Abstract

Although bradoriids locally are common components of the Cambrian biota, they have been reported previously from Antarctica only from Tertiary glacial deposits. Here, we describe the bradoriid, Bicarinella evansi new genus and species, collected in situ from the upper Lower Cambrian (Botomian) of the Pensacola Mountains in East Antarctica. Bicarinella evansi n. gen and sp. is characterized by a subtriangular carapace with a well-defined marginal rim, subequal anterior and posterior lobes that are elongated into sharp ridges extending one-third the length of the carapace, and a broad dorsal node placed between the anterior and posterior lobes. The surface of the carapace exhibits three kinds of ornamentation: fine pitting, pustules, and reticulae. Several smaller carapaces with reduced ornamentation collected from the same bed are interpreted as instars of this species. Bicarinella n. gen. is assigned to the family Hipponicharionidae and appears to be closely related to AlbrunnicolaMartinsson, 1979, or HipponicharionMatthew, 1886. Although strong archaeocyath faunal similarities demonstrate a close biogeographic relationship between Australia and Antarctica in the Early Cambrian, the possible sister group relationship of Bicarinella n. gen. to Hipponicharion, which is otherwise unknown from Gondwana, may suggest a separate biogeographic pathway to East Antarctica that did not involve Australia.

You do not currently have access to this article.