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Taphonomy, distribution and palaeoecology of stalked barnacles (Crustacea, Cirripedia) from the Bohemian Cretaceous Basin, Czech Republic

Kocova-Veselska M., Koci T.

Geology, Geophysics and Environment

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2015

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Vol. 41, no. 1

97--98

EN

The Cirripedia are marine crustaceans that as adults are usually sessile, attached to hard substrata or to other organisms by their first pair of antennas. The carapace completely envelops the body, and in most forms it secretes a calcareous shell, with an opening where they stretch out for food. Today cirripedes remain a highly successful group of crustaceans, both in number of species and abundance (Newman & Abbott 1980). The preferred habitats of modern Cirripedia are widely diverse, ranging from the uppermost littoral to abyssal depths. Being principally filter feeders in the intertidal food chain, they modify the habitat structure and affect the abundance and population structure of other intertidal organisms, and are vital to the ecological balance of the near-shore marine system (Chan 2007). However, most Late Mesozoic cirripede genera are extinct which means that, apart from associated faunal elements, there is little except overall capitular morphology that can be used to identify palaeoenvironmental conditions (Buckeridge 1983). Stalked barnacles most often occur in the fossil record as dissociated plates of capitulum and peduncle, because soon after death plates tend to disarticulate and become scattered, similar to modern lepadids and scalpellids (Hauschke et al. 2011). Whilst certain species of balanids are readily distinguishable from each other in the fossil record, others may easily be confused, especially when preserved as isolated plates. Species-level determination of fossil remains may commonly be achieved by the recognition of either some, or a combination of a few major features of single plates: conical or cylindrical plate, smooth or ribbed surface, shape of growth lines of inner and upper surface, position of apex, etc. (Collins et al. 2014). The barnacles form a predominant part of the arthropod assemblage throughoutthe Bohemian Cretaceous Basin (BCB) and are a common component of the mesofaunal fossil remains of the Upper Cretaceous pelagic and mainly nearshore-shallow marine deposits in the BCB. Barnacles from shallow water deposits possess relatively heavily calcified capitular plates (in comparison to pelagic forms) as an adaptation to high-energy environment. However, they could inhabit also microenvironments behind larger boulders, where the water current is not so turbulent. Although most of these cirripede shells involved rapidly break down into separate plates or valves after death, species of the Cretaceous genus Stramentum Logan provides some notable exceptions. Under certain conditions, individual plates of heavily calcified stramentids have remained articulated during fossilization and their occurrence appears to be restricted to three exceptional 2015, vol. 41 (1): 97–9898circumstances: when their cypris larvae attached directly to a substrate (e. g. ammonite shells); when cirripedes were embedded in black shales; or when cirripedes were rapidly buried. All Czech stramentids are known only as epizoans of the body chamber of smooth planispiral ammonites with widely spaced, shallow ribs, such as Collignoniceras Breistroffer and Lewesiceras Spath (Kočová Veselská et al. 2013). In addition, one articulated capitulum of Arcoscalpellum angustatum (Geinitz) is documented from the BCB; only a few reports of complete Arcoscalpellum are known from the Cretaceous deposits. The predation on cirripedes is also known from the BCB. The penetrative holes and non-pentrative pits of ichnogenus Sedilichnus Müller, caused by carnivorous naticid and muricid gastropods, are present on two capitular plates of Cretiscalpellum glabrum (Roemer). Microborings, which are more abundant on capitular cirripede plates from the BCB, are developed as small connected channels and could be caused by algae, hydroids, fungi or even clionid sponges. Similar data of predation on cirripede valves are poorly known, e. g. from the Campanian locality Ivö Klack in southern Sweden (Gale & Sørensen 2015).

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Dynomenid crabs (Decapoda, Brachyura) from Upper Cenomanian-Lower Turonian nearshore, shallow-water strata in the Bohemian Cretaceous Basin, Czech Republic

Kocova-Veselska M., Koci T.

Geology, Geophysics and Environment

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2014

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Vol. 40, no. 1

89--90

EN

Conditions of preservation of small crabs at nearshore deposits in the Bohemian Cretaceous Basin (BCB) were poor and fossil record is mostly restricted to fragmentary pereiopods, i.e. isolated propodi or dactyli, whereas crab carapaces in the area are rather rare. Excluding three specimens of dynomenid Graptocarcinus texanus Roemer, 1887 and one necrocarcinid carapace fragment, no other carapaces are known from the nearshore deposits of the BCB. These partially crushed carapaces lacking chelipeds or other appendages come from the lower Turonian calcareous siltstones at Kamajka. By contrast, crab claws and isolated dactyli are more common in the BCB, but notoriously difficult to identify (Jagt et al. 2010, Veselska 2011). In view of the confused taxonomy of isolated claws, its identity has not been recognised and claws were described as fragments of the necrocarcinid species Necrocarcinus avicularis Fritsch (in Fritsch & Kafka 1887). However morphology of crab chelipeds originally described as N. avicularis is in fact typical of graptocarcinines (dynomenids); claws are covered with small tubercles and are rectangular in outline with a distinctive bulge on propodus/carpus articulation. The bulge closed the space between propodus and carpus when bent and probably protected the claws when crabs moved between coral colonies or during feeding, similar to extant dynomenids (Jagt et al. 2010, Van Bakel et al. 2012, Kocova Veselska et al., submitted). Jagt et al. (2010) prefer to use parataxonomy for such cases and suggest using "form genus" Roemerus Bishop, 1983 for isolated dynomenid chelae. Between 2001 and 2013, the authors conducted field works in the upper Cenomanian-lower Turonian nearshore, shallow-water bioclastic limestones to marly siltstones at Velim, Chrtniky and Kamajka situated approximately 60-100 km east of Prague along the southern and eastern margins of the BCB, which are interpreted to have been laid down under high-energy conditions (Zitt et al. 1997a, b). During these sessions, 200 kg of rubble were amassed and screened through a 1 mm-sieve with a result of an additional isolated dactyli and cheliped fragments. Whereas strata containing brachyuran crabs at Kamajka are exclusively of early Turonian age, crustaceans from Chrtniky and Velim are from upper Cenomanian and early Turonian nearshore sediments alike. A recent re-examination of these new finds together with crab chelipeds originally described as N. avicularis deposited in the National Museum (Prague) has revealed that all alleged necrocarcinid claws or dactyli from nearshore strata in the BCB indeed correspond to the diagnosis of the dynomenid "form genus" Roemerus, in size, ornament, development of the fixed and movable fingers and presence of ovate depressions in dactylus and fixed finger (Veselska 2011, Kocova Veselska et al., submitted). Although still not found connected with carapaces, these claws may be conspecific with the co-occurring, carapace-based species, G. texanus, at Kamajka.

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Revision of cirripeds type specimens described by Kafka (1885) and Fritsch & Kafka (1887), exluding stramentidae, deposited in the National Museum in Prague

Koci T., Kocova-Veselska M., Kubajko M.

Geology, Geophysics and Environment

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2012

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Vol. 38, no. 4

482--83

EN

Despite almost two centuries of palaeontological research on the Bohemian Cretaceous Basin (BCB) knowledge of cirripedes from the near-shore, shallow and pelagic facies remains poor. The first studies dealing with cirripedes from the BCB were published by Reuss (1844, 1845-1846), followed by Kafka (1885), Fritsch & Kafka (1887) and Fric (1911). Cirripedes from the BCB were revised by Withers (1935), with mention of collections of A. Fric, J. Perner and J. Sulc. Withers also listed 11 species of cirripeds (including two stramentids) from the BCB: Zeugmatolepas cretae (Steenstrup 1837); Calantica (Scillaelepas) conica (Reuss 1845); C. (Titanolepas) tuberculata (Darwin 1851); Cretiscalpellum glabrum (Roemer 1841); C. striatum (Darwin 1851); Scalpellum (Arcoscalpellum) angustatum (Geinitz 1843); S. (Arcoscalpelluni) maximum (J. De C. Sowerby 1829); Loriculina laevissima (von Zittel 1885); Stramentum pulchellum (G. B. Sowerby 1843); Proverruca vinculum Withers, 1914; Brachylepas fallax (Darwin 1851). Withers (1935: 162) suggested that Pollicipes striatus belongs to Cretiscalpellum glabrum. But the reexamination of the material revealed that the systematic position of P. striatus is different and actually belongs to Cretiscalpellum striatum, because its carina (Fritsch & Kafka 1887: 9, fig. 16) bears both longitudinal and transversal lines in contrast to carina of C. glabrum with only fine transversal lines. Most of these specimens are deposited in the National Museum in Prague, from which we examined and verified these original types: carina of Scalpellum maximum Sowerby var. bohemica Kafka from Kuneticka Hora (in Fritsch & Kafka 1887: 6, fig. 7A), now belongs to Arcoscalpellum maximum (J. De C. Sowerby); tergum of Pollicipes kosticensis Kafka from Kostice (in Kafka 1885, tab. II, fig. 4), now belongs to Cretiscalpellum striatum (Darwin); carina, scutum, tergum, rostrum, laterae of Pollicipes fallax Darwin from Lhota Uhfeticka (in Fritsch & Kafka 1887: 10. fig. 17 c, t, t, r) and rostrum of P. fallax Darwin from Chocen (in Kafka 1885, tab. III., fig. 2r), now belong to Brachylepas fallax (Darwin). Both scutum and tergum of Z. cretae were donated to the Natural History Museum in London (inv. no. 31673-4). Unfortunately, predominantly part of the original specimens from the NM collection, carinal plates (4 scuta and 4 terga) of Z. cretae and all specimens of Proverucca vinculum, which were important part of Sulc's fossil collection were lost at the end of The Second World War during bombing of historical building of the National Museum in Prague (Sklenaf, pers. com., 2012).

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Occurence and revision of genera Oncopareia Bosquet, 1854 (Decapoda: Aastacidea: Thaumastochelidae) and Ctenocheles Kishinouye, 1926 (Decapoda: Axiidea: Ctenochelidae) from the Bohemian Cretaceous Basin

Kocova-Veselska M., Hyzny M.

Geology, Geophysics and Environment

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2012

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Vol. 38, no. 4

484--485

EN

Ctenocheles Kishinouye, 1926 is a heterochelous ghost shrimp typically with pectinate major claw with long lingers and acicular teeth. Isolated chelipeds are the most common remains in the fossil record of these decapod crustaceans, with several fossil species of the genus described only on the basis of isolated eheliped fragments (Schweitzer & Feldmann 2001). This type of chelipeds evolved homoplastically in different lineages of decapod crustaceans (Tshudy & Sorhannus 2000) and can be easily misidentified as remains of other decapod crustacean taxa as shown in the case from the Bohemian Cretaceous Basin (BCB). Very similar major claw is also known in an astacidean genus Oncopareia Bosquet, 1854, which has been considered as relatively well represented genus in the BCB (Mertin 1941), whereas Ctenocheles has not been identified in the respective area until now. Part of the material attributed to the latter taxon was at the disposal since the 19 century, but because of confused taxonomy of isolated pectinate claws (Feldmann et al. 1990; Tshudy & Sorhannus 2000) its identity has not been recognized and these claws were mistakenly classified as remains of genus Stenocheles Fritsch in Fritsch & Kafka (1887). Later, Mertin (1941) and Glaessner (1969) questionably synonymised Stenocheles with Oncopareia. Reexamination of the Cretaceous decapods deposited in the National Museum in Prague revealed that all supposed specimens of the lobster genus Oncopareia Bosquet, 1854 originating from the Middle Coniacian calcareous elaystones of the Brezno Formation in the BCB actually belong to Ctenocheles. This material together with newly collected specimens from the same locality represents one of the oldest records for this genus and simultaneously the best preserved fossil material of Ctenocheles reported up to date (see also Hyzny et al. in press).