A new Early Devonian operculate tetracoral genus from eastern Australia

WA Museum Records and Supplements | Updated 1 decade ago

Abstract - Chakeola, a solitary latest Lochkovian to late Emsian (Early Devonian) new genus of the operculate tetracoral family Calceolidae, is characterised by: opercular septa that are present from adjacent to the median septum to the lateral extremities of the operculum; a lack of rootlets on the counter face of the corallite; a weak counter opercular face in mature specimens; and eccentric growth increments on the external opercular surface. The type species, C. johnsoni new species, is described from latest Lochkovian pesavis Zone), early Pragian (sulcatus Zone) and late Pragian (pireneae Zone) strata of the Garra Formation, Wellington, NSW. C. whitehousei new species is described from the Ukalunda Beds (perbonus Zone, mid-Emsian), near Ukalunda, Queensland. Specifically indeterminate occurrences of the genus from the Mudgee district in New South Wales are in: the Taylors Hill Formation (?kindlei Zone, late Pragian); the Sutchers Creek Formation (serotinus Zone, late Emsian); and possibly the Mullamuddy Formation (sulcatus Zone, early Pragian). Rhizophyllum calceoloides from the Tabberabbera Formation (Emsian), Victoria also belongs in this new genus. Calceola sinensis and Calceola sandalina acuminata from Emsian strata in northern Vietnam are also assigned to this genus.

Chakeola thus ranges from the latest Lochkovian (pesavis Zone) to the late Emsian serotinus Zone; it presumably arose from Rhizophyllum or a related form, and probably gave rise to Calceola in the Emsian in eastern Australia or SE Asia. The occurrence of the genus in eastern Australia and Vietnam provides further evidence of faunal exchange during the Early Devonian. This study concludes that features of the exterior and interior surfaces of the opercula of genera of the Calceolidae are diagnostic at the generic level.