Annales Societatis Geologorum Poloniae (2012), vol. 82: 151–159.
MID DLE MIO CENE (EARLY BADE NIAN)
AM PHIS TE GINA (FO RA MINIFERIDA) FROM OLIMPÓW
(CEN TRAL PA RATE THYS, PO LAND)
Ma³gor zata GON ERA
Na ture Con ser va tion In sti tute, Pol ish Acad emy of Sci ences, Al. A. Mick iewicza 33, 31- 120 Kraków, Poland, e-mail: gon era@iop.kra kow.pl
Gon era, M., 2012. Mid dle Mio cene (Early Bade nian) Am phis te gina (Fo ra miniferida) from Olimpów (Cen tral Pa rate thys, Po land). An nales So cie ta tis Ge olo go rum Po lo niae, 82: 151–159.
Ab stract: Speci mens of Mid dle Mio cene (Early Bade nian) Am phis te gina from the Pol ish Car pa thi ans were
ex am ined. A sec tion, sam pled at the Olimpów quarry, dis plays chloral gal car bon ates, rich in rho do lith nod ules. Symbiont- bearing fora mini fera (Am phis te gina, El phid ium and As terigerinata) con sti tute 15– 57% of the to tal fora mini fera as sem blage. Am phis te gina hau erina d’Or bigny, 1846 is the only spe cies of the ge nus in the de pos its stud ied.
The sen si tiv ity of larger fora mini fera to wa ter tur bu lence and light avail abil ity was ap plied in a re con struc tion of the com mu nity habi tat. The di ame ter and thick ness of the Am phis te gina tests in di cate that the habi tat was a zone of low light pene tra tion and weak en ergy – a pa laeoen vi ron ment, simi lar to that of the mod ern A. ra di ata (Hottinger et al., 1993). Changes in the spheric ity of the Am phis te gina tests re flect a tem po ral drop of ba thyme try in the mid dle part of the sec tion. This is sup ported by other en vi ron men tally con trolled fea tures of the fo rami ni-f eral as sem blage: the per cent ages oni-f both plank tonic and symbiont- bearing ni-forms, as well as the pro por tions oni-f ro bust and flat forms of El phid ium. It is pos si ble that this varia tion in depth was due to eustatic changes in sea level, caused by Event Mi3 of the Mid dle Mio cene cli matic cool ing. The spi ral di ame ter of the test was at its low est value then, in di cat ing that ma tur ity was reached at a faster rate. The pe riod of shoal ing of fered the best life con di tions for Am phis te gina in this par ticu lar area.
Key words: Fo ra mini fera, Am phis te gina, Mid dle Mio cene, Pa rate thys, Po land.
Manu script rceived 16 August 2011, accepted 4 September 2012
IN TRO DUC TION
Amphistegina is a highly stenotopic, Re cent rep re sen ta
-tive of the foraminifera. Its oc cur rence is re stricted to ar eas of car bon ate sed i men ta tion, at low lat i tudes and in wa ters of nor mal sa lin ity (Murray, 1973; Larsen, 1976; Hallock, 1985). As a symbiont-bear ing larger foraminifera, the ge nus is re stricted to the euphotic zone (i.e. not deeper than ca. 100–120 m).
Am phis te gina origi nated in the Eo cene and spread as
two main phy lo ge netic linea ges (Larsen, 1978). Am phis te
-gina could hold stra tigraphic sig nifi cance for the
water fa cies of car bon ate plat forms, if the taxo nomic changes in these evo lu tion ary linea ges (i.e., the mor pho -logi cal vari ants and their time ranges) were bet ter de fined. The facies of car bon ate plat forms are quite com mon in the Pa rate thys (Fig. 1A; Pis era, 1996) and con tain Am phis te
gina at some lo ca tions. A com pre hen sive study of the ge
-nus in this area was pre sented by Rögl and Brandstätter (1993). The authors stressed the mor phomet ric as pects of its tax on omy, con sid ered the palaeo geo graphic seaways of this
larger fora mini fera, and its ap pli ca bil ity in stra tigra phy.
Amphistegina from Ko ryt nica (a Mid dle Mio cene site in the
Pol ish part of Pa rate thys) was in cluded in the study (lo ca -tion shown in Fig. 1B).
The pres ent study deals with Am phis te gina from the Olimpów Lime stone (Or bu lina su tu ralis Zone of the Mid -dle Mio cene). The re search is in tended as a con tribution to the tax on omy and palaeo geo graphic sig nifi cance of these larger fora mini fera.
GEO LOG I CAL BACK GROUND
In a palaeo geo graphic sense, the Olimpów Lime stone oc curs at the south ern mar gin of the Car pa thian Fore deep. The stud ied sec tion con sti tutes a patch of the Mid dle Mio cene cover, de pos ited in the Car pa thi ans as piggy back ba -sin sedi ments. Af fected by the syn- and post- depositional, struc tural evo lu tionof the base ment, as well as by later ero sion and deg ra da tion pro cesses, the cover has been pre -served only as small, iso lated frag ments (Gon era, 1994a).
Car bon ates are rela tively scarce. At pres ent, the Olimpów quarry pro vides the only ac ces si ble out crop of these Mio cene de pos its. The sec tion con sists of al gal wack stone fa -cies of early Bade nian age (Gon era, 1994b).
In the Olimpów quarry (GPS co or di nates: N49°59' 47.34''; E21°43' 59.09''), bioclastic lime stones are ex posed. They are interbedded with lay ers of poorly con sol i dated car bon ate mud and clays with siliciclastic con tent and cal -car e ous al gae nod ules (Fig. 2). These soft in ter ca la tions were sam pled for a study of the foraminifera. Be sides red al gae as the pre dom i nant rockform ing ma te rial, the re sid -uum is made up of the rich, skel e tal de bris of chloralgal biotas. Al though nu mer ous, the fos sils are mo not o nous, with re spect to the ta- xonomic groups pres ent. Apart from rhodoliths, only foraminifera, bryo zoans (Pouyet and Tarkowski, 1998) and ostracodes are rep re sented. In the foraminifera as sem blage, the fol low ing taxa are com mon:
Lobatula lobatula (Walker and Ja cob, 1798), Textularia sp.
div., Elphidium sp. div., Asterigerinata planorbis (d’Orbi-gny, 1846), Eponides haidingeri (d’Orbi(d’Orbi-gny, 1846),
Discorbis sp. div., and Amphistegina (Gonera, 1994b). The
Amphistegina con tent of the as sem blage varies from 10–
39% (Fig. 2: sam ple 7 and sam ple 4, re spec tively).
Fig. 1. Study area. A – Cen tral Paratethys (af ter Rögl and Steininger, 1984) – Neo gene, fring ing ba sin of Med i ter ra nean Tethys. B – Geological sketch map of Carpathian Foredeep and flysch overthrust zone in south ern Po land (af ter Alexandrowicz, 1971)
Fig. 2. Geo log i cal map of study area and sec tion, show ing lo ca -tion of de pos its sam pled (tax on omy in Gonera, 1994b); sam ples con tain ing Amphistegina used in biometrical study are shaded. Explanations in the map as in Fig. 1
MA TE RI ALS AND METH ODS
In or der to ap pre ci ate the spe cies of Am phis te gina pres -ent, the ap proach to ge nus tax on omy, pro posed by Larsen (1978), was ap plied. Ac cord ingly, the fol low ing fea tures were taken as species- diagnostic: the pat tern of su tures, the com plex ity of the spi ral side, the char ac ter is tics of the ap er -tu ral face, the test- surface or na men ta tion and the form of the pe riph ery. On the ba sis of ob ser va tions on the liv ing
Am phis te gina, some fea tures have been in ferred as re flect
-ing in tra spe cific varia tion, de pend -ing on light avail abil ity and wa ter tur bu lence (Larsen and Droo ger, 1977), e.g. the shape of the test in pro file (ro bust ver sus slim). The pres ent pa per fol lows this spe cies con cept for the ge nus. Ac tu al is tic prin ci ples and ecologic data on Re cent Am phis te gina have been ap plied to the pa laeoen vi ron men tal in ter pre ta tion of the Olimpów sam ples.
The size of the fora mini fera test and its spheric ity and con vex ity are the ba sic mor phomet ric fea tures, ap plied to the re con struc tion of habi tat. Fol low ing this ap proach to pa laeoen vi ron men tal ana lysis, these meas urements were gath -ered for the Am phis te gina speci mens from the Olimpów Limestone. The inves ti ga tions were di rected at the mud stone in ter ca la tions of the sec tion (Fig. 2). Suf fi cient num -bers of Am phis te gina speci mens, re trieved from seven soft-rock sam ples, yielded data that were sum ma rized by means of gen eral, sta tis tical pro ce dures (mean value, stan dard de -via tion and me dian cal cu lated us ing Ex cel®Soft ware). For each sam ple, about 300 speci mens were meas ured.
RE SULTS
Tax on omy
In the Olimpów sec tion, only one mor pho type of Am
-phis te gina was de tected (Fig. 3). The tests are low
trochospi ral, with 16 to 20 cham bers at the last whorl. The aper ture, as an in te rio mar gi nal slit on the um bili cal side, is bor -dered by a lip. The ap er tu ral face is very low, with minute sculpt ing. The main cham ber su tures of the ven tral side are twisted back wards and for wards and also are bent back -wards into a pe riph eral arch (Fig. 3). The tooth plate ex tends from the ap er tu ral face to the pre vi ous sep tum; the cham ber lu men is di vided by this. The junc tions of the tooth plate with the wall de fine the star shaped traces of ad di tional su -tures. The tooth plate su ture is rather short, re stricted to the oral part of the main su ture and the main cham ber is shaped. The su tures on the dor sal side are rela tively sharpan gled. Between the cham ber su tures, there are short in ter sep tae, with the shape of a sim ple line. Dex tral coil ing di -rec tions domi nate in the speci mens stud ied (Fig. 4).
This mor phol ogy is in dica tive of a phy lo ge netic phase, in ter me di ate be tween Am phis te gina ma milla (Fichtel and Moll, 1798) and Am phis te gina ra di ata (Fichtel and Moll, 1798), a line age in ferred by Larsen (1978). The pres ence of in ter sep tae only in some cham bers in di cates that the speci -mens ex am ined be long to Am phis te gina hau erina d’Or -bigny, 1846. The tests dis play a coil ing di rec tion that is the same in both end mem bers of the line age.
Hab i tat
From con sid er ations of ecol ogy, the pres ence of in situ
Amphistegina in a fos sil com mu nity in di cates a sa lin ity of
30–45‰ and a warmcli mate tem per a ture as the ba sic, en vi -ron men tal con di tions. Its dis tinc tive morphotype re flects both a dy namic re gime of wa ter mo tion and the met a bolic re quire ments of al gal sym bi o sis (Hansen and Burchardt, 1977; Leutenegger, 1977; Lee et al., 1979; Hallock and Glenn, 1986; Hallock et al., 1991). As re cent field stud ies have shown, CaCO3 in ten sive se cre tion is in dic a tive of both
higher light in ten sity and in creased wa ter mo tion (Hallock, 1981; Kuile and Erez, 1984; Hallock et al., 1986; Hallock et
al., 1991). Ac cord ing to these au thors, the test shape of
these larger foraminifers can be a use ful tool for the rec og -ni tion of these palaeoenvironmental con di tions.
The ap pli ca tion of Am phis te gina for pa laeoe co logi cal in ter pre ta tion is jus ti fied by some of its bio logi cal char ac -ter is tics. The spheric ity (ax ial di ame -ter to spi ral di ame -ter) of the test is a struc tural com pro mise be tween the hy dro dy -namic fac tors of habi tat and the meta bolic re quire ments of al gal sym bi onts (Hal lock, 1979; Röttger and Hal lock, 1982; Hottinger, 1983). Ac cord ing to field ob ser va tions and labo -ra tory ex peri ments on liv ing Am phis te gina, it has been do-cumented that wa ter mo tion is more im por tant than light in pro duc ing an increased thick ness of the test (sphe ric ity > 0.5), whereas in ter me di ate test thick ness (0.4 < T/D < 0.5) is found in quiet en vi ron ments, with a mod er ate to high level of light pene tra tion (Hal lock, 1979, 1981; Hal lock and Glenn, 1986; Hal lock et al., 1986). Ro bust fo rami nif eral tests im ply a current swept en vi ron ment, whereas thin, frag -ile tests in di cate quiet, low- light en vi ron ments (Brasier, 1975; Trif fle man et al., 1991). The re la tion of um bili cal side thick ness (L1) to spi ral side thick ness (L2) in test con -vex ity de notes in creased strength of the shell to re sist being crushed (Wet more and Plot nick, 1992). Liv ing in fa vour able, en vi ron mental con di tions, the fora mini fera tend to ma ture in a mini mal pe riod of time and re pro duce at a rela tively small adult size, whereas those of stressed popu la tions grow more slowly and ma ture at a larger size (Brad -shaw, 1961; Hal lock, 1974; Hal lock et al., 1986).
Con sid er ing the size- frequency dis tri bu tion of the specimens, only those of sam ples 4, 5 and 6 are unimo dal, rep re sent ing a nor mal popu la tion struc ture (Fig. 4). In a fo -rami nif eral popu la tion show ing this kind of dis tri bu tion, the empty tests in the sedi ment are of postre pro duc tion ori gin. There fore these three sam ples, lo cated in the mid dle part of the Olimpów sec tion, rep re sent the grad ual ac cu mu la tion of post- reproductive shells over a longer pe riod of time. On the other hand, in sam ple 2, all age- stages are equally fre quent, which re flects the sud den death of all liv ing speci mens. The re main ing three popu la tions (sam ples 1, 9 and 10) ex hibit bi mo dal dis tri bu tions com pris ing two types of speci mens, young and adult. The mor tal ity of the young speci mens was ex tremely high in the up per most sam ple of the sec tion. Appar ently, the com mu nity stayed very close to le thal lim its dur ing this pe riod. In view of the as sump tion that the mean di ame ter cor re sponds to re pro duc tive ma tur ity (Dodd and Stanton, 1981), the size- frequency dia grams in di cate the most fa vour able con di tions dur ing sedi men ta tion of sam ple
Fig. 3. Spec i mens of Amphistegina from Olimpów Lime stone; tests were taken from the sam ple 9. Pat terns of Amphistegina test su -tures are pro vided be low
4 and highly un fa vour able con di tions at the top of the de -pos its ex am ined (sam ple 10).
The spheric ity (T/D in dex) does not ex ceed 0.4 in the 76– 98% of in ves ti gated tests of the Am phis te gina (Fig. 5). Ap par ently, these speci mens rep re sent the thin test mor pho -type. Such tests re sulted from a quiet wa ter habi tat and low level of light. The ex am ined tests of Am phis te gina dis play
al most equally con vex spi ral and um bili cal sides (Fig. 6); the predomi nance of spiral- side con vex ity is only slightly marked.
The test meas ure ments in di cate that the Am phis te gina of the Olimpów Lime stone is the mor pho type, char ac ter is tic for low light and quiet wa ters, namely the deep, euphotic zone. The same de po si tional en vi ron ment also was in ferred
AMPHISTEGINA (FORAMINIFERIDA) FROM OLIMPÓW
155
Fig. 4. Size-fre quency data for Amphistegina, col lected in Olim- pów sec tion (ar rows in di cate me dian value). N – to tal num ber of mea sured tests, DEX – per cent age of dextrally coiled spec i mens
Fig. 5. Vari a tion in T/D values (sphe ric ity) of Amphistegina from Olimpów sec tion. SLI – per cent age of slen der (T/D < 0.4) forms
for the Olimpów Lime stone on the ba sis of bryo zoa (Pouyet and Tar kowski, 1998). This in di cates con di tions very simi -lar to those in hab ited nowa days by Am phis te gina ra di ata (Fichtel and Moll, 1798) (Hal lock, 1984; Hottinger et al., 1993), the taxon that is re garded as an end- member of the phy lo ge netic line age con sid ered.
DIS CUS SION
The Olimpów Am phis te gina dis plays struc tural char ac teris tics, typi cal of the spe cies Am phis te gina hau erina d’Or -bigny, 1846. The pos ses sion of in ter sep tae in some of the cham bers only is a promi nent fea ture, dis tin guish ing this mor pho spe cies from both A. ma milla Fichtel and Moll, 1798 and A. ra di ata Fichtel and Moll, 1798; in ter sep tae are ab sent in A. ma milla, whereas A. ra di ata has them in each cham ber. How ever, there are dif fer ing views on such speci mens, with re gard to their spe cies status. They are treated ei -ther as sepa rate taxa (Larsen, 1978; Papp and Schmid, 1985), or lumped as syno nyms of A. ma milla (Rögl and Han sen, 1984; Rögl and Brandstätter, 1993). The pres ent ac count fol lows the former opin ion.
Larsen (1978) con sid ered A. hau erina to be the an ces -tor of A. ra di ata and, in some cases, as a de scen dant of A.
ma milla. In this phy lo ge netic con cept, the in ter sep tae were
highly evolv ing struc tures of the test. The other morpholo-gic fea tures seem to be con ser va tive. The pat tern of twist ing of cham ber su tures did not un dergo a mean ing ful change in sub se quent mem bers of the phy letic line age. These struc -tures be came more crooked in the younger rep re sen ta tives of the line age (A. hau erina and A. ra di ata), by com pari son with their an ces tor (A. ma milla). The fun da men tal, evo lu tion ary change pro ceeded through the in creas ing (ad vanc -ing) com plex ity of the in ter sep tae, as can be traced in the fos sil rec ord. Mor pho spe cies, lack ing these struc tures, do not ex ist at the pres ent day (A. ma milla dis ap peared from the fos sil rec ord in the Mid dle Mio cene). In stead, tests with a highly up graded set of in ter sep tae have de veloped. The in -ter sep tae were lo cated in only some cham bers at the ini tial stage. Their con struc tion was as sim ple as a short, lin ear par ti tion (A. hau erina). Later (A. ra di ata) in ter sep tae were ar ranged in the ad vanced struc tures with the shape of a me -an der ing arc. Along with the de crease in cham ber number, com pli ca tions oc curred in the in ter sep tae sys tem. Moreo -ver, on the um bili cal side, ad di tional, ir regu lar branches formed along the cham ber su tures. At the same time, the av -er age numb-er of cham b-ers un d-er went a re duc tion: six teen at
A. ma milla, then four teen at A. ra di ata. One can specu late
that in ter sep tae and the branches of the cham ber su ture took on the func tion of cham ber su tures them selves – that is, the main te nance of the tro chospi ral struc ture of the shell. Were these ad di tion ally de vel oped struc tures a more ef fec tive ad -ap ta tion? Maybe the cham bers be came much more spaced and, through this, more suit able for the main te nance of sym -bi otic al gae (Hal lock, 1982, 1988; Hal lock et al., 1991). In this con text, it is worth not ing that the pro gres sion of in ter -sep tae is stronger on the spi ral side of the tests – the one turned up ward to the light source. The de vel op ment of this fea ture as an ad ap ta tion must have a highly com peti tive mean ing, be cause only this Am phis te gina is pres ent to day; both A. ma milla and A. hau erina dis ap peared from bioce-noses in the geo logi cal past.
The Mid dle Mio cene Am phis te gina hau erina of the Olimpów Lime stone is pre domi nantly dex trally coiled (nu meri cal data in Fig. 4). Also other mem bers of the phy lo ge netic line age dis play this di rec tion: A. ma milla as A. hau
-erina an ces tral and A. ra di ata as its re cent de scen dant.
Fig. 6. Vari a tion in con vex ity (L1/L2) in Amphistegina pop u la -tion from Olimpów sec -tion (ar rows in di cate me dian value)
How ever, sin is tral ity has been as cribed to the Mio cene A.
hau erina from both the Pa rate thys and Indo- Pacific re gions
(Larsen, 1978). The Mid dle Mio cene A. ma milla (in clud ing
A. hau erina) from the Pa rate thys was re ported as be ing dex
-trally coiled (Rögl and Brandstätter, 1993). The appar ent confu sion is un clear. Nev er the less, dif fer ences in coil ing di -rec tion is a phe nome non com mon in na ture, but the rea sons for this re main un known. In spite of many in ves ti ga tions, there is a lack of gen eral agree ment: is it a ge neti cally or en -vi ron men tally con di tioned pro cess (Hal lock and Larsen, 1979)?
There is a need for elu ci dation of the stages of evo lu tion, lead ing from A. ma milla to A. ra di ate, and for des ig -nation of the stra tigraphic ranges of these stages. It is to be ex pected that the rec og ni tion and elu ci da tion of the con
secu tive mor pho spe cies would have use ful stra tigraphic ap pli ca tions. The is sue is prom is ing as such a tool in epi con ti -nen tal and pe riph eral ba sins – such as the Pa rate thys. These ap pli ca tions are ex pected to be ad van ta geous, as car bon ate plat form sedi ments are char ac ter is ti cally poor in or thos tra -tigraphic mark ers (above all Glo bi ger in ina). In this case, good rec og ni tion of the phy letic stages of Am phis te gina is ex pected to be a sup port ing – or even vi tal – tool for reso lu -tion to bi os tra tigra phy (Hal lock, 1982). It could be that the de pos its con tain ing both taxa (A. ma milla and A. hau erina) should be dated, as be ing older than the de pos its, com pris -ing solely A. hau erina. Cur rently, while it is un known (not de ter mined) if and when this di ver gence oc curred, inferen-ces on this prob lem are not pos si ble. Ten ta tively only spe-culation is pos si ble: it could be that the Olimpów Lime stone
AMPHISTEGINA (FORAMINIFERIDA) FROM OLIMPÓW
157
Fig. 7. Depth in ter pre ta tion, based on test shape (sphe ric ity) of Amphistegina and other foraminiferal in dexes. Endosymbiont taxa con -sid ered in this chart for Asterigerina, Elphidium and Amphistegina. The dotted bar in di cates the shoal ing ep i sode
is younger than the de pos its com pris ing only A. ma milla or both taxa of Am phis te gina; the lat ter is the case of the Ko -ryt nica Clay.
In the Cen tral Pa rate thys, Am phis te gina al ready is ac -cepted as a mean ing ful stra tigraphic marker. In the part of the Cen tral Pa rate thys, situ ated north of the Car pa thi ans (Fig. 1A), this fora mini fera con sti tutes a use ful tool for dis -tin guish ing the below-evaporite Bade nian (e.g., Skawina For ma tion) from the younger Bade nian (Al ex androwicz, 1997; Gon era et al., 2000). Lithos tra tigraphic hia tuses oc cur in the Bade nian sa lin ity de pos its (Wielic zka For ma tion). It is worth noting that in the south ern ar eas of the Cen -tral Pa rate thys Am phis te gina also per sists in the younger part of the Bade nian (Rögl, 1998). The re treat of this taxon above the saline de pos its was due to re mark able en vi ron -mental changes (Szczechura, 1982). This trans for ma tion now is in ter preted as a pro cess, driven by the Mid dle Mio -cene de te rio ra tion of cli mate (Gon era et al., 2000; Gon era, 2001; Bic chi et al., 2003). This cru cial pe riod has been cor re lated with the Mi3 Event of global cli mate cool ing (stan -dard scale ac cord ing to Miller et al., 1991). North of the Car pa thi ans, the tem pera ture in this earlier part of the Bade -nian ceased to be high enough for Am phis te gina. Al though con di tions for car bon ate sedi men ta tions con tin ued to ex ist, the bio tas of these ar eas never again con tained the ther mo -phi lous fora mini fera, ben thonic (i.e., Am -phis te gina,
Hete-rostegina, Bore lis) or planktonic (Glo bi geri noi des), which
had been pres ent ear lier.
In the mid dle part of the Olimpów sec tion (sam ples 4, 5 and 6) the Am phis te gina speci mens dis play a higher spheri -city than those of the lower and up per parts of the sec tion. Does this appar ent trend in spheric ity in di cate shoal ing con di tions, with in tense wa ter mo tion? To ver ify this hy pothe sis, ad di tional, depth controlled fea tures of the fo rami nif eral com mu nity were in ves ti gated. The per cent age of plank -tonic forms, the per cent age of symbiont- bearing speci mens and the pro por tions of ro bust and flat forms of El phid ium (E. cris pum (Linne, 1758) and E. fichte lia num (d’Or bigny, 1846), re spec tively) were ex am ined (Fig. 7). The data con -firm that the depth of the sedi men tary area de creased in this part of the sec tion. The re corded trend in ba thyme try was ei ther due to tec tonic move ment (up lift of the sea bot tom, fol -lowed by deep ing in this par ticu lar area) or the shoaling of the sedi men tary area, as a re sult of eustatic sea-level change (swing). In the sec ond pos si bil ity, in creased spheric ity of the Am phis te gina tests must have been a sig nal, cor re spond -ing to the Mi3 Event. If this was the case, the bio met ri cal ex ami na tion of larger fora mini fera ap pears not only to be a pre cise method for the re con struc tion of pa laeoen vi ron -ment, but also a prom is ing, ecos tra tigraphic tool.
CON CLU SIONS
1. Only one mor pho spe cies of Am phis te gina (Am phis
-te gina hau erina d’Or bigny, 1846) ap pears in the Olimpów
Lime stone.
2. The hab i tat of Amphistegina from the Olimpów Limestone was the sea bot tom of the deep, euphotic and low-en ergy zone.
3. There is an up ward change in the spheric ity of Am
-phis te gina tests in the stud ied sec tion. This in di cates an ephem eral shoal ing of the ba sin for the mid dle part of the sec tion. The change in ba thyme try was con firmed, on the ba sis of other mem bers of the fo rami nif eral as sem blage. The con clu sion on shoal ing in this part of the sec tion is sup -ported by plank tonic forms, symbiont- bearing forms, and
El phid ium mor pho types.
4. This shoal ing epi sode cor re sponded to the best en vi ron mental con di tions for Am phis te gina in the area con sid -ered – the spi ral di ame ter of the speci mens is small est and is an in di ca tion of rapid at tain ment of ma tur ity. The popu la -tion struc ture was unimo dal in this in ter val, which in di cates its nor mal popu la tion struc ture (grad ual ac cu mu la tion of post- reproductive tests in the sedi ment).
5. The bio met ric analy sis of the test shape of the larger fora mini fera, when used in pa laeoen vi ron men tal analy sis, also ap pears to be an ef fec tive tool for ecos tra tigra phy. In the case stud ied, this method was used to trace piv otal events in global stra tigra phy. This is es pe cially valu able in epi con ti nen tal areas of sedi men ta tion, de void of plank tonic fora mini fera.
Ac knowl edg ments
The au thor would like to thank Dr. Ewa Malata (In sti tute of Geo log i cal Sci ences of the Jagiellonian Uni ver sity; Kraków, Po land), an Anon y mous Re viewer for com ments that helped to im -prove the manu script, and Dr. Bo gus³aw Ko³odziej (In sti tute of Geo log i cal Sci ences of the Jagiellonian Uni ver sity; Kraków, Po -land) for help in tak ing the pho to graphs for Fig. 3.
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