Vol 58, No 2 (2024)
Vol 58, No 2 (2024)
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- Category: Vol 58, No 2 (2024)
Authors: Michael Krings
Full version (46,703 kB)Abstract: Fungal spores from the Lower Devonian Rhynie chert are frequently colonized by other fungi; however, only a few of these colonizers have been described. Rhizophydites bicornis nov. sp., which occurs on certain thin-walled fungal spores, is monocentric and characterized by inoperculate zoosporangia that are broadly citriform or spindle-shaped, ovoid, inversely triangular, or irregular, up to 25 μm high and 40 μm wide, and usually lie with their long axis perpendicular to the point of insertion on the host. They typically have two lateral opposite discharge papillae. In some cases, secondary zoosporangia have developed from the walls of old sporangia. Similarities between R. bicornis and the extant Rhizophydium goniosporum and R. transversum (Rhizophydiales) are used to suggest affinities of the fossil to the Chytridiomycota.
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- Category: Vol 58, No 2 (2024)
Authors: Lukáš Laibl & Václav Micka
Abstract: Barrande’s larva is an early developmental trilobite stage (protaspis) characterized by an effaced, gently vaulted circular exoskeleton about 1 mm in diameter. This early stage was described in 1943 by Robert Růžička. The reinvestigation of all known specimens provides new insights into morphology, ecology, and systematic assignment of this peculiar trilobite stage. The absence of palpebral lobes and eye ridges in Barrande’s larva suggests this protaspid stage belongs to a blind trilobite species. Moreover, the meraspides of a blind conocoryphid trilobite Conocoryphe, which comes from the same strata, fit well the estimated size of the meraspid specimens of Barrande’s larva. It is therefore assumed, that Barrande’s larva is a protaspid stage of Conocoryphe. The large size of Barrande’s larva, its slightly inflated exoskeleton with wide glabella, and low abundance at the type locality indicate lecithotrophic development.
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- Category: Vol 58, No 2 (2024)
Authors: Michal Mergl
Abstract: Three types of microborings are described on corallites of auloporid corals from the Acanthopyge Limestone, Choteč Formation, Middle Devonian (Eifelian) of Central Bohemia. Straight unbranched galleries and swellings of Irhopalia isp. are interpreted as being produced by a phototroph, likely a chlorophyte. Two other rare ichnospecies likely represent sponge borings (Entobia? isp., Dendrina? isp.). The microborings are preserved by the hydrated iron oxide mineral casts after pyrite fillings. The perfect three-dimensional preservation of the microborings represents an alternative for the resin casting method, which cannot be used in solid limestone, where the microborings are filled by precipitated calcium carbonate.
