The radiation of early Silurian spiriferide brachiopods, with new taxa from the Llandovery of Iran

Although there were Late Ordovician spiriferides in the superfamily Cyrtioidea, namely Eospirifer and Odakella, only the former genus survived the terminal Ordovician extinction, and only Eospirifer is known from the earliest Llandovery (Rhuddanian). However, in the succeeding mid-Llandovery (Aeronian), the spiriferides radiated to include not only more species within Eospirifer and Striispirifer in the Eospiriferidae, but also the new genus Iranospirifer described here, which is the earliest representative of the other family within the superfamily, the Hedeinopsidae. The Ordovician species were confined to the South China continent and the Boshchekul volcanic island arc in Kazakhstan, but by the Aeronian the superfamily had spread westwards to various other continents, including the main Gondwanan superterrane (which included Iran) in the early Aeronian, and Avalonia-Baltica and Laurentia in the late Aeronian. The new species Eospirifer ghobadiae and Iranospirifer qarabilensis are both described from the lower Aeronian of Iran, and there is a note on the Aeronian rhynchonellide Stegocornu, which is endemic to Iran and nearby areas.