ABSTRACT
Although the Jurassic arguably marks the period of most important echinoid evolution, the only echinoid material so far described from the Jurassic of Australia comprises a single regular echinoid (cidaroid) spine from the Newmarracarra Limestone (Middle Jurassic: Bajocian Stage) of the northern Perth Basin, Western Australia. A second but dissimilar “regular” spine is here recorded from this area and horizon, together with aboral fragments of two irregular echinoids identified as Clypeus cf. michelini (Wright). These fragments significantly extend the known geographical range of very early cassiduloid echinoids, and indicate that the order Cassiduloida (one of the earliest “irregular” orders) achieved rapid, widespread distribution soon after its apparent origin in the Jurassic, ranging from Britain into southeastern Gondwanaland by the Bajocian.
