Upper Ordovician sponge spicules from Gondwana: New data from Peru and Libya

CARRERA M. G; GUTIERREZ MARCO, J. C; GHIENNE, J.F; CHACALTANA, C.

Ghent

Simposio; IGCP 591 The Early to Middle Paleozoic Revolution. Closing Meeting Abstracts, Ghent University; 2016

Data of Middle to Upper Ordovician sponges outside Laurentia and the Australian associations, are to sparse that any new record significantly contribute to the global diversity of the group. Conspicuous sponge spicules assemblages and a partially complete sponge have been recorded from Peru and Libya. Only one mention of isolated Ordovician spicules have been previously recorded in Peru and also a mention of spicules has been reported from Libya. The spicule association recorded from Peru comes from Sandbian beds of the Calapuja Formation west of Lake Titicaca. It consists of isolated hexactins, pentactins and ropes or divergent tufts of elongate, large monaxons in subparallel orientation. Some of these monaxon groupings are clavate masses of slightly divergent, mainly smooth monaxons some of them ornamented. These forms resemble the genus Pyritonema Mc Koy (= Hyalostelia Hinde). The other groups are related to root- tufts of hexactinellids with long monaxons including anchoring terminations. The genus Pyritonema has been revised by Botting (2005). It is commonly misinterpreted and related with root-tufts. According to this, several forms including in the genus have to be reconsidered. The spicules from the Upper Ordovician of Libya come from the base of the Melaz Shuqran Formation in the Tihemboka Arch, west of the Murzuq basin. The assemblage consists of simple hexactines, hexactine- based stauracts and pentacts and some isolated large monaxons. Different sizes or rank of hexactines occurred; some of them in apparent original arrangement. This association agrees with the characteristics of the Protospongioid Reticulosan Hexactinellids.ReferencesBotting, J.P., 2005. Exceptionally well-preserved Middle Ordovician spongesfrom the Llandegley Rocks Lagerstätte, central Wales. Palaeontology 48,577?617. 10 (6), 2053?2066.