Estonian Journal of Earth Sciences, 2016, 65, 2, 115–123
doi: 10.3176/earth.2016.09
A new microconchid species from the Silurian of Baltica
Michał Zatońa, Olev Vinnb and Ursula Toomc
a
b
c
Faculty of Earth Sciences, University of Silesia, Będzińska 60, 41-200 Sosnowiec, Poland; mzaton@wnoz.us.edu.pl
Department of Geology, University of Tartu, Ravila 14A, 50411 Tartu, Estonia; olev.vinn@ut.ee
Institute of Geology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia; ursula.toom@ttu.ee
Received 5 April 2016, accepted 29 April 2016
Abstract. The diversity of Silurian microconchids is still poorly understood. Here, a new microconchid tubeworm species,
Palaeoconchus wilsoni, is described from the Silurian (Ludlow) encrusting rugose corals from Estonia (Saaremaa Island) and a
brachiopod shell from Sweden (Gotland). In Estonia, the microconchids are a dominant constituent of the encrusting assemblages,
associated with cornulitids, Anticalyptraea, auloporids, trepostome bryozoans, hederelloids and enigmatic ascodictyids. It is
notable that these Silurian encrusting assemblages are clearly dominated by tentaculitoids (microconchids, cornulitids and
Anticalyptraea) which very often co-exist on the same coral host. Morphologically similar microconchids and Anticalyptraea may
have exploited a more similar ecological niche than the straight-shelled cornulitids. However, the clear predominance of
microconchids over Anticalyptraea in the communities may indicate that this genus was a less effective competitor for food than
microconchid tubeworms.
Key words: Microconchida, encrustation, epibionts, Estonia, Gotland.
INTRODUCTION
Microconchid tubeworms were very common sedentary
tentaculitoids associated with Palaeozoic firm and hard
substrate habitats. Appearing during the Late Ordovician,
these tiny, spirorbiform encrusters inhabited marine
palaeoenvironments until the Middle Jurassic (Late
Bathonian) when the group became extinct (Zatoń &
Vinn 2011). However, between the Early Devonian and
at least the Late Triassic, some species were also able
to colonize a variety of non-marine habitats (Taylor &
Vinn 2006; Zatoń et al. 2012a). The opportunistic nature
of microconchids is evident in their domination during
the post-extinction intervals when they were either the
most abundant (Zatoń & Krawczyński 2011a; Zatoń
et al. 2013, 2014a) or even the sole encrusters of shelly
and microbial substrates (Fraiser 2011; He et al. 2012;
Yang et al. 2015).
Although microconchids were locally very abundant,
the knowledge about their taxonomy and diversity is
very patchy both in time and space. In the marine
Palaeozoic, the most recognized, albeit still poorly
known, are Devonian forms (Zatoń & Krawczyński
2011a, 2011b; Zatoń et al. 2012b). The least recognized
are those coming from the Late Ordovician, Silurian and
Permian, while those from the marine Carboniferous are
completely unknown with respect to their taxonomic
identity. In order to draw any conclusions about the
diversity dynamics of the group through their evolutionary
history, an urgent requirement is to recognize the
taxonomic status of as many species as possible from
different palaeogeographical regions. This is hampered
by the few specialists on the group, the very conservative
morphology of microconchids and the poor preservation
of many specimens.
In the present paper we describe a new microconchid species from the Silurian of Baltica (Gotland
and Estonia). As Silurian microconchids are very poorly
recognized, with only two species having been formally
named (Vinn 2006), any additional taxonomic data are
important to enrich our knowledge about the diversity of
this group of encrusters in the Silurian period.
MATERIAL AND METHODS
Material and its provenance
Tens of specimens come from the temporary excavations
in the town of Kuressaare and Muratsi locality in
Saaremaa Island, Estonia (Fig. 1A). The specimens were
found encrusting rugose corals derived from bluishgrey, argillaceous nodular limestones and marls of
the Kuressaare Formation (Ludfordian Stage, Ludlow,
Fig. 2). The deposits originated in a normal marine,
shallow shelf palaeoenvironment corresponding to an
open shelf facies zone (Kaljo 1970). One specimen was
© 2016 Authors. This is an Open Access article distributed under the terms and conditions of the Creative Commons Attribution
4.0 International Licence (http://creativecommons.org/licenses/by/4.0).
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Estonian Journal of Earth Sciences, 2016, 65, 2, 115–123
Fig. 1. Sketch map of the Baltic region showing the sampled localities of Saaremaa Island, Estonia (A) and Östergarn, Gotland,
Sweden (B). Ord., Ordovician; Sil., Silurian; Dev., Devonian.
Fig. 2. Lithostratigraphical scheme showing the position of the Kuressaare Formation in Saaremaa Island, Estonia and Hemse
Beds in Gotland, Sweden (based on Hints et al. 2008). B., Beds; Fm., Formation.
found encrusting a brachiopod shell which comes from
Östergarn in Gotland, Sweden (Fig. 1B). The specimen
was derived from a pocket of greenish-grey marl in
a dense crinoidal limestone belonging to the Hemse
Beds (Gorstian Stage, Fig. 2), which originated in
a normal marine, shallow shelf palaeoenvironment
(Larsson 1979).
116
Methods
After cleaning, the fossils were inspected under a
binocular microscope and the best-preserved specimens
were further analysed using a Philips XL30 environmental scanning electron microscope (ESEM) at the
Faculty of Earth Sciences in Sosnowiec, Poland. The
M. Zatoń et al.: New microconchid from the Silurian of Baltica
specimens were studied in an uncoated state using
back-scattered electron (BSE) imaging. Both external
features and internal microstructural details on sectioned
specimens have been documented.
For palaeoecological data, 21 rugose corals were
inspected under the binocular microscope and all
epibionts encountered were determined and counted.
This procedure provides a general insight into the
diversity, abundance and dominance of encrusters,
allowing for comparisons with other examples reported
in the literature.
The specimens are housed at the Institute of Geology
at Tallinn University of Technology in Tallinn, Estonia
(abbreviated GIT 687).
SYSTEMATIC PALAEONTOLOGY
Class TENTACULITA Bouček, 1964
Order MICROCONCHIDA Weedon, 1991
Genus Palaeoconchus Vinn, 2006
Type species. Palaeoconchus minor Vinn, 2006
Palaeoconchus wilsoni sp. nov.
Figures 3A–F, 4A, B
Material. Tens of specimens encrusting rugose
corallites and one specimen encrusting a brachiopod
shell, including the holotype (GIT 687-117-1) and five
paratypes (GIT 687-3-1, GIT 687-3-2, GIT 687-110-1,
GIT 687-109-1, GIT 687-117-2).
Locality. Kuressaare, Saaremaa Island, Estonia.
Sratigraphy. Kuressaare Formation (Ludfordian Stage,
Ludlow, Silurian).
Etymology. In honour of Mark A. Wilson (The College
of Wooster, Ohio), our great friend and scientist working
on hard substrate biotas, including microconchids.
Differential diagnosis. From the Silurian Palaeoconchus
minor Vinn and Palaeoconchus tenuis Sowerby,
the new species differs in the presence of distinct
perpendicular ridges and nodes. From Annuliconchus
siluricus Eichwald, it differs in the presence of distinct
nodes and a complete lack of annuli within the lumen.
Description. Tubes planispirally (dextrally) coiled,
up to 2.7 mm in diameter. Umbilicus open, varying in
width among specimens, with rounded margin and steep
slope. Aperture varies in outline from elliptical to
horseshoe-like. Tube exterior ornamented by thick
transverse ridges (ribs), running from the base of the
umbilical slope to the tube base. On the umbilical margin
the ridges are distinctly thickened, forming elevated
nodes. On the nodes, the ridge may split into a few
finer ridges. The transverse ridges are crossed by fine
longitudinal striae running in the direction of tube
growth. Albeit irregularly, the striae are developed
over the entire surface of the tube. Tube origin barely
visible, but may be ornamented with thin, transverse
ridges. Although tube microstructure is not well
preserved, its microlamellar fabric is still discernible.
However, any distinct (pseudo)punctae disturbing the
microlaminae are not evident. Probably the original
microstructure was punctate, but was later obliterated
by diagenesis.
Comparison. Although externally the specimens investigated may be somewhat similar to those of
Annuliconchus siluricus Eichwald, the tube lumen is
smooth, lacking the annulations characteristic of the
genus Annuliconchus (see Vinn 2006). The new species
also has distinct nodes which are absent in Annuliconchus
siluricus. The absence of any distinct punctae, which
are normally clearly visible on the exfoliated, external
tube surface, is a difference from species referred
to the genus Microconchus (e.g., Zatoń et al. 2013,
2014b). Instead, the lamellar microstructure of the
tube, which originally was probably pseudopunctate,
makes the species very close to the genus Palaeoconchus, which dates back to the Late Ordovician
(Vinn 2006).
The species Palaeoconchus minor Vinn from the
Upper Ordovician (Ashgill) of Estonia differs in its
smaller size (up to 1.2 mm, see Vinn 2006, table 1) and
much smoother external surface that bears only weakly
developed growth lines; it may also possess septa (Vinn
2006). From the species Palaeoconchus tenuis Sowerby
from the Silurian (Wenlock) of England (see Vinn 2006),
the new species differs in having stronger ornamentation of the tube exterior in the form of distinct,
perpendicular ridges and nodes. With respect to external
ornamentation, Palaeoconchus wilsoni sp. nov. differs
from younger, Devonian marine species. For example,
Palaeoconchus variabilis from the Upper Devonian of
Russia (see Zatoń & Krawczyński 2011a) possesses
finer transverse riblets and lacks thickened nodes.
Palaeoconchus sanctacrucensis from the Lower–Middle
Devonian of Poland (see Zatoń & Krawczyński 2011b)
has thickened transverse ribs but lacks distinct nodes.
Palaeoconchus angulatus (Hall) from the Middle
Devonian of the USA (see Zatoń et al. 2012b) has
finer ornamentation and irregularly distributed smaller
tubercles.
Occurrence. Silurian (Ludlow) of Gotland and Estonia.
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Estonian Journal of Earth Sciences, 2016, 65, 2, 115–123
Fig. 3. Palaeoconchus wilsoni sp. nov. from Saaremaa Island, Estonia (A–E) and Gotland, Sweden (F). A, holotype, GIT 687117-1, Kuressaare. B, paratype, GIT 687-3-1, Kuressaare. C, paratype, GIT 687-3-2, Kuressaare. D, paratype, GIT 687-110-1,
Kuressaare. E, paratype, GIT 687-109-1, Kuressaare. F, GIT 305-1-1. Scale bars 500 µm.
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M. Zatoń et al.: New microconchid from the Silurian of Baltica
Fig. 4. Sectioned and polished tube of Palaeoconchus wilsoni sp. nov. from Kuressaare, Estonia, GIT 687-1-1. A, smooth lumen,
devoid of any annulations; scale bar 200 µm. B, diagenetically altered tube, showing poorly preserved lamellar microstructure
(arrowed); scale bar 50 µm.
DISCUSSION
As the Silurian microconchids are very poorly recognized
in comparison to their Devonian representatives, the
identification of a new species – Palaeoconchus wilsoni –
clearly suggests that much work is left to be done in
order to recognize the full diversity of these encrusters
during their early evolutionary history. The abundant
specimens of P. wilsoni found encrusting rugose corals
indicates that encrusting microconchids were very
common in shallow, shelfal palaeoenvironments during
Silurian times, increasing the chances for finding even
more species in the future.
As only one specimen of P. wilsoni was found
encrusting a brachiopod shell from Gotland, we focus
here on the more abundant specimens from Estonia. As
evidenced from the rugose corals (mostly Entelophyllum
and Trypalasma) from the Ludlow Kuressaare Formation
of Saaremaa Island, microconchids were prolific components of encrusting communities. Rugosans were
abundant in the soft-bottom community of the Kuressaare
Formation (Kaljo 1970) and were among the most
available hard substrates in the community. In addition
to numerous rugosans, the tabulate Favosites forbesi
was common. Larger stromatoporoids were represented
only by Parallelostroma typicum (Kaljo 1970). Some
hard substrates were also provided by numerous
rhynchonelliform brachiopods and crinoids (Kaljo 1970).
Molluscs are represented by two species of bivalves
(Pteronitella retroflexa and Ilionia prisca) and one
nautiloid species (Michelinoceras bullatum) (Kaljo
1970). The rugose corals served as a hard substrate for
a number of different epibionts (Fig. 5), which apart from
rugose spatfall and microconchids, consist of the tabulate
Aulopora, trepostome bryozoans and such problematic
encrusting taxa as the cornulitid Conchicolites (e.g.,
Vinn & Mutvei 2005), tentaculitoid Antycalyptraea
(e.g., Vinn & Isakar 2007), hederelloids (e.g., Wilson
& Taylor 2006) and ascodictyids (e.g., Olempska &
Rakowicz 2014; Wilson & Taylor 2014). No borings
were recognized. Excluding confamilial rugose spatfalls,
the rugose corals are encrusted by a total of seven
encrusting taxa. However, on any given rugose corallite,
microconchids are either the only encrusters or the
dominant ones, distinctly outnumbering the rest of the
epibionts (Fig. 6). The large number of microconchids
(up to 42 individuals), at different ontogenetic stages,
suggests continuous colonization of the same coral
substrate by successive spatfalls. The overwhelming
presence of epibionts on different sides of the rugose
epithecae and their absence in the calyx suggests that
colonization probably occurred during the life of the
coral hosts. In some instances the calyx is occupied by
a few individuals of young rugose corals, suggesting
fouling after death of the host.
Very little qualitative and quantitative data are
available on epibionts colonizing rugose corals and such
data concern epibionts of post-Silurian rugose corals.
When compared with other encrusted rugose corals,
it seems that epibiont diversity present on the Silurian
specimens from Estonia is not small, especially given
that these corals are small-sized (up to 4.5 cm in height),
suggesting that they did not offer much space for
colonization. When we look at the encruster diversity
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Estonian Journal of Earth Sciences, 2016, 65, 2, 115–123
Fig. 5. Encrusted rugose corals from Saaremaa Island, Estonia. A, auloporids (white arrow), cornulitid Conchicolites (black
arrow) and two associated microconchids, GIT 687-3, Kuressaare. B, Anticalyptraea (white arrows) and trepostome bryozoan
colony (black arrow), GIT 687-8, Muratsi. C, ascodictyids (black arrows) and associated microconchids, GIT 687-7, Kuressaare.
D, cornulitid Conchicolites (black arrows), GIT 687-11, Kuressaare. E, rugose spatfalls within the calyx (black arrow) and a hederelloid
colony (white arrow), GIT 687-13, Kuressaare.
Fig. 6. Frequency of particular encrusters on the rugose corals from Kuressaare, Estonia. N = number of rugose corals.
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M. Zatoń et al.: New microconchid from the Silurian of Baltica
(36 taxa in total) present on the large rugose corals
from the Middle Devonian Hamilton Group of the USA
(see Baird & Brett 1983), it seems that coral size mattered
and controlled the diversity of the encrusters. However,
as was recently pointed out by Mistiaen et al. (2012),
such features as size and even ornamentation are not the
sole factors determining the diversity of the epibionts.
Indeed, there are examples where still larger corals than
those studied here possessed fewer epibiontic taxa. Sando
(1984) found only four encruster taxa (the foraminifer
Tolypammina?, the bryozoan Eridopora, the brachiopod
Petrocrania and microconchids) colonizing larger (up to
7 cm in height) individuals of the coral Barytichisma sp.
from the Upper Mississippian of Utah. Recently, Zatoń
et al. (2015) found that the Upper Devonian rugose
corals from Russia, which are similar in size and
ornamentation to the Silurian corals studied here, were
encrusted by seven taxa. However, excluding encrusting
confamilial rugose corals and auloporid tabulates which
formed the main biomass of the coral biostrome, the
other epibionts consisted of dominant foraminifera and
single specimens of productid brachiopods, stromatoporoids, microconchids and cornulitids. Thus, with
respect to both diversity and abundance, the Silurian
corals are much richer.
The abundance of microconchids also differs
between particular coral-encrusted assemblages. In
the case of the Middle Devonian corals from the
USA, Baird & Brett (1983, table 5A) recorded that
microconchids were the most abundant of all encrusters
present. Sando (1984) noted that microconchids were
the second dominant group following the foraminifer
Tolypammina on his Carboniferous corals. Recently,
Balon (2015) found that microconchids were the second
most abundant group encrusting Middle Devonian
rugose corals from the Holy Cross Mountains in
Poland. On Upper Devonian rugose corals from
Russia, on the other hand, microconchids were a
minor component of the encrusting assemblages
(Zatoń et al. 2015).
If not depending on the size and external sculpture
of the host, such differences in the composition of the
encrusting assemblages may have resulted from biological factors. It is known (e.g., Pineda et al. 2002;
Paul D. Taylor, pers. comm. 2016) that modern sessile
communities are controlled by the availability of larvae
(‘larval supply’) that can recruit onto new hard substrates, and that the proximity of source populations is
therefore very important. This, however, is difficult to
detect in the fossil record.
Other factors responsible for the composition of the
encrusting assemblages are those concerning external
environment. Zatoń et al. (2015) pointed out that the
scarce epibionts on Late Devonian rugose corals, and
especially the distinct rarity of microconchids, probably
resulted from low-productivity, oligotrophic conditions.
Indeed, microconchids are known to have occurred
abundantly in shallow-marine palaeoenvironments where
nutrient delivery and resultant productivity were probably
high (Zatoń et al. 2012a). It is also known from Recent
marine environments that sclerobionts are least abundant
when sedimentation is high and productivity is low
(Lescinsky et al. 2002). Thus, it is possible that the
diverse epibiotic community containing numerous
microconchids colonizing the Silurian rugose corals
resulted from a very suitable palaeoenvironmental setting
characterized by a low sedimentation rate and sufficient
productivity to support a diverse, suspension-feeding
community. The late Ludfordian (Kuressaare Formation)
is supposed to be characterized by arid climate, high
δ13C and δ18O values and intense evaporation in low
palaeolatitudes where Saaremaa was then located
(Bickert et al. 1997). Such climatic conditions favoured
the formation of reefs and carbonate platforms on
shallow shelves (Bickert et al. 1997). Sediments of the
Kuressaare Formation are not typical of shallow shelf
developing in arid climate. They are characterized by
argillaceous limestones and marls which indicate local
terrigenous sediment influx from a nearby continent
(Jürgenson 1988). Moderate terrigenous sediment influx
together with nutrients may have also been responsible
for relatively high marine productivity in the late
Ludfordian of Saaremaa. Similar palaeoenvironmental
conditions may have supported other Silurian encruster
communities where microconchids were also abundant,
such as those developed on stromatoporoids from the
Pridoli of Saaremaa Island (Vinn & Wilson 2012) or
the calices of camerate crinoids from the Wenlockian of
the USA (Liddell & Brett 1982).
An interesting aspect of the encrusting community
of the Kuressaare Formation is the abundance of other
tentaculitoid tubeworms in the association, such as
Conchicolites and Anticalyptraea in addition to dominant
microconchids. This fact indicates that microconchids
did not outcompete their suspension-feeding close
relatives. This can be explained by differences in the
ecology between various encrusting tentaculitoid tubeworms, so that they did not occupy exactly the same
ecological niche in the ecosystem. There is a possibility
that ecological niches of similar spirally coiled
Anticalyptraea and microconchids were more similar
than were niches of microconchids and non-spiral
Conchicolites. If this is true, the lower abundance of
Anticalyptraea among the tentaculitoids in the community
may have resulted from the competition pressure with
more effective microconchids.
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Estonian Journal of Earth Sciences, 2016, 65, 2, 115–123
Acknowledgements. Financial support to O. V. was provided
by a Palaeontological Association Research Grant, Paleontological Society Sepkoski Grant and Estonian Research
Council projects ETF9064 and IUT20-34. This manuscript is
a contribution to IGCP 591 ‘The Early to Middle Palaeozoic
Revolution’. Paul D. Taylor (London) and Mikołaj Zapalski
(Warsaw), the journal referees, are greatly acknowledged for
their thorough corrections, useful remarks and comments which
helped to improve this paper.
REFERENCES
Baird, G. C. & Brett, C. E. 1983. Regional variation and
paleontology of two coral beds in the Middle Devonian
Hamilton Group of western New York. Journal of
Paleontology, 57, 417–446.
Balon, K. 2015. Epibionts on the Middle Devonian Corals
from the Laskowa Quarry, Holy Cross Mountains.
Unpublished M. Sc. Thesis, University of Silesia, Faculty
of Earth Sciences, 51 pp. [in Polish].
Bickert, T., Pätzold, J., Samtleben, C. & Munnecke, A. 1997.
Paleoenvironmental changes in the Silurian indicated by
stable isotopes in brachiopod shells from Gotland, Sweden.
Geochimica et Cosmochimica Acta, 61, 2717–2730.
Bouček, B. 1964. The Tentaculites of Bohemia. Publication of
Czechoslovakian Academy of Sciences, Prague, 125 pp.
Fraiser, M. L. 2011. Paleoecology of secondary tierers from
Western Pangean tropical marine environments during
the aftermath of the end-Permian mass extinction.
Palaeogeography, Palaeoclimatology, Palaeoecology,
308, 181–189.
He, L., Wang, Y., Woods, A., Li, G., Yang, H. & Liao, W.
2012. Calcareous tubeworms as disaster forms after the
end-Permian mass extinction in south China. PALAIOS,
27, 878–886.
Hints, O., Ainsaar, L., Männik, P. & Meidla, T. (eds). 2008.
The Seventh Baltic Stratigraphical Conference: Abstracts
and Field Guide. Geological Society of Estonia, Tallinn,
158 pp.
Jürgenson, E. 1988. Deposition of the Silurian Beds in the
Baltic. Valgus, Tallinn, 175 pp. [in Russian, with English
summary].
Kaljo, D. (ed.). 1970. The Silurian of Estonia. Valgus, Tallinn,
343 pp. [in Russian, with English summary].
Larsson, K. 1979. Silurian tentaculitids from Gotland and
Scania. Fossils and Strata, 11, 1–180.
Lescinsky, H. L., Edinger, E. & Risk, M. J. 2002. Mollusc
shell encrustation and bioerosion rates in a modern
epeiric sea: taphonomy of experiments in the Java Sea,
Indonesia. PALAIOS, 17, 171–191.
Liddell, W. D. & Brett, C. E. 1982. Skeletal overgrowths
among epizoans from the Silurian (Wenlockian) Waldron
Shale. Paleobiology, 8, 67–78.
Mistiaen, B., Brice, D., Zapalski, M. K. & Loones, C. 2012.
Brachiopods and their auloporid epibionts in the
Devonian of Boullonais (France): comparison with other
associations globally. In Earth and Life, International
Year of Planet Earth (Talent, J. A., ed.), pp. 159–188.
Springer.
Olempska, E. & Rakowicz, Ł. 2014. Affinities of Palaeozoic
encrusting ascodictyid ‘pseudobryozoans’. Journal of
Systematic Palaeontology, 12, 983–999.
122
Pineda, J., Riebensahm, D. & Medeiros-Bergen, D. 2002.
Semibalanus balanoides in winter and spring: larval
concentration, settlement, and substrate occupancy.
Marine Biology, 140, 789–800.
Sando, W. J. 1984. Significance of epibionts on horn corals
from the Chainman Shale (Upper Mississippian) of Utah.
Journal of Paleontology, 58, 185–196.
Taylor, P. D. & Vinn, O. 2006. Convergent morphology in
small spiral worm tubes (‘Spirorbis’) and its palaeoenvironmental implications. Journal of the Geological
Society, London, 163, 225–228.
Vinn, O. 2006. Two new microconchid (Tentaculita Bouček
1964) genera from the Early Palaeozoic of Baltoscandia
and England. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 2006/2, 89–100.
Vinn, O. & Isakar, M. 2007. The tentaculitid affinities
of Anticalyptraea from the Silurian of Baltoscandia.
Palaeontology, 50, 1385–1390.
Vinn, O. & Mutvei, H. 2005. Observations on the morphology
and affinities of cornulitids from the Ordovician of
Anticosti Island and the Silurian of Gotland. Journal of
Paleontology, 79, 726–737.
Vinn, O. & Wilson, M. A. 2012. Epi- and endobionts on
the Late Silurian (Early Pridoli) stromatoporoids from
Saaremaa Island, Estonia. Annales Societatis Geologorum
Poloniae, 82, 195–200.
Weedon, M. J. 1991. Microstructure and affinity of the enigmatic
Devonian tubular fossils Trypanopora. Lethaia, 24, 223–
227.
Wilson, M. A. & Taylor, P. D. 2006. Predatory drillholes
and partial mortality in Devonian colonial metazoans.
Geology, 34, 565–568.
Wilson, M. A. & Taylor, P. D. 2014. The morphology and
affinities of Allonema and Ascodictyon, two abundant
Palaeozoic encrusters commonly misattributed to the
ctenostome bryozoans. Studi Trentini di Scienze Naturali,
94, 259–266.
Yang, H., Chen, Z.-Q., Wang, Y., Ou, W., Liao, W. & Mei, X.
2015. Palaeoecology of microconchids from microbialites near the Permian–Triassic boundary in South
China. Lethaia, 48, 497–508.
Zatoń, M. & Krawczyński, W. 2011a. Microconchid tubeworms across the upper Frasnian–lower Famennian
interval in the Central Devonian Field, Russia. Palaeontology, 54, 1455–1473.
Zatoń, M. & Krawczyński, W. 2011b. New Devonian microconchids (Tentaculita) from the Holy Cross Mountains,
Poland. Journal of Paleontology, 85, 757–769.
Zatoń, M. & Vinn, O. 2011. Microconchids and the rise of
modern encrusting communities. Lethaia, 44, 5–7.
Zatoń, M., Vinn, O. & Tomescu, A. M. F. 2012a. Invasion of
freshwater and variable marginal marine habitats by
microconchid tubeworms – an evolutionary perspective.
Geobios, 45, 603–610.
Zatoń, M., Wilson, M. A. & Vinn, O. 2012b. Redescription
and neotype designation of the Middle Devonian microconchid (Tentaculita) species ‘Spirorbis’ angulatus Hall,
1861. Journal of Paleontology, 86, 417–424.
Zatoń, M., Taylor, P. D. & Vinn, O. 2013. Early Triassic
(Spathian) post-extinction microconchids from western
Pangea. Journal of Paleontology, 87, 159–165.
Zatoń, M., Zhuravlev, A. V., Rakociński, M., Filipiak, P.,
Borszcz, T., Krawczyński, W., Wilson, M. A. & Sokiran, E.
M. Zatoń et al.: New microconchid from the Silurian of Baltica
2014a. Microconchid-dominated cobbles from the Upper
Devonian of Russia: opportunism and dominance in a
restricted environment following the Frasnian–Famennian
biotic crisis. Palaeogeography, Palaeoclimatology, Palaeoecology, 401, 142–153.
Zatoń, M., Hagdorn, H. & Borszcz, T. 2014b. Microconchids
of the species Microconchus valvatus (Münster in
Goldfuss, 1831) from the Upper Muschelkalk (Middle
Triassic) of Germany. Palaeobiodiversity & Palaeoenvironments, 94, 453–461.
Zatoń, M.,
Borszcz, T.,
Berkowski, B.,
Rakociński, M.,
Zapalski, M. K. & Zhuravlev, A. V. 2015. Paleoecology
and sedimentary environment of the Late Devonian coral
biostrome from the Central Devonian Field, Russia.
Palaeogeography, Palaeoclimatology, Palaeoecology,
424, 61–75.
Uus mikrokonhiidiliik Baltika Silurist
Michał Zatoń, Olev Vinn ja Ursula Toom
Siluri mikrokonhiitide mitmekesisust on vähe uuritud. On kirjeldatud uut mikrokonhiidiliiki Palaeoconchus wilsoni,
mis leiti Saaremaalt rugooside ja Gotlandilt käsijalgse küljest. Eestis moodustavad mikrokonhiidid peamise osa
inkrusteerivast faunast ja esinevad koos kornuliitide, Anticalyptraea, auloporiitide, sammalloomade, hederelloidide
ning problemaatiliste askodiktüiididega. Tähelepanuväärne on tentakulitoidide (mikrokonhiidid, kornuliidid ja
Anticalyptraea) domineerimine kirjeldatud Siluri-vanuste inkrusteerivate loomade koosluses. Tentakulitoidid esinesid tihti koos samal peremeeskorallil. Morfoloogiliselt sarnaste mikrokonhiitide ja Anticalyptraea ökoloogilised
nišid olid sarnased ning erinesid sirgekojaliste kornuliitide nišist. Mikrokonhiitide suurem arvukus Anticalyptraea’dega
võrreldes viitab nende suuremale efektiivsusele toitumiskonkurentsis.
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