Silicified Middle Cambrian trilobites from Kyrgyzstan

Abstract:  A medium diversity silicified Middle Cambrian faunal assemblage occurs in an olistolith of bioclastic limestone within Silurian siliciclastic turbidites on the slopes of Arpatektyr Mountain in the eastern Alai Range, Kyrgyzstan. The fauna includes the trilobites Raragnostus cf. mirus , Altikolia kurshabica sp. nov., Corynexochina weberi , Dorypyge richthofeniformis , aff. Jincella sp., Olenoides comptus , Skreiaspis aff. spinosus and Suluktella mambetovi sp. nov. Three of these taxa ( C .  weberi , O .  comptus and R . cf.  mirus ) are considered locally to be characteristic of the Pseudanomocarina Beds, although Pseudanomocarina itself is not present. Altikolia and Suluktella are endemic to early Palaeozoic terranes of Central Asia, Corynexochina also occurs in South China and Skreiaspis is known elsewhere exclusively from the Middle Cambrian of 'West' Gondwana. Because of preservation in full relief, the silicified trilobite fauna allows a detailed understanding of some morphological structures, related especially to trilobite enrolment, otherwise inadequately known for many Mid-Cambrian polymerid trilobites.     

First report of craniide brachiopods in the Palaeozoic of Iran (Pseudocrania,Ordovician), and Early to Mid‐Ordovician biogeography of the Craniida

Abstract: Lower Ordovician faunas of Bohemia (Perunica), Baltica and North China include the oldest known representatives of the Order Craniida, but otherwise in Gondwana and associated terranes, the record of craniides is sparse. Pseudocrania insperata sp. nov. from the Lashkarak Formation of the Eastern Alborz Mountains is the first and as yet only record of the occurrence of craniides in the Middle Ordovician (Darriwilian) of Iran and temperate to high latitude peri‐Gondwana. Pseudocrania was known hitherto only from the Middle Ordovician of Baltoscandia and the Chu‐Ili terrane of Kazakhstan.     

BILLENGSELLIDE AND ORTHIDE BRACHIOPODS: NEW INSIGHTS INTO EARLIEST ORDOVICIAN EVOLUTION AND BIOGEOGRAPHY FROM NORTHERN IRAN

Abstract:  The eastern Alborz Mountains of Iran comprise a significant peri-Gondwanan terrane relevant to the early evolution of late Cambrian – early Ordovician brachiopods incorporated into the emerging benthic biota of the Paleozoic Evolutionary Fauna. A low diversity brachiopod assemblage from the late Tremadocian unit of the Lashkarak Formation contains six new species including the polytoechioideans Polytoechia and Protambonites and the orthoideans Paralenorthis, Ranorthis, Tarfaya and Xianorthis . The fauna preserves the earliest records of Polytoechia , unknown previously outside Laurentia and the Uralian margin of Baltica, and of Paralenorthis and Ranorthis , which were widespread along Gondwanan margins and in Baltica from the Floian (Arenig), plus Xianorthis , known hitherto only from the Floian of South China. The enigmatic Tarfaya has an impunctate shell fabric and setigerous perforations along the posterior margin, indicating placement within the Orthoidea in a new Family Tarfayidae. New species of Polytoechia , Protambonites , Paralenorthis, Ranorthis , Tarfaya , Xianorthis are described.