Revised systematics and palaeobiogeography of some Late Triassic colonial invertebrates from the Pacific region

Abstract

Revision of type and additional material of Upper Triassic colonial organisms from New Zealand, New Caledonia, Timor, Siberia, Canada and Chile, previously interpreted as Bryozoa or Cnidaria, provides new insights into their palaeobiology, systematic affinity and palaeobiogeography. Heterastridium conglobatum Reuss remains of uncertain hydrozoan affinity, and could be spheractinoidean, hydroidean, or even milleporine. H. conglobatum disciforme n. subsp. (=“forma” disciforme sensu Gerth) is described from New Zealand. The distribution of Heterastridium in the Murihiku and Torlesse terranes of New Zealand-New Caledonia is documented, and it is recorded as ranging through the Middle and Late Norian (Rutherfordi, Columbianus, and Cordilleranus Zones). Its extreme rarity in the Torlesse terrane is thought to be the result of unsuitable facies. “Monotrypella” timorica Vinassa de Regny, described as a bryozoan, is a calcareous demosponge of uncertain family and genus. “M” maorica Wilckens is shown to be the senior synonym of Eoheteropora katzi Morozova. Eoheteropora is considered to be a tabulate coral, and is shown to be of circum-Pacific distribution from Late Triassic to Early Jurassic time. The genus includes the Norian E. maorica (New Zealand-New Caledonian Murihiku terrane, and Kolymskij massif, Siberia), Rhaetian E. caledonica n.sp. (New Caledonia), Toarcian E. tipperi (Henderson & Perry) (British Columbia, Canada), and possibly also an undescribed form from the Early Jurassic of Chile.