L ate O rdovician brachiopods from P eru and their palaeobiogeographical relationships

A S andbian brachiopod association from the C alapuja F ormation, in the P eruvian A ltiplano, north‐west of L ake T iticaca, has allowed a re‐examination of the palaeobiogeographical relationships between G ondwana and A valonia during the L ate O rdovician, when the palaeocontinents are considered to be already very distant from one another. The brachiopod fauna includes the new species O nnizetina calapujensis sp. nov., H orderleyella chacaltanai sp. nov., D rabovinella minuscula sp. nov. and T asmanella curtiseptata sp. nov., as well as C aeroplecia sp., D inorthis cf. flabellulum and T unariorthis cardocanalis . In addition, C olaptomena expansa expansa and H eterorthis retrorsistria , known from the B ritish B urrellian S tage of the C aradoc S eries (late S andbian) in W ales and the W elsh B orderlands, have also been identified. The brachiopod collection is the most diverse known from a single locality in the whole C entral A ndean B asin. Within it, forms with clear G ondwanan links occur, such as the new species of O nnizetina , D rabovinella and H orderleyella , and typical representatives of the A valonian faunas, such as the W elsh C olaptomena expansa expansa and H eterorthis retrorsistria . The brachiopod species exchange between the P roto‐ A ndean margin of G ondwana and A valonia, now believed to be possible during the late S andbian, allows a reconsideration of the global taxonomic affinities of both regions. With this in mind, detrended correspondence analysis ( DCA ) and cluster analysis have been applied to an updated rhynchonelliformean brachiopod matrix consisting of presence/absence data. The scatter plot resulting from the DCA allows a vivid visualization of the grouping and geographical trends of the S outh A merican localities with respect to A valonia– B altica and the M editerranean margin of G ondwana during the S andbian. Our results agree with previous palaeogeographical reconstructions, depicting A valonia very close to B altica and already distant from G ondwana. As a few brachiopod species, with low dispersal potential, would have been able to migrate between those distant palaeocontinents, the existence of intermediate islands in the R heic O cean, permitting the transit by island hopping of eurythermal species, must be considered.