Article

Diverse early endobiotic coral symbiont assemblage from the Katian (Late Ordovician) of Baltica

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Abstract

A diverse early endobiotic coral symbiont assemblage has been detected within heliolitid tabulate corals of Katian age from northwestern Estonia. This assemblage indicates that the earliest endobiotic coral symbiont communities were not restricted to North America. The symbiotic endobiont assemblage comprises abundant Cornulites aff. celatus and rare Conchicolites hosholmensis and Chaetosalpinx sp. The cornulitids are the earliest known symbiotic endobionts of this group. The symbiotic endobionts presumably occurred in certain hosts only and preferred Protoheliolites dubius over Propora speciosa. This record indicates that early endobiotic cornulitids were more diverse than previously thought and appeared in large numbers in the Katian. It is possible that the appearance of abundant skeletal symbiotic coral endobionts may coincide with the Global Ordovician Biodiversification Event, supporting the hypothesis of escape from increased predation.

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... The Ordovician of Baltica has a relatively good record of certain and possible cases of symbiosis (Männil, 1959;Vinn and Mõtus, 2012;Vinn et al., 2014a, b). In this study we focus only on confirmed cases of symbiosis where the skeletal structures indicate that both organisms were growing together. ...
... In this study we focus only on confirmed cases of symbiosis where the skeletal structures indicate that both organisms were growing together. Conulariids (Männil, 1959), cornulitids (Vinn and Mõtus, 2012) and possible polychaetes (Männil, 1959;Vinn, 2004Vinn, , 2005Vinn et al., 2014a,b) were common symbionts in bryozoans and tabulate corals of the Ordovician of Baltica. ...
... Among tabulates, associations with cornulitids and possible polychaetes (i.e. Chaetosalpinx) are known (Vinn and Mõtus, 2012). Only three symbiotic associations between non-colonial animals, hosted by brachiopods (i.e. ...
... The Ordovician bryozoans of Estonia are well-known (e.g., Bassler 1911;Modzalevskaya 1953;Männil 1959;Lavrentjeva 1990;Gorjunova 1992Gorjunova , 1996Pushkin and Gataulina 1992;Gorjunova and Lavrentjeva 1993). The eastern Baltic fauna of cornulitids in the Ordovician is somewhat less studied (Vinn and Mõtus 2012;Vinn 2013, Vinn andMadison 2017), but only a single case of intergrowth between cornulitids and other invertebrates has been previously reported from the Ordovician of Estonia (Vinn and Mõtus 2012), and this topic definitely needs further study. ...
... The Ordovician bryozoans of Estonia are well-known (e.g., Bassler 1911;Modzalevskaya 1953;Männil 1959;Lavrentjeva 1990;Gorjunova 1992Gorjunova , 1996Pushkin and Gataulina 1992;Gorjunova and Lavrentjeva 1993). The eastern Baltic fauna of cornulitids in the Ordovician is somewhat less studied (Vinn and Mõtus 2012;Vinn 2013, Vinn andMadison 2017), but only a single case of intergrowth between cornulitids and other invertebrates has been previously reported from the Ordovician of Estonia (Vinn and Mõtus 2012), and this topic definitely needs further study. ...
... The thin and low rim around the cornulitid aperture does not provide any evidence of the bryozoan's attempt to overgrow an infesting organism. The architecture of this association is very similar to many other Paleozoic symbiotic associations of worm-like organisms and large colonial animals (Zapalski 2009;Zapalski and Hubert 2011;Vinn and Mõtus 2012). In these associations worm-like symbionts are always oriented perpendicular to the growth surface of large colonies; their bodies are always completely embedded within the host colony leaving only apertures free on the host's growing surface. ...
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Three species of trepostome bryozoans formed syn vivo associations with the Cornulites in the Late Ordovician of Estonia. Cornulites sp. and Mesotrypa excentrica presumably formed a true symbiotic association. This is the first known case of symbiosis between cornulitids and bryozoans. It is not known whether this symbiotic association was obligatory of facultative for the cornulitid, but it was facultative for the bryozoan. In this association cornulitids may have competed for the food with bryozoans and the association may have been parasitic. The remaining associations between cornulitids and bryozoans were accidental. Most common skeletonized endobionts of the Ordovician bryozoans were not cornulitids, but conulariids and rugosans.
... Alternatively, endobiotic conulariids may have been dwarfed forms of free-living conulariids that died at mature ages. The architecture of these bryoimmurations is similar to many Paleozoic symbiotic associations between worm-like organisms and large colonial animals (Oekentorp, 1969;Zapalski, 2009;Zapalski and Hubert, 2011;Vinn and Mõtus, 2012). In the latter associations, elongate symbionts are always oriented perpendicular to the growth surface of large colonies; their bodies are always completely embedded within the host colony, leaving only their apertures free on the host's growing surface. ...
... The number of symbiotic associations involving bryozoans increased markedly in the Late Ordovician and this could be related to the GOBE (Vinn et al., 2018). Vinn and Mõtus (2012) suggested that increased diversity of animals with massive skeletons such as corals, stromatoporoids and bryozoans, combined with the increased predation pressure, created perfect conditions during the GOBE for the rapid evolution of endobiotic symbionts among biomineralizing and nonbiomineralizing taxa. ...
Article
The trepostome bryozoans Diplotrypa abnormis, D. bicornis, D. petropolitana, Esthoniopora communis, Esthoniopora subsphaerica, Mesotrypa excentrica, M. expressa, M. raritabulata, and Monotrypa jewensis have symbiotic associations with the conulariid Climacoconus bottnicus in the Upper Ordovician of Estonia. All bryoimmured conulariids are very small and oriented perpendicular (or nearly so) to the growth surface of the host trepostome colony. Muddy seafloors may have promoted this symbiosis between conulariids and bryozoans because the former required a hard substrate for attachment. It is possible that the numerous smaller specimens among endobiotic conulariids usually died as juveniles together with their bryozoan host, or alternatively, the smaller endobiotic conulariids may have been Lilliput forms of free-living conulariids that died at a mature age. Conulariid-trepostome associations were likely not a result of accidental intergrowth of two organisms. Additional protection against predators provided by the calcitic bryozoan skeleton may have been among the benefits for the conulariid symbionts. Usually trepostomes with conulariid symbionts do not contain other invertebrates, but in the Katian in some cases they also hosted Anoigmaichnus bioclaustrations. The exact type of symbiosis between trepostomes and conulariids remains unresolved, but most likely the associations were slightly parasitic or commensal. The available data suggest that bryozoans preferred cnidarians over the other invertebrates as symbionts.
... Conchicolites may have preferred to settle on non-living hard substrates. There are no previous reports of Conchicolitesbryozoan symbiosis, but endobiotic Conchicolites has been described from Late Ordovician tabulates of Estonia (Vinn and Mõtus, 2012). It is not known whether Conchicolites hosholmensis was an obligatory coral symbiont, or if it occurred as encrusters on biogenic and abiogenic substrates, as well. ...
... It is not known whether Conchicolites hosholmensis was an obligatory coral symbiont, or if it occurred as encrusters on biogenic and abiogenic substrates, as well. The relatively thin walls of C. hosholmensis could be interpreted as indicating obligatory symbiosis (Vinn and Mõtus, 2012). In contrast to the Conchicolites-tabulate association, the Conchicolites-Fistulipora association probably was accidental. ...
... A bioclaustration is created when a skeletonized host organism embeds a symbiont within its mineral tissues (Palmer and Wilson, 1988). These symbiont cavities in host organisms have only rarely been reported from the Ordovician (Palmer and Wilson, 1988;Tapanila, 2005;Vinn and Mõtus, 2012). The Ordovician was a time of significant biodiversification, termed the Great Ordovician Biodiversification Event (GOBE). ...
... Worm bioclaustrations have previously been described from the Late Ordovician corals of Baltica (Vinn and Mõtus, 2012). The earliest parasites in Baltica are known from the Middle Ordovician bryozoans of northern Estonia (Vinn personal observations). ...
... The record of hard substrate trace fossils is much more complete, comprising Trypanites borings in brachiopods (Vinn 2005) and bryozoans (Wyse Jackson & Key 2007). Recently bioclaustrations have also been described from the Ordovician of Estonia (Vinn & Mõtus 2012). ...
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The ichnogenus Oikobesalon is here described from the Ordovician of Baltica for the first time. All the specimens in this study were found on Osmussaar Island, Estonia. They belong to the ichnospecies Oikobesalon coricaceum. In the Cambrian and Ordovician, Oikobesalon seems to have occurred only in cold to temperate seas. The Oikobesalon trace-maker presumably used its burrow permanently for dwelling and searched for its food through the burrow aperture that likely opened to the sediment-water interface.
... Thus, Silurian cornulitids were prone to symbiosis with other invertebrates. There may have been a slight escalation in the evolution of the endobiotic life mode in cornulitids as the number of such associations increases from the Ordovician (Dixon 2010;Vinn & Mõtus 2012;Vinn et al. 2018a) to the Silurian (Franzén 1974;Dixon 2010;Vinn & Wilson 2016). The latter fact supports predator-driven evolution of endobiotic life modes among cornulitids (Vinn 2009(Vinn , 2010. ...
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Cornulites sp. and Fistulipora przhidolensis formed a symbiotic association in the Pridoli (latest Silurian) of Saaremaa Island, Estonia. This Cornulites sp.–F. przhidolensis association is the youngest example of cornulitid–bryozoan symbiosis. Symbiosis is indicated by intergrowth of both organisms. The cornulitids are completely embedded within the cystoporate bryozoan colony, leaving only their apertures free on the growth surface of bryozoan. In terms of food competition, this association could have been slightly harmful to F. przhidolensis as Cornulites sp. may have been a kleptoparasite. There may have been a small escalation in the evolution of the endobiotic life mode of cornulitids as the number of such associations increased from the Ordovician to Silurian. It is likely that Palaeozoic bryozoan symbiosis reached its maximum in the Late Ordovician. Most of the symbiotic bryozoans in the Palaeozoic are trepostomes, and the diversity of symbiotic associations was also greatest among trepostomes.
... During the Great Ordovician Biodiversification Event (GOBE), as increasingly complex ecosystems were becoming more extensive and diverse, symbiotic relationships between organisms also evolved, including examples of both parasitism and commensalism (Servais and Harper, 2018). These relationships are often difficult to identify in the fossil record due to a lack of direct evidence, but examples of probable symbiotic relationships between drilling and encrusting symbionts and their hosts are known from the Ordovician in a number of marine invertebrate groups, including graptolites (Bates and Loydell, 2000), echinoderms (Deline, 2008), chitinozoans (Grahn, 1981), bryozoans (Palmer and Wilson, 1988), corals (Vinn and Mõtus, 2012), and brachiopods (Vinn, 2005;Zhan and Vinn, 2007;Vinn et al., 2014). ...
Article
An example of parasitic drilling in a rhynchonelliform brachiopod is described from the Shiyanhe Formation (Katian, Upper Ordovician) of Henan, central China. The boring extends into the shell almost perpendicular to the surface. The shell has been serially sectioned, and the trace (including boring and bioclaustration) has been modeled in three dimensions. Healing of the shell evident in serial sections supports a long-term relationship between the brachiopod and borer that we interpret as parasitic. Platyceratid gastropods, found at the same locality as these brachiopods, are the most likely drilling organism. Previous reports of Paleozoic brachiopod parasitic traces can be classified into two main groups, constructive association and destructive association, depending on whether parasites damage brachiopod shells. The example in this study belongs to the second type as the brachiopod shell has been partly damaged by the borer. http://dx.doi.org/10.1017/jpa.2019.102
... The earliest tabulate hosted symbiotic associations are known from the Late Ordovician (Tapanila 2005). Late Ordovician tabulates hosted cornulitids both in Baltica (Vinn and Mõtus 2012) and Laurentia (Dixon 2010). Chaetosalpinx and Helicosalpinx bioclaustrations are common in the Late Ordovician tabulates of North America (Tapanila 2004). ...
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Rare symbiotic rugose corals in tabulates occur in the lower Rhuddanian strata of Estonia. Thirteen out of 1115 coralla of early Rhuddanian tabulate corals of Estonia and two out of 353 coralla of Sheinwoodian tabulate corals of Gotland and Estonia contain rugose coral endobionts. Endobiotic rugose corals occur in Paleofavosites balticus (Linnaeus 1767), Paleofavosites sp., Mcleodea sp., Heliolites interstinctus (Linnaeus 1767), and Catenipora gotlandica (Yabe 1915). Endobiotic rugose corals include Tryplasma sp., Helicelasma sp., Streptelasma estonica Dybowski 1873, Streptelasma sp., Kodonophyllum cf. tubaeformis Kaljo 1957, and Palaeophyllum? sp. The latter rugose corals commonly occur independently from tabulates in the early Silurian of Estonia. It is most likely that symbiosis between rugose corals and tabulates was not obligate, but facultative. Symbiotic rugose corals presumably benefitted from growth within a stable (positionally) substrate. Rugose corals seem to have no strong negative effect on the growth of tabulates.
... This diversification was a part of the large Ordovician radiation, and as a result numerous and ecologically diversified groups of invertebrates colonized the early Palaeozoic seafloors (Servais et al., 2010). Increasing complexity of modes of life, including feeding, motility and position in the sediment or water column, among others, triggered interspecific relationships between various organisms (e.g., Vinn and Mõtus, 2012;Vinn and Wilson, 2015). Most modern crinoids, unlike their Palaeozoic relatives, are unstalked forms; in today's seas stalked crinoids are comparatively rare, restricted to deeper environments, and similar to their Palaeozoic relatives, are passive suspension feeders (Macurda and Meyer, 1974). ...
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Coral-crinoid associations, where a coral overgrew a crinoid's stem, were among the very common Palaeozoic benthic associations, lasting until the end of the Palaeozoic. Many skeletal overgrowths described so far document syn vivo relationships. This type of interaction is unknown from later, Meso-and Cenozoic deposits, and to date has been unknown from recent seas. Here we analysed two individuals of the crinoid Metacrinus rotundus collected from mesophotic depths off the Japanese Pacific coast, overgrown by a single zoantharian polyp of Abyssoanthus sp. (Anthozoa: Hexacorallia: Zoantharia: Abyssoanthidae), and by some sea anemones identified as Metridioidea sp. indet. (Hexacorallia: Actiniaria). These azooxanthellate hexacorals do not possess skeletons, and were located below the host's feeding fan. Our microtomography examinations showed that the anemones did not modify the host's columnals. These specimens offer a good ecological analogue to similar associations of rugose, Cladochonus-like and tabulate corals known from the Palaeozoic. While in our specimens competition for food between hexacorals and crinoid likely does not occur, such interactions are possible. Both zoantharians and sea anemones show similar corallite/oral disc diameters to rugose corals and Cladochonus-like cnidarians that overgrew crinoids in the Palaeozoic, and therefore they probably obtained similar sizes of food particles. In environments with low relief seafloors these hexacorals benefited from their elevated position, and therefore stronger feeding currents. As both Actiniaria and Zoantharia have their phylogenetic roots deep in the Palae-ozoic, and coral-crinoid associations are common among Palaeozoic tabulate and rugose corals, we speculate that also Palaeozoic non-skeletal corals, inferred from molecular studies, may have also developed this strategy of settling on crinoids, and therefore occupying similar ecological niches to these hexacorals described here. This report documents that coral-crinoid associations, characteristic of Palaeozoic benthic communities, and thought to have disappeared by the end of Permian, exist in modern seas.
... The earliest macroscopic endobiotic invertebrate symbionts are known from the Late Ordovician of North America and Baltica (Elias, 1986;Tapanila, 2005;Dixon, 2010;Vinn and Mõtus, 2012). These endobionts are among the best examples of symbiotic interactions in the fossil record (Taylor, 1990;Taylor and Wilson, 2002). ...
... The discovery of the Anoigmaichnus odinsholmensis and Mesotrypa bystrowi assemblage indicates that the endobiotic symbiont diversity was higher in the Ordovician than previously thought. This new symbiotic endobiont and other similar recent discoveries from the Ordovician ( Dixon, 2010;Vinn and Mõtus, 2012a,b) show that the early diversification of endobiotic symbionts was more intense than previously known and presumably reflected the GOBE. The combination of several geological and biological processes helped generate the GOBE ( Servais et al., 2009). ...
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Spiral embedment cavities that formed around metazoan endosymbionts are preserved in the septa and intercorallite spaces of Columnopora and Calapoeciacorals from Manitoulin Island, Ontario. These are the oldest described Helicosalpinx asturiana, and this report extends the range of these trace fossils from the Richmondian (Ashgill, Upper Ordovician) to the Givetian (upper Middle Devonian). The sinistrally coiled traces show regular morphology, suggesting a physiological basis for their shape. Coral growth parameters are not affected by the presence of Helicosalpinx, suggesting that the endosymbiont was not parasitic and not in direct competition for resources with the host. H. asturiana is interpreted as trace fossil evidence of commensalism.Two additional endosymbiotic traces occur in Late Ordovician Columnopora. The particular association of straight, cylindrical Chaetosalpinx with Columnopora is widespread during the Richmondian. A dependent association is suggested to have originated between the endosymbiont and Columnopora prior to the Richmondian expansion and to have continued into the Hirnantian (latest Ordovician). The association between this endosymbiont and host is the earliest known temporally and globally significant inter-metazoan symbiosis. Although host corals, Columnopora and Calapoecia, did not survive the end-Ordovician mass extinction events, both Chaetosalpinx and Helicosalpinx occur in other host corals during the Silurian and Devonian.
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The following differences were found between the members of the cornulitids, Cornulites and Conchicolites. Both genera have egg-shaped embryonic shells, which presumably calcified after the settling of larva to the substrate, but the embryonic shells in Cornulites are larger than in Conchicolites. Cornulites has a regularly foliated shell ultrastructure and pseudopuncta, whereas the shell ultrastructure in Conchicolites is prismatic. In Cornulites the outer part of the shell contains numerous vesicular cavities that were never observed to cross the interspaces of the surface annulae, indicating cyclic shell secretion. In several species the vesicles are internally coated by calcitic lamellae that are oriented subparallel to the shell surface. In Conchicolites the vesicular shell structure is absent and the calcitic prisms are deposited at the shell aperture more or less at right angles to the longitudinal shell axis. The function of the surface annulae in Cornulites and transverse ridges in Conchicolites may have been to strengthen the shell wall and protect it against longitudinally developing cracks. Vesicular structure in Cornulites seems to have provided a stronger shell for less material and smaller cost of energy. Differences between Cornulites and Conchicolites indicate that the two taxa were probably unrelated and that cornulitids may be a polyphyletic taxon. Cornulites shares the most characters with the lophoporates and tentaculitids. Biological affinities of Conchicolites are controversial, and its morphologic features need further revision to affiliate this group with certainty to any extant animal phylum.
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The problematic fossil Anticalyptraea Quenstedt, 1867, traditionally interpreted as a phorid gastropod, is here assigned to the Class Tentaculita. Its dextrally coiled substrate-cemented tube, bulbous initial chamber, vesicular tube wall and pseudopunctate microlamellar shell structure closely resembles Trypanopora (Tentaculita), but Anticalyptraea differs in having the cones of the pseudopunctae orientated in the opposite direction. Pseudopunctae orientated similarly to Anticalyptraea occur in Cornulites and thick-walled tentaculitids. Anticalyptraea differs from gastropods in having pseudopunctae and a vesicular shell structure.
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The earliest endosymbiotic tubeworms have been discovered within skeletons of the tabulate coral Heliolites sp. from the Silurian (Ludlow) of Podolia, Ukraine. The new tubeworm species has a maximum diameter about I mm, a slightly conical tube, a smooth lumen in the tube and a lamellar wall structure. The tube wall is 0.05-0.10 mm thick. The new endosymbiotic tubeworm Coralloconchus bragensis n. gen. and sp. shares zoological affinities with the tentaculitids (incertae sedis) and is assigned to the Family Cornulitidae (Tentaculita, Comulitida).
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Morphological similarities indicate that Palaeozoic problematic tubeworms, e.g. tentaculitids, cornulitids, microconchids, trypanoporids, Anticalyptraea, and Tymbochoos, form a monophyletic group. This group may also include hederelloids. Members of this group share affinities with lophophorates and their evolution could have partly been driven by predation. The extinction of Palaeozoic tubeworms in the Middle Jurassic was possibly at least partly caused by the ecological pressure by serpulid and sabellid polychaetes. The input of Palaeozoic tubeworms to the general ocean biocalcification system may have been smaller in the Ordovician to Jurassic than that of calcareous polychaetes in the Late Triassic to Recent. There seems to have been some correlation between the aragonite–calcite seas and the skeletal mineralogy of Triassic–Recent polychaete tubeworms.
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Although there have been numerous isolated studies and reports of symbiotic relationships of polychaetes and other marine animals, the only previous attempt to provide an overview of these phenomena among the polychaetes comes from the 1950s, with no more than 70 species of symbionts being very briefly treated. Based on the available literature and on our own field observations, we compiled a list of the mentions of symbiotic polychaetes known to date. Thus, the present review includes 292 species of commensal polychaetes from 28 families involved in 713 relationships and 81 species of parasitic polychaetes from 13 families involved in 253 relationships. When possible, the main characteristic features of symbiotic polychaetes and their relationships are discussed. Among them, we include systematic accounts, distribution within host groups, host specificity, intra-host distribution, location on the host, infestation prevalence and intensity, and morphological, behavioural and/or physiological and reproductive adaptations. When appropriate, the possible directions for further research are also indicated.
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Endosymbionts are organisms that live within the growing skeleton of a live host organism, producing a cavity called a bioclaustration. The endosymbiont lives inside the bioclaustration, which it forms by locally inhibiting the normal skeletal growth of the host, a behaviour given the new ethological category, impedichnia . As trace fossils, bioclaustrations are direct evidence of past symbioses and are first recognized from the Late Ordovician (Caradoc). Bioclaustrations have a wide geographic distribution and occur in various skeletal marine invertebrates, including tabulate and rugose corals, calcareous sponges, bryozoans, brachiopods, and crinoids. Ten bioclaustration ichnogenera are recognized and occur preferentially in particular host taxa, suggesting host-specificity among Palaeozoic endosymbionts. The diversity of bioclaustrations increased during the Silurian and reached a climax by the late Middle Devonian (Givetian). A collapse in bioclaustration diversity and abundance during the Late Devonian is most significant among endosymbionts of host coral and calcareous sponge taxa that were in decline leading up to the Frasnian–Famennian mass extinction.
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Two endosymbionts, Chaetosalpinx sibiriensis and Coralloconchus bragensis, occur in Silurian tabulate corals of Podolia. The endosymbiotic worms responsible for C. sibiriensis bioclaustrations in tabulates are found only in certain species: Paleofavosites cf. collatatus, Heliolites sp. A, Heliolites sp. B, Heliolites sp. C, Favosites gothlandicus, Favosites sp. A. One to six C. sibiriensis-infested tabulate species are known from Late Homerian to Ludfordian, in the reef-related community. Chaetosalpinx sibiriensis preferred certain tabulate species over the others, but showed no preference for the favositid or heliolitid type of morphology.
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The Upper Ordovician Pirgu Regional Stage of the East Baltic is represented by numerous formations, which characterize the lithological variability of the rocks and are used in the geological mapping of the region. Onshore-Offshore drill core profiles from northern Estonia to southern Lithuania provide data on the distribution and succession of the formations. The formations described are arranged into four groups, each comprised of units with similar and characteristic lithological composition and depositional facies. Chitinozoan biozonation and bentonite (K-bentonite) beds are used to correlate selected sections and in the facies analysis of the described formations. Special attention is paid to the age and interpretation of the Jonstorp Formation in the East Baltic and Scandinavia. Correlations of the Pirgu Stage across the East Baltic are presented, and the use of the last occurrence of the chitinozoan Acanthochitina barbata Eisenack as a marker for the lower boundary of the stage is discussed.
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Symbiotic relationships involving physical contact between worms and solitary rugosan polyps are recorded by the following structures in North American Late Ordovician corals: (1) Trypanites borings enclosed within septal swellings in two specimens, (2) vermiform grooves and openings along the external wall of one corallum, and (3) a chamber containing a unique brown tube within one individual. These features are indicative, respectively, of commensal boring polychaete annelids that penetrated through coralla, commensal epizoic worms of unknown taxonomic affinity that attached to the side of a polyp, and a tubicolous worm (possibly a polychaete) that was likely a parasitic endozoan. Symbionts comparable to the latter two types are also known from two specimens of Devonian solitary rugose corals. Indirect evidence suggests that symbioses between solitary rugosans and the worms that produced Trypanites borings as dwelling structures in the sides of coralla were relatively common. However, direct evidence that the hosts were alive has been found in only two corals. In both cases, worms bored through septa within the calices and came into contact with basal surfaces of the polyps, which secreted skeletal material that sealed off the intruders. The rarity of such structures suggests that the encounters were inadvertent. If boring worms favored upcurrent portions of objects in order to maximize feeding benefits and avoid sedimentation, their locations indicate that the concave sides of curved coralla faced toward prevailing currents when in life positions. “Opportunistic” worms are known to have attached to the sides of polyps only in rare instances when the hosts became temporarily exposed as a result of accidents or abnormalities. This indicates that coralla normally served to shield polyps from colonization by nonboring epizoans. Worms that apparently extended up through openings in basal surfaces of polyps likely obtained sustenance parasitically within the central cavities. They could have entered the hosts through their mouths, or via the calices when parts of the polyps detached from their coralla and contracted radially. The rarity of this type of relationship in solitary Rugosa suggests that the worms entered inadvertently. Symbioses involving physical contact between worms and polyps seem to have been rare throughout the history of solitary rugose corals. Both groups apparently tolerated such associations when they did occur, although the rugosans secreted structures in their coralla that served to isolate the symbionts. In doing so, they recorded the presence of worms not likely to be preserved as body fossils. The interpretation of such features provides information on the physiology and ethology of both organisms, on the history of symbiotic relationships, and on the diversity of soft-bodied organisms in ancient environments.
Article
The new ichnogenus Tremichnus is proposed to include simple circular-parabolic pits, with or without associated stereom swellings, on fossil echinoderms, primarily crinoids. Tremichnus is a common trace fossil that is largely confined to columns and calyces of Paleozoic crinoids; the ichnogenus ranges at least from Middle Ordovician to Permian, and perhaps into the Mesozoic. Four new ichnospecies are also defined: T. paraboloides, the type species, comprising deep circular-parabolic pits, 0.15-3.5 mm, without associated gall-like swellings: T. cysticus, similar, though smaller pits surrounded by cystose masses of stereomatic secretion; T. minutus, uniformly small, non-overlapping pits commonly surrounded by raised rims; and T. puteolus, very large, shallow pits generally with a concentric inner ring-like groove. A similarly large pit, T. sp. aff. T. puteolus occurs on diploporitan cystoids. Review of mode of occurrence of these pits suggests that Tremichnus was the work of a sessile, host-selective epibiont, probably a parasite or a commensalistic filter feeder. The pits were apparently produced by a combination of embedment (i.e., inhibition of stereom growth) and some true boring (i.e., removal of stereom). -Author
Article
Brett, Carlton E. 197807 15: Host-specific pit-forming epizoans on Silurian crinoids. Lethaia, Vol. 11. pp. 217–232. Oslo. ISSN 0024–1164. Circular-parabolic pits occur commonly on the endoskeletal remains of certain Paleozoic crinoids. Detailed study of several hundred specimens, representing about 30 pelmatozoan species from the Upper Silurian Rochester Shale of New York and Ontario, reveals that such pits occur exclusively in seven species of crinoids. Furthermore, there are consistent differences in the morphology and orientation of holes occurring on the different crinoid species. This suggests that distinct epizoan species settled selectively on given hosts. The relationship between the hole-producing epizoans and crinoid hosts is inferred to have been a form of dependent commensalism. Preliminary surveys of other Paleozoic crinoid assemblages reveal similar host-selectivity by pit-producing epizoans. Crinoidepizoan pairs apparently co-evolved through considerable spans of geologic time as related genera and species of different ages, from Silurian to Pennsylvanian, exhibit similar pits.
Article
Conoidal shells of Cornulites celatus n. sp. occur commonly within host coralla of Propora conferta Milne-Edwards and Haime, 1851, sensu lato, from the Laframboise Member of the Ellis Bay Formation (Ashgill: Upper Ordovician) at Pointe Laframboise on western Anticosti Island. Examples have also been found at the same locality in the tabulate corals Paleofavosites sp., Acidolites arctatus Dixon, 1986, and A. compactus Dixon, 1986, and the stromatoporoid Ecclimadictyon sp., but not in other associated tabulate coral species. Growth interference between the shells and their hosts indicates a commensal relationship. C. celatus apparently had a more limited paleoenvironmental range than its principal coral host species, which occurs abundantly elsewhere on the island without its endobiotic partner. The diagnosis of Cornulites is emended to include forms having a two-layered shell wall with a distinctive outer layer consistently preserved as prismatic calcite. This new species extends the known stratigraphic range of cornulitids in commensal relationships with corals and stromatoporoids from the Silurian back to the Upper Ordovician.
Article
The adult shell (teleoconch) of the enigmatic tubular Givetian fossil Trypanopora is comprised of two principal layers: an outer fibrous prismatic layer and an inner micro-lamellar (irregular cross-bladed) layer, with local, closely-spaced disruptive punctation. The fine preservation suggests an original calcite composition. The shell microstructure shows great similarities with that of both vermiform ‘gastropods’ and tentaculitoids, suggesting a close affinity between Trypanopora and these groups. The septa have an irregular micro-lamellar (cross-bladed) microstructure in continuity with the inner wall, and a morphology unlike that of any known mollusc. The class Tentaculitoidea is emended to include two new orders: Microconchida for the vermiform ‘gastropods’ and Trypanoporida for Trypanopora and allied genera. □Trypanopora, microstructure, protoconch, teleoconch, fibrous prismatic layer, micro-lamellar layer, tubulation, septation, vermiform ‘gastropods’, Tentaculitoidea, Microconchida, Trypanoporida.
Article
Four stromatoporoid species from a stromatoporoid biostrome in the middle Ludlow Hemse Beds, Gotland, Sweden, show intergrowths with syringoporid tabulate and rugose corals, and indicate close relationships between particular coral and stromatoporoid species. The stromatoporoid Clathrodictyon convictum always contains ?Syringopora and this tabulate is rarely found in the other stromatoporoids. C. convictum is also closely associated with Tryplasma flexuosum (rugosa) while Petrozium pelagicum (rugosa) occurs only in the stromatoporoids Plectostroma intermedium and Parallelostroma typicum. The microstructure of ?Syringopora within the stromatoporoids is composed of an inner lamellar layer and an outer radial layer of calcite crystals. Diagenetic alteration has affected the microstructure which differs from recently described Devonian forms having only a radial layer. This shows variability in the structure of the tabulates within stromatoporoids. Information is sparse on the range of such variation and assessment of the relative importance of taxonomic, palaeoenvironmental and diagenetic effects is not possible in the present sample. No evidence is found to prove the precise nature of the relationships; they were not parasitic but may have been mutually symbiotic, or (most probably) commensal. The results suggest that the corals selected the most suitable stromatoporoid species for their requirements. Stromatoporoid morphology may have had an important influence on the association, where corals are more abundantly associated with those stromatoporoid species which adopted a high profile. Overall the associations appear to have allowed the corals to explore higher energy habitats otherwise unavailable to their delicate branching structure.
Article
The tabulate coral Pleurodictyum americanum Roemer has been cited as an example of a host-specific organism occurring exclusively on the shells of gastropods, particularly Palaeozygopieura hamiltoniae (Hall). Examination of over 1600 specimens of P. americanum, from the Middle Devonian Hamilton Group of western New York, reveals additional complexities which require reinterpretation. While substrate selectivity for Palaeozygopieura shells is evident in all 42 subsamples, a variety of other substrates were also utilized by Pleurodictyum including corals, brachiopods, other molluscs and pebbles. Recent scleractinian corals inhabiting soft bottoms show similar substrate preference, selecting for the tubes of live serpulids, or gastropod shells (invariably with a secondary sipunculid host), but also occasionally settling on unoccupied shells or pebbles. Shell surfaces of P. hamiltoniae, preserved as external molds on the Pleurodictyum epitheca, exhibit encrustation by worm tubes and bryozoans as well as borings and mechanical shell damage, suggesting that these were not the shells of live gastropods. However, the invariant aperture-downward orientation and the high degree of selectivity of P. americanum strongly suggest that the shells were occupied by secondary hosts. □Substrate specificity, commen-salism, tabulate coral, gastropod, sipunculid, Devonian, Hamilton Group, New York.
Article
The encrusting tentaculitoid tubeworms (Middle Ordovician to Middle Jurassic) have their acme of diversity in the Middle Paleozoic and they form a part of the Paleozoic evolutionary fauna. Most of the morphological and ecological innovations of encrusting tentaculitoid tubeworms appeared during the initial phase of their evolution in the Ordovician and Silurian, and no innovations appeared after the Devonian. The evolutionarily most successful (long lasting) were general hard substrate encrusters, and the most successful morphologies supported this life mode. The morphologies that lasted the longest appeared in the beginning of tentaculitoid tubeworm evolution (during the Ordovician). The ecological innovations with the shortest durations were associated with highly dependent distorting symbiotic and endosymbiotic life modes. Predation pressure may have led to evolution of defensive morphologies (e.g. spines and thick vesicular walls) and endosymbiotic life mode in cornulitids, trypanoporids, Anticalyptraea and Streptindytes.
Article
Tymbochoos sinclairi (Okulitch, 1937) has a laminar tube structure and pseudopuncta similar to the tentaculitoids. This suggests that Tymbochoos belongs to the Tentaculitoidea Boucek, 1964. (c) 2006 Elsevier Masson SAS. All rights reserved.
Article
Cornulitids appeared in the Middle Ordovician, and the earliest repairs to their shells are reported from the Upper Ordovician (Katian) of Baltica and North America (Hirnantian). Shell repair is common in the Silurian (Sheinwoodian) unattached cornulitid Cornulites cellulosus from the Baltica and is interpreted here as a result of failed predation. Scalloped, divoted and embayed type of shell repairs occur in three species of Cornulites. The species with the most repairs, C cellulosus, yielded a shell repair frequency of 20.7% with 29 specimens. There are probable antipredatory adaptations, such as spines and extremely thick vesicular walls, in the morphology of Silurian cornulitids. The morphological and ecological evolution of cornulitids could thus have been partially driven by predation. (C) 2008 Elsevier B.V. All rights reserved.
Article
Commensalism in the narrow sense can be understood as an interaction strictly neutral for one organism and positive for the other. Neutral interaction is the absence of interaction and as such it cannot be proven (the proof of absence cannot be made) and consequently it can be regarded as a concept unfit for empirical science. In the broad sense it is often understood as a weak (positive or negative) interaction on one hand and positive on the other. This approach also seems imperfect, as weak interactions should be regarded rather as mutualism or parasitism, respectively. The borders between interactions (commensalism/parasitism and commensalism/mutualism) are difficult to define; hence commensalism should rather be considered as a theoretical interval within the continuum of interactions. Detection of commensalism in recent associations is rather difficult, while in the fossil record it seems impossible. Commensalism as a null hypothesis in paleoecology cannot be retained, as the possibility of making a type II error is very high. The terms "paroecia" and "endoecia" seem to be more useful to use in cases when a particular ecological relationship is difficult to prove.
Article
Much research has suggested that anxiety is involved in the temporomandibular joint syndrome (TMJ), but it is not clear whether it is a cause or a consequence of the disorder. The present study attempts to resolve this issue. Thirty-two patients suffering from temporomandibular joint syndrome and 32 sex- and age-matched dental clinic controls completed the Spielberger State-Trait Anxiety Inventory, the Eysenck Personality Questionnaire and a standardized inventory of bodily symptomatology. TMJ patients scored significantly higher on Eysenck's neuroticism and introversion scales (both P less than 0.05) and had higher trait anxiety scores (P less than 0.005) when compared with controls. These results suggest that TMJ patients have personalities that are vulnerable to life stresses, but that they are not more anxious than controls at any given time. Such a personality profile is similar to that found in other 'functional' syndrome patient groups, such as individuals with globus pharyngis. We suggest that certain stress prone personalities express anxiety in the form of a predictable set of physical syndromes which may be subject to changes with time.
Article
This study begins to redress our lack of knowledge of the interactions between colonial hosts and their parasites by focusing on a novel host-parasite system. Investigations of freshwater bryozoan populations revealed that infection by myxozoan parasites is widespread. Covert infections were detected in all 5 populations studied and were often at high prevalence while overt infections were observed in only 1. Infections were persistent in populations subject to temporal sampling. Negative effects of infection were identified but virulence was low. Infection did not induce mortality in the environmental conditions studied. However, the production of statoblasts (dormant propagules) was greatly reduced in bryozoans with overt infections in comparison to uninfected bryozoans. Overtly-infected bryozoans also grew more slowly and had low fission rates relative to colonies lacking overt infection. Bryozoans with covert infections were smaller than uninfected bryozoans. High levels of vertical transmission were achieved through colony fission and the infection of statoblasts. Increased fission rates may be a strategy for hosts to escape from parasites but the parasite can also exploit the fragmentation of colonial hosts to gain vertical transmission and dispersal. Our study provides evidence that opportunities and constraints for host-parasite co-evolution can be highly dependent on organismal body plans and that low virulence may be associated with exploitation of colonial hosts by endoparasites.
Article
The importance of ecological interactions in driving the evolution of animals has been the focus of intense debate among paleontologists, evolutionary biologists, and macroecologists. To test whether the intensity of such interactions covaries with the secular evolutionary trend in global biodiversity, we compiled a species-level database of predation intensity, as measured by the frequency of common predation traces (drillings and repair scars ranging in age from Ediacaran to Holocene). The results indicate that the frequency of predation traces increased notably by the Ordovician, and not in the mid-Paleozoic as suggested by multiple previous studies. Importantly, these estimates of predation intensity and global diversity of marine metazoans correlate throughout the Phanerozoic fossil record regardless of corrections and methods applied. This concordance may represent (i) an ecological signal: long-term coupling of diversity and predation; (ii) a diversity-driven diffusion of predatory behaviors: an increased probability of more complex predatory strategies to appear at higher diversity levels; or (iii) a spurious concordance in signal capture: an artifact where rare species and less-frequent (e.g., trace-producing) predatory behaviors are both more detectable at times when sampling improves. The coupling of predation and diversity records suggests that macroevolutionary and macroecological patterns share common causative mechanisms that may reflect either historical processes or sampling artifacts. • macroecology • macroevolution
The Seventh Baltic Stratigraphical Conference. Abstracts and Field Guide
  • O Hints
  • L Ainsaar
  • P Männik
Hints, O., Ainsaar, L., Männik, P., Meidla, T. (Eds.), 2008. The Seventh Baltic Stratigraphical Conference. Abstracts and Field Guide. Geological Society of Estonia, Tallinn, p. 46.
Direct evidence of ancient symbiosis using trace fossils From Evolution to Geobiology: Research Questions Driv-ing Paleontology at the Start of a New Century
  • L Tapanila
Tapanila, L., 2008. Direct evidence of ancient symbiosis using trace fossils. In: Kelley, P.H., Bambach, R.K. (Eds.), From Evolution to Geobiology: Research Questions Driv-ing Paleontology at the Start of a New Century, Paleontological Society Short Course, October 4, 2008: Paleontological Society Papers, 14, pp. 271–287.
The Tentaculites of Bohemia. Publication of the Czechoslovakian Academy of Sciences
  • B Bouček
Bouček, B., 1964. The Tentaculites of Bohemia. Publication of the Czechoslovakian Academy of Sciences, Prague. 125 pp.
Parasitism on favositids (Tabulata)
  • M K Zapalski
Zapalski, M.K., 2004. Parasitism on favositids (Tabulata). Palaeontology Newsletter 57, 194.