Unusual brachiopod fauna from the Middle Triassic algal meadows of Mt. Svilaja (Outer Dinarides, Croatia)

Abstract

Ladinian deposits at Mt. Svilaja in Dalmatia (Outer Dinarides, Croatia) yielded an abundant brachiopod fauna of low diversity interpreted as a parautochthonous assemblage representing an ecosystem of dasycladacean submarine meadow. The fauna consists of four named species and one left in open nomenclature. The most common is the spiriferinideFlabellocyrtia flabellulumChorowicz and Termier, 1975 (Spiriferinida) accounting for more than 70% of the material. The athyridideCassianospira humboldtii(von Klipstein, 1845) is the only species known from elsewhere (Anisian of Southern Alps). The new species of SpiriferinidaThecocyrtella dagysiiHalamski, Bitner, Kaim, Kolar-Jurkovšek, and Jurkovšek n. sp. differs from other representatives of the genus in having a deep ventral sulcus.Albasphe albertimagniHalamski, Bitner, Kaim, Kolar-Jurkovšek, and Jurkovšek n. gen. n. sp. is a new brachiopod that possesses a dorsal septum with an intra-septal cavity and dorsal submarginal ridges, both features in common with AalenianZellaniaMoore, 1855 from which it differs in lack of the ventral septum and of ventral submarginal ridges. They are interpreted as members of a sparsely recorded paedomorphic evolutionary line of terebratulides with secondarily lost loop, described formally herein as Gwyniidina Halamski and Bitner n. subordo and subdivided into newly emended Dispheniidae Grant, 1988 (Dispheniinae Grant, 1988 with the only genusDispheniaand Albasphinae Halamski and Bitner n. subfam. withAlbaspheandZellania) and Gwyniidae MacKinnon, 2006 (including RecentGwyniaandSimpliciforma). In contrast to previous interpretations, the trocholophe lophophore ofGwyniais interpreted herein as secondarily simplified.

Otapirian (Rhaetian) Terebratulida (Brachiopoda) of Zealandia

“…monstrifera is recorded from Alaska (Blodgett andClautice 2000, Sandy 2001), but Sandy (2001) comments that "serial sections indicate internal differences between this form and typical Lobothyris and it is thought to represent a new genus" (p. 397). Subfamily ZEILLERIINAE Schuchert, 1929 Following Manceñido (1993), Baeza-Carratala andGarcia Joral (2014) and Halamski (2015), the authorship of the Zeillerioidea, Zeilleriidae and Zeilleriinae is accepted as being Schuchert in Schuchert and leVene (1929), rather than Allan (1940).…”

The Anisian (Middle Triassic) brachiopod fauna from Qingyan, Guizhou, south-western China

“…This genus has been reported from the Upper Triassic in the Southern Alps, Carpathians, and Hungary (Alvarez & Rong 2002). Recently, Halamski et al (2015) described a species from the Ladinian of Croatia. The Qingyan species Cassianospira wachangpoensis (Stiller, 1999) is, to date, the known oldest species of the genus.…”

“…Of these, genera: Angustothyris, Schwagerispira, Spirigerellina, Coenothyris, Nudirostralina, Costirhynchopsis, Koeveskallina, Lepismatina, Dagyssia, Thecocyrtella, and Mentzelia have been widely reported from the eastern and western Tethyan regions, with some elements even occurring in the Himalayan region, suggesting the development of near-global distributions. Moreover, Cassianospira is confined to Qingyan during the Anisian, but this taxon spread rapidly to Croatia, Alps, Hungary, and Carpathians in the western Tethys region during the Ladinian and late Triassic (Alvarez & Rong 2002;Halamski et al 2015).…”

Virtual palaeontology: the effects of mineral composition and texture of fossil shell and hosting rock on the quality of X-ray microtomography (XMT) outcomes using Palaeozoic brachiopods

“…Among the several tomographic techniques currently available, X-ray based methods have increasingly been piloted to fossil and modern brachiopods using both XMT (e.g., Hagadorn et al, 2001;Pakhnevich, 2007Pakhnevich, , 2009Pakhnevich, , 2010Pakhnevich, , 2011Pakhnevich, , 2014Pakhnevich, , 2017Angiolini et al, 2010;Błażejowski et al, 2011;Gaspard, 2013;Seidel and Lüter, 2014;Halamski et al, 2015;Streng et al, 2016) and SRXTM (e.g., Perez-Huerta et al, 2009;Motchurova-Dekova and Harper, 2010;Kaloyan et al, 2014), with varying degrees of success in terms of image resolution and authenticity. One of the key challenges for the use of XMT and SRXTM for palaeontology is the choice of the fossil samples to be scanned, as the resolution of resultant scanned images critically depends on the degree of contrast in the mineralogy between the fossils and the materials that surround them or infill their inner cavities: generally, the greater the disparity in mineralogy between the fossils and the neighboring materials, the higher the resolution and authenticity of the reconstructed fossil internal structures.…”