Early Devonian echinoderms from South Africa

85 Pages·1999·41.5 MB·English

EARLY DEVONIAN ECHINODERMS FROM SOUTH AFRICA
PETERA. JELLANDJOHANNES N. THERON
Jell, P.A. & Theron. J.N., 1999 06 30: Early Devonian echinoderms from South Africa.
Memoirs ofthe QueenslandMuseum 43( 1): 1 15-199. Brisbane. ISSN 0079-8835.
EchinodermsoftheLowerDevonianBokkeveldGroupintheCapeProvince, SouthAfrica,
haveplayedanimportantroleinsedimentarystudiesoftheregionbuttheirtaxonomicstatus
hasbeenknown fromonly a fewcursorypapers. Wehereprovidetaxonomictreatmentofall
availablecrinoid(15species),asterozoan(11)andblastoid(2)speciesrevisingallpreviously
described taxa and morethan doublingtheknowndiversity. Palaeobiogeographicaffinities
appeartobewith EuropeandtheUSAbutknownfaunasofSouthAmericaandAustraliaare
small andalmostcertainly incompletelyknown. New taxadescribedarethecrinoid genera
Mcmdehterinus nelsom\ Eekidoevinus interhrachiatus, Sacrinus gamkaensis, S. hexensis,
Monaldicrinus johni and Othozechnus royi and the asterozoan genera Aulacolatiaster
breviramus and Hoichkissastermaerodentatus. Hexuraster is introduced as a replacement
for preoccupied Hexura Spencer. New species are the crinoids Kopjlcrinus halbichi,
Crudeocrinus plenarius and Thalamocrinus arenaceus and the asterozoans Marginura
hilleriandEugasterellaafricana, 3SouthAfrica, crinoids, starfish, ophiuroids, Early
Devonian, Bokkeveld.
Peter A. Jell, Queensland Museum, P.O. Box 3300, South Brisbane 4101, Australia;
JohannesN. Theron, GeologicalSurveyofSouthAfrica, P.O. Box572, Bellville 7530, South
Africa; 20September. 1998.
Echinoderms were first recorded from the (1936) described carpoids from Gamkapoort,
Lower Devonian Bokkeveld Group of South Breimer & Macurda (1972) described blastoids
Africa as early as 816 byDrG. Thorn, aclergy- from the Ceres/De Dooms area and Ruta &
1
man by occupation but also an ardent amateur Theron (1997) described carpoids in detail. In
fossil collector. He gathered 'endlessnumbersof thispaperwe have revisedthe description and in
specimens of shells, trilobites and encrinites or many cases the assignment of previously
stonelilies'fThorn, 1830).Thuscrinoidswerethe described echinoderms (crinoids, blastoids and
first echinoderms described (Salter, 1856). The asterozoans) and have described substantial new
Devonian age for the Bokkeveld fossils was collections from the South African Museum, the
assignedaboutthe sametime(Sandberger, 1852; Geological Survey of South Africa (mainly
Sharpe & Salter, 1856) but in the second halfof collected by J.N.T. during stratigraphic field
the 19th century very little was attempted on the mapping during the 1970s to 1990s) and the
identification of these fossils. Rogers and private collection of Mr Roy Oosthuizen of
Schwarz mapped these rocks in detail beginning Klaarstroom.
in 1895 and assembled extensive fossil STRATIGRAPHIC SETTING
collections that formed the subject ofnumerous
studies illuminating the fossil distribution and The clastic Cape Supergroup borders the
stratigraphical setting. Their Devonian age was southern and western parts of South Africa for
also confirmed by comparison with faunas from 800km eastwards and almost 300km northwards
South America and Europe (Corstorphine, 1897; from Cape Town (Fig. 1). The Supergroup is
Schwarz, 1906; Reed, 1904, 1906; Knod, 1908; divided into a lower, predominantly arenitic
Clarke, 1913; Kozlowski, 1923). In a Table Mountain Group, conformably overlain by
comprehensive review ofthe Bokkeveld fauna. the markedly argillaceous Bokkeveld Group,
Reed (1925) recorded the first carpoid, blastoid which in turn is overlain by the more arenitic
andstarfish. Echinodermscompriseonlyaminor Witteberg Group (Fig. 2).
element in the fauna however, and detailed The Bokkeveld Group consists of a cyclical
descriptions of the various echinoderms in alternation of predominantly argillaceous and
several collections have been rare. Ophiuroids arenaceous units. Each ofthese extensive Iitho-
have been mentioned by Rossouw (1933), stratigraphic units is given formation status (Fig.
Spencer(1930, 1950a) and Rilett (1971).Rennie 2). The 6 lower formations which can be traced
116 MEMOIRS OF THE QUEENSLAND MUSEUM
-30
100 200 Km
i i i
- 1 BOKKEVELD GROUP N
*1 Vanrhynadorp
* \ 1i
\k
-32 OO +> $>
t
<*
" Ceresi•e5f^c--^>rfs e*^t2^^^T^if- _
S^
-34 Cape Town If—1 01 "£port Elizabeth
^LV^~P*^V*""" INDIAN OCEAN
18 22 24 26— 28 30
i_ i I i i i i j 1 1
FIG. 1. Sketch map ofSouth Africashowingoutcrop areasofthe BokkeveldGroup in solidblack,
throughout the outcrop area are collectively their stratigraphic occurrence so that for many
referredtoastheCeres Subgroup. Theupperpart yearstherewasnoclarityastowhetheranyzonal
ofthe sequence in the west, with5 formations, is schemecouldbe developed. Thefaunas varyata
designated the Bidouw Subgroup, whilst gross level with geography (Schwarz, 1906;
eastwardsthelaterallyequivalentTakaSubgroup Theron, 1972; Oosthuizen, 1984) in that
consists of3 formations (Theron, 1972; Theron brachiopods and echinodermsaremorecommon
&
Johnson, 1991). Thickness ofthe Bokkeveld in the west, with conulariids, corals and hyoliths
Groupismuchgreaterintheeastthaninthewest. more prevalent towards the east.
These alternating lithostratigraphic units Usually, marine invertebrate faunas are most
represent 5 major, sheet-like, superimposed, commonintheCeres Subgroup,butarefoundup
coarsening-upward cycles which feather out to the level ofthe Karoopoort Formation in the
southwards into a relatively homogeneous westandtheKariesFormationintheeast(Fig.2).
mudstone-siltstone sequence. This southward Although present throughout the Bokkeveld
decrease of coarser elastics is linked to a Group, plantandespeciallytrace fossils,become
progressive thickening ofthe argillaceous units abundant in the northwestern outcrop areas. A
and of the Bokkeveld Group. The arenaceous wide variety oftypically shallow marine ichno-
units vary from fine-grained quartz arenites to genera occur with large numbers ofa variety of
immature arkosic arenites, either horizontally the uncommon pentameral stellate trace fossil
laminated or planar to trough cross-bedded. Asteriacites (Fig. 3) at various horizons within
Hummocky cross stratification becomes a these proximal arenites (Theron, 1972).
prominent structure northwards (Theron et al.,
1995). Theargillaceousunitsconsistofdarkgrey Examination of sediment/phyla associations
shale, mudstone and siltstone with thin reveals distinct affinities ofcertain species for a
intercalated lenses of fine to medium grained particular lithology (Reed, 1907; Theron, 1972;
lithic sandstone. The latter reveal swaley Oosthuizen, 1984). Since a large percentage of
cross-stratificationandoftenmarkedripplecross the Bokkeveld fauna is benthic organisms, they
laminated zones towards the north. are likely to be fades controlled. Trilobites and
cephalopodstendtooccurmainly inargillaceous
Weathering of the sequence gives rise to horizons in contrast to the gastropods, bivalves,
hogback topography, the more resistant arenites andbrachiopodswhich are foundmore evenly in
creatingridgeswhereas the interveningargillites arenites and argillites. Among echinoderms, the
generally weather predominantly recessively. crinoids are found in a variety ofsediment types
This distinctive weathering minimises good from mudstonesto lithic arenites. Although stem
exposures ofthe argillites. fragmentsareprolific,well-preservedcrownsare
Althoughnumerousfossilshavebeencollected largely confined to finer grained sediments.
and described, little attention has been paid to Although scarce, ophiuroids, carpoids and
EARLY DEVONIAN ECHINODERMS OF SOUTH AFRICA 117
Q«*rti«»« iiitdiltM,alttalana.ulnarinndatnna.amdhm-tafbi*-«<aln*d.thin-I*thtak-bnddarf.planar
andtroann aroaa-baddad.
KAROOPOORT FORMATION hSoIrHtaetanantaalaannddarakand>raatalaaaa,thltaatttaadr,prripapdtoaajnlanrattaiaenanarmthownarIdmar,aafltaaaal-llaaaaaaaad.hMbraa-tgwrraslanlandd,,rtahrienpblaadndtardr,aaa>p«ta.
OSBERQ FORMATION aadalaaaand arttatana,Hna-laawdlnai aretnnd.tMn-tatMeb-bnddad.aartiaatalandrfc*a*tlaarinatad,
planarand trowphornaa-baddad,chananhwaaaeare.Inlraalaallanaaa,blatarbalad.planttranawata.
KLIPBOKKOP FORMATION SMtalana.aHtynadalanaand»k*nraandaleaabada,II**-laaadhHa-aralaad.horteaatalandrtppto
laarinatnd, planarnraaa-baddlnflpredaaiatataa.traapaaraaa-aaddlnfnaaara,abandnntHp*t*aartia.
Intraelaatlanaaa,blaiwrkaiad,aaa>aplanttrapataata.
WUPPERTAL FORMATION •ra_tabo>nMttMdaaaarrlbblaaaantlnaaalddnw.,aiitalahadoa,atiatpailnappnllaaaaUnnrtttaatttnnrrdanainphaHltraanantaaaaa.aanftlntar-aatfahaanrdahama--gbraadldaaadd,,abthaiand-atMarIkhplpeMh-atbaardfcdaa,dh.rtbroaralliaaaattalla.naaanad,
WA8O0MBERQ FORMATION $C^(3s ahfrttlraataolaaaatalnadnaaataadbaltaataaar.barlaarda,tltailaaabWtaadrdaaadaalaaaadaaataa.aa.aaaarvaarharliaatalandripptalaataalad,
BOPLAA9 FORMATION \J3 •aaadndtartaaanfah.aUrnaaa-a-tbaadaaddakdj,rat-hianrabltntnrdaa.latahtinl-anlaaaaI,Maaka-wbnad*daa*d,inrnrilaioantatlaaaanldanrba>apataallapattaaaatlaIdr,anpalaaanlaar,
TRA-TRA FORMATION W a•Ibrataadtaaaaalarnipdptaairtayarmkaad,atbalnalaarabnadtlaalnaaarndthtlrna-abaadtdaaada,Haa,atadMantaiantar,aerliapapttalaannadaaa.ilpalraanatrIaraaaaalaaaaitlan.alad,
HEXRIVER FORMATION MSffife? aSarnadaaal-abnaad,daldl,aa-tbhliaabiatdrtaaaal-aaalrallannaada,a.thin- ta thlak-baddad,aadlaa aaala plaaarft traapb
^y^t*> ftlltataaa, allty aadataaa,parallal-laalnalad, aaaalva. harltanlal-,rlppla- aadailaraaraaa
VO0R3TEH0EK FORMATIOI laalaatad,abandanl rtppla-aarha, hlalarballan,laaallMaraaalaaaaa. m
QAMKA FORMATION VA Inndaiann,Una-tamidhna areaid.tMn- I*ihtok-ftaddnd,paraMallaalnalad.plaaararaaa baddad.
OVDO FORMATION 4r****0»*.htadatanaI aMalanaft afciartMn-baddad aandatana.aaallaradlaaaMara
baddhn.abandaalhtataraalloa
Oaartiaaaaandatanaaapaa-MUna aralnad,tMn-tatMak-baddad,planarftahaMawtreat*,areaa-bada
FIG. 2. StratigraphicsectionofSouth African Devonian. Thecoarsesandstonesattopandbottom ofsectionare
contiguous parts ofthe Witteberg (C3) andTable Mountain (CI) Groups, respectively and indicate upperand
lowermarginsoftheBokkeveldGroup(C2).Allsedimentsaresiliciclastics;solidblack=mudslone,horizontal
dashes =siltstone and close dots = fine sandstone. Fossil contentis indicated by: star- echinoderms; convex
down symbol= shells; convex upsymbol = trilobites; twocurved linescrossingtowardsrighthandend = fish;
leafshaped symbol = plant fragments. A shorthand nomenclature to reflect cyclicity within the Bokkeveld
Grouphasemergedsothattheshales(S)alternatewiththesandstones(Q)andarenumbered fromthebaseup;
thus theGydo Formation isC2S1. the Gamka Formation isC2Q1, the Voorstehoek Formation is C2S2. etc.
blastoids are similarly found mainly in mud- northward advance of the shoreline and
stones, shales or silty shales. progression of shelf and delta slope sediments
Faunal community structures are recognised (Gydo Formation) acrossthe sand-shoal Rietvlei
(Boucot, 1971; Hiller & Theron, 1988). The Formation. The latterconstitutingthe uppermost
overall decrease ofBokkeveld invertebrates and unitoftheTableMountainGroup,wasdeposited
increase in plant fragments and ichnofossils to in a wide shallow embayment open to the
the north as the argillaceous units become southeast and flanked by a mature low gradient
sandier,suggestsashallowingofthebasin inthat coastal plain (Rust, 1973).
direction. There is a corresponding decrease in The Bokkeveld sequence reflects the most
fossil content in a southerly direction approach- dynamic phase ofthe Cape Basin development,
ing the deep basin (Theron, 1970, 1972; Theron
when, at the Pragian-Emsian transition, tectonic
&Loock, 1988).
activity and accelerated downwarping evolved.
PALAEOGEOGRAPHICAL SETTING Pulsatory cyclicity in the vertical stacking ofthe
upward coarsening sequences implies techn-
The conspicuous change from a few thousand ically controlled regressions and transgressions
metres of supermature sand (Table Mountain (Theron, 1972; Tankard & Barwis, 1982). These
Group)tothepredominantlymuddysedimentsof majorcyclesrepresenttheprogradation oflobate
the BokkeveldGroupthroughouttheCapeBasin wave-dominated deltas along a coastline of
&
inthe EarlyDevonian, isinterpretedasanoverall moderately high marine energy (Tankard
IIS MEMOIRSOFTHE QUEENSLAND MUSEUM
Isteriacites sp. A. assemblageo\ i() or more complete or partial individual traces m close proximity.
1 1 J51 from Vanrhynsdorp(C2S2 i. \1 2.| Photocourtesy ofJohn Almond|
Barwis. 1982; Thcron & Loock. 1988). coquinites.Fossilsarealsogenerally sparseinthe
Nearshorc deposits grade southward into thick reworked sands ofthe delta platform. Wave and
shelf mudstones. with the greater thickness tidal activity created interspersed barrier
towards the eastern Cape reflecting increased washovcr sheets and tidal inlet and channel fill
dounwarpingin that direction, sequences thai were not \ery conducive to die
preservationoffossils.
An idealised Bokkeveld genetic sequence
consists of sediments laid down successively in On the other hand the dark grey mud and
the shelf, delta slope and delta platform sihstonesofthe BokkeveldGroupcontaina rich
environmentsduring the constructional phase of invertebrate fauna, especially brachiopods and
deltagrowth.Thisisinturnoverlainby ncarshorc bivalves, which are preserved as scattered
marine reworked deltaic deposits, which internal and external moulds- Coquinites, where
represent the sediments that evolved during ihe present,arerclativeh thinbutlaterallypersistent;
dcstruclional phase of delta development aswaterdepthincreasedcoquinitesbecamerarer.
(Tankard & Barwis. 1982). Storm activity is Ebbingstormsurgecurrentsentrained shellsand
well-documented in the delta platform sediment from the scafloor and carried them
sediments, which represent the distributary seawards,to where hollowsandslonn-generalcd
mouth bar. inlerdistributary bag and tidal flat channels acted as traps in which shells and
disarticulated crinoidal material accumulated
deposits, espccialh in the northern Bokkeveld
(Hiller&Theron. 19X8)
fades(TheronetaL 1995) Fossilsaregenerally
sparse in these sand-, silt-, and mudstones. but Generally, post-mortem transport of fossils
occasional occur as rclativeh thick lenticular was limited as indicated bv the minimal
EARLY DEVONIAN ECHINODERMS OF SOUTH AFRICA
Grahamstown
V
14
FIG. 4. Sketch map of South Africa indicating the localities from which Lower Devonian echinoderms are
known. The 2 frames around the Ceres and Ladismith-Prince Albert districts are enlarged in Figs 5 and 6,
rPelsaptefcotnitveienl;y.!4Ke=yKataoban/uAmlbeexraenddrilaoc;al1i5ti=esNoouugtsai/dVeretdheefofrrta;me2s3:=5K-euBrubcokolmasntdrsa;nd6;=24G=roWoatrrimvwiaetrehroobgetreg;;1216==
Clanwilliam.
mechanical damage to shells. Disarticulated in the northern proximal shallow marine beds
shellsarecommonbutrarelydisplayevidenceof substantiate the original abundance of starfish
abrasion or breakage. Furthermore the and brittle stars in the marginal Bokkeveld seas.
vulnerability of the multiplated echinoderm The relative rarity ofasterozoan body fossils in
skeletons to post-mortem disaggregation the Bokkeveld sequence is therefore a reflection
generally make preservation of whole crowns ofthe disintegration oftheir complex skeletons
relatively rare. In the Gydo and Waboomberg after death. Both ophiuroids and asteroids
Formations preservation ofechinoderms still in probably constituted quite an important
life position, indicates predominantly gentle component of the normal prevalent benthic
currents and sudden burial, perhaps by marine biota ofthe Bokkeveld Group.
smothering mud clouds. Sudden influxes offine Available data allow correlation (Boucot,
sediment may have come either from the rivers 1971; Hiller & Theron, 1988) ofseveral benthic
feeding the deltas, or as a result of a storm invertebrate fossil communities with various
generating a blanket of wave-stirred mud depositional subenvironments in a delta
&
(eTnhveirroonn,men1t9a72l;sHcielnlaerrio isThseurpopno,rte19d88b)y. Thihgihs cinoamrptliceuxl:ate1, abrtaidcahlifolpaotdcsomamnudniitnfyaudnoamlinbaitveadlvbeys
concentrations of brittle stars (adult as well as inhabited the sheltered, back-barrier environ-
immature individuals), constituting lenticular ment; 2, the distributary mouth bar community
'starfish beds' in the Waboombergmudstones in dominated by brachiopods, occupied the
association with large numbers of infaunal relatively turbulent shallow water setting at the
bivalves preserved at a high angle to bedding seaward edge ofthe delta platform; 3, the delta
with their umbones pointing upwards. slope community was of intermediate aspect,
Co-occurring fenestellid bryozoans, all with the dominatedbybrachiopodsbut morediverse with
apices of their cones directed upwards suggest infaunal bivalves, gastropods, crinoids,
overturning by gentle currents. In locally cricoconariids and especially trilobites; 4, the
overlying beds well-preserved carpoids are shelfcommunity,whichalthough still dominated
associated with an ostracod fauna and with by brachiopods, is the most diverse community;
exquisitely preserved Lingula, which are not in brachiopods constitute <l/2 the diversity of the
lifeposition (Ruta&Theron, 1997; Beckeretal., assemblage, with trilobites. bivalves and
1994). The frequency ofasterozoan trace fossils gastropods well represented and echinoderms.
120 MEMOIRS OF THE QUEENSLAND MUSEUM
FIG. 5. More detailed localitymap ofCeres districtasoutlinedby lefthandframe in Fig. 4. l=Hottentotskloof;
2=Theronsberg Pass; 3=Tafelberg/Boplaas; 4=Matroosberg/Vredelus; 8=Hex River Pass; 9M3ydo Pass;
10=Die Vlakte; 12=Klipfontein/Lakenvlei; 13=Swaarmoed; 21=Eselfontein; 25=Ceres. Thickblack lines are
roads; thin crossed line (lowerright) isarailway; thinblack lines are streams.
hyolithids, corals, bryozoans, conulariids and In the Gydo and Gamka Formations, which
cephalopodscomprisingasignificantproportion. constitute the oldest deltaic cycle, these
communities are well-represented. Shelf and
EARLY DEVONIAN ECHINODERMS OF SOUTH AFRICA 121
FIG.6.MoredetailedlocalitymapofPrinceAlbert-LadismithdistrictsasoutlinedbyrighthandframeinFig.4.7
=GamkapoortDam; 16=Vleiland; 17=Koudeveld; 18=Gamkaskloof; 19=BosIuiskloof;20=Damascus;22
= Vrischgewaagd. Thick black linesareroads; thin black lines are streams.
slope communities are found in the Voorstehoek
Formation and in western outcrops of the
Waboomberg Formation, shelf community CRINOIDS 1 i 3 4
assemblages have been identified as well. In OphiocrinusslangeriSalter. 1856 G G
many of the other formations, available Ophiocrinussp. cfmariae(Kier, 1952) cfS G
collections are general&ly too small for com- CorochnusimbecillusSchmidt. 1941 s G
munity analysis (Hiller Theron, 1988).
Mandelacrinusneisomgen. etsp,nov. cfG cfG
FAUNALAFFINITIES Monocycliccamerateindet. cfG
All Bokkeveld echinoderm specimens known Arthroacantha?sp. ?G
to the authorswere included in thepresentstudy. EckiJocnnusinierbrachiatuss.cn.etsp nov.
Affinities of the taxa identified (Table 1) are Kopficrinushatbwhisp.nov. G
highly equivocal. One bias in this assessment is Mortaldicrinusjohnigen.etsp.nov. cfG cfG
the variation in levels ofknowledge from other Sacrinusgamkaensisgen.etsp.nov. cfG
partsoftheworld.ThefaunaofNorthAmericais Sacrinushexensisgen. etsp nov cfG
the best known and in general, most recently Cradeocrinusplenariussp. nov G G
sktnuodiwend;buitn mEuarnoypehacvoempnaotrabbeleynlgairvgeenfaaumnoasdearme Thalamocnnusarenaceussp. nov. G
taxonomic treatment; South America and Othozechnusroyigen etsp.nov. cfG
ASTEROZOANS
Australia have faunas of this age but they are
poorly known (e.g. Australian crinoids (Jell, AulucUihaslcrhreviramusgen etsp.nov. cfG cfG
1999) as demonstrated in this volume). Early Ulrichaste?macrodentusgen etsp nov G G
Devonian echinoderms from other parts of the HaughlonasterreediRilett, 1971 cfG cfG
world are virtually unknown and not able to be Hexurasicrweitzi(Spencer. 1950a) F F 1- ;
compared. At species level the South African Encrinastertischbeinianus(Roemer. 1862) S
faunahasacrinoidandanasterozoan incommon Marginurahillerisp nov G
Eugasterellaa/ncanasp.nov.
&
TABLE 1. Faunal affinities of the South African S1t9r7a1tasterohoensisKLeshne LeVasseui; S
echinodermsdealtwithhereincomparedwithEurope Stratasterstuckenbergi(Rilett, 1971) G
(A1u)s,trNaolirath(4)A.mGer=itchaeg(2e)n,usSoocuctuhrsAimnetrhiactacon(t3i)neanntd; BLASTOIDS
cfG-acloselyrelatedgenusoccursincommon; S= PacfwblastusdickiBreimer&Macurda.1972 S
the species alsooccurs in thatcontinent; and F =the BrachvschismaootheizeniBreimer & G
family is incommon. Macurda. 1972
122 MEMOIRS OF THE QUEENSLAND MUSEUM
with Europe, a crinoid and an asterozoan with Subclass CAMERATAWachsmuth
North America and a blastoid in common with & Springer, 1881
South America. At the generic level most Order DIPLOBATHRIDA
matches are with North America, then Europe, Moore & Laudon, 1943
then a very few with South America and Superfamily RHODOCRINITOIDEA
Australia. The 25 South African echinoderms Roemer, 1855
Family OPSIOCRINIDAE Kier.1952
dealt with herein do not provide a statistically
large enough sample to make any compelling Although Kier (1958) advocated elimination
arguments and thus the affinities must be of the Opsiocrinidae after he recognised that
considered unknown at this stage. Brachiopod Opsiocrinus was dicyclic, Ausich ( 1986) found
affinities(Boucotetal., 1969)placeSouthAfrica the family useful in his classification of the
in the cool water Malvinokaffric Realm Rhodocrinitoidea. Frest & Strimple (1981) and
suggesting that further study ofSouth American Ausich (1986) recognised that several of his
echinoderms may reveal closer affinities. familial characters are of generic standing in
some cases in the same group. With this in mind
theclassificationmaybeconsidered preliminary.
SYSTEMATIC PALAEONTOLOGY Frest & Strimple (1981) and Ausich (1986)
recognised the cofamilial relationship of
The following abbreviations indicate Opsiocrinus and Ophiocrinus; weconsiderthese
treexpto:s-itoBrriietsisfhorMtuhesemuatmerioafl NdaitsucruaslsedHiisntotrhye (g1e9n8e6r)a cslyanssoinfyicmasti(osneheebreelionwb)u.tWfeolluosweinAgusIiCcZhN5S
Article 40 the family name based on the junior
(BMNH). Geological Survey of South Africa, synonym remains valid.
Pretoria (PRV), Geological Survey of South
Africa, Bellville in Capetown (B), Roy Ophiocrinus Salter, 1856
Oosthuizen Collection, Zwartskraal, Prince
Albert (RO), South African Museum, Capetown TYPE SPECIES. OphiocrinusstangeiiSalter, 1856from
(SAM), Geological Collections, Stellenbosch the Lower Devonian Bokkeveld Series, South Africa; by
monotypy.
University, South Africa (SU), Rhodes
University, Grahamstown (RUGDNH), Natal DIAGNOSIS. Infrabasals 5, forming a pentagon
Museum, Durban (NM) and Sedgwick Museum, completely or almost completely concealed by
Cambridge University, England (SM A). All stem; interbrachials numerous, depressed, small,
illustrationsareoflatexcaststakenfromexternal regular, especially in proximal part ofinterrays;
CD
moulds unless otherwise stated; they are interray conspicuous, with anitaxis of
whitened with a sublimate of ammonium subquadrate anal plates variously developed in
chloride forphotography. fieldofsmall irregularplatesoneitherside.Anns
1 or20, freeandbecomingcuneatethenbiserial
distal to last ami division, unbranched distally.
Class CRINOIDEA Miller, 1S21 Stem circular or pentagonal in section, with
narrow marginal crenularium, heteromorphic.
Terminology follows Moore & Teichert REMARKS. The only significant differences
(1978). Measurements are given as: length, betweenOpsiocrinusKier,1952andOphiocrinus
parallel to the central axis; width, transverse to, appear to be the number of amis, length of
but never cutting orjoining the central axis; and anitaxis and cross section ofthe stem. Frest &
depth, normal to, and mayjoin central axis. Strimple(1981, table 1) showedthatthe2 genera
FIG. 7. OphiocrinusstangeriSalter, 1856. A, deformedcrownwithpinnulatebiserial arms, R039, *1. B, C-D
interray view ofcrown showing 3 vertical columns ofanal plates B4603, *2. C, small specimen showing
uniserial armswell away from thecaandbiserial armon lefthigh up, B4544, x3. D,holotypecrownwithC-D
interrayonleft,with 1stinterprimibrachsupporting4analplates,with uniserialbrachialsproximallygradually
becomingcuneatethenbiserialdistally,SMA3441,y4.E,basalviewofsmallcupshowingsubpentagonalstem
facet, fromtheGydo Formation inaquarryonE sideofroadN fromPrinceAlfred's Hamlet, 1km SofGydo,
B4670, ><5.F,smalldeformedcrown SAM13479, x2.G,twocrownscompressedinthesamedirection,thaton
left withdiminishedcrownlengthand thaton rightcompressedlaterallyandshowingtheinfrabasal circleton
top ofthe stem viewedfrom insidethecup. SAMK972. x 1.25.
EARLY DEVONIAN ECHINODERMSOF SOUTH AFRICA
123
124 MEMOIRS OF THE QUEENSLAND MUSEUM
aredistinguishedonly bythenumberofarmsand
inthenatureofamibrachials. Althoughthereisa
reversal (clearly a typographical error) between
their text and table 1 with Ophiocrinus being
credited with cuneatc brachials in the text bul
biserial ones in table 1. Regardless of this
confusion the larger collection of O. stangerh
now available,allowsconfirmationthat thearms
inbothgeneraprogressdistally from rectangular
tocuneatctobiserial. Lengthoftheanitaxis,with
4plates inonegenusand2 intheothercouldwell
be considered a specific discriminator if
CD
consistent (1 intcrnn is available for
Ophiocrinus and 2 for Opsiocrinus). Some
camerate genera contain species with different
numbers of arms. One specimen of O, stangeri
(Fig. 2C)hasa raywithonly 2amisasopposedto
theusual4 inadjacentrays;a2ndspecimen(Fig.
IB) showsthebeginningsofthe radial interplate
ridge patterns so prominentin some Opsiocrinus
mariae Kicr. 1952 (Kesling & Clulman. 1975.
frontispiece, pi.40. figs 11-14); several
specimens (Fig. iA. 2A, 3B) have slight, barely
visible re-entrants in the proximal margin of(he
basal plates which probably accomodated the
corners of the infrabasal pentagon as in O.
mariae. This indicates that orientation of the
infrabasal pentagon to the basal circlet changed
from the exterior to the interior as describedby
Kicr (1958. fig. 1) in 0, mariae because the
interiorofthecupin 0. stangeri (Fig. 3E) shows
the infrabasal pentagon with the angles at the
sutures between basals and the sutures between
FIG. 8. Ophiocrinus stangeri Sailer, 1856. plate
infrabasalsat thecentreofthebasals.Thestemof diagramshowingstemfacetasdashedcircle,radials
the North American species is inferred to be black and only 2 incompleteanus from halfofone
pentagonal because of the shape of the ray;posteriorinterray at 12 o'clock.
attachment facet on the cup. In O. stangeri the
stem is roundbut inatleast I specimen(Fig. 1G) members and we suggest that Ophiocrinus and
tpheentaagtotnaaclh.mTenhtusfwaceetsyonrontyhmeis1estthceoselu2mngeanlerias Olipnseiaogcerriantuhsercotnhsatnit2uttheatIhgaednbuseeannsdepbaerlaotnegsitnoceI
despite theirgeographicand stratigraphic (Early the Early Silurian (Jell 1999, fig. 2).
Devonian vs Middle Devonian) separations.
Ausich (1986:87) inferred 2 lineages within the Ophiocrinusstangeri Salter.1856
Opsiocrinidae from the Llandovery into the (Figs 7-10)
Devonianwiththe2Devoniangeneraonseparate
lineages based on cup shape, prominence of Ophi19a7c8r:imTt4s2Ss.tafnigge.ri23S8a.l2t.er. 1856:223.pi.25, fig.20; IIbaghs,
ridgesandarmnumbers.However,cupshapeand
ridge pattern are identical in the 2 Devonian MATERIAL. HOLOTYPE: SMA3441 fromDe Dooms.
genera and taking die rudimentary ridge pattern 1 lex Rivier Poorl (donated to the Sedgwick Museum.
in a specimen of Ophiocrinus even the Cambridgein 1932 fromdiecollectionofDrW. Slanger.
interbrachialornament maybeallied.Therelation BB44552263-4f5r3o0m BfurcokmlaGnadsm,kaepaosoterrtn DCaapme (PCr2oSviIn)e.e(BC425S4l4).,
of the infrabasal circlet to the basal circlet is B4553, B4603 from Gvdo Pass (C2S1), B4551, B4552
another feature which seems to join the 2 from Gamkapoort Dam (C2S1), RUGDNHl from Klein
Devonian genera. Other monophylctic camerate ECaaba, Alexandria district, eastern Cape (Voorstehoek
genera are known to have 10 and 20 armed Formation), B4579; RO S1Z RO S20 from Grootrivier.