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

• Autorzy: Kocova-Veselska M. , Koci T.
• Konferencja: XVth International Conference of Young Geologists Her'lany 2014 : Międzybrodzie Żywieckie, Poland, May, 8th-10th 2014
• Języki publikacji: EN

Abstrakty

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.

Słowa kluczowe

EN

deposit; BCB; Kamajka

• Wydawca: Wydawnictwa AGH
• Czasopismo: Geology, Geophysics and Environment
• Rocznik: 2014
• Tom: Vol. 40, no. 1
• Strony: 89--90
• Opis fizyczny: Bibliogr. 7 poz.

Twórcy

autor

Kocova-Veselska M.

• Charles University, Faculty of Science, Institute of Geology and Palaeontology; Albertov 6, 128 43 Prague 2, Czech Republic

autor

Koci T.

• National Museum, Department of Palaeontology; Vaclavske nam. 68, 115 79 Prague 1, Czech Republic

Bibliografia

• 1. Fritsch A. & Kafka J., 1887. Die Crustaceen der bohmischen Kreideformation. Selbstverlag, in Commission von F. Rivnac, Prag.
• 2. Jagt J.W.M., Fraaije R.H.B., Van Bakel B.W.M. & Artal P., 2010. Necrocarcinus ornatissimus Forir, 1887, and Prehepatus werneri Fraaye & Collins, 1987 (Upper Maastrichtian, The Netherlands) revisited, with notes on other Cretaceous dynomenid crabs (Decapoda, Brachyura). [in:] Castro P., Davie P.J.F., Ng P.K.L. & Richer de Forges B. (eds), Studies on Brachyura, a homage to Daniele Guinot, Crustaceana Monographs, 11, 173-195.
• 3. Kocova Veselska M., Koci T. & Kubajko M., submitted. Dynomenid crabs (Decapoda, Brachyura) and stalked barnacles (Cirripedia, Scalpellomorpha) from upper Cenomanian-lower Turonian nearshore, shallow-water strata in the Bohemian Cretaceous Basin, Czech Republic, [in:] Fraaije R.H.B., Hyzny M., Jagt J.W.M., Krobicki M. & Van Bakel B.W.M. (eds), A homage to Pal Midler, an eminent Hungarian palaeocarcinologist, Scripta Geologica, Special Issue, 9.
• 4. Van Bakel B.W.M., Guinot D., Corral J.C. & Artal P., 2012. Graptocarcininae n. subfam., an extinct subfamily of Dynomenidae Ortmann, 1892 (Crustacea, Brachyura, Podotremata). Zootaxa, 3543, 40-52.
• 5. Veselska M., 2011. Preliminary revision of the Cenomanian and Turonian decapods - genera Necrocarcinus Bell, 1863 and Graptocarcinus Roemer, 1887 (order Decapoda Latreille, 1802, infraorder Brachyura Latreille, 1802) from the Bohemian Cretaceous Basin. Zpravy o geologickych vyzkumech v roce 2010, 128-131 [in Czech with English abstract].
• 6. Zitt J., Nekvasilova O., Bosak P., Svobodova M., Stemprokova-Jirova D. & Stastny M., 1997a. Rocky coast facies of the Cenomanian-Turonian boundary interval at Velim (Bohemian Cretaceous Basin, Czech Republic). First part. Vestnik Ceskeho Geologickeho Ustavu, 72, 83-102.
• 7. Zitt J., Nekvasilova O., Bosak P., Svobodova M., Stemprokova-Jirova D. & Stastny M., 1997b. Rocky coast facies of the Cenomanian-Turonian boundary interval at Velim (Bohemian Cretaceous Basin, Czech Republic). Second part. Vestnik Ceskeho Geologickeho Ustavu, 72, 141-155.