An explanation for low endemism of Triassic crinoids fromthe epicontinental Germanic Basin, Poland

Geological Quarterly, 2005, 49 (3): 331–338 An explanation for low endemism of Triassic crinoids from the epicontinental Germanic Basin, Poland Mariusz A. SALAMON and Robert NIED
WIEDZKI M. A. Salamon and R. NiedŸwiedzki (2005) — An explanation for low endemism of Triassic crinoids from the epicontinental Germanic Basin, Poland. Geol. Quart., 49 (3): 331–338. Warszawa. A summary of known crinoid taxa in the Polish part of the Triassic Germanic Basin, including their presence elsewhere, is documented. At present, 13 taxa and 3 ecophenotypes of crinoids have been recorded from that area, only one of them being endemic. In the Lower Muschelkalk and lower part of the Middle Muschelkalk, taxa widespread both in the Tethys and Germanic Basin, or Tethyan taxa, dominate. In the Upper Muschelkalk crinoids are very rare in Poland, being represented by Encrinus liliiformis and Holocrinus sp. Many of the species occurring in the central part of the Germanic Basin in the Upper Muschelkalk have not been recorded in the eastern part of the basin. The degree of endemism of the crinoid fauna in the Muschelkalk is markedly lower than the degree of endemism of the rest of the benthonic macrofauna. This probably resulted from huge number of crinoids forming “crinoid gardens” that produced large number of larvae, increasing the chances of successful geographical expansion of crinoids. Mariusz A. Salamon, University of Silesia, Department of Palaeontology and Biostratigraphy, Bêdziñska 60, PL-41-200 Sosnowiec, Poland, e-mail: ; Robert NiedŸwiedzki, Wroc³aw University, Institute of Geological Sciences, Cybulskiego 30, PL-50-204 Wroc³aw, Poland, e-mail: (received: March 9, 2004; accepted: April 18, 2005). Key words: Germanic Basin, Poland, Triassic, Muschelkalk, crinoids, biogeography. INTRODUCTION Almost 160 years of research on the occurrence of Triassic crinoids in the Polish eastern part of the Germanic Basin has revealed 13 taxa and 3 ecophenotypes (Table 1, Fig. 1). Almost all the species are known from Upper Silesia (except for Holocrinus sp.), where the crinoid research has long been undertaken and from where the richest material comes from, including almost all of the complete specimens collected so far. 9 taxa, represented by isolated skeletal elements, occur in the Holy Cross Mountains (Salamon, 2003), and 5 taxa in the North-Sudetic Basin (G³uchowski and Salamon, 2005; Table 1). However, in the latter area the upper part of the Lower Muschelkalk, as well as the Middle and Upper Muschelkalk is not exposed. Some undetermined crinoidal fragments were recorded in boreholes in the Fore-Sudetic Monocline and Podlasie area (Senkowiczowa and Kotañski, 1979). Crinoids in the Tatra Mountains are rare. 120 calyces and crowns assigned to Dadocrinus grundeyi have been found in a single thin layer in the Middle Triassic deposits of the Zawrat Kasprowy (Lefeld, 1958). Apart of this, in many sites of the Tatra Mountains, there are crinoid limestones or dolomites which, how- ever, contain only isolated, mostly undeterminable skeletal fragments. This article analyses the degree of endemism of crinoidal assemblages from Southern Poland in comparison with the endemism of other benthonic macrofauna. THE DEGREE OF ENDEMISM OF THE MUSCHELKALK CRINOID FAUNA Published work suggests a considerable proportion of endemic taxa (as endemic fauna we state species known only from Upper Silesia, the Holy Cross Mountains and the North-Sudetic Basin) among the crinoid fauna of the Polish Muschelkalk (Table 1; see also Fig. 1). According to Assmann (1937), 5 out of 10 taxa mentioned by him from Upper Silesia area were endemic. Later investigations, however, showed that 3 of them (Holocrinus dubius, Silesiacrinus silesiacus and Encrinus spinosus) occur in the Tethys, one species (Encrinus robustus) is known from the entire Germanic Basin and the last one (Dadocrinus kunischi) probably is an ecophenotype (cf. G³uchowski, 1986; Hagdorn and G³uchowski, 1993; Hagdorn et al., 1997). Therefore, at present, none of the 5 endemic spe- 332 Mariusz A. Salamon and Robert NiedŸwiedzki Table 1 isolated columnals only (Hagdorn and G³uchowski, 1993). Therefore, the lack of any data about this taxon from the Tethys may result from insufficient recognition of Tethyan material. ReCrinoid species Palaeogeographic distriPalaeogeographic distribuOther locations of bution of Silesian crition of Silesian crinoids described crinoids cently, Salamon (2005) has denoids (Assmann, 1937) (modern data) in Poland scribed a crinoid of uncertain palaeogeographic status (HoloDadocrinus Tethyan both in the Tethys and the Holy Cross Mts?; gracilis Germanic Basin Lower Silesia? crinus sp., known only from the Holy Cross Mountains; Table 1, Dadocrinus endemic Ecophenotypes (for distribu– kunischi tion see D. gracilis) Fig. 1), probably an immigrant from the Tethys. Additionally, the Dadocrinus unknown from Silesia Ecophenotypes (for distribu– grundeyi tion see D. gracilis) species Dadocrinus grundeyi and Dadocrinus unknown from Silesia Ecophenotypes ?(for distri– Dadocrinus sp. nov. described by sp. nov. bution see D. gracilis) G³uchowski (1986) and Hagdorn Holocrinus unknown from Silesia both in the Tethys and the Holy Cross Mts.; and G³uchowski (1993) from Upacutangulus Germanic Basin Lower Silesia per Silesia, are now considered as Holocrinus endemic both in the Tethys and the Holy Cross Mts.; ecophenotypes (e.g. Hagdorn, dubius Germanic Basin Lower Silesia 1996). This was also shown by Holocrinus unknown from Silesia endemic Holy Cross Mts. morphological analysis of calyces meyeri of D. gracilis, D. kunischi and D. Holocrinus sp. no data ? Holy Cross Mts. grundeyi (Salamon and NiedŸwiedzki, 2004). It is worth noting Encrinus unknown from Silesia Tethyan Holy Cross Mts.; radiatus Lower Silesia that all crinoid taxa known from Silesiacrinus endemic Tethyan Holy Cross Mts. the North-Sudetic Basin and the silesiacus Holy Cross Mountains are Encrinus Tethyan Tethyan – Tethyan or occur both in the aculeatus Tethys and the Germanic Basin Encrinus endemic Tethyan – (with the exception of H. meyeri). spinosus 13 species from the Polish Encrinus endemic ? Germanic – part of the Germanic Basin are robustus known, one of them considered Carnallicrinus Germanic both in the Tethys and the Holy Cross Mts. to be endemic (see also carnalli Germanic Basin Figs. 2–5). To compare the deEncrinus unknown from Silesia both in the Tethys and the Holy Cross Mts. gree of endemism of crinoids liliiformis Germanic Basin with the general macroE. brahli Tethyan both in the Tethys and the – invertebrate endemism of the Germanic Basin Muschelkalk of Upper Silesia, „Encrinus” Tethyan no data – we have analysed published data cf. granulosus from Upper Silesia (Assmann, 1937, 1944; Hagdorn and G³uchowski, 1993). The benthic macrofauna of the North-Sudetic cies sensu Assmann (1937) can be considered as endemic. Basin and especially of the Holy Cross Mountains remains More (...truncated)