aerial imagery was obtained using an eBee senseFly drone Imagery wasprocessed using Agisoft PhotoScan Pro 116 and Georectified on to the South AfricanCoordinate System (Hartebeesthoek 94 Lo27 EPSG2052 SA 2010 GEOID) and laterconverted to World Geodetic System (WGS) 84 Universal Transverse Mercator (UTM)Zone 35S for convenience Survey control points were established at twelve locationsacross the site (SOM F3) These were then exploited for a feature based foot survey ofthe landscape using a Leica GPS1200+ Differential Global Positioning System (DGPS)which enabled sub-centimetre accuracy of surveying positions This recorded the locationof all pits caves trenches historical structures and geological outcrops DGPS survey wasprocessed with Leica Geo Office and exported to ascii format Both the Aerial imageryand survey data were imported into ESRI software ArcMap and ArcScene 104 Historicalimagery (Peabodyrsquos map and the later maps of (Cooke 1991 Seacuteneacutegas et al 2002 Thackerayet al 2008 Gommery et al 2012) were georectified on to the aerial imagery allowing for adirect comparison between our new data and the previous maps (Fig 3) The raw DGPSdata (converted to UTM 35s) has been provided in addition to drone aerial imagery andour new georectified site map made available via figshare

Faunal analysisThe Boltrsquos Farm faunas are curated across three international institutions The Universityof California Expedition sample is now curated at the University of California Museumof Paleontology (UCMP) at the University of California Berkeley (Cooke 1991 Cooke

Edwards et al (2019) PeerJ DOI 107717peerj6202 923

Figure 3 Newmap of Boltrsquos Farm with areas of pit location error highlighted AndashD Colours representerrors by source (A) Errors pit locations in the lsquoAves Cave Complexrsquo including Pit5 8 13 14 15 Arm Pit(B) Errors in location of Pit 11 and U Cave (C) Misidentification of Pit 23 (D) Misidentification of Pit 16as new site Milo B and errors in the location of BBA and BBB

Full-size DOI 107717peerj6202fig-3

1993 Monson Brasil amp Hlusko 2015) Decades of intermittent processing and cataloguinghas produced a substantial sample across most of the pits across the Boltrsquos Farm complexDirect evaluation of specimens to establish primary identification were made in referenceto the extensive body of published descriptions of the UCMP and larger South Africanrecord an extensive database of measurements photographs and notes on South Africanfossils and an unpublished summative manuscript on the UCMP collections provided byHBS Cooke (HBS Cooke pers comm 2008) These collections were studied directly byone of us (JWA) during two data collection periods in 2007 and 2012 in collaboration withDr Alan Shabel (Department of Integrative Biology UC Berkeley)

Two South African institutions (Evolutionary Studies Institute University of theWitwatersrand Johannesburg Ditsong National Museum of Natural History Pretoria)are repositories for some Boltrsquos Farm specimens and have been regularly studied by JWAover the course of the last 15 years and were evaluated specifically for this study duringfield seasons in 2015ndash2017 Fossils described from recent excavations at Boltrsquos Farm (egthose conducted since the UCAE) were not available for direct study and any reference tothese fossils in our review of the biochronologically relevant taxa comes from published

Edwards et al (2019) PeerJ DOI 107717peerj6202 1023

Table 2 Summary of localities discovered subsequent to UCAEmappingGPS coordinates as first published and where possible new accurateDGPS data

New Locality1996ndash2016

WGS 84 position and reference SA Hartebeesthoek 94 Lo27(This publication)

UTM -35 Location(This publication)

Waypoint 160 S2602prime020primeprimeE2742prime500primeprime(Seacuteneacutegas et al 2002) minus71441694Y 2880778398X 7120373913N571413117E

Brad Pit A and B S2602prime028primeprimeE2742prime442primeprimeandS2602prime026primeprimeE2742prime438primeprime(Gommery et al 2012)

minus71285624Y 2880805139X 7120347183N571257110E

U Cave S261prime4920primeprimeE2742prime5425primeprime(Thackeray et al 2008) minus71570450Y 2880386746X 7120765408N571541822E

Brigitte Bones A S2601prime574primeprimeE2742prime386primeprime(Gommery et al 2012) Not located fromprovided coordinates

Not located fromprovided coordinates

Brigitte Bones B S2601prime576primeprimeE2742prime382primeprime(Gommery et al 2012) Not located fromprovided coordinates

Not located fromprovided coordinates

Alcephaline Site S2602prime008primeprimeE2742prime490primeprime(Seacuteneacutegas et al 2002) minus71428251 2880756014 712039354N571398117E

Frankyrsquos Cave S2601prime446primeprimeE2742prime366primeprime(Gommery et al 2012) minus71087901 2880229732 7120922934N571057728E

Carnivore Pit S2601prime578primeprimeE2742prime391primeprime(Gommery et al 2012) minus7116772 2880654998 7120497072N571140817E

Domrsquos Site S2602prime020 E2742prime488primeprime(Thackeray et al 2008) minus71413037 2880786441 7120366659N571385409E

Machine Cave S2602prime066primeprimeE2742prime404primeprime(Thackeray et al 2008) minus71191354 2880923537 7120228221N571161893E

literaturemdashwith the exception of theMilorsquos A suids which were examined earlier (Gommeryet al 2012)

RESULTSCombining legacy maps and accurate spatial dataTable 1 shows the Peabody map localities and associated modern pit names and newDGPS coordinates for known locations Note that some pits from 1947 have now beenre-identified but were listed as lsquonew discoveriesrsquo by subsequent publications (Seacuteneacutegaset al 2002 Thackeray et al 2008 Gommery et al 2012) Table 2 presents a list of newlocales from work conducted between 1996ndash2016 which have published fauna associatedwith the deposits (Seacuteneacutegas amp Avery 1998 Seacuteneacutegas 2000 Seacuteneacutegas et al 2002 Thackerayet al 2008 Gommery et al 2012 Gommery et al 2014 Gommery et al 2016 Pickford ampGommery 2016)

Accurate locations of all pits across the Klinkerts and Greensleeves properties arepresented in Fig 2 These data have been overlain with a georectified version of Peabodyrsquosoriginal mapCooke (1991)rsquos interpretation of this map and subsequent publications whichrelocated pits and announced new localities Seacuteneacutegas et al (2002) Thackeray et al (2008)and Gommery et al (2012) with discrepancies and clarification of complicated areas shownin Fig 3

Importing and georectifying Peabodyrsquos original map with our DGPS data and publishedmaps from 1991ndash2012 identifies discrepancies in four areas (Table 1 Figs 3Andash3D) Three

Edwards et al (2019) PeerJ DOI 107717peerj6202 1123

of these relate to ambiguity in the first published map (Cooke 1991) from which allsubsequent maps until now were produced Firstly the precise locations of Pits 5 and13ndash15 are not easily discernible (Fig 3A) The location of Pit 11 is correctly identified byCooke (1991) (Fig 3B) The designation of Pit 23 is placed between two localities whereasPeabody labels Pit 23 as themore easterly of the two pits (Fig 3C) Through georectificationof the original map and archival research (SOM SF2 SF3) we have determined Pit 23 tobe the more easterly of the two pits however it has been continually misidentified in theliterature The location of Pit 16 is cut off the map allowing for this to be re-discoveredas a new site more than twenty years later (Fig 3D) Without direct comparison with theoriginal Peabody map it is impossible to interpret these complex areas on Cookersquos map

Seacuteneacutegas et al (2002) published a map following the Cooke (1991) version along withGPS coordinates for Pits 3ndash7 9 11ndash15 and 23 (Table 1) This new map features lsquoBrecciaoutcroprsquo from Cookersquos (1991) map and lsquonewrsquo locations Waypoint 160 Alcelaphine Site andthe Femur Dump (Seacuteneacutegas et al 2002 Gommery Seacuteneacutegas amp Thackeray 2008b) While thelatter is present as lsquoTit Hillrsquo on Peabodyrsquos map it was not copied over by Cooke (1991) andambiguity in this region led to misidentification of Pit 23 (Fig 3B) Most of the locationsreported in Seacuteneacutegas et al (2002) plot close to identifiable pits on new aerial imagery with afew exceptions Firstly lsquoBreccia outcroprsquo plots directly adjacent to Pit 6 making it possiblethat a breccia dump was mistakenly logged as an outcrop Digital comparison of both maps(Cooke 1991 Seacuteneacutegas et al 2002) show that the lsquoBreccia outcroprsquo locations do not correlatespatially There was uncertainty regarding which deposit represented Pit 12 resulting inthe creation of Pit 12A and 12B Moreover the location for Pits 5 and 13 while beingassociated with a pit on aerial imagery is not where the original Pits 5 13 and 14 are located(Fig 3A) Archival research of original field notebooks at the UCMP showed Pit 13 to be adump associated with Pits 5 and 14 (SOM SF5) which is not clear from looking at eitherthe Peabody or Cooke (1991) map

Thackeray et al (2008) present an overview of research at Boltrsquos Farm and includean updated map with several new localities along with GPS coordinates Plotting thesecoordinates on georectified aerial image shows several inconsistencies with the originalmapped pits (Fig 3) While Pit 14 was correctly identified as Benchmark Pit coordinatesgiven match those at Pit 8 (Fig 3A) Pit 5 was placed more than 20m away from the originalmapped pit They map in a pit which is identified as Pit 13 and given the name Arm Pithowever as stated above archival research reveals Pit 13 was a dump Ultimately ArmPit does correspond to a real world location and moving forward should continue withthis name without the designation of Pit 13 (Fig 3A) GPS coordinates show that Pit 11 isincorrectly identified as a new site X Cave while U Cave located to the south is labelled Pit11 (Fig 3B) Following Cooke (1991)rsquos map and Seacuteneacutegas et al (2002) Pit 23 is incorrectlyidentified (Fig 3C)

Gommery et al (2012) present nine newly discovered localities with GPS coordinatesWhile many of the discoveries are legitimate with coordinates that plot close to identifiablepits (Brad Pit AndashC Alcelaphine Site Domrsquos Cave) others are misidentifications of old sitesor there are issues with the coordinates Several misidentifications continue through theliterature including Pit 11 Pit 23 Pit 14 and Pit 5 (Fig 3) The new sites Milo A and Milo

Edwards et al (2019) PeerJ DOI 107717peerj6202 1223

Table 3 List of Pits with maximum andminimum depositional ages as indicated by biochronologi-cally informative species

Pit Number Max Age Min Age

Pit 1 lt233 Ma 078Pit 2 NA NAPit 3 lt233 Ma189 Ma 078Pit 4 lt233 Ma NAPit 5 lt233 Ma NAPit 6 lt233 Ma 078Pit 7 44 Ma 25 Ma (20 Ma)Pit 8 NA NAPit 10 lt37 Ma NAMilo A 303ndash258 gt195Pit 11 lt2 Ma NAPit 14 303ndash258 gt195Pit 15 NA NAPit 16 lt233 Ma 099 MaPit 23 303ndash258 gt195Pit 25 lt233 Ma 078Jackal Cave NA NANew Cave lt233 Ma NAWaypoint 160 lt50 NABrad Pit NA NA

B correspond to localities mapped by the UCAE in 1947 lsquoBushman outcroprsquo and Pit 16respectively (Fig 3D) Using both supplied coordinates and overlaying our georectifiedmap we were unable to align Brigitte Bones A or B with any identifiable pits (Fig 3D)

Some of the issues raised here were addressed by Pickford amp Gommery (2016) whoused but did not publish in full Peabodyrsquos original map Access to this allowed them toidentify and correct many errors made especially in the area they have called the lsquoAvesCave Complexrsquo However while Pits 8 14 and 15 are correctly identified Pit 5 is incorrectlylabelled Pit 13 Direct comparison with the map published in Pickford amp Gommery (2016)was not possible due to small size of their map which limited accurate georectification

Biochonologically Significant Boltrsquos Farm FaunaA full description of the biochronologically-informative faunas from the Boltrsquos Farmlocalities described to date is provided in full in our SOM (Text S1) and the summedresults of our evaluation are presented in Table 3 We wish to emphasise that the faunaldata and descriptions provided here and within supplementary online material whilereflecting a substantial advance over prior taxon-focused or summative publications on theBoltrsquos Farm fossil faunas is only inclusive of specimens broadly relevant for establishingbiochronological interpretations of the pit deposits The descriptions and discussion shouldnot be taken as a comprehensive description or listing of taxa from these deposits acrossthese institutions

Edwards et al (2019) PeerJ DOI 107717peerj6202 1323

There is insufficient faunal data from Pits 2 8 15 17 Jackal Cave and Brad Pit A and Bto establish a biochronological age bracket for these deposits The majority of the describedBoltrsquos Farm localities were deposited after 233 Ma given the regular recovery of Equusspecimens that must postdate the entry of the genus into Africa (Table 3 Geraads Raynalamp Eisenmann 2004) A probable minimum depositional age boundary of 078 Ma can beestablished for Pits 1 3 and 25 by the occurrence of the extinct bovid Antidorcas reckiwhich disappears from South African deposits after the formation of Elandsfontein (Kleinet al 2007 Braun et al 2013) Pit 16 contains extinct three-toed horse (Eurygnathohippus)and was likely deposited prior to 099 Ma (SOM Text S1) Pits 4 5 and New Cave lackfauna that can restrict the minimum depositional age

Only the Pits 7 10 14 23 Waypoint 160 and Milorsquos A deposits contain fauna thatmay have been deposited prior to 233 Ma The recovery of an extinct elephant (Elephas)from Pit 7 suggests a maximal depositional age of 44ndash25 Ma (potentially extending to 20Ma SOM Text S1) however as noted above the provenance of the specimen within thedeposits is unknown and a recent U-Pb age indicates some flowstones in the cave formedltsim18 Ma (Pickering et al 2018) As such an in depth study of the Pit 7 stratigraphy andpotential associations of the specimen will be necessary to to establish a robust chronologyfor this location The Pit 10 deposits contain the type specimen of the herpestid Ictonyxbolti (subsequently subsumed into Prepoecilogale bolti Cooke 1985) known only to occurin the late Pliocene (sim37ndash25 Ma) from northern and eastern African deposits (SOMText S1) The Pit 14 23 and Milorsquos A deposits all contain Stage IMetridiochoerus andrewsicraniodental remains that are morphologically analogous to those recovered from theMakapansgat Member 3 deposits (303ndash258 Ma) (Partridge 1973 Herries Curnoe ampAdams 2009 Herries et al 2013) This may reflect a similar maximal depositional agehowever the limits of the South African suid record mean that at present we can onlyinfer deposition of these specimens prior to 195 Ma (SOM Text S1) Finally althoughWaypoint 160 has been previously suggested to date to after the Langebaanweg E Quarrydeposits (sim52 Ma Roberts et al 2011) and prior to the Makapansgat Member 3 deposits(303ndash258 Ma) as noted above and in SOM Text S1 without an established FAD or LADfor Euryotomys bolti and the recent identification of Panthera cf leo such a Pliocene ageis not clearly supported by the fauna Equally recent U-Pb ages suggest flowstones in thecave formed at ltsim23 Ma supporting the notion that at least some of this deposit is EarlyPleistocene (Pickering et al 2018)

DISCUSSIONThe extensive history of research at Boltrsquos Farm has yielded a substantial and diverse faunalsample from the known localities The palaeontological significance of Boltrsquos Farm haslagged behind that of other South African deposits due to the divided curation of materialsfrom across the deposits the sporadic history of excavation and confusion over locationand nomenclature of specific pits

The combination of several different teams working at Boltrsquos Farm through the decadesoften with significant time between excavations and collections and the disturbance of

Edwards et al (2019) PeerJ DOI 107717peerj6202 1423

many of the deposits by lime mining has cumulatively lead to the present situation ofmultiple names for individual deposits and ambiguity as to the exact location of a numberof the pits While attempts have been made to reconcile disparity between the naming ofdeposits and faunal assemblages (Monson Brasil amp Hlusko 2015) and to build new namingstrategies for the pits (Pickford amp Gommery 2016) the lack of an overarching approachfocused on the accurate spatial identification of original and recently discovered pits hasonly added to the confusion

By digitally overlaying Peabodyrsquos original map (Monson Brasil amp Hlusko 2015) andsubsequently published maps (Cooke 1991 Seacuteneacutegas et al 2002 Gommery et al 2012) withnew aerial imagery and survey data we are able to recognise pit misidentifications anderrors with naming (Fig 3) Spatially accurate mapping of palaeontological sites is crucialfor ongoing work especially palaeomagnetic and Uranium-Lead (U-Pb) dating whichboth require secure stratigraphic contexts In addition the provision of 3D surveyingbenchmarks across the site means that all future fossil and geological samples can berecorded in situ and to a high degree of spatial accuracy thereby resolving the issue ofcontextual and provenance problems The work presented here is the first of its kindconducted on the site since 1947ndash1948 reinforcing the need for these types of surveys tobe conducted both in the context of ongoing excavation and with the analysis of historicalcollections

Given our comparison of Peabodyrsquos original map with published material and the errorsin naming identified (Fig 3) we strongly recommend that all pits be referenced by theirnumber or original title where possible (Table 1 Fig 2) For the majority of pits across thesite this is the numerical designator assigned during the UCAE (eg Pits 1ndash23) Howeverfor all truly new sites subsequently discovered (eg Waypoint 160) their first publishedname should be used to prevent any further confusion Since no material was recoveredfrom lsquolsquoBushman outcroprsquorsquo it should henceforth be known by the first name associated withpublished faunal material lsquolsquoMilorsquorsquo Additionally due to the questionable name attributedPit 3 by the UCAE the numerical designator (3) or new HRU name (Cobra Cave) isfavoured (Table 1)

Biochronological assessment of the faunal specimens from the Pits suggests that parts ofthe Boltrsquos Farm complex may be the oldest in the Blaubank Stream Valley possibly formingas early as the mid- (eg Pits 7 and 10) or late (eg Pits 14 23 and Milorsquos A) Plioceneand therefore prior or contemporaneous with the formation of the Makapansgat Member3 deposits (303ndash258 Ma Herries et al 2013) Recent U-Pb ages for flowstones at someof these deposits (Pit 7 Pit 14 Waypoint 160 Pickering et al 2018) may help to furtherrefine or constrain these ages when combined with in depth stratigraphic interpretationand other chronological methods These ages appear to suggest that deposits within theCradle are all younger thansim32 Ma With a combined record that may span over 2 Ma ofdeposition Boltrsquos Farm representsmdashalongside Sterkfonteinmdashone of few site complexes tocover such a long span of time in the Cradle region providing a rare opportunity for moredetailed comparisons of the fauna from these different localities through time (Pickeringet al 2018 Herries et al 2018)

Edwards et al (2019) PeerJ DOI 107717peerj6202 1523

Additionally within the Cradle it is unusual to have an extensive site complex likeBoltrsquos Farm that is devoid of hominin specimens and a small non-hominin primatesample in such close proximity to well-known hominin- and primate-bearing sites (egSterkfontein Swartkrans Rising Star) There are many potential reasons why hominins orprimates may not occur within the Boltrsquos Farm deposits which warrant mention There arenumerous references within the original field notes of Camp to australopithecine and lsquolsquoapemanrsquorsquo remains from Pit 3 (SOM SF6 SF7 SF8) however these specimens are not knownto have been subsequently catalogued within any current collections It is possible thatthese specimens were incorrectly identified in the field (eg reclassified as non-homininprimate or other mammal remains) or that they were accidentally integrated into otherfossil samples during the removal of Boltrsquos Farm materials which saw them organisedand packed at the Ditsong National Museum of Natural History prior to export We canestablish that some specimens were simply never accessioned For example while Pit 3is the only location from which a single stone tool is known to have been recoveredhowever Camprsquos notes provide insight citing that he lsquolsquoscraped out 10ndash15 blades andgave them to the (Bolt) sistersrsquorsquo (SOM SF9) He goes on to list artefacts lsquolsquothin bladesquartz chips One core of chert and some slate artefactsrsquorsquo none of these artefacts areknown today Equally variable taphonomic processes exert a strong mediating role infaunal assemblage composition (Brain 1981 Pickering 1999 Adams 2006 Pickering et al2004 Val amp Stratford 2015) and the taphonomic histories of these Pits have not yet beenaddressed (excepting Pit 23 see Brain 1981) Ultimately it is important to highlight that abias towards excavating and analysing the well-known hominin fossil sites located nearbymay be distorting our perception of how regularly hominins primates and archaeologicalmaterials were integrated into the Cradle localities In this respect the Boltrsquos Farm Pitsmay be typical of penecontemporaneous deposition across the region in representationof fauna

CONCLUSIONS AND FUTURE RESEARCHIn the more than 80 years since Broom first prospected at Boltrsquos Farm continued researchhas proven the value of the site to yield important palaeontological remains the summedsample of which indicates an extensive depositional history that has been suggested to dateback into the Pliocene

Boltrsquos Farm differs significantly from other sites in the Cradle in two ways Firstlywhile palaeokarst features are commonplace throughout the Cradle most fossil bearingsites are either caves (eg Sterkfontein) or single palaeokarst deposits (eg Malapa) It isunprecedented to have such a high density of fossil bearing palaeokarst deposits and activecaves in a small area as is the case at Boltrsquos Farm Additionally biochronology suggeststhere is significant temporal variation within and between the more than twenty knownlocalities across the site The unique conditions which have led to the preservation of somany palaeokarst remnants and caves is inherently linked to the geology observed at thesite requiring further research to fully disentangle

It is critical to the next stage of research at Boltrsquos Farm that all areas be accuratelymapped and a uniform naming scheme be settled on As a result the detailed survey

Edwards et al (2019) PeerJ DOI 107717peerj6202 1623

provided here seeks to clarify the naming issues and we present the first new map of thesite in more than 70 years Our study highlights the importance of field survey pairedwith high-resolution spatial mapping and drone survey as our new map and site surveyingcontrol points allow the historical fossil collection to be accurately placed within its originalcontext The continued use of 3D data collection methodologies at the site will rectify someof the problems researchers have encountered Although the site has been disturbed bymining activities and some contexts destroyed the importance of this information is onlybeing realised as new methods enable these distinct areas to be dated While additionalbiochronological dating (after full description of more recently excavated faunas) andabsolute dating methods will provide clarification of the age of deposits spatial aidsprovided here should be adopted by researchers continuing to excavate at Boltrsquos Farm toensure an accurate spatial and contextual record of all finds from this key palaeontologicalsite in the Cradle

ACKNOWLEDGEMENTSThe authors wish to thank Dr Robert Anemone and one anonymous reviewer for helpfulsuggestions which improved this manuscript The authors wish to thank Stepheny Potzeand Lazarus Kgasi for access to the site and assistance with fieldwork Stephany Potze wasthe SAHRA permit holder during initial stages of field work Dominique Gommery andLazarus Kgasi SAHRA permit holders during surface survey Ditsong National Museum ofNatural History Pat Holroyd for access to original notes and collections of UCAE UCMP Tara R Edwards thanks Tesla Monson for assistance support and helpful discussion JustinW Adams thanks Alan Shabel for assistance support and expertise at UCMP J Gaylordlandowner of Greensleeves We thank Norbert Plate of iQlaser (httpwwwiqlasercoza)for his time equipment andprovision of aerial imagery Elevation data available fromUSGS

ADDITIONAL INFORMATION AND DECLARATIONS

FundingFunding received from Australia Research Council (grant FT120100399 to Andy IRHerries and DP170100056 to Andy IR Herries and JW Adams) the La Trobe UniversityHumanities and Social Science Internal Research Grant Scheme (2015-1-HDR-1 toBrian J Armstrong and 2017-1-HDR-0009 to Tara R Edwards) and National ResearchFoundation African Origins Platform (grant AOP150924142990 to Robyn Pickering) Thefunders had no role in study design data collection and analysis decision to publish orpreparation of the manuscript

Grant DisclosuresThe following grant information was disclosed by the authorsAustralia Research Council FT120100399 DP170100056The La Trobe University Humanities and Social Science Internal Research Grant Scheme2015-1-HDR-1 to BJA 2017-1-HDR-0009National Research Foundation African Origins Platform AOP150924142990

Edwards et al (2019) PeerJ DOI 107717peerj6202 1723

Competing InterestsThe authors declare we have no competing interests

Author Contributionsbull Tara R Edwards conceived and designed the experiments performed the experimentsanalyzed the data contributed reagentsmaterialsanalysis tools prepared figures andortables authored or reviewed drafts of the paper approved the final draftbull Brian J Armstrong conceived and designed the experiments performed the experimentsanalyzed the data contributed reagentsmaterialsanalysis tools prepared figures andortables approved the final draftbull Jessie Birkett-Rees Alexander F Blackwood performed the experiments analyzed thedata contributed reagentsmaterialsanalysis tools prepared figures andor tablesapproved the final draftbull Andy IR Herries conceived and designed the experiments authored or reviewed draftsof the paper approved the final draftbull Paul Penzo-Kajewski performed the experiments analyzed the data contributedreagentsmaterialsanalysis tools approved the final draftbull Robyn Pickering authored or reviewed drafts of the paper approved the final draftbull Justin W Adams conceived and designed the experiments performed the experimentsauthored or reviewed drafts of the paper approved the final draft

Field Study PermissionsThe following information was supplied relating to field study approvals (ie approvingbody and any reference numbers)

South African Heritage Resource Agency approved the study (Permit ID 866 Ref No922330032)

Data AvailabilityThe following information was supplied regarding data availability

Edwards Tara (2018) Edwardsetal_BFSOM figshare Fileset httpsdoiorg10261815bce7a0611c4b

REFERENCESAdams JW 2006 Taphonomy and palaeoecology of the Gondolin Plio-Pleistocene cave

site South Africa Unpublished PhD Thesis Washington University St LouisAdams JW Olah AHMcCurryMR Potze S 2015 Surface model and tomographic

archive of fossil primate and other mammal holotype and paratype specimens of theDitsong National Museum of Natural History Pretoria South Africa PLOS ONE10(14)e0139800 DOI 101371journalpone0139800

Anemone RL Conroy GC Emerson CW 2011 GIS and paleoanthropology incorporat-ing new approaches from the spatial sciences in the analysis of primate and humanevolution Yearbook of Physical Anthropology 5419ndash46

Edwards et al (2019) PeerJ DOI 107717peerj6202 1823

Armstrong BJ Blackwood AF Penzo-Kajewski P Mentor CG Herries AIR 2018Terrestrial laser scanning and photogrammetry techniques for documenting fossil-bearing palaeokarst with an example from the Drimolen Palaeocave System SouthAfrica Archaeological Prospection 25(1)45ndash158 DOI 101002arp1580

Bailey GN Reynolds SC King GCP 2011 Landscapes of human evolution models andmethods of tectonic geomorphology and the reconstruction of hominin landscapesJournal of Human Evolution 60257ndash280 DOI 101016jjhevol201001004

Berger LR Hawks J De Reuiter DJ Churchill SE Schmid P Delezene LK Kivell TLGarvin HMWilliams SA Desilva JM Skinner MMMusiba CM Cameron NHolliday TW Harcourt-SmithM Ackermann RR Bastir M Bogin B Bolter DBrophy Cofran ZD Congdon KA Deane AS DemboM DrapeauM Elliot MCFeurriegel EM Garcia-Martinez D Green DJ Gurtov A Irish JD Kruger A LairsMF Marchi D Meyer MR Nalla S Negash EW Orr CM Radovcic D SchroederL Scott JE Throckmorton Z Tocheri MW Vansickle CWalker CSWei P ZipfelB 2015 Homo naledi a new species of the genus Homo from the Dinaledi ChamberSouth Africa eLife 4e09560 DOI 107554eLife09560

Birkenfeld M Avery MD Horwitz LK 2015 GIS virtual reconstructions of the temporaland spatial relations of fossil deposits at wonderwerk cave (South Africa) AfricanArchaeological Review 32(4)857ndash876 DOI 101007s10437-015-9209-4

Brain C 1981 The hunters or the hunted An introduction to African cave taphonomyChicago University of Chicago Press

Braun DR Levin NE Stynder D Herries AIR ArcherW Forrest F Roberts DLBishop LC Matthews T Lehmann SB Pickering R Fitzsimmons KE 2013MidPleistocene hominin occupation at Elandsfontein Western Cape South AfricaQuaternary Science Reviews 82145ndash166 DOI 101016jquasci201309027

Broom R 1936 A new fossil Anthropoid skull from South Africa Nature 138486ndash488Broom R 1937 Notices of a few more new fossil mammals from the caves of the

Transvaal Annals and Magazine of Natural History 20509ndash514DOI 10108000222933708655373

Broom R 1939 A preliminary account of the Pleistocene carnivores of the Transvaalcaves Annals of the Transvaal Museum 19331ndash338

Broom R 1948 Some south African Pliocene and Pleistocene mammals Annals of theTransvaal Museum 211ndash38

Camp CL 1948 University of California African expeditionmdashsouthern section Science108550ndash552 DOI 101126science1082812550

Conroy G Anemone R Van Regenmorter J Addison A 2008 Google earth GIS andthe great divide a new and simple method for sharing palaeontological data Journalof Human Evolution 55751ndash755 DOI 101016jjhevol200803001

Cooke HBS 1963 Pleistocene mammal faunas of Africa with particular referenceto southern Africa In Howell FC Bourliegravere F eds African ecology and humanevolution Chicago Aldine press 65ndash116

Cooke HBS 1985 Ictonyx bolti a new mustelid from cave breccias at boltrsquos farmSterkfontein area South African Journal of Science 81618ndash619

Edwards et al (2019) PeerJ DOI 107717peerj6202 1923

Cooke HBS 1991 Dinofelis barlowi (Mammalia Carnivora Felidae) cranial materialfrom Boltrsquos Farm collected by the University of California African expeditionPalaeontologica Africana 289ndash21

Cooke HBS 1993 Undescribed suid remains from Boltrsquos Farm and other Transvaal cavedeposits Palaeontologica Africana 307ndash23

Dart RA 1925 Australopithecus africanus the Man-Ape of South Africa Nature115195ndash199 DOI 101038115195a0

DellrsquoUnto N Landeschi G Apel J Poggi G 2017 4D recording at the trowelrsquos edgeusing three-dimensional simulation platforms to support field interpretation Journalof Archaeological Science Reports 12632ndash645 DOI 101016jjasrep201703011

Delson E 1984 Cercopithecid biochronology of the African Plio-Pleistocene correlationamong eastern and southern hominid-bearing localities Courier ForschungsinstitutSenckenberg 69199ndash218

De l Del la Torre I Arroyo A Proffitt T Martiacuten Ramos C Theodoropoulou A 2015Archaeological fieldwork techniques in stone age sites Treballs drsquoarqueologia200021ndash0040 DOI 105565revtda51

Dirks PHGM Berger LR Roberts EM Kramers JD Hawks J Randolph-QuinneyPS Elliott M Musiba CM Churchoff SE De Ruiter DJ Schmid P BackwellLR Belyanin GA Boshoff P Hunter KL Feurriegel EM Gurtov A HarrisonJDG Hunter R Kruger A Morris H Makhubela TV Peixotto B Tucker S 2015Geological and taphonomic context for the new hominin species Homo naledi fromthe Dinaledi chamber South Africa eLife 4e09561 DOI 107554eLife09561

Fernaacutendez-Lozano J Gutieacuterrez-Alonso G 2016 Improving archaeological prospectionusing localized UAVs assisted photogrammetry an example from the Roman GoldDistrict of the Eria River Valley (NW Spain) Journal of Archaeological ScienceReports 5509ndash520 DOI 101016jjasrep201601007

Geraads D Raynal J Eisenmann V 2004 The earliest human occupation of NorthAfricaa reply to Sahnouni et al (2002) Journal of Human Evolution 46751ndash761DOI 101016jjhevol200401008

Gibbons A 1991 A new look for archaeology Science 252918ndash920DOI 101126science2525008918

Gommery D Badenhorst S Potze S Senegas F Kgasi L Thackeray JF 2012 Prelimi-nary results concerning the discovery of new fossiliferous sites at Boltrsquos Farm (Cradleof Humankind South Africa) Annals of the Ditsong National Museum of NaturalHistory 233ndash45

Gommery D Seacuteneacutegas F Kgazsi L Vilakazi N Kuhn B PickfordM Herries AIR Han-cox J Saos T Segalen L Aufort J Thackeray JF 2016 Boltrsquos Farm cave system dansle cradle of humankind (Afrique du Sud) un exemple drsquoapproche multidisciplinairedans lrsquoeacutetude des sites agrave primates fossiles Revue de primatologie Epub ahead of printJan 31 2017

Gommery D Seacuteneacutegas F Potze S Kgasi L Thackeray JF 2014 Cercopithecoidea materialfrom the Middle Pliocene Site Waypoint 160 Boltrsquos Farm South Africa Annals ofthe Ditsong Museum of Natural History 41ndash8

Edwards et al (2019) PeerJ DOI 107717peerj6202 2023

Gommery D Seacuteneacutegas F Thackeray JF 2008b Plio-Pleistocene fossils from femurdump Boltrsquos farm cradle of humankind world heritage site Annals of the TransvaalMuseum 4567ndash76

Gommery D Thackeray JF Seacuteneacutegas F Potze S Kgasi L 2008a The earliest primate(Parapapio sp) From the Cradle of Humankind World Heritage Site (Waypoint 160Boltrsquos Farm South Africa) South African Journal of Science 104405ndash408

Herries AIR Curnoe D Adams JW 2009 A multi-disciplinary seriation of early Homoand Paranthropus bearing palaeocaves in southern Africa Quaternary International202(1ndash2)14ndash28 DOI 101016jquaint200805017

Herries AIR Murszewski A Pickering R Mallett T Johannes-Boyau R ArmstrongB Adams JW Baker S Blackwood AF Penzo-Kajewski P Kappen P Leece ABMartin J Rovinsky D Boschiani G 2018 Geoarchaeological and 3D visualisationapproaches for contextualising in-situ fossil bearing palaeokarst in South Africaa case study from thesim261 Ma Drimolen Makondo Quaternary International48390ndash110 DOI 101016jquaint201801001

Herries AIR Pickering R Adams JW CurnowDWarr G Latham AG Shaw J2013 A multi-disciplinary perspective on the age of Australopithecus in South-ern Africa In Reed K Fleagle J Leakey R eds The paleobiology of Australop-ithecus Vertebrate paleobiology and paleoanthropology Dordrecht SpringerDOI 101007978-94-007-5919-0_3

Holmes K 2007GIS simulation of the earliest hominid colonisation of Eurasia OxfordArchaeo press 154

Jarvis A Reuter HI Nelson A Guevera E 2008Hole-filled SRTM for the globe Version4 Available at http srtmcsicgiarorg

Jorayev GWehr K Benito-Calvo A Njau J De la Torre I 2016 Imaging and pho-togrammetry models of Olduvai Gorge (Tanzania) by unmanned aerial vehicles ahigh-resolution digital database for research and conservation of early stone age sitesJournal of Archaeological Science 7540ndash56 DOI 101016jjas201608002

Klein RG Avery G Cruz-Uribe K Steele TE 2007 The mammalian fauna associatedwith an archaic hominin skullcap and later Acheulean artifacts at ElandsfonteinWestern Cape Province South Africa Journal of Human Evolution 52164ndash186DOI 101016jjhevol200608006

Linnaeus C 1758 Systema naturae per regna tria naturae secundum classes ordinesgenera species cum characteribus differentiis synonymis locis In Editio decimareformata Holmiae Stockholm Laurentii Salvii

Lock G Stancic Z (eds) 1995GIS in archaeology a European perspective London Tayloramp Francis

MokokweWD 2007 Goldsmiths preliminary study of a newly discovered Pleistocenesite near Sterkfontein Unpublished MSc Thesis University of the WitwatersrandJohannesburg

Monson TA Brasil MF Hlusko LJ 2015Materials collected by the southern branch ofthe UC Africa Expedition with a report on previously unpublished Plio-Pleistocenefossil localities Paleobios 321ndash17

Edwards et al (2019) PeerJ DOI 107717peerj6202 2123

Nigro JD Ungar PS De Ruiter DJ Berger LR 2003 Developing a geographic infor-mation system (GIS) for mapping and analysing fossil deposits at SwartkransGauteng Province South Africa Journal of Archaeological Science 30317ndash324DOI 101006jasc20020839

Oheim KB 2007 Fossil site prediction using geographic information systems (GIS) andsuitability analysis the two medicine formation a test case Palaeogeography Palaeo-climatology Palaeoecology 251(3ndash4)354ndash365 DOI 101016jpalaeo200704005

Partridge TC 1973 Geomorphological dating of cave openings at MakapansgatSterkfontein Swartkrans and Taung Nature 24675ndash79 DOI 101038246075a0

Peabody FE 1954 Travertines and cave deposits of the Kaap escarpment of South Africaand the type locality of Australopithecus africanus Dart Geological Society of AmericaBulletin 65671ndash706 DOI 1011300016-7606(1954)65[671TACDOT]20CO2

Pickering TR 1999 Taphonomic interpretations of the sterkfontein early hominid site(Gauteng South Africa) reconsidered in light of recent evidence Unpublished PhDThesis University of Wisconsin Madison

Pickering TR Dominguez-RodreigoM Egeland CP Brain CK 2004 Beyond leopardstooth marks and the contribution of multiple carnivore taxa to the accumula-tion of the Swartkrans Member 3 fossil assemblage Journal of Human Evolution46(5)595ndash604 DOI 101016jjhevol200403002

Pickering R Herries AIRWoodhead JD Hellstrom JC Green HE Paul B RitzmanT Strait D Schoville BJ Hancox H 2018 U-Pb dated flowstones restrict SouthAfrican early hominin record to dry climate phases Nature Epub ahead of print Nov21 2018 DOI 101038s41586-018-0711-0

PickfordM Gommery D 2016 Fossil suidae (Artiodactyla Mammalia) from Aves Caveand nearby sites in Boltrsquos Farm palaeokarst system South Africa Estudios Geoloacutegicos72e059 DOI 103989egeol42389404

Reynolds SC 2007 Temporal variation in Plop-Pleistocene Antidorcas (MammaliaBovidae) horncores the case from Boltrsquos farm and why size matters South AfricanJournal of Science 10347ndash50

Roberts DL Matthews T Herries AIR Boulter C Scott L Dondo C Mtembi P Brown-ing C Smith RMH Haarhoff P BatemanMD 2011 Regional and global contextof Late Cenozoic Langebaanweg (LBW) palaeontological site West Coast of SouthAfrica Earth Science Reviews 106(3ndash4)191ndash214 DOI 101016jearscirev201102002

Seacuteneacutegas F 2000 Les faunes de rongeurs (Mammalia) Plio-Pleacuteistocegravenes de laprovince de Gauteng(Afrique du Sud) mises au point et apports systeacutematiquesbiochronologiques et preacutecisions paleacuteoenvironnementales Non publieacutee thegravesedoctorat Universiteacutemontpellier ii et ephe Montpellier

Seacuteneacutegas F Avery DM 1998 New evidence for the murine origins of the otomyinae(Mammalia Rodentia) and the age of Boltrsquos Farm (South Africa) South AfricanJournal of Science 94503ndash507

Seacuteneacutegas F Thackeray JF Gommery D Braga J 2002 Scientific notes palaeontologicalsites on lsquoBoltrsquos Farmrsquo Sterkfontein valley South Africa Annals of the TransvaalMuseum 3965ndash67 DOI 104000primatologie2715

Edwards et al (2019) PeerJ DOI 107717peerj6202 2223

Thackeray JF Gommery D Seacuteneacutegas F Potze S Kgasi L Mcgrae C Prat S 2008 Asurvey of past and present work on Plio-Pleistocene deposits on Boltrsquos Farm Cradleof Humankind South Africa Annals of the Transvaal Museum 4583ndash89

Trueman CNG Field JH Dortch J Charles BWroe S 2005 Prolonged coexis-tence of humans and megafauna in Pleistocene Australia Proceedings of theNational Academy of Sciences of the United States of America 1028381ndash8385DOI 101073pnas0408975102

Val A Stratford DJ 2015 The macrovertebrate fossil assemblage from the NameChamber Sterkfontein taxonomy taphonomy and implications for site formationprocesses Palaeontologica Africana 501ndash17

Werdelin L Peigne S 2010 Carnivora In Werdelin L Sanders W eds Cenozoicmammals of Africa Berkeley University of California Press 603ndash658

Zipfel B Berger LR 2009 New Cenozoic fossil-bearing site abbreviations for collectionsof the University of the Witswatersrand Palaeontologia Africana 4477ndash81

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