Contr. Tert. Quatern. Geol. 30(1-2) 29-39 1 fig., 5 tabs Leiden, June 1993
The distribution of Pliocene Nassariidae (Mollusca, Gastropoda) from the western Mediterranean: palaeoecological and historical considerations
Carles Gili
and
Jordi Martinell
Facultad de Geologia
Universidad de Barcelona
Barcelona, Spain
Gili, Carles, & Jordi Martinell. The distribution of Pliocene Nassariidae (Mollusca, Gastropoda) from the western Mediterranean: palaeoecological and historical considerations. — Contr. Tert. Quatern. Geol., 30(1-2): 29-39, 1 fig., 5 tabs. Leiden, June 1993.
The palaeobiogeographyand palaeoecology (and possible factors determining these) oftwenty-seven species ofnassariid gastropod which inhabited the Mediterranean and of the Atlantic Ocean the Pliocene Tables of for these parts during are analysed. presence-absence species and faunal affinity indexes are presented. The study ofthe causal factors ofthis distribution is based onecological aspects, mainly
available and historical with the of conditions and relying on outcrop data, aspects regard to present knowledge general changes prevailing in the area during the Pliocene.
Key words — Mollusca, Gastropoda, Nassariidae, Pliocene, Mediterranean,palaeobiogeography,palaeoecology.
C. Gili and J. Martinell, Departamento de Geologia dinamica, Geofisica i Paleontologia, Facultad de Geologia, Universidad de
Universitaria de Barcelona; zona Pedralbes, E-08071 Barcelona, Spain.
Contents (1976, 1982b), Gili & Martinell (1990) and Gili
(1991). A taxonomic revision, based on modern cri- Introduction 29 p. is in order deal with teria, a necessary step to more Material and methods p. 29 general palaeontological problems, especially when Distribution characteristics 31 p. working at the specific level. considerations 34 Ecological p. and The present study comprises a qualitative Historical considerations p. 36 quantitative analysis of presence-absence tables of Conclusions 37 p. the within the species study area (western Mediter- Acknowledgements p. 38 ranean) and relates the results obtained to data References p. 38 available on the ecological conditions expressed in
the strata from which the species have been col-
and the historical Introduction lected, on modifications having
occurred in the the area during Pliocene. of this of The aim study is to present a description the distribution of geographical patterns twenty- MATERIAL AND METHODS seven species of nassariid gastropod which inhab- ited the Mediterranean and the Atlantic The material under consists of data parts of study locality
Ocean the Pliocene. for of the Nassarius during The palaeobiogeo- twenty-seven species genus
distribution is with the aid of 1806 lat. in in graphical interpreted Dumeril, s. (Table 1) outcrops the the causal both and factors, ecological historical, eastern and western Mediterranean and in some which underlie such distribution Atlantic close the Strait of patterns. localities to Gibraltar;
As is made the have been in a starting point, reference to sys- they grouped the fourteen basins or tematic revision of the species studied by Martinell zones indicated in Fig. 1. 30
the location ofthe basins - Fig. 1. Map showing studied. Abbreviations are as follows: MA Atlantic Morocco;
H - Huelva; MM - Mediterranean Morocco; A - Algeria; BE - Baix Ebre; BL - Baix Llobregat; AE - Alt
- - - Empordà; R Roussillon; CR Rhône basin; AM Alpes Maritimes; CI - western Italian basin; S -
Sicily; T - Tunisia; NI - northern Italy.
the has and another Part of present study focused on outcrops species were located (Table 1), study of in northwestern Mediterranean indicated the In basins, as the strata in which species occur (Table 2). in Table 2. Data have been obtained from direct based these a addition, a quantitative analysis on
of fossil with tables comparison our own collections speci- using faunal affinity matrices as calculated
housed in various and universities the Dice index mens museums according to (Cheetham & Hazel,
de carried (Museu de Geologia Barcelona; Institut Royal 1969) was out (Tables 3 and 4). Every table
des Sciences naturelles de la Belgique, Brussels; was used for the analysis of different aspects of the
Departement des Sciences de la Terre, Universite biogeographical study.
Claude Bernard, Lyon; and Museum national By grouping the data available for all deposits of
d'Histoire naturelle, Paris), making sure that any one basin distinguished (Table 1), it is possible locality data could be verified and taphonomic to determine whether problems result from 'non-
characteristics were known. These data have been significant' absences or collection failure. This pro-
the complemented with bibliographical data thought to cedure permits inclusion in the same register of
be relevant with to the studied those which lived all of the regard species (Gili, species at or many
in 1991). localities in one basin, but are found only one or
few Literature data should be used with caution ifone localities. This table results from a direct study is level it is the material working at species as quite common to of and from a literature search.
whether the the encounter uncertainty as to specific To ensure a maximum reliability of data,
author that for need be name used by one corresponds to those the various zones to as homoge-
applied to our material. Consequently, these data neous as possible. Therefore, we have fewer data for
do the have been used only sparingly as they not allow a following basins: Moroccan Atlantic, Moroccan
and more precise discrimination. Mediterranean, Algeria Tunisia, mainly
The following course was taken: a qualitative because these are the basins that have been studied
in the least analysis based on presence-absence tables was car- detail. This fact must be taken into ried out, in relation to the basins in which the account when interpreting the results and when 31
SPECIES H BEBE BL AE R CR AM CI S T A MM MA NI N. Bas.
N.JV. pliomagnus (SACCO, 1904)1904) + + + +t + + + + + +++ + + + + 14
N.JV. companyoicompanyoi (FONTANNES,(FONTANNES, 1879) + + + +++ + + + ++ + 9
N. obliquatusobliqualus (BROCCHI,(BROCCHI, 1814) + 11
N.JV. clathratusclathratus (BRONN, 1788)1 788) + +f + + + ++++ ++++ + 10
+ + 1 1 N.JV. prismaticus (BROCCHI,(BROCCHI, 1814) + ++ + + +++ + + + ++ + 11
N.JV. bisotensisbisotmsis (DEPONTAILLER,(DEPONTAILLER, 1879)1879) + 1
1 N.JV. ligusticus (BELLARDI, 1882)1882) + 1
N.JV. aff.aff. ligusticus (BELLARDI, 1882) + 1
14 N.JV. semistriatussemistriatus (BROCCHI, 1814) + ++ + + 4-++ + ++ + + +++ + + + +
N.JV. elatuselatus (GOULD,(GOULD, 1845) ++ + + + +++ + ++++++ + + + 11
M. martinelli (GILI,(GUJ, 1992) ++ 11
N.JV. cabrierensiscabrierensis (FLSC.(FISC. & TOURN., 1873) + + + + + + + + 8
N.JV. macrodon (BRONN, 1831)1831) + +++ + + ++++ + + + 8
N.JV. reticulatus (LINNÉ,(LINNÉ, 1758) + + + + +++ + + + ++ + + 11
N.JV. corrugatus (BROCCHI, 1814) + 11
N.JV. bugellensis (BELLARDI, 1882) ++ + +3+ 3
+ N.JV. angulatus (BROCCHI,(BROCCHI, 1814) + + + ++ + +++ + + + + + + 12
N.JV. asperulus (BROCCHI,(BROCCHI, 1814) + ++ + + + ++66
N.JV. serraticosta (BRONN, 1830) ++ ++ ++ + + ++ +++ + + + + 11
N.JV. catulloi (BELLARDI, 1882) + ++ + + ++55
N.JV. productusproduclus (BELLARDI, 1882)1882) + + + 3
N.JV. turbinellus (BROCCHI, 1814)1814) + + + +4+ 4
N.JV. quadriserialis (BON.(BON. inin MICH., 1838) + +2+ 2
N.JV. bollenensis (TOURNOUER,(TOURNOUER, 1838) + + ++ + 4
N.JV. gibbosulusgibbosulus (LINNÉ, 1758)1758) + +++ + +++ + + +++8+ 8
N.JV.pyrenaiatspyrenaicus (FONTANNES, 1879) + + + ++ + ++66
N.JV. temtoturritus (BORSON, 1820) + ++ + +++ + +++ + +f + 99
N. Sp.-Basin 12 5 14 15 14 14 22 1212 1313 10 88 8 6 22
Table 1. Presence of species in the various basins. Abbreviations are as follows: N. Bas. - number of basins; N. Sp.-Basin - number of
species in each basin.
conclusions. The table of The use of the index a drawing presence per out- affinity permits quantifica-
tion of the thatexist between faunas of crops (Table 2) permits to distinguish more concrete relationships
of the distribution within each basin aspects or different basins (Table 3), or between different out-
between different zones. Yet, not only must our crops within the same basin or between different
all Data obtained allow diverse knowledge of the fauna then be comparable for zones (Table 4). to test
but also of be distribution and deposits, a uniformity sampling must hypotheses as to patterns underly-
ensured. Therefore, this table depends exclusively ing causes.
on the material and deposits studied personally.
of the Thus, only twenty-three twenty-seven species
have been considered. Another essential factor, ta- DISTRIBUTION CHARACTERISTICS phonomy, must be considered when evaluating eco-
those beds of the logical factors of distribution. Only for The overall distribution twenty-seven species
which has demonstrated the in the is follows: a taphonomic study used present investigation as
fossil fauna to correspond to a palaeocommunity or — twenty are found both in the eastern and western
'census assemblage' (Hallam, 1972; Kidwell & Bos- Mediterranean;
useful. Others this cri- — fifteen found also in the Atlantic to ence, 1991) are not meeting are adjacent
terion must be disregarded. Thus, the fauna from the Mediterranean;
the Can — five restricted the Albareda outcrop (Baix Llobregat basin) are to western Mediterranean;
has — restricted in northern not been considered as it represents an accu- two are to deposits Italy
Adriatic Pliocene of the mulation level, its record corresponding to a (the eastern
thanatocoenosis (Fiirsich, 1990). Mediterranean). 32
found Relevant in the presence table for the species or decreases of affinity indices between adjacent
the different is result in in zones (Table 1) the strikingly high rows and columns, which strongly different
number of species present in the majority of these sectors of the matrix, would indicate the existence of basins. Only in five zones has a low number of geographical regions (sets of basins) distinguishable
species (fewer than ten) been found. The Baix Ebre by populations. The sudden changes in the indices basin has would for which causal yielded only five species. Fifty percent of correspond to the fringes, a
all basins between twelve is No of this yield and fifteen species. explanation needed. phenomenon type
have is observed in Table if of In two zones, up to twenty-two species been 3. Thus, the values the
this the maximum number faunal of encountered, being affinity indices are not governed by either
observed. these hypotheses, it must be concluded that the
On the other hand, the number of species that are zones established within the study area do not rep-
distributed is also Two have widely high. species resent geographical areas, nor palaeobiogeographi-
in cal should be considered been found fourteen of the zones considered, six transcendence; they as species are found in between ten and twelve zones points of reference only. This strengthens the basic and anothereight in between five and nine basins. A uniformity of distribution of the species. These
number of five nassariid faunas thus be considered have low, albeit, important species are may to found in few and six have been been of Pliocene basins, species part a unique biogeographical pro- located the included the exclusively in only one of zones vince, which western Mediterranean, a considered. part at least of the eastern Mediterranean and the
Atlantic the Strait of In total, these data suggest a certain degree of adjacent closest to Gibraltar.
in the distribution the the homogeneity of twenty-seven However, some observations on affinity
within the of values the basins The affin- species study area. Yet, some cases of a few of are possible. restricted or strongly discontinuous distribution ity values between the Baix Ebre basin (BE) and the must be considered in causal analysis. others form the lowest set of the matrix, with a
The of the faunal matrix the value of the study affinity among unique 0.55, some being equal to 0.5,
below this value. This does with such zones (Table 3) allows a quantitative evaluation of rest not occur this distribution. As a set the values are or in other cases. Other in high very regularity zones, particular high. Only 12.1% of the indices is found between the Moroccan Mediterranean(MM) and Algeria (A)
0.3 and values between 0.46 and 0.61 low and values. From these 0.45; (quite produce not very high
for Values between 0.62 and basins little material has been stud- high) account 29.6%. no or only very
0.77 for 40.7% of all values between ied and literature data few. It is therefore account data; are possi-
and considered and ble that the lower 0.78 0.93 are very high, values are due to the lack of data. account for 17.6% of the indices. In total, 81.3% of However, the Tunisia (T) and Moroccan Atlantic all values in of and if are excess 0.5, indices are (MA) zones, for which literature data are also few,
than the taken as or 0.5, the values do not have been equal higher percentage affinity appear to rises The value of all the These to 86.8%. mean indices affected adversely. results seem to be quite obtained is 0.62. This confirms the view that the correct. distribution of the of the affin- twenty-seven species is strongly In some zones an overestimation real
values have taken since homogeneous. ity may place only twenty- The in which the have been situated have way zones seven species been considered and not all on the matrix (Table 3) allows to formulate various nassariids. This holds especially true for northern
if the faunal affin- where simple hypotheses. For example, Italy (NI) from more species than studied
inverse ity were an function of the distance which herein have been recorded (not recorded from the
the its values would diminish separates basins, regu- western Mediterranean).
from left in each and would Once larly to right row, the basic uniformity of these twenty-seven increase from to in each col- regularly top bottom species was established, the distribution in the set of
of the matrix. be this is data in umn However, as may seen, basins yielding the was considered more not the case: no or to such is detail. The table the regularity tendency illustrating presence by out- observed. It thus be concluded that the in five may affinity crops (Table 2) considers twenty-one deposits
the in relation the under basins with amongst zones, to species twenty-three species. Here, it may be
is of that the of the discussion, not a function distance. seen majority deposits yield between
the sudden and six and Secondly, discontinuous increases ten species. This does not represent a high 33
M SI V MV C ABAB N. Out. SPECIES SO VH ET PBI'B TT PVPY P CS MF MS MB FT VR N ND M SI
+ ++++ + + 9 N.JV. pliomagnus + +++ + ++++ +
+ N.JV. companyoi ++ + + 3
2 N.JV. clathratus + +f
N.JV. prismaticus + + +++ + + + ++ +++ + 99
/ 1 N.JV. bisotensisbisotensis +
N.JV. ligusticus + 1
+ + N.JV. aff.aff. ligusticus + + 2
17 N.JV. semistriatussemistriatus + + + + + ++ + + + ++ + + ++++++ + + + +
+ + ++f + N.JV. elatuselatus + + + + + +4 + + ++ + + + ++++++ + + 19
+ 1 N.JV. martinelli + 1
N.JV. cabrierensis + + + + + + + +++++ + + + 11
N.JV. macrodon + + + 3
N.JV. reticulatus + + + + + + + + + + 10
N.JV. bugellensis + + + + + 5
+++ + 8 N.JV. angulatus + ++ + ++++ + +
N.JV. serraticosta + + +++ + +++++ + + + 8
N.JV. catulloi + +++ + +++ + + +++ + 8
N.JV. turbinellus ++ ++ + + + 5
+ N.JV. quadriserialis ++ 2
N.JV. bollenensis + + ++++ + + + ++++ + + 9
+ N.JV. gibbosulus + + + + ++ + 6
N.JV. pyrenaicus + + + + + + 6
N.JV. turritus + + + + 4
N. Sp.-Outcrop 5 10 13 7567 5 6 11 14 5 88 949 4 1891 8 9 10 951639 5 1 6 3
of in the various N. Out. - number of N. - number of in each Table 2. Presence species outcrops. outcrops; Sp.-Outcrop species outcrop.
of Key outcrops:
— Baix Ebre (BE) basin: SO - Sant Onofre;
— Baix Llobregat (BL) basin: VH - St. Vicenç dels Horts; ET - El Tarc; PB - Plaça de les Bruixes; TT - Torrent del Terme; PV - Pi d’En
Valls; P - Papiol; — Alt Emporda (AE) basin: CS - Cementiri de Siurana; MF - St. Miquel de Fluvià; MS - Mas Siurana; MB - Mas la Brava; FT - Feixa
Torta; VR - Vila-robau;
— Roussillon (R) basin: N - Néfiach; ND - Nidolères; M - Millas;
— - Alpes Maritimes (AM) basin: SI - Saint Isidore; V - Vence; MV - St. Martin du Var; C Costamagna; AB - Cava di Villanova.
number of the total of studied The C and is in this amount species. MV, AB), diversity high respect;
majority of species are not found in a large number both high and low affinities amongst their deposits
in the of the Alt of of localities, 86.95% being found between one (in case Emporda, affinity mean
low and ten outcrops (Table 2). Only few species are 0.41); or principally (Alpes Maritimes, affinity
widely distributed. Generally, this distribution is mean of 0.39) are seen.
highly heterogeneous and contrasts with the homo- A comparison of the affinity indices between the
observed in the of the zones/ basin and those other basins geneity comparison outcrops of one of
basins where the different deposits are situated indicate that low values are always found in relation
also in Maritimes and diverse (Tables 1, 3). The heterogeneity is apparent to Alpes deposits, values,
the populations in the matrix of affinity between never regularly high or low, in relation to deposits of
Low other deposits (Table 4). values are quite common, zones.
being lower than or just over 0.5. High or very high Even though sampling of these deposits has been
values in of the uniform and the that are very rare. Deposits some zones, extensive, possibility some
Baix PV and have attention be ruled e.g. Llobregat (VH, ET, PB, TT, P), species escaped cannot out
and in Roussillon ND and & in particular, (N, M), pre- (Gili Martinell, 1989; Gili et al., press), we
affinities affinities of 0.64 and believe that the observed is sent strong (mean heterogeneity an expres-
In the Alt sion of 0.81, respectively). Emporda (CS, MF, a peculiar distribution characteristic, rather
FT and and than of Diverse MS, MB, VR) Alpes Maritimes (SI, V, collection failure. faunal assem- 34
MA H MM A BE BL AE R CR AM Cl S T NI sum
MA ,67 ,43 ,29 ,55 ,60 ,57 ,50 ,50 ,43 ,66 ,53 ,63 ,43 6,79
H ... ,60 ,50 ,35 ,54 ,74 ,69 ,62 ,65 ,92 ,80 ,73 ,65 7,79
MM ... ,63 ,46 ,55 ,52 ,73 ,64 ,53 ,50 ,66 ,33 ,53 6,08
A ... ,46 ,64 ,52 ,64 ,64 ,53 ,60 ,66 ,44 ,53 5,66
BE ... ,53 ,50 ,42 ,53 ,30 ,35 ,44 ,53 ,30 3,90
BL ... ,76 ,79 ,79 ,72 ,62 ,59 ,66 ,72 5,65
AE ... ,83 ,83 ,70 ,81 ,79 ,64 ,76 5,36
R ... ,93 ,77 ,77 ,81 ,58 ,72 4,58
CR ... ,72 ,77 ,81 ,58 ,72 3,60
AM — ,71 ,69 ,56 ,82 2,78
Cl — ,80 ,64 ,71 2,15
S — ,61 ,74 1,35
T — ,63 ,63
NI
Table 3. Faunal affinity between basins (see key of basins in Fig. 1.).
in of the all sediments blages are support overall homogeneity. For deposits studied four types of Thus, low affinities between deposits, either in close have been distinguished, viz■ blue-grey clays, sandy geographical proximity or not, correspond to signif- clays, limey clays and yellow sands (Robba & icant faunal differenceswhich must be explained by Ostinelli, 1975; Andres, 1980; Martinell & Dom-
historical Mar- ecological or factors. ènech, 1986a, 1990; Gonzalez Delgado, 1987;
As be in Table tinell, 1988). may seen 5, a large
number of outcrops, especially those situated in the ECOLOGICAL CONSIDERATIONS central of the uniform part study area, display quite
In order to study this causal aspect of distribution characteristics.
number data each the nassariid the greatest possible of abiotic for Amongst species studied, there are
been studied have in outcrop have compiled. Only deposits ten which been found strata that present personally and containing 'census assemblages' quite different ecological factors [Nassarius have been considered. Data include water tempera- pliomagnus (Sacco, 1904), N. companyoi (Fontannes, ture, salinity, sedimentation depth and sediment 1879), N. clathralus (Bronn, 1788), N. prismaticus type (Table 5). (Brocchi, 1814), N. semistriatus (Brocchi, 1814), N.
Early Pliocene (Zanclean) temperature was elatus (Gould, 1845), N. angulatus (Brocchi, 1814), N. higher than at present and differed slightly during serraticosta (Bronn, 1830), N. turritus (Borson, 1820)
and the Late Pliocene (Piacenzian) (Sue, 1984; Cravatte N. reticulatus (Linne, 1758)]. They are here con-
of be with wide & Sue, 1985; Demarcq, 1985). Because a lack of sidered to species a ecological tole- notable in between the Another found in differences this respect dif- rance. seven species are also a ferent localities in the this factor cannot certain environmental in fewer study area, type, although have played an important role in nassariid distribu- numbers than the previous ones [N. macrodon tion. Temperature differences due to water depth (Bronn, 1831), N. cabrierensis (Fischer & Tournouer, have not been taken into account. 1873), N. pyrenaicus (Fontannes, 1879), N. turbinellus
All with the Onofre bol- outcrops, exception of Sant (Brocchi, 1814), N. catulloi (Bellardi, 1882), N.
(SO) expose strata laid down in marine haline water lenensis (Tournouer, 1838) and N. gibbosulus (Linne,
Martinell & These tolerant in (Martinell, 1988; Domènech, 1984, 1758)]. species are some aspects
the various but in others. there six 1990; Clauzon et al., 1990). Despite not Finally, are species, the
recorded in the for the which in palaeodepths literature out- least tolerant, have only been found one
bisotensis crops, we think it possible to differentiate between setting [N. (Depontailler, 1879), N. ligusticus sediments of shallow depth (between 0 and -50 m) (Bellardi, 1882), N. aff. ligusticus, N. martinelli Gili, and those -100 and of greater depths (between -200 1992, N. productus (Bellardi, 1882) and N. quadri- m) (Robba & Ostinelli, 1975; Martinell & Dom- serialis (Bonelli in Michelotti, 1838)].
ènech, 1984, 1985, 1990; Martinell & Marquina, The overall homogeneity of the distribution is
Nolf Clauzon thus function of the 1984; & Cappetta, 1988; et al., 1990). a two factors: important 35
SO VH ET PB TT PV P CS MF MS MB FT VR N ND M SI V MV c AB sum.
so — ,53 ,55 ,66 ,40 ,55 ,66 ,53 ,40 ,77 ,46 ,40 0 ,62 ,43 ,53 ,29 ,40 0 ,20 ,25 8,63
VH — ,87 ,59 ,66 ,63 ,76 ,75 ,27 ,44 ,55 ,40 ,18 ,66 ,53 ,60 ,32 ,32 ,40 ,18 ,25 9,36
ET — ,70 ,55 ,63 ,83 ,81 ,44 ,57 ,57 ,33 ,14 ,76 ,64 ,78 ,36 ,33 ,14 ,21 ,25 9,04
PB — ,66 ,92 ,66 ,57 ,33 ,53 ,53 ,33 0 ,66 ,50 ,59 ,38 ,33 ,25 ,31 ,40 7,95
TT — ,73 ,63 ,53 ,60 ,31 ,46 ,60 0 ,46 ,43 ,53 ,43 ,40 ,30 ,55 ,50 7,46
PV — ,59 ,50 ,36 ,43 ,57 ,36 0 ,57 ,40 ,50 ,40 ,36 ,29 ,33 ,44 6,10
P — ,72 ,25 ,63 ,63 ,25 ,17 ,63 ,50 ,57 ,50 ,38 ,16 ,35 ,43 6,17
CS — ,53 ,64 ,73 ,42 ,13 ,64 ,70 ,75 ,35 ,42 ,13 ,20 ,24 5,88
MF — ,46 ,46 ,80 0 ,46 ,57 ,53 ,29 ,60 0 ,18 ,25 4,60
MS — ,63 ,62 0 ,50 ,35 ,44 ,47 ,31 0 ,14 ,18 3,64
MB — ,46 ,22 ,50 ,47 ,55 ,35 ,31 0 ,14 ,18 3,18
FT ... 0 ,31 ,43 ,40 ,43 ,40 0 ,18 ,25 2,40
VR — ,22 ,20 ,18 0 0 0 0 0 ,60
N ... ,71 ,89 ,24 ,46 0 ,14 ,25 2,69
ND — ,84 ,22 ,43 0 ,13 ,17 1,79
M ... ,21 ,40 0 ,13 ,15 ,89
SI — ,53 ,20 ,53 ,50 1,76
V — 0 ,18 ,50 ,68
MV ... ,29 ,50 ,79
c — ,66 ,66
AB —
Table 4. Faunal between of in Table affinity outcrops (see key outcrops 2).
of with notable be number species a ecological tole- explained by ecological factors, are attributable
and the fact that the other but it is rance level, majority of the to factors not evaluated, quite possible
similar character- that will be able determine their outcrops present physicochemical we not to nature. istics. The Alt Emporda (AE) and Alpes Maritimes
noted above be basins have lower faunal A particular event may now (AM) affinity indices, even
the similar conditions explained on basis of the ecological analysis. though ecologically prevailed,
The low Baix Ebre 0.41 and 0.39 To affinity indices between the (BE) on average, respectively. explain
basins be be the it is and all other may interpreted to this, necessary to consider aspects not taken into result of the where had consideration here. Alt is this being only zone strata Emporda a bay setting been laid down in saline waters. This effect is not with quite distinctive environments. Martinell
the of exclusive fifteen different produced by occurrence some spe- (1982a) distinguished faunal asso-
but the low number of that able nassariid faunas in these associa- cies, by species are ciations; certain of
survive under such conditions. The of but to majority tions differed from those found in others, no these (four out of five) display maximum tolerance. exclusive species were found. The Alpes Maritimes
laid down in deltaic The study of the affinity matrix (Table 4) resulting sediments were a prograding from the of the in the front enclosed in a ria which would presence species deposits (Gilbert delta),
other of distri- the of different envi- (Table 3), may help explain aspects explain range highly ecological bution, especially those referring to the hetero- ronments which have not been evaluated directly.
the indices between The existence of four found in geneity of affinity deposits. species only one or
In of the Baix and two and restricted this basin two basins, Llobregat (BL) outcrops to exaggerates
Roussillon faunal affinities between the between the (R), outcrops differences faunas of each deposit
values of 0.64 and within this basin. This are high (mean 0.81, respec- is the only zone where deep- tively). This matches the homogeneous abiotic char- water sediments have been found. This, together acteristics for all localities within each zone with the of these exclusive (identi- presence species, causes cal depth, salinity and sediments), and also in the the low affinities in the Alpes Maritimes basin in
of basin estuarine same type (in both cases settings). relation to the levels of the other zones, and also to
The low affinities between either in its outcrops, own deposits. close which The of the Baix geographical proximity or not, cannot deposits Llobregat zone (BL) 36
yield quite high affinity indices (between 0.4 and Messinian. At least twelve species are common to
0.78) in comparison with those of the Roussillon the Mediterraneanand the Atlantic Pliocene. More-
The Alt basin have the MediterraneanPliocene has ten in zone (R). Emporda outcrops over, species of with Atlantic in which diverse affinity indices in comparison to those common the Miocene, are found additional forms which Baix Llobregat and Roussillon, with values ranging an seven are very from low to similar to Pliocene from the Mediterranean. very (0) very high (0.81). species considered direct All this indicates similarities and differences These Miocene forms may be pre-
the decessors the Messinian- amongst the populations of species considered (Gili, 1991). During factors Zanclean transition extension of the Atlantic here which are not caused by ecological an
thus considered above, but probably by biotic factors. area was produced.
absences From the data available Certainly in some cases, 'non-significant' (Caprotti, 1973; Riba,
affect the affinities. these are insuffi- Peres, it that climatic condi- may However, 1981; 1989) appears
for these similarities and tions the and cient to offer explanations were very constant during Zanclean, differences. changes leading to differentiation of the Late
In general, high values in comparisons of affinity Pliocene (climatic warming, marine regression)
for of different and without marked indices outcrops basins, are the result arose gradually progressively, of similarities in basin type, whereas oscillating or discontinuities, although with certain pulsations
dissimilar basin The low values characterise types. (Martinell & Domenech, 1986b). These stable con-
in the of certain also in of discontinuity distribution species ditions are an important factor terms
be characteristics con- an for the may explained by ecological providing explanation homogeneous
the distribution of the sidered for the outcrops. For example, N. productus nature of species studied,
(Bellardi, 1882), and probably also N. asperulus which was previously explained by ecological
in (Brocchi, 1814), are only found sandy deposits factors.
(Tables 1, 5). For other species, such as N. bugellensis Above, the existence of four species found exclu-
(Bellardi, 1882), N. quadriserialis or N. turbinellus, sively in the Alpes Maritimes basin (N. bisotensis, N.
with and also however, their discontinuous distribution ligusticus, N. aff. ligusticus N. martinelli) was
be indicated. These have been respect to ecological data considered, cannot considered, from an
have had limited explained. Other species such as N. bollenensis show a ecological viewpoint, to a very
restriction highly continuous but restricted distribution (Table tolerance. However, such an important
offer distribution be 1), and data available do not any explanation in their cannot explained solely by
Three be considered: that since other limited in either. explanations may factor, species equally
found for N. tolerance are more commonly. Except
— the distribution be determined certain it is that this is due to the fact that may by a ligusticus, possible
in found the ecological factor not detected during the present the deposits which they are are only
have been laid down in But study; ones to deep water. yet
— absences has be considered. As four are 'non-significant'; the species lived another aspect to these
in the Pliocene fossil in special places and has not yet been found; species appear record, they
— of be considered endemic Mar- a problem taxonomic nature exists; our spe- may to represent Alpes
in the literature. itimes distribution cies concept differs from that zone species. Their restricted
be than reflection of their recent may no more a
All that has been above the or non-relict pointed may explain appearance (neo-endemic species).
those other heterogeneity of the affinity indices amongst out- Amongst studied, two species (N.
of the and N. have been found in crops, in spite of a strong homogeneity popu- obliquatus corrugatus) one
lation of the various basins. of the basins only, viz • the northern Italian zone.
consid- Again, their restricted distribution may be
ered to reflect their neo-endemic nature, rather HISTORICAL CONSIDERATIONS reflection their low than be a of ecological
of nassariids from tolerance. The majority the twenty-seven
the Zanclean (Early Pliocene) in the western Medi- Consequently, the Mediterranean Pliocene
of Atlantic six neo-endemic those terranean probably were origin, having includes species amongst
entered the Mediterranean on the definitive re- studied. A closer look at the distribution reveals that
Strait of Gibraltar the do random in the opening of the subsequent to these species not appear at area, 37
OUTCROP LITHOLOGY BATHYMETRY SALINITY BASIN ZONE
Sant Onofre (SO) Blue clays <20m. brackish Bay BE
Plaga de les Bruixes (PB) Blue clays 10m. to cms. marine
El Tare (ET) Blue clays <40m. marine
Pi de'n Vails (PV) Blue clays <40m. marine Estuary BL
Torrent del Terme (TT) Blue clays <40m. marine
St. Vinceng dels Horts (VH) Blue clays <40m. marine
Papiol (P) Blue clays <40m. marine
St. Miquel de Fluvia (MF) Blue clays <25m. marine
Vila Robau (VR) Silty clays <25m. marine
Feixa Torta (FT) Blue clays <25m. marine Bay AE
Mas Siurana (MS) Blue clays <25m. marine
Mas la Brava (MB) Blue clays <25m. marine
Cementiri Surana (CS) Blue clays <25m. marine
Nidolères (ND) Sandy clays 10 to 25m. marine
Néfiach (N) Sandy clays 10 to 25m. marine Estuary R
Millas (M) Sandy clays <25m. marine
St. Isidore (SI) Blue clays 100 to 200m. marine
Costamagna (C) Blue clays 100 to 200m. marine Delta
Vence (V) Blue clays 100 to 200m. marine AM
St. Martin du Var (MV) Blue clays 100 to 200m. marine
Cava di Villanova (AB) Blue clays <50m. marine Bay
Zona Fluelva (H) Yellow sands <30m. marine Estuary H
Characteristics of Table 5. outcrops.
but are concentrated in two basins: the Alpes Mar- studied, which heterogeneity was also explained by
and the north of itimes, Italy. These alpine zones ecological considerations. havebeen strongly affected by tectonic changes dur-
which be related the ing the Neogene, may to CONCLUSIONS of For the Maritimes appearance new species. Alpes
concrete data to the The distribution in the western Mediterranean of area, more as sedimentology and geological structure are available. The struc- the species studied is a result of ecological and his- tural of the is related tectonic related. In complexity zone to torical factors, which are intimately some
ofthe et one factor to have become dominant processes Alpine range (Clauzon al., 1990). cases appears
of Gilbert delta in the River the The existence a type over others. In majority of cases both types of
Var basin could reflect insta- strong environmental factors combine, which makes it difficult to distin-
with formation of from the in bility, frequent enclaves, more or guish one type other, especially an less isolated from the and from other loca- overall of open sea interpretation palaeobiogeographical tions in the delta The isolationof distribution. (Gili, 1992). popu-
in both the of the lations enclaves of these types could have Therefore, homogeneity distribu- favoured of This then into the of the appearance new species. tion, taking account populations the would be reflected in the irregular distribution of different basins, and the heterogeneity, comparing these in the the basin. faunas of in have species different outcrops of outcrops particular, an ecological
in What has occurred these zones (environmental as well as a historical aspect. The homogeneity variability and strong speciation) contrasts with between basins is produced by a high number of
is in the the local what seen rest of basins studied (envi- species with a wide ecological tolerance, con-
All ditions of little diversification with ronmental stability and lack of speciation). these a notable historical data of in the number of different with similar abiotic are importance interpreting zones very heterogeneity when comparing populations of spe- characteristics (ecological aspects), and an impor- cific in relation the climatic in the the outcrops to twenty-seven species tant uniformity study area during 38
in which the and G., Paleothermic Pliocene, changes were gradual Demarcq, 1985. evolution during the Neogene in Mediterranean through the marine megafauna. In: G. progressive with time (historical aspects). Hamor Proc. VII Comm. Medit. (ed.). Congr. reg. on Neog. The heterogeneity between outcrops is produced Stratigr. Budapest. Budapest (Hungarian Geological Soci- by basins with diverse environments, in some cases ety): 371-375. diverse than what be evaluated more may on abiotic Fiirsich, F.T., 1990. Fossil concentrations and life and death
factors. with few D.G.E. Along a species with low tolerance assemblages. In: Briggs, & P.R. Crowther (eds). Pal-
aeobiology: a synthesis. Oxford (Blackwell Scientific Publica- and others with discontinuous distributions (ecologi- tions): 235-238. cal neo-endemic observed aspects), species are Gili, C. 1991. Els Nassariidae (Gastropoda: Prosobanchia) del which are not randomly distributed in deposits of Plioce de la Mediterrania occidental. Barcelona (Ph.D. thesis the various basins, but concentrated in two localities Univ. 563 Barcelona), pp. (unpubl.).
C. 1992. Nassarius martinelli n. with strong local environmental instability during Gili, sp. (Neogastropoda:
Nassariidae) del Plioceno del Mediterraneo occidental. — the Pliocene (historical factors). Rev. esp. Paleont., 7(2): 167-173. To sum it should be realised that deter- up, any Gili, C., & J. Martinell, 1989. Stratigraphical and geographical
mined distribution ofan of geographical assemblage distribution of Nassarius catulloi (Bellardi, 1882) (Neo-
of other — species (or any taxon) has an ecological as gastropoda:Nassariidade) in the Mediterranean Neogene.
well historical Both Boll. Malacol., 25(9-12): 273-280. as a aspect. components may Gili, C., & J. Martinell, 1990. al conocimiento del and the have Aportacion act simultaneously effects they on subgenera Sphaeronassa (Locard) (Gastropoda: Neo- distribution may increase or decrease reciprocally. del Plioceno mediterraneo del Atlantico gastropoda) y adya-
— Rev. cente. esp. Paleont., 5: 19-33. ACKNOWLEDGEMENTS Batllori & E. in Consideracions Gili, C., J. Navas, press. paleo-
biologiques sobre la presencia de Nassarius turbinellus (Broc- We wish to extend our best thanks the to following — chi, 1814) (Gastropoda: Nassariidae) al Plioce catala. who colleagues have facilitated our task our during Butll. Inst. cat. Hist. nat.
of the collections in their Messrs Gal- Gonzalez 1987. Tafonomia study care: J. Delgado, J.A., y paleoecologia en
diferentes de la Formación "Arenas de Huelva". lemi and J. Gomez-Alba (M. Geol. Barcelona), Dr yacimientos In: J. Civis (ed.). Paleontologia del Neógeno de Huelva (W A. Dr Dhondt (Inst. r. Sci. nat. Belg., Brussels), Prof. Cuenca del Guadalquivir). Salamanca (Universidad de Sala- G. Demarcq and Dr A. Prieur (Dept. Sci. Terre, manca): 89-125. Univ. and Dr A. natl Lyon) Lauriat-Rage (Mus. Hallam, A., 1972. Models involving population dynamics. In: Dr R. Hist, nat., Paris). Also, to Domenech (Dept. T.J.M. Schopf (ed.). Models in Paleobiology. San Francisco
& 62-80. Geol. din., Geof. i Paleont., Univ. Barcelona) for (Freeman, Cooper Co.): Kidwell, S.M., & D.W.J. Bosence, 1991. Taphonomy and time- her reflections and comments the during prepara- averaging of marine shelly faunas. In: P.A. Allison, & D.E.G. tion of this and and two paper, J.W.M. Jagt anony- Briggs (eds). Taphonomy. Releasing the Data Locked in the
mous reviewers for useful This is suggestions. paper Fossil Record [Topics in Geobiology, 9]. New York/London part of the project DGICYT PB90-0489. (Plenum Press): 115-209.
Martinell,J., 1976. Estudio de la fauna malacologica (Gastro-
poda) del Plioceno del Barcelona D. REFERENCES Emporda (Girona). (Ph.
thesis Univ 525 Barcelona), pp. (unpubl.).
Andres, 1980. Estudio tafonomico de 1982a. Pliocenic shallow marine environments I., malacologico y un Martinell, J.,
afloramiento del Neogeno de Bonares (Huelva). — Com. from NE Spain. — Boll. Soc. paleont. It., 21(2-3): 303-309.
prim. Congr. Nac. Malac., 1: 7-11. Martinell,J., 1982b. Estudio de los Buccinacea (Neogastropoda,
Caprotti, E., 1973. Origini ed affinita della malacofauna dello Gastropoda) del Plioceno de l'Emporda (Catalunya).
Piacenziano. — Riv. Ital. 237-251. Sistematica. — Butll. Inst. Hist, stratotipo Paleont., 79(2): Descriptiva y cat. nat., 48
Cheetham, A.H., &J.E. Hazel, 1969. Binary (presence-absence) (Sec. geol., 3): 61-90.
similarity coefficients. —J. Paleont., 43(5): 1130-1136. Martinell, J., 1988. An overview of the marine Pliocene of NE
Clauzon, G., J.P. Sue, J.P. Aguilar, P. Ambert, J. Cappetta, J. Spain. — Geol. Medit., 15(4): 227-233.
Cravatte, A. Drivaliari, R. Domenech, M. Dubar, S. Leroy, Martinell,J., & R. Domenech, 1984. Malacofauna del Plioceno
J. Martinell,J. Michaux, P. Poiron,J.L. Rubino, B. Savoye & de Sant Onofre (Baix Ebre, Tarragona). — Iberus, 4: 1-27.
1990. Pliocene J.L. Vernet, geodynamic and climatic evolu- Martinell, J., & R. Domenech, 1985. Caracteristiques tafonomi-
tions in the French Mediterranean In: R. i del marl de — region. J. Agusti, ques paleoecologiques Plioce l'Emporda.
R. & Martinell Iberian Centre Invest. Domenech, Julia J. (eds). Neogene Arqueol. Girona, Ser. monogr., 6: 1-70.
Basins, i Mem. 2: 131-207. & R. 1986a. Malacofaune Paleontologia Evolucio, esp., Martinell,J., Domenech, du Pliocene
Cravatte, J., & J.P. Sue, 1985. Climatic inferences from planc- marin de Saint Isidore (Bassin du Var, Alpes-Maritimes). —
tonic foraminifera and pollen Pliocene confronted data in Geobios, 19(1): 117-121.
NW Mediterranean area. In: G. Hamor Resumes VII & R. 1986b. Actividad bioerosiva el (ed.). Martinell,J., Domenech, en
Comm. Medit. — Congr. reg. on Neog. Stratigr. Budapest. Plioceno marino del Emporda (Catalunya). Paleont.
Budapest (Hungarian Geological Society): 156-158. Evol., 20: 247-251. 39
Martinell,J., & R. Domenech, 1990. Malacofaune du Pliocene occidental durant el Neogen i el Quaternari. — Treb. Inst,
marin du Roussillon: Taphonomie et paleoecologie. — cat. Hist, nat., 9: 45-62.
Paleobiol. cont., 17: 157-166. Robba, E., & F. Ostinelli, 1975. Studi paleoecologici sul Pliocene
Martinell, J., & M.J. Marquina, 1984. De la bathymetrie du ligure. 1. Testimonianze di predazione sui Molluschi
Pliocene marin du Baix Llobregat (Barcelone, Espagne). — pliocenici di Albenga. — Riv. Ital. Paleont., 81(3): 309-372.
Paleobiol. 333-338. 1984. and evolution of the Mediterranean cont., 14(2): Sue, J.P., Origin
Nolf, D., & H. Cappetta, 1988. Otholithes de poissons pliocenes vegetation and climate in Europe. — Nature, Lond.,
du Sud-Est de la France. — Bull. Inst. Sci. Sci. r. nat. Belg., 307(5950): 429-432.
Terre, 58: 209-271.
1989. Historia de la biota mediterranea de la Peres, J.M., y
colonizacion de las profundidades. In: R. Margalef (ed.). El
Mediterraneo occidental. Barcelona (Omega): 200-234. Manuscript received 28 October 1992, revised version accepted
Riba, O., 1981. Canvis de nivell i de salinitat de la Mediterrania 19 April 1993.