(
Ciencia s da Terra (UN L) Lisboa W 15 pp.83-902 Figs., I PI.
I
2003
Ab st rac t
Upper Paleocene-Early Eocene mollusks of Silveirinha
(Figueira da Foz, West Central Portugal)
Pedro
Calla pez
Departamento de Ciencias da Terra, Universidad e de Coimbra, 3000 ·272 Coimbra, Portugal. callapez @ci.uc.pt.
Key-w or ds: Upper Palaeocene, Gastropoda, Bivalvia, Silveirinha Formation, Portugal.
A collection of fossi l gastropods and bivalves assembled at the Thanct ianIYpresian vertebrate site of Silveirinha (Figueira da Foz, West Central Portugal) is analysed from the point of view ofsystematics and palaeoecology. The diversity is scarce but the age and exceptional characteristics of the site are factors tha I substantiate a detailed study. The taxa identified are:Btthynia sourestsp . nov.,Gyraulus antunesisp . nov.,Chlamys sp. and Card iiacea gen. sp. indet. The preva iling of freshwater gastropods and the oeeurrence of2 fragments of marine bivalves suggest a palaeoenv ironmental setting that is inconformity with interpretations already establ ished, whic h are based both in sedimento logic and vertebrate data. These interpretations point out the existence of a freshwatercnv ironment opened from time to time to marine influences, resulting from apalacoatlanticcoast placed somekilometres westwards.
Resu me
Palav ras-c have: Paleocenicosuperior, Gastropoda, Bivalvia,Areias e Argilas de Silveirinha.
Proccdc-scao estudo sistematicoc palcoccologicodeuma co lecceodemoluscos gastropodese bivalvesefectuadanajazidade Silveirinha(FormacaodasAreias eargi las deSilveirinha,deidade tanetianaa ipresiana),situadaJ3kma SuI de Figueirada Poz, junto
a
EN109.0 elencosistemat icoe
poucodivers ificado, mas a particularidade da sua idadc, eontexto faunistico e ecclogico, confcrcrn-lheurn interesse 6bv io dentrodasfaunas de moluscos eenoz6ieos de Portugal. Ostaxadcscritossilo:Bithynia soaresisp. nov.,Gyraulus antunesisp .nov.,Chlamys sp.eCardiacea gen. sp. indet. A dominencia de gastr6podes deague dcce,a par de2 Iragmentos rotadosde bivalvespertencemesafarmlias tipicasdeambientes marinhosou salobros, silo aspectos que concordam com as sinteses paleoecol6gicasja existentes e fundamentadas na analise dos vertebradoseem dados sedimcntol6gieos. Taisslnteses apontam paraambientede natureza fluvial,sujeitoainfluencias marinhas esporadicas.Introduction
D uri n g th e la st two de cades the clay-pi t ofSilvei rinha (fi g . I ) h as b ee n r eco gn ized as one of the m o st noto rious verteb ra te s ites for the cont inental Pal a eog en e o f Westem Eu rope. The first verteb rate rema ins we re found in 1977, by R. Pena do s R e is , a nd st udied by M. Te lles A ntunes {R ci s
et al.,
19 81 a , 198 1b; A ntu nes & Ru ssel , 19 8 1; A ntu n e set aI.,
19 8 7 ) . Ever s ince, t he cl a y u n it s of Silveirin ha h a v e bee n e x ha ust ive ly s amp le d f orpalaeontologie purposes, and bec ame th e ma in subject of ma ny syste matic and stra tig raph ic stud ies (sec Antuneset
al.,
1997, fo r exh a usti ve references) .C ibld asda T ~rra (UNL J , 15
FigureI - Simplified map of Baixo Mondego with indication of the d ay pit of Silveirinha.
Rcis
et al.,
198 1a) and M. Telles Antun es& D. Russel ( 1981), aspan
of preliminary check-lists that poi nted out the palaeo ntologie importan ce and di vers ity of th is site.The inverteb rate fossils of'S ilveirinha are represented by a few species o f aq ua tic gas tropo ds, biv al ves and ostracods. Neve rthele ss the scarce d iversity of this faun a, es pecia lly whe n co mpare d wit h th e large number of ve rtebra tes a lready kn own, th e age and ex ceptiona l ch aracteristics of the site are factors that substantiate a detailed study.
The present paper sets ou t to rev iew the fossil molluscs o f S il ve i ri nh a , w ith em p h asis on syste m ati c a nd palaeo biologic data.
Phylum MOLLUSCA Linn e, 1758
Class GASTROPODA Cuvier, 1797
Subc lass PRO SOB RANCH IA M ilne& Edward s, 1848
Order MESOGASTROPODA Th iele, 1925
Famil y Bith yn iida e G ray, 185 7
Genu s Birhyn iaLeac h,inAbel, 181 8
[Type spec ies:Bithynia tentaaslata(Linne, 1758) ] The ne xt system ati c d escription s ari se fr om a co llec tion housed in the Earth Sciences Department o f the New Unive rsi ty of Lisbon and as se mb led under guida nce o f M. Telles An tunes.
The s y stem a tic anal y si s o f Proso bra nc h ia and B asom m atoph ora we re ba sed , re spe ct iv e ly, in th e extensive monographs ofW. Wenz ( 1938-44) and A. Z ileh ( 1959-60). Bivalves were systematized after R. Moo re ( 1969) andR.Abbo tt& K.Boss (1989).
Systematic
d escriptionsFro m th e po int of view o f th e Me so- C eno zo ic sed imentary evo lution of th is contine ntal marg in, the Silve irinha Formation can be co nsidered as the ons ho re expre ssion of a maj or tect on o-sedimentary seq uence, posterior to the well-known late Ca mpa nian -Maastrichtian eve nts recorded by Taveiro and other co ntempora neous
formation s (Cunha, 1992 ; Cunha & Reis, 1992, 1995;
Reis, 1998). Th is early Palaeogene sequenc e (SLD6sensu
Cunha, 1992) is also doc ume nted in adjacent sectors of the co ntinental platform, be ing thicker and domina ted by car bonate facie s (Boillotet al.. 1975).
~
•
_ $It\....u F. (1. ~ )
NM _ _I:ocl'w ~
NtotI:mt.1Id QIoOIfno• .,.
•
NGeolog ical setti ng
The fossiliferou s units of Silveirinha outcrop near the na tio nal road EN I 09, abo ut 13 Km so uthw ard th e Mon dego estuary and the coa sta l town of Figuei ra da Foz (West Central Portugal).
Th e abundant fossil remai ns were found withi n a s ucces sion o f lenticular bed s of ca lclititic co nglo merates,
lam inated and cross-bedded sands tones,andbrownis h-red
clays (Reis, 1981; Reiset
al.,
1981; Soares& Reis, 1982; Soaresetal.,
1986). These siliciclastic units are articulated as positive elementary sequences dominat ed by peliti c facies , which are macroscopicall y an alogous to the late Cretaceo us co nt ine nta l sedi ments of Tave iro Formation (Antunes & Pais, 1978; Antun es, 1979; Reis, 1981).The s ilic ilas tic unit s of S ilveiri nha and adj ace nt outcro ps are usuall y designated as Silveirinha Formation or Silve irinha San ds and C lays (=A reias e Argilas de S ilveirinha in Soa res & Reis, 1980, 1982 ; Reis et al., 198 1a, 198 1b) . Evidence from fossil vertebra tes suggests that th e Formation is o f late Pal aeocene and/or lower Eoce ne age ( Antunes in Reis et
al.,
1981a ; Antunes &Russel, 1981;Antunes et al., 1987,Antunes et al., 199 7,
Estravis, 1992). These biostratigraphic data also corroborate th at S il vei rin ha Formation is th e mo st s ig ni fica nt sedi mentary record ofThanetian-Ypresian age outc ropping in the ons hore of the West Portuguese Ma rgin.
Bithyn ia sooresisp. nov . (Plate I, figs. Ia-b.za-b,Sa-b , 5- 12)
Ty pe material: 3 incomplete s hells an d 365 calcareous ope rcula .
Repository of specime ns : All spec imens arc hou sed in the co llections of pa laeontolo gy of the Earth Sciences Department of the New Univers ity of Lisbon .
EI)'moloc': The speci fic name is an homage to Prof. A. Ferreira Soares , autho r of fundamental id ea s and contrib utions conce rning the Meso-Cenozo ic stratigraphy and palaeontology of the West Portuguese Bas in.
Descripti on of the holctype: She ll small and thin , ovo idly co nical, w ith a minut e protoconch and 4 co nvex who rls crossed by very fine grow th-lines; aperture ova l, wit h a slightly ang led upper corn er. Diameter: 3,4 mm; Height:
2,4
rom.
Cuncias da Terra ( UNL), 15
operc ula are rather thickened and oval, with a subtriangular upper comer. The external surface is sculptu red with many con cent ric gro wth lines and lamellae. The maxima l hei ght and width meas ured are, respectively, of5,0 mm and 3,8 mm.These dimensions are equi valent to mature spec imens wit h es timated height of 12-14 mm and 5,5-6 whorls of coiling.
Remarks: Fossil mem be rs of the prc sobranch family Bithyniidae occur in fluvial and lacustrine sediments since the beg inn ing o f Ce nozo ic (Z ilch , 1960) . Th e prese nt spec ies is, much probably, the o lder member o f the ge nus recorded in Port ugal.
Oxfordian carbonace ous facies of Cabo Mondego, in the Nort hern Sec tor of the Lu sitanian Basin . Also in Portugal, other evidence is only documented from Cenozoic , mainly N eogen ic , la cu strine de posits o f Tagus Ba sin . T he occurre nce ofGyraulus antunesiin the Th anetian-Ypresian of Silveiri nha is the o lder record of this family found in the Palaeogene of Portugal.
Comparisons with contemporaneous Planorbidae from foreign European countr ies are difficult at present time. Gyraulus and other related ge nera are charac terized by mo rpho logi c c on vergence a nd st ro ng re sem bl an ce between spec ies. Th is diffi culty is increased by a po or preserv ation o f many fossil spec ime ns, allowing no more than gcneralistic approaches.
Subclass PULMONATA Cu vier, 18 17
O rder BASOMMATOPHORA Schmidt, 1855 Family Planorbidae Rafinesqu e, 1815
Genus Gyra ulusCharpentier, 1837 Subgenus Gyrauluss. str.
[Type species:Gyraulus (Gyraulus) hispidus(Draparnaud, 1805)]
C lass BIVALVIA Linne, 175 8
Subcl ass PTERIOMORPHIA Beurlen, 1944 O rder PT ERIOI DA Newell , 196 5 Famil y Pectinidae Rafinesque, 1815 G enus ChlamysReding,179 8
(Type specie s:Chlamys islandicusMuller, 1776 )
M aterial : A small fragmen t of va lve with the she ll
•
sculpture pre served .
Material: A fragm ent of valv e with the she ll sculpture partly preserved.
Chlamys sp. (Platc I, fi g. 4)
Reposito ry of sp ecimens: Th e specimen is hou sed in the co llecti o ns of p alaeonto logy o f th e Earth Sc ie nces Department of the New Un ive rsity of Lisbon .
Cardiaceagen . sp. indet. (Plate I, fig. 18)
HETERODONTA Neuma yr, 1884 VEN EROlDA H.& A.Ad am s, 1857 Subclass
Order
Des cription: Sma ll fragment of an obliquely ovat e and slightly convex valve, with four radial rib s and part ofthe ventral marg in. Th e sculpture is composed of rad ial ribs, na rro w and p rom inen t , w ith ro und ed sectio ns; th e intercalated interspaces have j ust abo ut the same width of the contiguous ribs, and are crossed by delicate growth-lines. Rem arks: Th is fragm ent sho ws elements of a typical sc u lptur e o f a Peet inidae fr o m the Chl a mys g ro up. However, some ot her diagno stic featu res related with the auricles and the umbonal regio n couldn 't be observed. As a result, the generic attribution o fChlamysis used here in a broad sense.
T he same valve also shows tr ace s of me ch anica l abrasion, suggesting a prolonged biostratonomic transport previous to sedimenta tion.
Repository of speci mens : All specimens are housed in the coll ections o f pala eo ntology of the Earth Scie nces Department of the New University of Lisbon .
Gy raulus antunesisp. nov. (PlateI ,figs. l 3a-b, 14-17)
Description of th e holotype: Shell small, hype rstrop hic, compressed and discoid, with slightly concave upper and lower surfaces . Apex subme rged. Spire with 4 fin ely grooved round and co nve x whorls. Th e shape of the aperture is unkno wn. Diam eter: 3,8 mm; Height: 1,1 mm .
Remarks: Planorbidae is one of the most import ant and widespread fam ily of freshw ate r gastropods. Recent and fossil speci es are characterized by discoid and frequently keeled sin is tra l she lls , charac teristi c of fluv ial and lacu str ine facies from middle Jurassic to present time.
Amo ng the old est known occurrences of this family are the pa vem ents of " Pla norbis" found in the Lat e
Etymology:
T he specific name is an acknowledgement to Prof.M .Te lles Antun es, who stimulated the studies of verte brate palaeontol ogy in Portugal and initiated two decade s of pa laeontologie re search es at the site of Silveirinha .Additional d escriptions: Th e holotype is an incomplete shell, in wh ich the body w horl and the aperture were not preserv ed. Thetype mat eria l also includes two internal moulds with a quarter of whorl each, sugges ting that the wh ole shell of a mature spec imen could have at least 5-6 who rls and 6 mm long. Th e rema ining types arc two minute fragments of sp ire, showing a submerged apcx.
CienciaJda Tura (UN L},15
Re posito ry of s peci m ens : The specimen is housed in the co llec t io ns o f pa laeontology of th e Earth Scie nces Department of the New Univers ity of Lisbon .
Desc r ip ti on : S mall fragment o f va lve with 6 nun long a nd 5 mm hei ght. The origin a l s he ll scu lpture was preserved and co ns ists of 4 radia l ribs sep ara ted by narrow and deep int e rspaces. Th ese ribs ha ve subrectangu lar
sections a nd arc covered by
3-4
fine radia l sulcus, andcrossed by growth- lines .
Rema r ks: The sty le of sculpture ob se rved resembles the rib bing of Heterod onta from the superfamily Cardiacea. Howe ve r, the fragment is too s mall and incomplet e to allow a mo re acc urate detennination .
Pataeobtotoglc
s ign ifica nceT he B ith yniid ae a re a n i nteres t ing exa mp le of prosobran ch gas tropods adap ted to freshw ater e nvi ron-me nts. Th is fam ily of opercu lated a nd ovoidly conical shells includes the common a nd w ide spread Palaearti c
Bithynia tentaculata (Li nne, 1758), which is th e be st kn own mod em European representa tive of th is archaic gro up (M a tos,1993),w ith or igins that back away, at least to the Palaeoce ne . Co ns ide ring the ecolog ic ad ap tat ions ofthi s and other mod em rela ted species, we can infe r w ith a sub stan tial degree of confidence that Bithynia soaresi was also a freshwater species, inhabitan t ofsoft and organi c ric h bottoms o f fluvial cha nne ls, pond s, ma rshes and inundated margins (fig .
2).
Th is a nalys is isin conformity
w ith the palacobiologic and pa laeobiogeographic
inter-pretations already es tab lished for Silveirinha, which are based bo th in Vertebrate and sedimen tologic data (Antu nes inReisetal.,198 1a; Antunes& Russel, 198 1). The same
kind of analog ies can be made aboutGyraulus antunes i.
T he Plano rb id ae a rc a t ypi cal group o f fres hwa ter
Basom matop hora , common in lac ustrine and alluv ial en-vironme nts since the m iddle J urass ic.
Th e presence of two abraded fra gments of marine
bivalves (Chlamys sp . a nd Card iacea indet.) deserves a
differen t explanation. Not excluding the po ssibility of these fragmen ts bei ng of reworked s hel ls, its occ urre nce is more likely an ind icati on ofthe pro xim ity
of
litto ral. Th e fresh-wa ter e nviro nme nt of Silveirinha fresh-was probab ly ope ned fro m time to time to marine influences, as the result of a palaeo atlantic coast pl aced some kilometre s westward s. Th ese marine influences were already noted aft cr the iden -tificat ion o f verteb rate s pecies be long ing to grou ps w ith brack ish or ma rg inal marine affin ities ( Antune sinReis
et al.,198 1a; Antunes& Rus sel , 198 1).Fig. 2
We wish to thank Professor M . Telles An tunes , who kindly pla ced to o ur d isposa l the collec tion o f fossil molluscs fro m Silvcirin ha, a nd to Dr. R. Al bu querque de Matos for the critical re vie w of the man uscript.
Refere nces
Abbott,R.& Boss,K.(1989)- A Classification a/the living Mollusca.American Malacologists Inc., Melbourne, Florida, 195 p.
Antunes, M. ( 1979) - Ensaio de stntesceritica acerca doCrctacico termin al edoPaleocenicode Portugal.Ctenctas da Terra.
l isboa, 5: 145- 174.
Antunes, M.; Casanovas, M.; Cuesta,M.; Checa,L.;Samafe, 1.&Agusti,1.(1997) - Eocene Mammalsfrom IberianPeninsula, ActesCon gresBiochroM'97,Mem. Trav. E.P.H.E., lnsl.Mon rpellie r,21: 337-352.
Antunes,M.; Estravis,C.& Russell,D.( 1987) - A new Condylarth (Mammalia) from the Early Eocene ofSilv eiri nha,Portugal.
MiinchnerGeowiss. AM. ,(A) 10: 219-224.
Antunes,M.& Pais, J. (1978) - Now sabreos depositosde Taveiro:estratigra f ia,paleomologia,idade, paleoecologia.Ciencias da Terra.Lisboa, 4 :109- 128.
Antunes,M.& Russel,D. (198 1) - Le giscmenl de Silveirinha (BasMondego, Portugal): la plusancicnne faune deve rtebres eocenesconnue enEurope.C.R.Acad.Sci. Paris,II,293: 1099-1102.
Boillot,G ; Dupe uble ,P.&Musel lec,P. (1975)- Carte geol6giquedu plateau continentalnord-portugais.Bulleti" Societe Geologique France,Paris, 7(14): 462-480.
Ciinda.r da Terra (UN LJ.15
Cu nha, P. ( 1992) - F.sl raligrafia e sedi menlolog ia dos depOsitos do Cn:uicico Superior e Tercian'o de Ponugal Central. a lnte de Coimbra.Unpublished PhD Thesis, Univers ity ofCoi mbra , 262 p.
Cunha, P.& Reis, R. ( 1992) - Stmesedaevolucao geod inamic a e palcogeografi ca do sec tor nortedaBacia Lusnamca, durante 0
Cretscico e Terciario.A etas /II Congreso Geolog ico de Espana y VII Congreso Latinoamerica no de Geo logia, I : 107- 112.
Cun ha, P.&Reis, R. (1995 ) - Cretaceous sedimentary and tectonic evolut ion of the northern sector of the Lusitanian Basin (Portugal).
Cretaceous Research,16: 155·170.
Estra vis,C.( 1992) -£Studo dos mamijeros do Eocentco inferio r de Sifvei rinha (Bauo Mondego).Unpubl. PhD Thesi s, FCTtUNL , Lisboa.
Matos, R. (1993) - lisle des gasteropodes terrestres, ffuviaulesetd ' eux sawnatres du Portugal. Tentative d'acrualisation.Vertigo,
3: 33-45.
MOCJre. R. ( 1969)-Treatise on Invertebrate Paleontology, pa rt N. MoIlu.u:a6 - Bivalvw ,3 vols. Univ.KansasPress, Boulder, 1224 p. Reis, R. (1981 ) - Lasedimentation continentale du Cretace terminal au Miocen e s ur 10 Bordure Occidentale du Portu gal. entre
CoimbraetLeiria.Unpublished PhD Thesis, University o f Nancy I, Nanc y, 153 p .
Reis. R. (1998) - Late Cre taceo us sedimentation and controls in Nazar e region (W Portugal ).Geo logos,2: 117- 120.
Reis, R.; Soare s, A.&Antunes, M. ( 198 1a) - As Areias c Argilas de Silvei rinha.Memorias e Noticias ,Coimbra , 9 1-92: 244·267.
Rcis, R.;Soares,A. & Antunes, M. (I 98 1b) - As Areias c Argi las de Silveirinha .Comun.lJEncontro Nactonol de Geocimcias ,
Coimbra.
Soares, A.; Lapa, M.& Marq ues,J.(1986) -Contribuit;1o para 0 conhecimentodaIitologiadas unidades mesc-cenozcicasdaBacia Lusitaniana a Norte do "acidente"daNazare (Sub-zona Setentrional).Memorim e Notieias ,Coi mbra, 102: 23-41 .
Soares, A.& Reis, R. ( 1980)- Co nsiderat;Oes sa bre as unidades litostratigraficas pe s-j urass leas na regil o do Baixo Mondego.Livro de Hom enagem a Orlando Ribei ro,Lisboa:183-202.
Soares. A. & Reis . R. ( 1982 ) - Esboco de enquadramento crc ncs tratigra fico das unidades lltic as pe s-j ura ssic as da Orla Mcso-Cenozoica Ocidental entre os paralelus de Pombal e Aveiro. Memorie s e Noticias,Coimbra, 93: 77-91 .
Wenz, W. (1938-44 ) - Gas tropoda, Teil I : Allge meiner teil und Prosobranchia./landbuch Paidozoolog ie;6, 1639 p.
Zilch, A. ( 1959- 60) - Gas tropoda, vol 2: Euthyn eura.Gebriide r Bom traege red.,Berlin, 834 p.
Ciencias da Tura( UNL,. 15
Plate I
Ia-b - Bithyni a soaresisp. nov. (x5). Paratype. 2a-b - Bithynia soaresisp. nov. (x5). Holotype . 3a-b - Bithynia soaresisp. nov. (x5). Paratype.
4 - Chlamys sp. (x7). Fragment o f valve with pa rt of the ventral margin. 5 - Bithy nia soaresisp. nov. (x4). External v iew of operculum.
6 - Bithyn ia soaresisp. nov. (x4). Internal view o f operculum. 7 - Bithynia soares tsp. nov. (x4). External view ofoperculum . 8 - Bithynia soaresisp. nov. (x4) . Internal view of ope rculu m. 9 - Bithynia soaresisp. nov. (x4) . Internal view of operculum. 10 - Bithyn ia soares tsp. nov. (x4). Internal view of ope rculum. II - Bithynia soaresisp. nov. (x4). External view o f operculum. 12 - Bithyn ia soa restsp. nov. (x4) . Externa l view o f operculum. 13a-b - Gyrau/us an tunestsp. nov. (x4). Hototype.
14 - Gy rau/us antunesisp. nov. (x4). Fragment o f who rl. 15 - Gy rau/us an tunesisp. nov. (x4). Fragm ent of whorJ.
16 - Gyra u/us antunesisp. nov. (x7 ). Fragment of spire showi ng the submerged apex. 17 - Gyraulus an tunesisp. nov. (x7). Fragment of spire showing the submerged apex. 18 - Card iacea gen . sp. indet. (x7). Fragment of va lve.
CienciasdaTerra (U NL),15
