Cythereis mesa: Methusalem or Lazarus?

5 Pages·1993·1.8 MB·English

by  Avraham Honigstein

343
Zitteliana
344
GEOLOGICAL AND PA L EONTO L O G CA L
1. I
BACKGROUND
Soft Senonian - Paleocene Sediments are widespread over (BiozoneM).Thesebiozonesandtheirstratigraphicpositions
Israel. The Late Coniacian - Campanian succession consists werecorrelatedwithzonesandmarkersofotherfossilgroups
mainlyofhomogenouschalks,overlainbymassivebrecciated (Reissetal.1985;Honigsteinetal.1987).
cherts ofLateCampanianage. Argillaceous chalks dominate TheSenonianostracodeassemblagesconsistofmorethan60
Maastrichtian strata. Paleocene Sediments consist mainly of different species. Species of the subfamilvTrachvleberidinae
marls and marly chalks (Flexer 1968). Most ofthese strata (e.g. group Cythereis) and ofthe genera Brachycythere and
containratherriehmacrofossilandmicrofossilassemblages. Protobuntonia are dominant as well as smooth forms (e.g.
TheConiacian-Campanianchalkscorrespondtoshallow- Cytherella).Allostracodespeciesaremarinetypesandpointto
water environments in an inner to mid-shelf region. The Sedimentationinamoderateshelfenvironment.
paleodepthcurveforthesedepositsshowsagradualsea-level Aftertheprominentdefaunationofostracodes(innumberof
rtihsees(eFal-leexveerledturali.ng19t86h)e,LfaotlelCoawemdpabnyiaans.igAnifriecannetwelodwseerai-nlgevoelf srpicehctiieasnasinwelIlsraaesl,inPaplopeuolcaetnieonstdreantsaitcyo)ntdauirningagtahienMariacshte-r
rise oecurred during the Maastrichtian. The strata were de- assemblagesofabout20differentspecies.ThemarinePaleo-
posited inaseries ofbasins in anouter-shelftoupper-slope cenefaunasaredominatedbythegeneraOrdoniya,Mauritsina
environment,withdysaerobicconditionsonthebottomofthe andsmoothforms(e.g.KritheandCytherella).Cristaeleberis
sea.TheenvironmentofthePaleoceneSedimentsissimilarto retimlataBasSIOUNI,1971andMegommatocytheredenticulata
that of the Maastrichtian, though somewhat shallower and (Eskir,1968)(describedbyHonigstein1984asOertliella}cf.
withmorenormalmarineconditions. rasbaalbekensis)arereportedfromSenonianstrataandproeeed
TheSenonianostracodefaunasofIsraelwerefirstdescribed intothePaleoceneofIsrael,asinneighbouringcountries(e.g.
byHonigstein(1984). Ostracodes are relativelycommon in BasSIOUNI 1971; Bassiouniand Luger 1990).Two LateSan-
Late Coniacian - Campanian Sediments and allow a bio- tonian - CampaniansubspeciesofCythereismesa reoceurin
zonation into five ostracode assemblage zones (S-l to S-5). EarlyPaleoceneSedimentsaltertheirdisappearencelastingthe
During Maastrichtian times, only few ostracodes oeeur wholeMaastrichtian.
CYTHEREIS MESA: OCCURRENCES AND
2.
EVOLUTIONARY STRATEGIES
2.1 THE OCCURRENCE OF CYTHEREIS MESA Cythereis or to any other known genus of the Trachy-
Cythereismesaanditsfoursubspeciesweredescribedfrom leberidinae. However, becauseofits typical external features
SenonianSedimentsbyHonigstein(1984,seealsoHonigstein for the Cytheracea, as well as its partly preserved internal
1985).These forms are known hitherto only from Israel. C. elements,itisattributedheretoCythereis.
mesa is a relatively large form, (0.8-1 mm length), which is ThesubspeciesofC.mesadifferbytheirornamentationof
characterized by astrongsubcentral node, adistinet median the carapace and the position ofthe posterior end. C. mesa
ridge and a prominent posteroventral node. Its ventral view centroleviata with a smooth carapace and C. mesa centro-
(PI.1, Fig. 5)issubtriangularandpiain,becauseofthesharp reticulata with a reticulated carapace, both with a centrally
edgeoftheelevatedventralridgetowardsthecontactmargin. pointedposteriorend,oeeurinLateConiacian-LateSantonian
C. mesa probably does not belong definetely to the genus strata(OstracodezonesS-ltoS-3).Thetwosubspecieswitha
Plate1
mesamesaHONIGSTEIN.-Femalecarapace,leftvalve,HarTuv-1,No.T-7364,Campanian.
mesamesaHonigstlin.-Malecarapace,rightvalve,Shefaram-1,No.T-7361,EarlyCampanian.
mesaventroreticulataHonigstein.-Female(?)carapace,leftvalve,Shefaram-1,No.T-7074,LateSantonian.
mesaventroreticulataHonigstein.-Malecarapace,rightvalve,BeerShevaSH9,T-7177,EarlyCampanian.
mesaventroreticulataHonigstein.-Malecarapace,ventralview,HarTuv-1,No.T-7364,Campanian.
mesamesaHonigstein.-Femalecarapace,dorsalview,NahalHavarim,SB320,EarlyPaleocene.
mesamesaHonigstein.-Malecarapace,leftvalve,HörHaHar,HH24,EarlyPaleocene.
mesamesaHonigstein.-Femalecarapace,rightvalve,HörHaHar,HH22,EarlyPaleocene.
mesaventroreticulataHonigstein.-Malecarapace,leftvalve,NahalHavarim,SB304,EarlyPaleocene.
mesaventroreticulataHonigstein.-Femalerightvalve,SdeBoqer,AR539,EarlyPaleocene.
Zitteliana,20,1993
Honigstein,A.,Hirsch,F., Rosenfeld,A.& Flexer,A.:Cythereismesa Platt
ventrallypointedposteriorend,C.mesamesa(smoothform; Iteration
PL1,Figs.1-2)andC.mesaventroreticulata(reticulatedform; Thefadingawayofataxondoesnotautomaticallymeanits
PI.1,Figs.3-5),weredescribedhithertofromLateSantonian- extinetion.Often,whenconditions,similartothosebeforethe
Campanian Sediments (Zones S-3 to S-5; Honigstein et al. disappearenceofthespeciesreoccur,restorationofthattaxon
1987). In Maastrichtian strata these ostracodes were not takes place. This phenomen, called by Jablonski Lazarus-
observed, even though they are relatively large and very effect,mayberelatedwithheterochrony.
distinctive.
InthetypesectionofPaleocenestratainsouthernIsraeland
Migration
intwoothernearbysections,sampledfortheinvestigationof
EarlyCenozoicostracodes,C.mesamesa(PI.1,Figs.6-8)and Migration offossil species in space and time oecurs often.
C.mesaventroreticulata(PI.1,Figs.9-10)reoccurinthelower Nerineids, common in Europe during the Bathonian, were
partoftheprofiles, appearing several meters above the K/T drivenawaybytheborealspreadduringtheCalloviantothe
boundary level and common in layers of the NP-3-NP-4 gondwanean shores of the Tethys. There, they found an
nannoplankton biozones (Moshkovitz, GSI; pers. comm.). ecologicshelter,evolvedfurtherandrecolonizedthenorthern
The Paleocene specimens ofboth subspecies of C. mesa are epicontinentalseasoftheTethysduringthemiddleOxfordian
shown to be taxonomically identical with their Senonian (Hirsch1979).Ostracodes,e.g.SimeonellabrotzenorumSohn,
counterparts(PI. 1). whichisreportedfromtheLadinianoftheSephardicprovince,
ThepossibilityofredepositionofLateCretaceousfossilsin migratedduringtheCarnianintotheAlpinerealm(Gerryetal.
PaleoceneSedimentswastakeninaccount,butcanbeexcluded 1990).
duetothegoodpreservationoftheostracodesandtheabsence
of coexisting Late Cretaceous foraminifera and calcareous Exccptionalsurvival
nannoplanktoninthesesamples(Siman-TovandMoshkovitz,
GSI, pers. comm.). Therefore, the reappearence of the two eveErxytrfoesmseillygrsoluopwfrevoomltuhteiobnrarcahteisopcoadnLbiengoublsaetrovethdeicnonmemarolny
subspecies of C. mesa after a 10 million years gap must be cockroach. This long-range phenomen braves evolution like
relatedtootherfactors.
biblicaloldMethusalem.ThismavapplyalsotoCristaeleberis
reüadataandMegommatocytheredenticulata,whichoeeurin
2.2 DISCUSSIONONEVOLUTIVESTRATEGIES IsraelcontinuouslyfromtheEarlySenoniantilithePaleocene,
Thegeneticmechanism,intendcdtoWarrantthesurvivalof crossingeventheK/Tboundary,whichrepresentsabarrierfor
theoriginalmodelthroughoutgenerationsisonlyvalidaslong manyfossilgroups.
as viable living conditions remain relatively the same. Some
species have a high adaptive tolerance, and thus a better 2.3 THECASEOFCYTHEREISMESA
possibility for long survival than very specialized taxa. The
latter are more vulnerable to changing conditions, and their ThetwoLateSantonian-CampaniansubspeciesofC.mesa
reactionis„perishorchange". reappearinsimilarquantitiesinEarlvPaleocenestrataofIsrael,
after a gap of 10 million years. No redeposited fossils were
foundinthesesamples.Therefore,whatevolutionaleffectcan
Heterochrony
beinvokedforthere-oecurrenceofidenticalformsaftersucha
TheconeeptofpaedomorphosiswasdevelopedbyGould longtimespan?
(1977), usingHaeckel'soldconeept forevolutivestrategies, ThedisappearenceofC.mesaduringtheMaastrichtianmay
amongwhichprogenesisand neoteny,mimicbackwardevo-
beduetooxygendeficiencyneartheseabottom.Afterthere-
lution.Theretardationorontheotherhand,theaccelerationof
establishmcntofbetterecologicalconditionsduringthePaleo-
reproduetive maturation can be caused by environmental
cene,arepetitionofthespeciesseemspossible.But,generally
changes.Thestrategyofprogenesis,thespeedingupofsexual Cytheracean species evolved fast and both subspecies sur-
maturity, is usedwhen conditions improvedramatically and prisingly reoccurinourmaterial(Lazarus-effect). But,where
cthoendoitrigoannsi,stmofreeelprtohdeucuergtehetmosetalkveesadasvafnasttagasepoofsssiubcleh.oOptnimtahle Mwaaassttrhiechtshiealnt?erC.fomrestaheresppreecsieenststoarmeilgartiavteelyilnatrogeduarnidngorntah-e
contrary, once all niches are fully packed and among other mented ostracode species that can be hardly overlooked.
fisactnoerost,ennuyt,ritehnetssbleocwianmgesdcoarwcne,athnedrseasvpionngseoofftthheeoorngtaongiesnmics fAlrtohmouagdjha,ceinttwaarseahsitwhietrhtosirmeiploarrteMdaasotnrliychftrioamn aIsnrdaelPaalnedocennoet
process by retardation. These strategies can be observed in rock formations, asJordan and Egypt (e.g. Bassiouni 1971,
Tlraitaisonsicchcaonngoedsonmtast,chpreeueseteadtiicngseeax-tlienveetliofnl,uewthuaetrieonsthe(Hpiorpsuch- Bfuatsusrieo,uCn.imaensdaLwuigllerbe1f99o0u)n,ditincaMnidndoltebeEaesxtcelrundMeadasttharticihntitahne
1992).
SedimentsandappeartobeanotherexampleoftheMethusa-
lem-cffect.Forthetimebeing,thequestionremainsunsolved.
.
347
REFERENCES
Bassiouni,M.A.A.(1971):Ostracoda(MauritsininaeundTrachyle- GoUIi),S.J.(1977):OntogenyandPhylogeny.-501pp.;Cambridge,
beridinae) und ihre Bedeutung für die Biostratigraphie des Mass.(BelknapPressofHarvardUniv.Press).
Maastrichtunddes AlttertiarvonJordanien. - Beih.geol.Jb., Hirsch,F.(1979):Jurassicbivalvesandgastropodesfromnorthern
Bassi1o0u6n:i,5-M5.2;AH.an&noLvuegre.r,P.(1990):MaastrichtianCoEarlyEocene Slienma.iandsouthernIsrael.-Isr.J.EarthSei.,28:128-163;Jerusa-
Ostracodafromsouthern Egvpt. Paleontology, Paleoecology, Hirsch,F.(1992):PatternsofevolutionbeforeextinecionofTriassic
PaleobiographyandBiostratigraphy. - Berlinergeowiss. Abh. conodonts.-Paleont.Soc.,Spec.Publ.,6:129;Knoxville,Te.
(A),120(2):755-928;Berlin. Honigstein,A.(1984):SenonianostracodesfromIsrael.-Geol.Sun
EsKER, G. L. (1968): Danian ostracodes from Tunisia. - Micro- Israel,Bull.,78:1-48;Jerusalem.
paleontology,14(3):319-333;NewYork. Honigstein,A.(1985): Cythereumesa mesa(Ostracoda),acorrect
FlexeSrc,opAu.s(1G9r6o8)u:pSt(rSaetniognriaapnhy-aPnadlefoacceinese)deinveIlsorpaemlenatndofadMjoaucenntt nEaarmtehfSoeir.,Cy3t4he(4r)e:is24m0e;sJaervuesnatlreoml.evlataHonigstein,1984.-Isr.J.
countries.-Isr.J.EarthSei.,17:85-114;Jerusalem. Honigstein,A.,Almogi-Labin,A.&Rosenfeld,A.(1987):Com-
Flexer,A.,Rosenfeld,A.,Lipson-Benitah,S.&Honigstein,A., binedostracodandplankticforaminiferabiozonationoftheLate
A19A86P.GReBlualtli.v,e7s0ea(1l1e)v:el16c8h5a-n1g6e9s9;duTnulnsga.theCrctaceousinIsrael.- C(2o)n:i4a1c-i6a0;nL-oEnadrolny.MaastrichtianinIsrael.-J.Micropaleont.,6
Gerrv,E.,Honigstein,A.,Rosenfeld,A.,Hirsch,F.&Eshet,Y. Reiss, Z., Almogi-Labin, A., Honigstein, A., Lewy, Z., Lipson-
(as199i0n)d:iTcahteorCsarofmanpaslaehoneintvyirconsnimse:ntoss.tra-codIns:anWdhaptalleyyn,omoRr.ph&s Bmuelntiitpalhe,sSt.r,aMtiogsrhakphoivciftrza,mSe.w&orZkakost,IsYr.ae(l1.98-5I)s:r.LJa.tEeaCrrtehtSaeci.e,ou3s4
Mdaoynb(uCrhya,pCm.an(ed&s.)H,alOls)t.racodaandglobalevents,87-100;Lon- (4):147-166;Jerusalem.