Three invertebrate fossil sites (one newly discovered) of early and middle Permian age in the Sydney Basin of New South Wales provide an insight into changing depositional environments that were dominated by marine glaciogenic conditions. The Allandale fossil site is a shell bed within the early Permian Allandale Formation (Dalwood Group) exposed in a railway cutting near Harpers Hill, where specimens of the large bivalve Eurydesma were first collected in 1831. Excavation of this site in 2011 during track upgrading allowed collection of many well-preserved Eurydesma specimens in a sandy conglomerate facies. One specimen has remnant colour banding under UV illumination.
A slightly younger bivalve-dominated faunal assemblage, exposed during excavations at Tocal near Paterson, is the first fossiliferous occurrence of Permian age recorded in that area and is assigned to the Rutherford Formation (Dalwood Group). Depositional environments at the Allandale and Tocal sites were nearshore marine, in moderately turbulent water.
|Permian fossils and palaeoenvironments of the northern Sydney Basin