Printer Friendly

Digestive structures in Ordovician trilobites Colpocoryphe and Flexicalymene from the Barrandian area of Czech Republic/Barrandeumi piirkonnas Tsehhi Vabariigis Ordoviitsiumi trilobiitidel Colpocoryphe ja Flexicalymene leitud seedetrakti elemendid.

INTRODUCTION

Skeletal remains of invertebrates, including trilobite exoskeletons, are abundant in the Barrandian area (e.g. Barrande 1852, 1872; Chlupac et al. 1998; Bruthansova et al. 2007 and references therein). More than 900 trilobite species have been described from Cambrian to Devonian rocks of this area (Valicek & Vanek 2001; Vanek & Valicek 2002) but remains of their soft parts are extremely rare (e.g. Snajdr 1990). Exceptionally preserved trilobites with remains of the digestive system were discovered in the Cambrian Buchava and Jince formations of the Skryje-Tyrovice and Pnbram-Jince basins as well as from the Ordovician Milina and Letna formations of the Prague Basin (Fatka et al. 2014; Fig. 1C herein).

Here, we describe the remains of an undoubted digestive system in three specimens of calymenoid trilobites; Colpocoryphe bohemica (Vanek, 1965), C. cf. bohemica and Flexicalymene (F.) pragensis Vanek & Vokac, 1997. Both specimens of the genus Colpocoryphe were recently collected at two localities situated in the lower levels of the Middle Ordovician Sarka Formation (Darriwilian = Oretanian Regional Stage; see Fig. 1C) in the western part of the Prague Basin (Fig. 1B); the specimen of Flexicalymene (F.) pragensis was collected by the junior author at the Brumlovka locality in shales of the Upper Ordovician Bohdalec Formation (Katian = Late Berounian Regional Stage; see Fig. 1C) in the eastern part of the Prague Basin (Fig. 1B). Two specimens are deposited in the palaeontological collections of the Czech Geological Survey Prague (CGS MD 001, 007). The third specimen is stored in the West-Bohemian Museum in Plzen (specimen number WBM S 06 160).

GEOLOGICAL SETTING

Sarka Formation

The Sarka Formation has been established by Kettner & Kodym (1919) and contains a highly diverse skeletal fauna (e.g. Havlicek & Vanek 1966, 1990; Fatka & Mergl 2009). Its thickness ranges from several metres in the marginal parts of the basin to nearly 300 m in segments with supposedly rapid synsedimentary subsidence (Havlicek 1981). General overviews of the stratigraphy and depositional setting of the Sarka Formation are available in Kukal (1962), Havlicek & Vanek (1966), Havlicek (1982, 1998), Havlicek & Fatka (1992) and Servais et al. (2008). Traditionally, the Sarka Formation was supposed to be time equivalent with the British Llanvirn (e.g. Havlicek & Vanek 1966); later, it was proposed that it corresponds to the interval from late Arenig to early Llanvirn (e.g. Kraft et al. 2001). Fatka et al. (2013) correlate the Sarka Formation with the Oretanian Regional Stage which is equal to the middle Darriwilian (Bergstrom et al. 2008). This formation is divided into two graptolite biozones, the Corymbograptus retroflexus and Didymograptus clavulus biozones (Kraft et al. 2001).

With the exception of several probably heterochronous, stratigraphically and geographically restricted horizons, the dark shales of the Sarka Formation are usually quite sparsely fossiliferous. Our knowledge of the contained fauna comes mainly from loose siliceous nodules. These nodules have long attracted the attention of private collectors by an abundant occurrence of well-to excellently preserved fossils. Unfortunately, such loose nodules do not provide information about their stratigraphic position and/or about the depositional setting (see Budil et al. 2007; Mergl et al. 2008).

Fossil associations of the Sarka Formation

Well-diversified trilobites, brachiopods, gastropods, echinoderms, phyllocarids, ostracods, bivalves, agnostids, hyoliths, cephalopods and conulariids, associated with graptolites and ichnofossils, have been studied for more than 150 years (see Barrande 1872; Havlicek & Vanek 1966, 1990; Mikulas 1991; Mergl 2002; Chlupac 2003; Kraft & Kraft 2003; Budil et al. 2007; Manda 2008; Mergl et al. 2008; Fatka & Mergl 2009; Steinova 2012; Polechova 2013; Aubrechtova 2015). Non-trilobite associations of the Sarka Formation have been analysed by numerous authors.

Havlicek (1982) recognized the Euorthisina Community, inhabiting a widely distributed subtidal, soft-bottom environment. This term was later replaced by the Euorthisina-Placoparia Community by Havlicek & Vanek (1990). The fauna of the deeper-water graptolite black shale was assigned to the 'pelagic fauna dominated by graptolites' of Havhcek & Vanek (1990) and Havhcek (1998). Mergl (2002) proposed that the generally poorly fossiliferous shales with phyllocarids (Caryocaris), graptolites, conulariids, nautiloids and trilobites should be classified as the Rafanoglossa Community within his Paterula Community Group. Vavrdova (1982) assigned samples from the Sarka Formation to the MPM (assemblage with dominant Micrhystridium) as well as to the SPH (assemblage with a dominance of small sphaeromorphs) phytoplankton communities. Mikulas (1991, 1998) ranged the ichnofossil assemblages, though with some reservations, to a transition from the Cruziana to the Zoophycos ichnofacies. Lefebvre (2007, p. 164) distinguished two biofacies based on stylophoran echinoderms. The western part of the Prague Basin was assigned to the comparatively shallower Mitrocystitid Biofacies representing the Echinoderm Taphofacies D, the eastern part of the basin was classified as an example of the deeper Lagynocystitid Biofacies of the Echinoderm Taphofacies E (Fig. 2).

Mitrocystites mitra and other echinoderm taxa occur in the fields at Myto and Rokycany, e.g. in the area from which both exceptionally preserved trilobite specimens originate, and the faunal association fits well with the Mitrocystitid Biofacies. However, M. mitra and Lagynocystis pyramidalis, i.e. typical forms of different echinoderm biofacies, are known to occur together in fields north of Rokycany as well as in the eastern part of the basin. Both taxa occur together with typical representatives of the Euorthisina-Placoparia Association.

Trilobite associations of the Sarka Formation

More than 50 species of trilobites occur as dominant elements of these fossil associations (Havhcek & Vanek 1966; Budil et al. 2007; Mergl et al. 2007). Mergl et al. (2008) prefer the name Placoparia Association instead of the Euorthisina-Placoparia Community of Havhcek & Vanek (1990); associations with common cyclopygids, Bohemilla and Girvanopyge were interpreted as an indication of the proximity of the Cyclopygid Biofacies of Fortey (1985). Bruthansova (2003) briefly discussed associations of Ordovician illaenid trilobites and preferred the designation 'dalmanitid-illaenid-calymenacean assemblage'; she also noted that illaenids do occur together with cyclopygids. Fatka & Mergl (2009) compared the Euorthisina Community of Havlicek with the atheloptic trilobite association of Fortey & Owens (1987) and considered the Middle Ordovician trilobite fauna for an example of the Dalmanitid-Calymenacean Fauna of Cocks & Fortey (1988).

The studied specimens of Colpocoryphe were collected from loose siliceous nodules at two localities in the western part of the Prague Basin. The diverse skeletal fauna found in nodules occurring at both localities belongs to the Placoparia Association of Mergl et al. (2008). The presence of the ichnogenus Arachnostega in the left part of the cephalon of the Colpocoryphe cf. bohemica specimen (Fig. 3) excludes deposition in an anoxic environment.

Bohdalec Formation

The Bohdalec Formation was established by Boucek (1928). Locally it contains an abundant skeletal fauna (e.g. Havlicek & Vanek 1966, 1990; Fatka & Mergl 2009). The thickness of this formation ranges from about 20 m in the marginal parts of the basin to nearly 500 m in segments characterized by supposedly rapid synsedimentary subsidence, e.g. within the territory of Prague (Havlicek 1981). General overviews of the stratigraphy and depositional setting of the Bohdalec Formation are available in Rohlich (1957), Havlicek & Vanek (1966, 1990), Havlicek (1982, 1998), Havlicek & Fatka (1992) and Servais et al. (2008). Traditionally, the Bohdalec Formation was assigned to ther British Caradoc Series (e.g. Boucek 1928, 1937; Kettner & Prantl 1947; Havlicek & Vanek 1966). Later on, the Bohdalec Formation was proposed to represent the youngest part of the Berounian Series by Havlicek & Marek (1973) and/or of the Berounian Regional Stage (Fatka et al. 1995). Fatka et al. (2013) correlate the Bohdalec Formation (late Berounian Regional Stage) with the middle Katian (Bergstrom et al. 2008). The formation has not been divided biostratigraphically and shows a complicated lithofacies development (Rohlich 2006).

Fossil associations of the Bohdalec Formation

Comparatively well diversified trilobites, brachiopods, bivalves, bryozoans, gastropods, ostracods, echinoderms, hyoliths, cephalopods, conulariids, rare agnostids and graptolites, associated with locally abundant ichnofossils from the Bohdalec Formation, have been studied for more than 150 years (see Barrande 1872; Havlicek & Vanek 1966, 1990; Mikulas 1988; Fatka & Mergl 2009). In the first comprehensive study of the Bohemian Upper Ordovician sequences, Boucek (1928) separated and described richly fossiliferous sediments of the so-called Polyteichus Facies, which is characterized by a dominance of carbonate-cemented silty shale. Within the Polyteichus Facies, two major skeletal assemblages have been distinguished by Havlicek (1982, 1998) and Havlicek & Vanek (1990), namely (1) the Hirnantia plateana and (2) the Svobodaina ellipsoides 'communities'. Black shale, which originated in a comparatively deeper environment, contains the Onniella michlensis Community, which is associated with a poor dalmanitid-calymenacean trilobite fauna of Cocks & Fortey (1988). The lower part of the formation contains characteristic elements of the widely distributed Paterula Association, such as small epiplanktic brachiopods, atheloptic trilobites and sparse ichnofossils (Mikulas 1988; Havlicek 1998; Fatka & Mergl 2009). At several outcrops, poor planktonic graptolites and trilobites of the Cyclopygid Biofacies occur in this association.

Trilobite associations of the Bohdalec Formation

More than 20 species of trilobites are abundant in fossil associations in the Bohdalec Formation (Havlicek & Vanek 1966, 1990; Vanek & Vokac 1997). Two associations have been distinguished on the basis of trilobites: the Onnia abducta Community, defined originally by Havlicek & Vanek (1990), and the interval with Declivolithus alfredi established in the lower part of the formation (see Rohlich 2006). This comparatively deeper environment provided rare pelagic elements such as Cyclopyge, Bohemilla and Sculptaspis, associated with scarce shallow-water elements.

The enrolled specimen of Flexicalymene (F.) pragensis, described here, is preserved as internal and external moulds. The dark shale in which it occurs represents a typical lithology of the lower part of the Polyteichus Facies (Onniella michlensis Community, Bohdalec Formation). The absence of ichnofossils in the sample with this trilobite argues for poorly oxygenated depositional environment.

METHODS

The methods used to analyse all trilobite specimens include standard light microscopy of external surfaces (Microscope NIKON SMZ 1500, Leica S8APO). Photographs were taken using digital cameras NIKON D 300 and Olympus SZX-ILLB200 after coating the samples with ammonium chloride. Drawings were made from photographs using Corel Draw X3 and Adobe Photoshop CS5. The terminology follows that proposed by Whittington & Kelly (1997), including the following abbreviations: sag. (sagittal), tr. (transverse). The chemical analyses was performed using Scan TESCAN Vega, EDS X-MAX 50 (Oxford Instruments).

STUDIED MATERIAL

Systematic palaeontology

Family CALYMENIDAE Burmeister, 1843

Subfamily COLPOCORYPHINAE Hupe, 1955

Genus Colpocoryphe Novak in Perner, 1918

Type species. Calymene arago Rouault, 1849; Llanvirn-Llandeilo (= Darriwilian), La Couyere, Ille-et-Vilaine, Brittany, France. By original designation.

Remarks. Vanek (1965) placed Colpocoryphe in the synonymy of Plaesiacomia Hawle & Corda, 1847. In agreement with Dean (1966, p. 304), Hammann (1983), Snajdr (1988, 1991), Pek & Vanek (1989), Vanek (1995), Valicek & Vanek (2001) and other authors, we maintain them as separate genera. The systematic revision of Colpocoryphe is, however, beyond the scope of this paper.

Discussion. Seven species and subspecies of the genus have been recorded in the Barrandian area (Fig. 1C; Table 1). The two specimens described herein are preserved as internal moulds in hard siliceous nodules, which represents a typical lithology of the Middle Ordovician Sarka Formation (Kukal 1962; Chvatal 2003; Drost et al. 2003). External moulds of both specimens were destroyed during the splitting.

Palaeoecology. Hammann (1983, p. 29, text-fig. 11) suggested a burrowing mode of life for Colpocoryphe; this lifestyle is generally accepted (e.g. Fortey & Owens 1987; Snajdr 1988; Havlicek & Vanek 1990). Gutierrez-Marco et al. (2002) and Vidal (1998) used the designation Colpocoryphe Biofacies, but its composition was not specified.

Specimen CGS MD 001, Colpocoryphe cf. bohemica (Vanek, 1965) Figure 3

Description. It represents a late meraspid (M-10), preserved as an internal mould of an articulated thorax associated with the cephalon and pygidium. The right pleural part of the thorax and pygidium are partly covered by rock matrix; the original exoskeletal material is dissolved. The left side of the cephalon bears an about 1 mm long cavity, representing a tiny ichnofossil of the genus Arachnostega (see Fatka et al. 2011; Ar in Fig. 3B).

The exoskeleton is preserved in a prone attitude; it is 9.7 mm long (sag.) and reaches 5.1 mm in maximum width (tr.). The width of the axial region of the thoracic segments ranges from 2.2 mm in the first segment to 1.1 mm in the tenth segment. The glabella is broken off, revealing an external mould of a complete hypostome. Posteriorly the axial part of the internal mould preserves a slightly narrowing tube-like structure, which we interpret as a remnant of the alimentary canal.

Alimentary canal. A comparatively narrow, three-dimensionally preserved tube-like relic is visible inside the thoracic and pygidial axes. This centrally placed and nearly parallel-sided tube extends from the posterior-most part of the glabella, through the occipital ring to the sixth thoracic segment. In the seventh and eighth segments, the alimentary canal bends to the left and seems to be interrupted in the ninth and tenth segments (G in Fig. 3B). Remains of the alimentary canal reappear in the left anterolateral part of the pygidial axis. The alimentary canal is visible on the occipital ring, but its anterior continuation on the glabella is not known, as the axial part of the cephalon shows only the lower ventral surface of the hypostome (Hy in Fig. 3B). The major part of the glabella is broken off and consequently the anteriormost parts of the alimentary canal are preserved only in narrow postero-lateral borders of the glabella, where imprints of two cephalic gut diverticulae are seen on the left side (Dc2 and Dc3 in Fig. 3B); one cephalic gut diverticula is developed in the right side (Dc3 in Fig. 3B). Small cavities developed left and right from the gut in the occipital ring most probably belong to thoracic gut diverticulae (Dt1 in Fig. 3B).

In dorsal view, the transversal width of the alimentary canal ranges from 0.47 to 0.52 mm in the thorax. The canal is narrower in the pygidium, where it measures only about 0.4 mm in tr. width. In dorsal and lateral views, the alimentary canal shows a bead-shaped contour.

Locality. This specimen was collected by the junior author (M. D.) at a small field SW of Myto - rybnlk svateho Stepana (= St. Stephan pond; locality 1 in Fig. 1B).

Remarks. Because of relatively poor preservation, this specimen is affiliated to Colpocoryphe bohemica only tentatively. Assignment to this species is, however, the most parsimonious because the two other species identified from the Sarka Formation, C. inopinata (Novak in Perner, 1918) and the poorly known C. zmudai Vanek, 1995, have been found only from the eastern part of the Prague Basin. In addition, these species are very rare, whereas C. bohemica is known from several hundred specimens (see Table 1).

Specimen WBM S 06 160, Colpocoryphe bohemica (Vanek, 1965) Figure 4

Description. The posterior five thoracic segments are articulated with the pygidium. The preserved part of the exoskeleton is 9.4 mm long (sag.) and 8.8 mm wide (tr.); the pygidium measures 4.8 mm in sag. length and 6.4 mm in tr. width. The axis of the thoracic segments as well as the pygidial axis display a distinct, axially placed, three-dimensionally preserved tube-like relic (Fig. 4), which we interpret as a remnant of the alimentary canal.

Alimentary canal. This structure extends through the thorax and pygidium to the axial tip. In dorsal view, the transversal width of the alimentary canal ranges around 1.4 mm in the thorax, being narrower in the pygidium, where it measures only about 0.85 mm in tr. width. The alimentary canal shows a bead-shaped contour in dorsal as well as in lateral view (Fig. 4). Fine and short transversal constrictions producing the bead-shaped contour of the alimentary canal seem to be related to the segmentation of the exoskeleton.

Although only incompletely preserved, this specimen shows morphological features indicating that it was partly or fully enrolled when entombed. A comparable preservation of the gut in an enrolled Cambrian trilobite Jiumenia anhuiensis was recently described and discussed by Zhu et al. (2014), who stressed the importance of enrollment for the preservation of trilobite soft parts.

Locality. This specimen was collected by the late V. Kordule (amateur collector of fossils in Pribram). After his sudden death the sample was purchased by the West-Bohemian Museum in Plzen in 2010. The outcrop from which the specimen was collected was not registered. However, the lithological characters of the nodule and the composition of the associated fossils agree with concretions occurring in fields north of Rokycany (P. Kraft, pers. comm. 2013; locality 2 in Fig. 1B).

Remarks. The affiliation of this specimen to Colpocoryphe bohemica is, in comparison with the previous sample, more reliable because the pygidium has 7-8 rings and a distinct postaxial elevation reaching the pygidial margin.

Based on a comparison with complete specimens of Colpocoryphe bohemica, the length (sag.) of the studied specimen is estimated to have been approximately 18 mm. The missing part of the body was likely destroyed during diagenetic processes, because it was situated outside the boundary of the nodule. Such a type of preservation suggests that the nodules were formed during early diagenesis (for a detailed discussion see Dabbard & Loi 2012).

Subfamily FLEXICALYMENINAE Siveter, 1977 Genus Flexicalymene Shirley, 1936

Type species. Calymene blumenbachii var. caractaci Salter, 1865; Marshbrookian, Caradoc (= Sandbian), England. By original designation.

Remarks. Only three Upper Ordovician species of the genus Flexicalymene have been recorded from the Barrandian area (Fig. 1C, Table 2). The studied specimen is assigned to Flexicalymene (F.) pragensis Vanek & Vokac, 1997, the only species of this genus known from the Bohdalec Formation. The systematic status of F. (F.) pragensis is somewhat problematic, as the species was established on more or less flattened specimens preserved in fine silty shale.

Specimen CGS MD 007, Flexicalymene (F.) pragensis Vanek & Vokac, 1997 Figure 5

Description. The exoskeleton is enrolled and strongly flattened; the cephalon and pygidium are visible on one surface, whereas the articulated thorax is visible on the opposite side of the mould (Fig. 5). Enrolment combined with flattening preclude direct measurement of some dimensions and allows of only approximate assessment of the original size. The specimen reaches 47 mm in maximum width (tr.). The length of the exoskeleton in a prone attitude is estimated to be about 105 mm (sag.).

Alimentary canal. A comparatively narrow but quite prominent swelling is visible along the inner axial surface of the external mould in the middle and posterior parts of the thorax (G in Fig. 5A). A furrow of comparable width and length is developed on the surface of the internal mould of the counterpart (G in Fig. 5B). A shallow, poorly cut furrow is seen also in the axial part of the internal mould of the pygidium (?G in Fig. 5C).

We interpret the axially placed and nearly parallel-sided structures that have developed as swellings and furrows as a poorly preserved remnant of the alimentary tract. This tube-like structure occurs in the medial part of the thorax, whereas its anterior continuation in the cephalon is not preserved. In dorsal view, the alimentary canal seems to have a bead-shaped contour, as in the two specimens of Colpocoryphe described above (cf. Fig. 4).

Locality. This specimen was recently collected by the junior author (M. D.) at the Brumlovka locality in Prague (locality 3 in Fig. 1B, C).

DISCUSSION

Decay of soft parts

Experiments on modern Limulus show that decay of the internal soft parts begins only a few hours after death and lasts for no more than one month (Babcock & Chang 1997; Babcock et al. 2000). The preservation of the gut in both specimens of Colpocoryphe and in Flexicalymene means that the processes of mineral precipitation leading to the preservation of delicate remains of internal soft parts must have started very early after the entombment of carcasses.

Dabbard & Loi (2012, pp. 100-101) suggested a model, in which the early diagenetic phosphogenesis linked to carbonate fluor-apatite (CFA) precipitation was more intensive in the upper few centimetres (5-10 cm) of sediment under oxic to suboxic conditions. The following silicification invokes a decrease in pH linked to sulphate reduction and pyrite precipitation in the anoxic zone.

Morphology of the alimentary tract

Recently, Lerosey-Aubril et al. (2011) distinguished two major morphological types of the alimentary tract: (1) a simple tube with a crop and (2) a simple tube flanked laterally with metamerically paired caeca (= gut diverticulae). Both morphologies have been found in Ordovician trilobites of the Prague Basin (Fatka et al. 2014).

As in the recently described Cambrian specimen of Jiumenia anhuiensis (see Zhu et al. 2014), a bell-shaped, anteriorly narrow glabella is present in Colpocoryphe. Metamerically paired caeca could be expected in such a glabella. We also agree with Zhu et al. (2014), who noted that the preservation of the gut as a sediment-like infilling is more common (see also Snajdr 1991) than the phosphatization of metamerically paired digestive caeca.

Preservation by phosphatization

Two of the studied specimens (CGS MD 001 and CGS MD 007) were collected from strongly weathered rocks which preclude chemical analyses. The third specimen (WBM S 06 160) is preserved in a dark grey, comparatively lightly weathered siliceous nodule. We have examined this specimen using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analyses with the intention of testing the suspected preservation of the digestive system by phosphatization (see Lerosey-Aubril et al. 2012; Zhu et al. 2014).

The SEM examination did not show any apparent differences between the enclosing rock matrix and the internal mould of the trilobite specimen.

The EDX analyses were undertaken at four different areas of the rock sample. Two spots were placed inside the supposed gut (guts 1 and 2 in Table 3), and two spots were located outside the trilobite body (matrices 1 and 2 in Table 3). This investigation did not show statistically important differences in the percentages of most of the analysed elements. The chemical composition of the material in the supposed gut and the surrounding rock matrix are very similar (Table 3).

The only exception is the distinctive enrichment by C and the relative depletion of Al inside the supposed gut. The interpretation of these data is quite difficult as the content of all other elements varies only very slightly. We do not have any explanation for the depletion of Al. It could not be excluded, however, that the enrichment by C reflects the differences in the initial composition of the bottom mud (= surrounding matrix) and the gut filled by partly digested food particles.

CONCLUSIONS

Two specimens belonging to Colpocoryphe show a simple tube in the occipital ring as well as in all thoracic segments and in the pygidium. In a complete specimen of Colpocoryphe, possible relics of two cephalic diverticulae and one thoracic diverticula are visible.

The glabella expands posteriorly and thus a simple gut associated with gut diverticulae is the preferred morphology of the intestine in Colpocoryphe (Fig. 6). The anterior part of the digestive tract is not preserved in Flexicalymene, but the posterior part shows a morphology comparable with that of Colpocoryphe.

doi: 10.3176/earth.2015.32

Acknowledgements. We would like to express our thanks to the referees Euan N. K. Clarkson (Edinburgh, Scotland) and Per Ahlberg (Lund, Sweden) for helpful comments and suggestions, which improved the clarity of the paper. The authors were informed about the existence of specimen WBM S 06 160 by Petr Kraft (Charles University, Prague), who generously provided also the photograph of this specimen. Martin Racek (Institute of Petrology and Structural Geology, Charles University, Prague) helped with chemical analyses. This study was supported by PRVOUK P44 of the Ministry of Education, Youth and Sports of Czech Republic and the Czech Geological Survey internal project No. 338800. This paper is a contribution to the International Geoscience Programme (IGCP) 591 'The Early to Middle Palaeozoic Revolution' and the Agence Nationale de la Recherche, Programme Blanc SIMI 5-6 RALI.

REFERENCES

Aubrechtova, M. 2015. A revision of the Ordovician cephalopod Bactrites sandbergeri Barrande: systematic position and palaeobiogeography of Bactroceras. Geobios, 48, 193-211.

Babcock, L. E. & Chang, W. T. 1997. Comparative taphonomy of two nonmineralized arthropods: Naraoia (Nektaspida; Early Cambrian, Chengjiang Biota, China) and Limulus (Xiphosurida; Holocene, Atlantic Ocean). Bulletin of National Museum of Natural Science, 10, 233-250.

Babcock, L. E., Merriam, D. F. & West, R. R. 2000. Paleolimulus, an early limuline (Xiphosurida), from Pennsylvanian-Permian Lagerstatten of Kansas, and taphonomic comparison with modern Limulus. Lethaia, 33, 129-141.

Barrande, J. 1846. Notice preliminaire sur le systeme Silurien et les Trilobites de Boheme. Hirschfeld, Leipzig, 97 pp.

Barrande, J. 1852. Systeme Silurien du centre de la Boheme. Vol. I. Prague, 935 pp.

Barrande, J. 1872. Systeme Silurien du centre de la Boheme. Vol. I, Suppl. I, 647 pp.

Bergstrom, S. M., Chen, X., Gutierrez-Marco, J. C. & Dronov, A. 2008. The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and to [delta[].sup.13]C chemostratigraphy. Lethaia, 42, 97-107.

Boucek, B. 1928. O vrstvach zahoranskych [d.sub.[epsilon]] ceskeho ordoviku [On the Zahorany beds dE of the Bohemian Ordovician]. Rozpravy Ceske Akademie Ved a Umeni, 37, 1-32 [in Czech].

Boucek, B. 1937. Stratigraphie et parallelisme de l'Ordovicien superieur de la Boheme. Bulletin Societe Geologique France, 5, 439-459.

Bruthansova, J. 2003. The trilobite Family Illaenidae Hawle et Corda, 1847 from the Ordovician of the Prague Basin (Czech Republic). Transactions of the Royal Society Edinburgh, Earth Sciences, 93, 167-190.

Bruthansova, J., Fatka, O., Budil, P. & Kral, J. 2007. 200 years of trilobite research in the Czech Republic. In Fabulous Fossils-300 Years of Worldwide Research on Trilobites (Mikulic, M. G., Landing, E. & Kluessendorf, J., eds), New York State Museum Bulletin, 507, 51-80.

Budil, P., Kraft, P., Kraft, J. & Fatka, O. 2007. Faunal associations of the Sarka Formation (Middle Ordovician, Darriwilian, Prague Basin, Czech Republic). Acta Palaeontologica Sinica, 46 Suppl., 64-70.

Burmeister, H. 1843. Die Organisation der Trilobiten aus ihren lebenden Verwandten entwickelt; nebst einer systematischen Uebersicht aller zeither beschriebenen Arten. Reimer, Berlin, 147 pp.

Chlupac, I. 2003. Phyllocarid crustaceans from the Middle Ordovician Sarka Formation at Praha-Vokovice. Bulletin of Geosciences, 78, 107-111.

Chlupac, I., Havlicek, V., Kriz, J., Kukal, Z. & Storch, P. 1998. Palaeozoic of the Barrandian. Czech Geological Survey, 183 pp.

Chvatal, M. 2003. Mineral assemblage of the Cerveny vrch locality. Bulletin of Geosciences, 78, 103-106.

Cocks, L. R. M. & Fortey, R. A. 1988. Lower Palaeozoic facies and faunas around Gondwana. In Gondwana and Tethys (Audley-Charles, M. G. & Hallam, A., eds), Geological Society, London, Special Publications, 37, 183-200.

Dabbard, M.-P. & Loi, A. 2012. Environmental control on concretion-forming processes: examples from Paleozoic terrigenous sediments of the North Gondwana margin, Armorican Massif (Middle Ordovician and Middle Devonian) and SW Sardinia (Late Ordovician). Sedimentary Geology, 267-268, 93-103.

Dean, W. T. 1966. The Lower Ordovician stratigraphy and trilobites of the Landeyran Valley and the neighbouring district of the Montagne Noire, south-western France. Bulletin of the British Museum (Natural History), Geology, 12, 247-353.

Drost, K., Linnemann, U., Wemmer, K., Budil, P., Kraft, P., Fatka, O. & Marek, J. 2003. Provenance, geotectonic setting, and early diagenetic processes of the Sarka Formation at Praha--Cerveny vrch (Ordovician, Barrandian, Czech Republic). Bulletin of Geosciences, 78, 147-156.

Fatka, O. & Mergl, M. 2009. The 'microcontinent' Perunica: status and story 15 years after conception. In Early Palaeozoic Peri-Gondwanan Terranes: New Insights from Tectonics and Biogeography (Bassett, M. G., ed.), Geological Society, London, Special Publications, 325, 65-102.

Fatka, O., Kraft, J., Kraft, P., Mergl, M., Mikulas, R. & Storch, P. 1995. Ordovician of the Prague Basin: stratigraphy and development. In Ordovician Odyssey: Short Papers for the 7th International Symposium on the Ordovician System (Cooper, J. D., Droser, M. L. & Finney, S. C., eds), pp. 241-244. The Pacific Section for Sedimentary Geology (SEMP), Las Vegas.

Fatka, O., Mikulas, R., Szabad, M., Micka, V. & Valent, M. 2011. Arachnostega Bertling, 1992 in Cambrian of the Barrandian area (Czech Republic). Acta Geologica Polonica, 61, 367-381.

Fatka, O., Lerosey-Aubril, R., Budil, P. & Rak, S. 2013. Fossilised guts in trilobites from the Upper Ordovician Letna Formation (Prague Basin, Czech Republic). Bulletin of Geosciences, 88, 95-104.

Fatka, O., Budil, P., David, M., Kozak, V., Micka, V. & Szabad, M. 2014. Digestive structures in Cambrian and Ordovician trilobites from the Barrandian area (Czech Republic). In IGCP 591 Field Workshop 2014, Kunming China 12-21 August 2014, Extended Summary (Zhan, R. B. & Huang, B., eds), pp. 49-51. Nanjing University Press 246.

Fortey, R. A. 1985. Pelagic trilobites as an example of deducing the life habits of extinct arthropods. Transactions of the Royal Society Edinburgh, Earth Sciences, 76, 219-230.

Fortey, R. A. & Owens, R. M. 1987. The Arenig Series in South Wales, 1. In The Arenig Series in South Wales, Stratigraphy and Palaeontology, Bulletin of the British Museum (Natural History), Geology, 41, 69-285.

Gutierrez-Marco, J. C., Robardet, M., Rabano, I., Sarmiento, G.N., San Jose Lancha, M. A., Araujo, P. H. & Pidal, A. P. P. 2002. Chapter 4: Ordovician. In The Geology of Spain (Gibbons, W. & Moreno, M. T., eds), pp. 31-49. Geological Society, London.

Hammann, W. 1983. Calymenacea (Trilobita) aus dem Ordovizium von Spanien; ihre Biostratigraphie, Okologie und Systematik. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft, 542, 1-177.

Havlicek, V. 1981. Development of a linear sedimentary depression exemplified by the Prague Basin (Ordovician-Middle Devonian; Barrandian area--central Bohemia). Sbornik Geologickych Ved, Geologie, 35, 7-48.

Havlicek, V. 1982. Ordovician of Bohemia: development of the Prague Basin and its benthic communities. Sbornik Geologickych Ved, Geologie, 37, 103-136.

Havlicek, V. 1998. Ordovician. In Palaeozoic of the Barrandian (Chlupac, I., Havlicek, V., Kriz, J., Kukal, Z. & Storch, P., eds), pp. 149-164. Czech Geological Survey, Prague.

Havlicek, V. & Fatka, O. 1992. Ordovician of the Prague Basin (Barrandian area, Czechoslovakia). In Global Perspectives on Ordovician Geology (Webby, B. D. & Laurie, J. R., eds), pp. 461-472. Balkema, Rotterdam.

Havlicek, V. & Marek, L. 1973. Bohemian Ordovician and its international correlation. Casopis pro Mineralogii a Geologii, 18, 225-232.

Havlicek, V. & Vanek, J. 1966. The biostratigraphy of the Ordovician of Bohemia. Sbornik Geologickych Ved, Paleontologie, 8, 7-69.

Havlicek, V. & Vanek, J. 1990. Ordovician invertebrate communities in black-shale lithofacies (Prague Basin, Czechoslovakia). Vesinik Ustredniho Ustavu Geologickeho, 65, 223-236.

Hawle, I. & Corda, A. J. C. 1847. Prodrom einer Monographie der bohmischen Trilobiten. Abhandlungen der Koniglichen Bohmischen Gesellschaft der Wissenschaften, 5, 119-292.

Hupe, P. 1955. Classification des trilobites. Annales de Paleontologie, 41, 91-325.

Kettner, R. & Kodym, O. 1919. Nova stratigrafie Barrandienu [New stratigraphy of the Barrandian]. Casopis Musea Kralovstvi Ceskeho, 93, 47-55 [in Czech].

Kettner, R. & Prantl, F. 1947. Nove rozdeleni a navrh jednotneho znaceni vrstev stredoceskeho ordoviku [New subdivision and proposal of designation for Central Bohemian Ordovician]. Vestnik Statniho Geologickeho Ustavu CSR, 23, 49-68 [in Czech].

Kraft, P. & Kraft, J. 2003. Middle Ordovician graptolite fauna from Praha--Cerveny vrch (Prague Basin, Czech Republic). Bulletin of Geosciences, 78, 129-139.

Kraft, P., Kraft, J. & Prokop, R. J. 2001. A possible hydroid from the Lower and Middle Ordovician of Bohemia. Alcheringa, 25, 143-154.

Kukal, Z. 1962. Petrograficky vyzkum sareckych vrstev barrandienskeho ordoviku [Petrographical investigation of the Ordovician Sarka beds in the Barrandian area]. Sbornik Ustredniho Ustavu Geologickeho, Odd. Geologicky, 27, 175-214 [in Czech, with English summary].

Lefebvre, B. 2007. Early Palaeozoic palaeobiogeography and palaeoecology of stylophoran echinoderms. Palaeogeography, Palaeoclimatology, Palaeoecology, 245, 156-199.

Lerosey-Aubril, R., Hegna, T. A. & Olive, S. 2011. Inferring internal anatomy from the trilobite exoskeleton: the relationship between frontal auxiliary impressions and the digestive system. Lethaia, 44, 166-184.

Lerosey-Aubril, R., Hegna, T. A., Kier, C., Bonino, E., Habersetzer, J. & Carre, M. 2012. Controls on gut phosphatisation: the Trilobites from the Weeks Formation Lagerstatte (Cambrian; Utah). PloS ONE, 7, e32934.

Manda, S. 2008. Trocholites Conrad, 1838 (Nautiloidea, Tarphycerida) in the Middle Ordovician of the Prague Basin and its palaeobiogeographical significance. Bulletin of Geosciences, 83, 327-334.

Mergl, M. 2002. Linguliformean and craniiformean brachiopods of the Ordovician (Trenice to Dobrotiva formations) of the Barrandian, Bohemia. Acta Musei Nationalis Pragae, Series B, 58, 1-82.

Mergl, M., Fatka, O. & Budil, P. 2007. Lower and early Middle Ordovician trilobite associations of the Prague Basin (Perunica, Czech Republic). Acta Palaeontologica Sinica, 46 Suppl., 320-327.

Mergl, M., Fatka, O. & Budil, P. 2008. Lower and Middle Ordovician trilobite associations of Perunica: from shoreface endemicicty to offshore uniformity (Prague Basin, Czech Republic). In Advances in Trilobite Research (Rabano, I., Gozalo, R. & Garcia-Bellido, D., eds), Publicationes del Instituto Geologico y Minero de Espana, Cuadernos delMuseo Geominero, 9, 275-282.

Mikulas, R. 1988. Assemblages of trace fossils in the "polyteichus facies" of the Bohdalec Formation (Upper Ordovician, Bohemia). Vestnik Ustredniho Ustavu Geologickeho, 63, 23-33.

Mikulas, R. 1991. Trace fossils from siliceous concretions in the Sarka and Dobrotiva Formations (Ordovician, central Bohemia). Casopis pro Mineralogii a Geologii, 36, 29-38.

Mikulas, R. 1998. Ordovician of the Barrandian area: reconstruction of the sedimentary basin, its benthic communities and ichnofacies. Journal of the Czech Geological Society, 43, 143-159.

Novak, O. in Perner, J. (ed.). 1918. Trilobiti D-[d.sub.1[gamma]] z okoli Prazskeho [Trilobites of D-[d.sub.1[gamma]] from the surroundings of Prague]. PalaeontologiaBohemiae, 9, 1-55 [in Czech].

Pek, I. & Vanek, J. 1989. Index of Bohemian Trilobites. Krajske vlastivedne museum Olomouc, 65 pp.

Polechova, M. 2013. Bivalves from the Middle Ordovician Sarka Formation (Prague Basin, Czech Republic. Bulletin of Geosciences, 88, 427-461.

Rohlich, P. 1957. Stratigraphy and facies of the Bohdalec Beds (Upper Caradoc of Central Bohemia). Sbornik Ustredniho Ustavu Geologickeho, 23, 373-479.

Rohlich, P. 2006. O takzvane polyteichove facii v bohdaleckem souvrstvi (ordovik, stredni Cechy) [On the so-called Polyteichus facies in the Bohdalec Formation (Ordovician, Central Bohemia)]. Geoscience Reserch Reports for 2005, 40-42.

Rouault, M. 1849. Memoire 1 sur la composition du test des Trilobites; 2 sur les changements de formes dus a des causes accidentelles, ce qui a pu permettre de confondre des especes differentes. Bulletin de la Societe Geologique de France, 6, 67-89.

Salter, J. W. 1865. A monograph of the British trilobites from the Cambrian, Silurian and Devonian formations. Monographs of the Palaeontographical Society, 81-128.

Servais, T., Dzik, J., Fatka, O., Heuse, T., Vecoli, M. & Verniers, J. 2008. Ordovician. In Geology of Central Europe (McCann, T., ed.), pp. 203-248. Geological Society, London.

Shirley, J. 1936. Some British trilobites of the family Calymenidae. Quarterly Journal of the Geological Society of London, 92, 384-422.

Siveter, D. J. 1977. The Middle Ordovician of the Oslo Region, Norway, 27. Trilobites of the family Calymenidae. Norsk Geologisk Tidsskrift, 56, 335-396 [for 1976].

Snajdr, M. 1956. The trilobites from the Drabov and Letna Beds of the Ordovician of Bohemia. Sbornik Ustredniho Ustavu Geologickeho, 22, 477-533.

Snajdr, M. 1985. Novi trilobiti z dobrotivskeho souvrstvi (ordovik, Cechy) [New trilobites from the Dobrotiva Formation (Ordovician, Bohemia)]. Casopis Narodniho Muzea, Rada Prirodovedna, 153, 146-149 [in Czech, with English abstract].

Snajdr, M. 1988. On the genus Colpocoryphe (Trilobita) from the Ordovician of Bohemia. Casopis pro Mineralogii a Geologii, 33, 11-20.

Snajdr, M. 1990. Bohemian Trilobites. Czech Geological Survey, 265 pp.

Snajdr, M. 1991. Zazivaci trakt trilobita Deanaspis goldfussi (Barrande) [On the digestive system of Deanaspis goldfussi (Barrande)]. Casopis Narodniho Muzea, Rada prirodovedna, 156, 8-16 [in Czech, with English abstract].

Steinova, M. 2012. Probable ancestral type of actinodont hinge in the Ordovician bivalve Pseudocyrtodonta Pfab, 1934. Bulletin of Geosciences, 87, 333-346.

Valicek, J. & Vanek, J. 2001. New index of the genera, subgenera, and species of Barrandian trilobites. Part A-B (Cambrian and Ordovician). Palaeontologia Bohemiae, 7, 1-49.

Vanek, J. 1965. New species of the suborder Calymenina Swinnerton, 1915 (Trilobita) from the Barrandian area. Sbornik Geologickych Ved, Paleontologie, 6, 21-37.

Vanek, J. 1995. New deeper water trilobites in the Ordovician of the Prague Basin Czech Republic. Palaeontologia Bohemiae, 5, 1-12.

Vanek, J. & Valicek, J. 2002. New index of the genera, subgenera, and species of Barrandian trilobites. Part C-D (Silurian and Devonian). Palaeontologia Bohemiae, 8, 1-74.

Vanek, J. & Vokac, V. 1997. Trilobites of the Bohdalec Formation (Upper Berounian, Ordovician, Prague Basin, Czech Republic). Palaeontologia Bohemiae, 3, 20-50.

Vavrdova, M. 1982. Phytoplankton communities of Cambrian and Ordovician age of Central Bohemia. Vestnik Ustrednlho Ustavu Geologickeho, 57, 145-155.

Vidal, M. 1998. Le modele des biofacies a Trilobites: un test dans I'Ordovicien inferieur de l'Anti-Atlas, Maroc [The trilobite biofacies model: a test in the Early Ordovician of the Anti-Atlas, Morocco]. C.R. Acad. Sci. Paris, Sciences de la Terre et des Planetes/Earth and Planetary Sciences, 327, 327-333.

Vodicka, J., Hroch, T. & Fatka, O. The first report of chitinozoans from the Letna Formation (Upper Ordovician, Prague Basin, Czech Republic) and their biostratigraphical significance. Geobios [in press].

Whittington, H. B. & Kelly, S. R. A. 1997. Morphological terms applied to trilobita. In Treatise on Invertebrate Paleontology, Part O Arthropoda 1 Trilobita, Revised, Vol. 1 (Moore, R. C. & Kaesler, R. L., eds), pp. O313-O329. Boulder, Colorado and Lawrence, Kansas.

Zhu, X. J., Lerosey-Aubril, R. & Esteve, J. 2014. Gut content fossilization and evidence for detritus feeding habits in an enrolled trilobite from the Cambrian of China. Lethaia, 47, 66-76.

Oldrich Fatka (a), Petr Budil (b) and Martin David (c)

(a) Charles University, Faculty of Sciences Institute of Geology and Palaeontology, Albertov 6, 128 43, Prague 2, Czech Republic; fatka@natur.cuni.cz

(b) Czech Geological Survey, Klarov 3, 118 21 Prague 1, Czech Republic; petr.budil@geology.cz

(c) Rozmberska 613/10, Praha 9-Kyje, 198 00, Czech Republic; ordovik@seznam.cz

Received 21 July 2015, accepted 18 September 2015

Table 1. Species of the genus Colpocoryphe Novak in Perner,
1918 in the Ordovician of the Prague Basin

Species                                  Formation   Number of
                                                     specimens

Colpocoryphe zarumila Snajdr, 1988       Klabava     <10
Colpocoryphe bohemica (Vanek, 1965)      Sarka       >500
Colpocoryphe inopinata (Novak in         Sarka       [+ or -]60
  Perner, 1918)
Colpocoryphe zmudai Vanek, 1995          Sarka       <10
Colpocorypheprima (Barrande, 1872)       Dobrotiva   [+ or -]50
  [= C. adisol Snajdr, 1985]
Colpocoryphe grandis grandis (Snajdr,    Liben       [+ or -]150
  1956)
Colpocoryphe grandis arecuna Snajdr,     Letna       [+ or -]60
  1988

Table 2. Species of the genus Flexicalymene Shirley, 1936
in the Ordovician of the Prague Basin

Species                         Formation     Number of
                                              specimens

Flexicalymene (F.) incerta      Zahorany      >300
  (Barrande, 1846)
Flexicalymene (F.) pragensis    Bohdalec      [+ or -] 100
  Vanek & Vokac, 1997
Flexicalymene (F.) declinata    Kraluv Dvur   >250
  (Hawle & Corda, 1847)

Table 3. Results of the energy dispersive X-ray (EDX)
analyses performed on the gut and the surrounding
sediment. The composition is expressed in weight
percentage (wt%). Some elements were not detectable
and/or the estimated proportions was below the
equipment's lower limit of reliability (referred as n)

Sample       C       O      Na    Mg    Al     Si

Matrix 1   7.26    53.91    n     n    4.42   29.02
Matrix 2   12.26   49.00    n     n    4.1    17.1
Gut 1      31.54   43.69   0.37   n    1.47   13.1
Gut 2      25.72   49.22    n     10   1.02   18.14

Sample      P      S      K      Fe

Matrix 1   9.54   6.86   1.04   3.26
Matrix 2   0.55   0.73   0.96   14.23
Gut 1       n      n     0.35    8.1
Gut 2       n      n      n     4.41

Fig. 1. Location of discovery sites, and the Ordovician
stratigraphy in the Barrandian area. A, map of the Czech Republic
and the Bohemian Massif showing the distribution of Ordovician
rocks in the Barrandian area. B, Ordovician of the Prague Basin
with the location of three outcrops that yielded the studied
specimens: 1, field near Myto; 2, fields north of Rokycany; 3,
Brumlovka locality. C, chart showing the correlation between global
series, stages, stage slices, time slices (TS), time units (TU) and
the regional chronostratigraphic and lithostratigraphic units
recognized in the Ordovician of the Prague Basin, and ranges of
species of Colpocoryphe and Flexicalymene (stratigraphy modified
from Bergstrom et al. 2008, Fatka et al. 2013 and Vodicka et al.
in press).

GLOBAL

SYSTEM       SERIES     STAGES      STAGE   TS   TU
                                    SLICE

ORDOVICIAN   UPPER    HIRNANTIAN     Hi2    6c   21

                                     Hi1

                        KATIAN       Ka4    6b   20

                                            6a   19

                                     Ka3    5d   18

                                     Ka2         17

                                     Ka1    5c   16

                       SANDBIAN      Sa2    5b   15

                                     Sa1    5a   14

             MIDDLE   DARRIWILIAN    Dw3    4c   13

                                     Dw2    4b   12

                                     Dw1    4a   11

                                                 10

                       DAPINGIAN     Dp3    3b   9

                                     Dp2

             LOWER      FLOIAN       Dp1    3a   8

                                     Fl3    2c   7

                                     Fl2    2b   6

                                     Fl1    2a   5

                      TREMADOCIAN    Tr3    1d   4

                                            1c

                                     Tr2    1b   3

                                     Tr1    1a   2

                                                 1

GLOBAL                REGIONAL

SYSTEM       SERIES      STAGES      FORMATIONS

ORDOVICIAN   UPPER      KOSOVIAN        KOSOV


                      KRALODVORIAN   KRALUV DVUR

                       BEROUNIAN     BOHDALEC 3
                                      ZAHORANY
                                       VINICE
                                        LETNA
                                        LIBEN

             MIDDLE   DOBROTIVIAN     DOBROTIVA

                       ORETANIAN       SARKA 2
                                          1
             LOWER     ARENIGIAN       KLABAVA

                      TREMADOCIAN      MILINA

                                       TRENICE

GLOBAL                SPECIES

SYSTEM       SERIES   Colpocoryphe zarumila
                      Colpocoryphe bihemica
ORDOVICIAN   UPPER    Colpocoryphe inopinata
                      Colpocoryphe zmudai
             MIDDLE   Colpocoryphe prima
                      Colpocoryphe gradis grandis
             LOWER    Colpocoryphe gradis arecuna
                      Flexicalymene (F.) incerta
                      Flexicalymene (F.) pragensis
                      Flexicalymene (F.) declinata
COPYRIGHT 2015 Estonian Academy Publishers
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2015 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Fatka, Oldrich; Budil, Petr; David, Martin
Publication:Estonian Journal of Earth Sciences
Article Type:Report
Geographic Code:4EXCZ
Date:Dec 1, 2015
Words:6646
Previous Article:Sparsely encrusted hardground in the Darriwilian calcareous sandstone of Cape Pakri, NW Estonia (Baltica)/Horedalt asustatud muistne tsementeerunud...
Next Article:A bio-chemostratigraphical test of the synchroneity of biozones in the upper Silurian of Estonia and Latvia with some implications for practical...
Topics:

Terms of use | Privacy policy | Copyright © 2020 Farlex, Inc. | Feedback | For webmasters