recalcitrant (or more commonly collected); however, in well-preserved sites such as the Phyllopod bed, spine and sclerite abundance is comparable, in disarticulated instances, to the proportions on complete fossils. Younger spines of possible wiwaxiid origin have been observed from the Valongo Formation (Middle Ordovician: Dapingian-Darriwilian) of northern Portugal and have been reported, if not described, from the Fezouata Biota See also Coeloscleritophoran References External links Burgess Shale fossils Cambrian invertebrates Prehistoric marine animals Prehistoric protostome genera Protostome enigmatic taxa Fossil taxa described in 1911 Cambrian Series 2 first appearances Miaolingian extinctions Taxa named by Charles Doolittle Walcott Wheeler Shale Paleozoic life of the Northwest Territories Cambrian genus extinctions