Olev Vinn & Mark A. Wilson

EPI- AND ENDOBIONTS ON THE LATE SI LU RIAN

(EARLY PRIDOLI) STROMATOPOROIDS

FROM SAAREMAA IS LAND, ES TO NIA

1

De part ment of Ge ol ogy, Uni ver sity of Tartu, Ravila 14A, Tartu 50411, Es to nia, olev.vinn@ut.ee 2

De part ment of Ge ol ogy, The Col lege of Wooster, Wooster, OH 44691, USA, mwilson@wooster.edu Vinn, O. & Wil son, M. A., 2012. Epi- and endobionts on the late Si lu rian (early Pridoli) stromatoporoids from Saaremaa Is land, Es to nia. Annales Societatis Geologorum Poloniae, 82: 195–200.

Ab stract: A di verse sclerobiont com mu nity is de scribed from the Kaugatuma For ma tion (lower Pridoli) of Saare-maa, Es to nia. The stromatoporoid sub strates stud ied here vary from low-domical to high-domical shapes. The com mu nity is nu mer i cally dom i nated by microconchids, which may have been char ac ter is tic of the sclerobiont fauna in the Pridoli of Baltica. Palaeoconchus aff. tenuis, Anticalyptraea calyptrata, Aulopora sp., sheet-like bryo zoans, branch ing bryo zoans, erect bryo zoan hold fasts, rugosans, favositids, discoidal cri noid hold fasts, starlike cri noid hold fasts and sheetstarlike stromatoporoids en crust the domical stromatoporoids. Endobionts are rep re -sented by em bed ded, sym bi otic rugosans, Aulopora sp., and two rare borings Trypanites.

Key words: Encrustation, sclerobionts, stromatoporoids, sym bi o sis, bioerosion, Pridoli, Baltica. Manuscript re ceived 1 September 2012, ac cepted 16 November 2012

IN TRO DUC TION

There is a con sid er able change in the com po si tion of hardsub strate com mu ni ties be tween the Si lu rian and De vo -nian. In gen eral, Si lu rian en crust ing fau nas were dom i nated by bryo zoans and echinoderms, sim i lar to those of the Or -do vi cian (Tay lor and Wil son, 2003). In the De vo nian, hard-sub strate fau nas were dom i nated by microconchids, hederelloids and tab u late cor als, al though bryo zoans and echinoderms were still com mon (Sparks et al., 1980; Bor -deaux and Brett, 1990; Tay lor and Wil son, 2003; Zapalski, 2005; Bose et al., 2011; Rakociñski, 2011; Zatoñ and Krawczyñski, 2011; Zatoñ and Borszcz, in press). En crust -ing faunas on Llandovery, Wen lock and Lud low stromato-poroids have been stud ied in de tail by sev eral au thors (e.g., Kershaw, 1980; Segars and Lid dell, 1988; Lebold, 2000), but stromatoporoid encrusters from the Pridoli have not re -ceived such at ten tion. Encrustation pat terns and bioerosion are rel a tively well known for west ern Baltica, es pe cially for Gotland, Swe den (Kershaw, 1980; Nield, 1984; Beuck et

al., 2008). How ever, lit tle pub lished data on sclerobionts

are avail able from the Si lu rian of east ern Baltica (Kaljo, 1970; Vinn and Wil son, 2010a, b). The only pub lished re -cord of Pridoli sclerobionts for Baltica is the de scrip tion of a hardground fauna from the Ohesaare cliff, Saaremaa (Vinn and Wil son, 2010a). The en crust ing fau nas of the Pridoli are glob ally less stud ied than those of the rest of the Si lu rian, be cause of the smaller num ber of avail able lo cal i ties.

The aims of this pa per are: 1) to de scribe a hardsub -strate as so ci a tion from the early Pridoli of the east ern Bal tic for the first time; 2) to com pare the early Pridoli hardsub strate as so ci a tion with the anal o gous as so ci a tions in the Si -lu rian of Baltica and be yond; and 3) to study both the up per sur face and cryp tic sur face sclerobionts in or der to find sim -i lar -i t-ies and d-if fer ences be tween these com mu n-i t-ies.

GEO LOG I CAL SET TING OF THE AREA

The Baltica palaeocontinent was lo cated in equa to rial latitudes dur ing the late Si lu rian (Melchin et al., 2004). The area of mod ern Es to nia was cov ered by shal low epicontinental sea char ac ter ized by a wide range of trop i cal en vi ron -ments and di verse biotas (Hints et al., 2008). On Saaremaa Is land, the late Si lu rian suc ces sion is rep re sented by car bon -ate rocks of shal low shelf or i gin. These rocks are rich in shelly fau nas, usu ally of very good pres er va tion. The most com mon fos sil groups are brachi o pods, cor als, stromatopo-roids, echinoderms, trilobites, ostracods, molluscs, fishes, eurypterids, bryo zoans, cono donts, chitinozoans, scoleco-donts, acritarchs, al gae and stromatolites (see Kaljo, 1970; Hints et al., 2008). The coastal cliffs are the best Pridoli ex -po sures on Saaremaa.

The Kaugatuma cliff (2.5 m high) is on the west ern coast of the Sorve Pen in sula, a few ki lo me ters south from its north ern neck and about 100 m from the coast line

(58°7'22''N, 22°11'36''E) (Fig. 1). The rocks be long to the mid dle part of the Äigu Beds of the Kaugatuma For ma tion (Fig. 2) (Hints et al., 2008). Stromatoporoids were col lected from the low er most layer of green ishgrey, nod u lar, ar gil la -ceous wackestone, of open shelf or i gin (Hints et al., 2008). Skel e tal de bris con sists mostly of echinoderm and brachi o -pod frag ments. Com plete, large cri noid hold fasts and colu-mnals oc cur in great num bers; Enallocrinus is es pe cially com mon (Ausich et al., 2012). There are also ostracods, trilobites, gas tro pods, bryo zoans and fish frag ments (Hints

et al., 2008).

MA TE RIAL AND METH ODS

Eigh teen stromatoporoids were col lected from the Kau- gatuma cliff (Saaremaa, Es to nia) for a study of encrustation and bioerosion (Fig. 1). Five stromatoporoid spe cies are known from the Äigu Beds: Actinostromella vaiverensis,

Densastroma astroites, Pachystylostroma sp., Parallelo-stroma typicum, P. minosi (Kaljo, 1970). The Parallelo-

stromatopo-roids were re moved from the shale ma trix with a ham mer and their ori en ta tion was in di cated. Sub se quently, the

stro-matoporoids were cleaned with brushes and wa ter. The encrustation area was mea sured, us ing a centi metre grid on a trans par ent, plas tic film. Only ar eas clean of ma trix were counted. The area en crusted by fos sils was mea sured, us ing a milli metre grid on a trans par ent, plas tic film. For the branching co lo nial or gan isms, such as auloporids, the encrusta -tion area was counted as the area within the per im e ter of the encruster. The en crust ing fos sils and pos si ble signs of bioerosion were stud ied us ing a bin oc u lar mi cro scope. All fig ured spec i mens are de pos ited in the Mu seum of Nat u ral His tory (Mu seum of Ge ol ogy), Uni ver sity of Tartu (TUG), Es to nia.

RE SULTS

Six teen of the 18 stromatoporoids were pre served in the life po si tion, while two were over turned. The stromatopo-roid shapes are low- to high-domical (sensu Kershaw, 1981, 1984; Kershaw et al., 2006). Both up per and cryp tic sur -faces were used by sclerobionts. The stromatoporoid sclero- bionts on the up per sur faces are nu mer i cally (i.e., by num -ber of spec i mens in the com mu nity) dom i nated by

Palaeo-conchus aff. tenuis (Microconchida) (51.4%, N = 43)

(Fig. 3), bryo zoans (20.3%, N = 17) (Fig. 4) and cor als (14.4%, N = 12) (Fig. 5). The mi nor groups in clude root-and star-like cri noid hold fasts, Anticalyptraea calyptrata (Tentaculitida), and sheetlike stromatoporoids (Fig. 6, Ta -ble 1). The cryp tic sur faces yielded only sheet-like (N = 2) and branch ing bryo zoans (N = 1) (Ta ble 1).

6.2% of stromatoporoids up per sur faces (to tal 892 cm2) and 9.5% of the cryp tic sur faces (to tal 79 cm2) are cov ered by sclerobionts (Ta ble 2). The larg est area on the up per sur -faces is cov ered by sheet-like stromatoporoids (54% of to tal skel e tal cover), fol lowed by bryo zoans (24.5% of to tal skel e -tal cover) and cor als (18.9% of to -tal skel e -tal cover) (Fig. 7). Mi nor groups by skel e tal cover in clude Palaeoconchus aff.

tenuis (1.4%), cri noid hold fasts (0.6%) and Anticalyptraea calyptrata (0.3%) (Fig. 7, Ta ble 2). Endobi otic rugosans (N = 2) oc curred at the up per sur face of a sin gle

stromato-196

Fig. 1. Lo ca tion of Kaugatuma cliff (Äigu Beds, Kaugatuma For ma tion, early Pridoli) on Saaremaa Is land, Es to nia

poroid. They grew al most per pen dic u lar to the sur face of the stromatoporoid. Their ap er tures (4.9 to 8.0 mm in di am -e t-er) ar-e slightly -el -e vat-ed abov-e th-e stromatoporoid sur fac-e (Fig. 8). A sin gle Aulopora sp. en crusted a sheet-like stro-matoporoid; it grew endobiotically in the stromatoporoid, with its up ward-turned ap er ture free on the

stromatopo-roid’s sur face. Two microconchids have over grown a sheet- like bryo zoan. Only two stromatoporoid spec i mens showed a sin gle bor ing, pos si bly be long ing to Trypanites.

DIS CUS SION

The Kaugatuma stromatoporoids in hab ited a soft bot -tom, on a shal low shelf. They pre sum ably lived in the zone be tween the fair-weather and storm wavebases, as in di cated by the com mon oc cur rence of over turned stromatoporoids and con sid er able, shelly lag de bris.

Ta ble 1

Fau nal com po si tion of stromatoporoid-sclerobiont as so ci a tion

taxa

Upper surface Cryptic surface No. of specimens No. of substrates (total N = 18) No. of specimens No. of substrates (total N = 3) Palaeoconchus aff. tenuis 43 (51.2%) 8 Anticalyptraea calyptrata 3 (3.6%) 2 Sheet-like bryozoans 15 (17.9%) 9 2 (66.7%) 1 Erect bryozoans holdfasts 2 (2.4%) 2 Branching bryozoans 1 (33.3%) 1 Aulopora sp. 4 (4.8%) 3 Favositids 2 (2.4%) 2 Rugosans (epibiont) 4 (4.8%) 3 Rugosans (endobiont) 2 (2.4%) 1 Root-like crinoid holdfasts 5 (5.9%) 3 Star-like crinoid holdfasts 1 (1.2%) 1 Stromatoporoids 1 (1.2 %) 1 borings Trypanites 2 (2.4%) 2

Fig. 3. Palaeoconchus aff. tenuis from Kaugatuma cliff,

Saare-maa, Äigu Beds, Pridoli. TUG 1628-1. Scale bar is in mil li me ters Fig. 4. Sheet-like bryo zoan from Kaugatuma cliff, Saaremaa, Äigu Beds, Pridoli. TUG 1628-2. Scale bar is in mil li me ters

Fig. 5. Aulopora sp. from Kaugatuma cliff, Saaremaa, Äigu Beds, Pridoli. TUG 1628-3. Scale bar is in mil li me ters

The di ver sity of the higher tax o nomic groups of Kauga- tuma sclerobiont fauna is com pa ra ble with sev eral, other ex -am ples of Si lu rian hard-sub strate as so ci a tions (Brett and Lid dell, 1978; Segars and Lid dell, 1988; Lebold, 2000). The fau nal com po si tion of the Kaugatuma stromatoporoids is char ac ter is tic of the Si lu rian. The high num ber of bryo -zoans (20.3% up per-sur face com mu nity) in the com mu nity is es pe cially typ i cal for the Si lu rian. How ever, the nu mer i -cal dom i nance of microconchids (51% of the up per-sur face com mu nity) is strik ing (Fig. 6). In this as pect, the Kauga-tuma sclerobiont as so ci a tion is sim i lar to the Ohesaare hardground fauna from the late Pridoli of Saaremaa. How -ever, in Ohesaare the microconchids (87.8 % of sclerobiont spec i mens in the up per-sur face com mu nity) are even more com mon than in Kaugatuma. Thus, the high nu mer i cal abun dance of microconchids may have been char ac ter is tic of Pridoli hard-sub strate com mu ni ties on Baltica.

Echinoderms are usu ally a very im por tant com po nent of Si lu rian hardground com mu ni ties (Halleck, 1973; Fran-zén, 1977; Keeling and Kershaw, 1994). The Kaugatuma stromatoporoid sclerobiont com mu nity dif fers from sev eral other ear lier Si lu rian com mu ni ties by a low num ber of echi-noderms (Fig. 6). The scar city of echiechi-noderms among sclerobionts here is pe cu liar be cause the bioclasts in the sur -round ing rock ma trix mostly be long to cri noids. How ever, these rock-form ing cri noid taxa were soft-bot tom dwell ers (Ausich et al., 2012). This is sup ported by the large num ber of soft-bot tom cri noid hold fasts found in the life po si tion, in the same layer with the stromatoporoids stud ied.

The pres ence of only bryo zoans on the cryp tic sur faces could ei ther be ex plained by tax o nomic po lar ity be tween the up per-sur face and cryp tic-sur face com mu ni ties, or by a sam pling bias, since the up per-sur face area stud ied was 11 times larger than that of the cryp tic sur face (Ta ble 2). The dom i nance of bryo zoans on cryp tic sur faces is also char ac ter is tic for a late Sheinwoodian (Wen lock) sclerobiont as so ci a tion from Saaremaa (Vinn and Wil son, 2012). In ad di

-tion, cryp tic sur faces of a late Pridoli hardground from Saaremaa are sim i larly dom i nated by bryo zoans (Vinn and Wil son, 2010a). How ever, the open sur face sclerobiont as -so ci a tions from Wen lock (Vinn and Wil -son, 2012) and late Pridoli (Vinn and Wil son, 2010a) of Saaremaa were dom i -nated by cor als and bryo zoans re spec tively. Thus, in spite of dif fer ences be tween the up per sur face com mu ni ties of these Bal tic Si lu rian sclerobiont as so ci a tions, it is pos si ble that dom i nance by bryo zoans may rep re sent a gen eral char ac ter -is tic of cryp tic sclerobiont com mu ni ties of the Si lu rian of Baltica.

The sheet-like stromatoporoids are most im por tant in this Kaugatuma fauna in terms of area of encrustation on the up per-sur face com mu nity (54.1% of the encrustation area), which dif fers from that of Ohessaare hardground fauna, whereas the sheet-like bryo zoans form 63.3% skel e tal cover on the up per sur face and 92.3% on the cryptic sur face (Fig. 7, Ta ble 2). How ever, bryo zoans are also im por tant by area of encrustation on the Kaugatuma stromatoporoids (24.5% of skel e tal cover). In con trast to the Ohesaare hard-ground fauna, microconchids are un im por tant by the area of encrustation on Kaugatuma stromatoporoids. An other dif -fer ence be tween the Kaugatuma stromatoporoid sclerobiont fauna and the Ohesaare hardground fauna is the pres ence of en crust ing cor als in the for mer. Kaugatuma stromatoporoids ex hibit mod er ate, to talen crust ing cov er age as com -pared to the other Or do vi cian to De vo nian an a logues from North Amer ica and Baltica (Brett and Lid dell, 1978; Segars and Lid dell, 1988; Lebold, 2000).

Over growth was not com mon in the Kaugatuma sclerobiont com mu nity, in di cat ing low com pe ti tion for space be -tween the sclerobionts. In most cases, it is likely that the stromatoporoids were en crusted post mor tem be cause sclerobionts have not dis turbed their growth. How ever, rare em -bed ded sym bi otic rugosan endobionts (Fig. 8) rep re sent a

syn vivo as so ci a tion oc cur ring only in a sin gle

stromatopo-roid (to tal N = 18). Sim i lar syn vivo stromatopostromatopo-roid-rugose

198

Ta ble 2

Skel e tal cover of up per and cryp tic sur faces of stromatoporoids

Taxa

Upper surface (892 cm2) Cryptic surface (79 cm2) Encr. area (cm2) % of encrusted

area

% of substrate

area Encr. area (cm 2

) % of encrusted area

% of substrate area

Palaeoconchus aff. tenuis 0.80 1.4 0.09

Anticalyptraea calyptrata 0.17 0.3 0.02

Sheet-like bryozoan 12.10 21.8 1.36 7.0 93.3 8.86

Erect bryozoan holdfast 1.50 2.7 0.17

Branching bryozoan 0.5 6.7 0.63

Aulopora sp. 6.17 11.1 0.69

Favositids 0.70 1.3 0.08

Rugosans (epibiont) 2.85 5.1 0.32

Rugosans (endobiont) 0.75 1.4 0.08

Root-like crinoid holdfasts 0.30 0.5 0.03 Star-like crinoid holdfasts 0.08 0.1 0.01

Stromatoporoids 30.00 54.1 3.36

Total 55.42 (6.2% of

upper surface)

7.50 (9.5% of cryptic surface)

as so ci a tions are known from the Sheinwoodian of Saaremaa (Vinn and Wil son, 2012), the Si lu rian of Gotland (Mori, 1969, 1970; Kershaw, 1981, 1987) and the De vo nian of Spain (Soto and Méndez-Bedia, 1985). The ex act na ture of these sym bi otic as so ci a tions is dif fi cult to in ter pret from fos -sil ma te rial, leav ing any thing be tween par a sit ism and mutu-alism pos si ble. An Aulopora sp. tube, em bed ded within a stromatoporoid, with a free ap er ture on the stromatoporoid sur face, rep re sents a sym bi otic as so ci a tion of some kind.

The vir tual lack of bioerosion on the Kaugatuma stro-matoporoids is a strik ing char ac ter is tic of this hard-sub -strate as so ci a tion. The ex tremely low rate of bioerosion in Kaugatuma con trasts with the sit u a tion on the Ohesaare hardground (late Pridoli). Bioerosion is de pend ent on the time of ex po sure and also on the sed i men tary en vi ron ment. Palaeozoic bioerosion was gen er ally higher in muddy bot -tom en vi ron ments and lower in reef and sand fa cies (Ta-panila et al., 2004). The Kaugatuma stromatoporoids grew on a muddy bot tom with a high amount of car bon ate de bris (mostly crinoidal). Thus, one would ex pect to find mod er ate to high bioerosion on the Kaugatuma stromatoporoids on the ba sis of the sed i men tary en vi ron ment. If there were very short ex po sure times, one also would ex pect a low encrus-tation rate. How ever, the mod er ate encrusencrus-tation rate of the Kaugatuma stromatoporoids in di cates that the ex po sure

time of stromatoporoids was not short. Lescinsky et al. (2002) found that in mod ern oceans bioerosion is higher at the more pro duc tive sites. They also found that the higher encrustation rates are as so ci ated with more pro duc tive sites.

Fig. 6. Fau nal com po si tion of stromatoporoidsclerobiont as so -ci a tion from Kaugatuma cliff, Saaremaa, Äigu Beds, Pridoli

Fig. 7. Encrustation area of up per and cryp tic sur faces of stro-matoporoids by sclerobiont taxa from Kaugatuma cliff, Saaremaa, Äigu Beds, Pridoli

Fig. 8. Endobiotic rugosan in stromatoporoid from Kaugatuma cliff, Saaremaa, Äigu Beds, Pridoli. TUG 1628-4. Scale bar is in mil li me ters

Thus, if the mod er ate encrustation rate for the Kaugatuma stromatoporoids is ex plained by mod er ate pro duc tiv ity, then the bioerosion rate would also be sim i larly mod er ate. The mod er ate encrustation rate, com bined with the very low bioerosion rate of the Kaugatuma stromatoporoids, would be better ex plained by a low abun dance of bor ing or gan isms in the Kaugatuma en vi ron ment, com bined with a rel a tively long ex po sure time of the sub strate, in di cat ing rather low pro duc tiv ity. How ever, the Lescinsky et al. (2002) pro duc -tiv ity hy poth e sis was based on lim ited ma te rial from the mod ern ocean, so the Kaugatuma stromatoporoid bioerosion and encrustation pat terns al ter na tively might be ex -plained by fac tors, other than pro duc tiv ity, such as ex po sure time and sed i ment cover.

Ac knowl edge ments

O.V. is in debted to the Sepkoski Grant (Paleontological So ci -ety), Es to nian Sci ence Foun da tion grant ETF9064 and the tar get-fi nanced pro ject (from the Es to nian Min is try of Ed u ca tion and Sci ence) SF0180051s08 (Or do vi cian and Si lu rian cli mate changes, as doc u mented from the bi otic changes and depositional en vi -ron ments in the Baltoscandian Palaeobasin) for fi nan cial sup port. M.W. thanks the Na tional Geo graphic So ci ety and the Wengerd and Luce Funds at The Col lege of Wooster.

We are grate ful to Harry Mutvei and Miko³aj Zapalski for con struc tive re views.

REF ER ENCES

Ausich, W. I., Wil son, M. A. & Vinn, O., 2012. Cri noids from the Si lu rian of west ern Es to nia. Acta Palaeontologica Polonica, 57: 613–631.

Beuck, L., Wisshak, M., Munnecke, A. & Freiwald, A., 2008. A gi -ant bor ing in a Si lu rian stromatoporoid an a lyzed by com puter to mog ra phy. Acta Palaeontologica Polonica, 53: 149–160. Bor deaux, Y. L. & Brett, C. E., 1990. Sub strate spe cific as so ci a

tions of epibionts on Mid dle De vo nian brachi o pods: im pli ca -tions for paleoecology. His tor i cal Bi ol ogy, 4: 221–224. Bose, R., Schnei der, C. L., Leighton, L. R. & Polly, P. D., 2011.

In flu ence of atrypid mor pho log i cal shape on De vo nian epi-skeletobiont as sem blages from the lower Genshaw For ma tion of the Tra verse Group of Mich i gan: a geo met ric morphometric ap proach. Palaeo ge ogra phy, Palaeoclimatology, Palaeo -ec ol ogy, 310: 427–441.

Brett, C. E. & Lid dell, W. D., 1978. Pres er va tion and paleoecol ogy of a Mid dle Or do vi cian hardground com mu nity. Paleobi -ol ogy, 4: 329–348.

Franzén, C., 1977. Cri noid hold fasts from the Si lu rian of Gotland. Lethaia, 10: 219–234.

Halleck, M. S., 1973. Cri noids, hardgrounds, and com mu nity suc ces sion: the Si lu rian Lau relWaldron con tact in south ern In -di ana. Lethaia, 6: 239–252.

Hints, O., Ainsaar, L., Männik, P. & Meidla, T. (eds) 2008. The Sev enth Bal tic Strati graphi cal Con fer ence. Ab stracts and Field Guide. Geo log i cal So ci ety of Es to nia, 46 pp.

Kaljo, D., 1970. The Si lu rian of Es to nia. Valgus, Tallinn, 343 pp. [in Rus sian].

Keeling, M. & Kershaw, S., 1994. Rocky shore en vi ron ments in the Up per Si lu rian of Gotland, Swe den. Geologiska Före-ningens i Stock holm Förhandlingar, 116: 69–74.

Kershaw, S., 1980. Cav i ties and cryp tic fau nas be neath non-reef stromatoporoids. Lethaia, 13: 327–338.

Kershaw, S., 1981. Stromatoporoid growth form and tax on omy in a Si lu rian biostrome. Jour nal of Pa le on tol ogy, 55: 1284–1295.

Kershaw, S., 1984. Pat terns of stromatoporoid growth in levelbot -tom en vi ron ments. Palae on tol ogy, 27: 113–130.

Kershaw, S., 1987. Stromatoporoid–coral inter growths in a Si lu -rian biostrome. Lethaia, 20: 371–380.

Kershaw, S., Wood, R. A. & Guo, L., 2006. Stromatoporoid re -sponse to muddy sub strates in Si lu rian lime stones. Geolo-giska Föreningens i Stock holm Förhandlingar, 128: 131–138. Lebold, J. G., 2000. Quan ti ta tive anal y sis of epizoans on Si lu rian stromatoporoids within the Brassfield For ma tion. Jour nal of Pa le on tol ogy, 74: 394–403.

Lescinsky, H. L., Edinger, E. & Risk, M. J., 2002. Mol lusc shell encrustation and bioerosion rates in a mod ern epeiric sea: taphonomy ex per i ments in the Java Sea, In do ne sia. Palaios, 17: 171–191.

Melchin, M. J., Coo per, R. A. & Sadler, P. M., 2004. The Si lu rian Pe riod. In: Gradstein, F. M., Ogg, J. G. & Smith, A. G. (eds), A Geo logic Time Scale 2004. Cam bridge Uni ver sity Press. Cam bridge, pp. 188–201.

Mori, K., 1969. Stromatoporoids from the Si lu rian of Gotland, part I. Stock holm Con tri bu tions in Ge ol ogy, 19: 1–100.

Mori, K., 1970. Stromatoporoids from the Si lu rian of Gotland, part II. Stock holm Con tri bu tions in Ge ol ogy, 22: 1–152.

Nield, E. W., 1984. The bor ing of Si lu rian stromatoporoids – to -wards an un der stand ing of lar val be hav ior in the Trypanites or gan ism. Palaeo ge ogra phy, Palaeoclimatology, Palaeo ec -ol ogy, 48: 229–243.

Rakociñski, M., 2011. Sclerobionts on up per Famennian cepha lo pods from the Holy Cross Moun tains, Po land. Palaeobiodi -ver sity and Palaeoenvironments, 91: 63–73.

Segars, M. T. & Lid dell, W. D., 1988. Microhabitat anal y ses of Si -lu rian stromatoporoids as sub strata for epibionts. Palaios, 3: 391–403.

Soto, F & Méndez-Bedia, I., 1985. Estudio de una asociación coral rugoso-estromatopórido en el arrecife de Arnao (Fm Moniello, Asturias, NO de EspaÔa). Trabajos de Geología, 15: 203–209. Sparks, D. K., Hoare, R. D. & Kesling, R. V., 1980. Epizoans on the

brachi o pod Paraspirifer bownockeri (Stew art) from the Mid -dle De vo nian of Ohio. Pa pers on Pa le on tol ogy, 23: 1–105. Tay lor, P. D. & Wil son, M. A., 2003. Palaeo ec ol ogy and evo lu tion

of ma rine hard sub strate com mu ni ties. EarthSci ence Re -views, 62: 1–103.

Tapanila, L., Cop per, P. & Edinger, E., 2004. En vi ron men tal and substrate con trol on Pa leo zoic bioerosion in cor als and stro-matoporoids, Anticosti Is land, east ern Can ada. Palaios, 19: 292–306.

Vinn, O. & Wil son, M. A., 2010a. Microconchid-dom i nated hard-ground as so ci a tion from the late Pridoli (Si lu rian) of Saa-remaa, Es to nia. Palaeontologia Electronica, 13.2.9A. Vinn, O. & Wil son, M. A., 2010b. Oc cur rence of gi ant bor ings of

Osprioneides kampto in the lower Si lu rian (Sheinwoodian) stromatoporoids of Saaremaa, Es to nia. Ichnos, 17: 166–171. Vinn, O. & Wil son, M. A., 2012. Encrustation and bioerosion on

late Sheinwoodian (Wen lock, Si lu rian) stromatoporoids from Saaremaa, Es to nia. Carnets de Géologie, CG2012_A07: 183– 191.

Zapalski, M. K., 2005. Palaeo ec ol ogy of Auloporida: an ex am ple from the De vo nian of the Holy Cross Mts., Po land. Geobios, 38: 677–683.

Zatoñ, M. & Borszcz, T., (in press). Encrustation pat terns on post-ex tinc tion early Famennian (Late De vo nian) brachi o -pods from Rus sia. His tor i cal Bi ol ogy, DOI:10.1080/ 089129 63.2012.658387.

Zatoñ, M. & Krawczyñski, W., 2011. New De vo nian mi croconchids (Tentaculita) from the Holy Cross Moun tains, Po -land. Jour nal of Pa le on tol ogy, 85: 757–769.