36 Wing-like brachiopods endemic to a future Zealandia

Brachiopoda, Spiriferinida: Rastelligera sp.

During the Triassic and Jurassic about 200 species of brachiopods were present in the seas around southern Pangaea and the newly-forming Gondwana (future Zealandia). One particularly unusual group of brachiopods known as Rastelligera is well-represented in the University of Otago Geology Museum collections. This is a genus of spiriferinid brachiopods (these have a coiled spiralium which supported the lophophore during life) that are distinguished by a very long, wing-like hingeline. Around eight species are known and all are endemic to Zealandia. The first of these species was named in 1913. Most of the others were named in 1968 by JD (Doug) Campbell, a paleontologist and botanist who was on the staff of the Department of Geology from 1959 until his death in 2001.

Part, counterpart and steinkern (internal mould) of a specimen of the extinct brachiopod, Rastelligera. The calcareous external shell has been completely dissolved away. Image credit: JH Robinson.

These distinctive brachiopods are found throughout a 2000 metre thick sequence of Triassic rocks in Southland and South Otago from the Hokonui Hills to Nugget Point.  They became extinct at the end of the Triassic, a time when many other brachiopods also disappeared from the fossil record.

The name Rastelligera refers to the distinctive “comb-teeth” and was coined by James Hector in 1878 (in Latin, rastellus refers to the teeth on a rake). Some of these brachiopods are also described as mucronate, an unusual word which means to end abruptly in a point. The elongate, wing-like shape may have helped to anchor the brachiopods on the seabed and the many teeth ensured the animal could securely hold its valves closed. Because the shell material has usually been dissolved away over time, the fossils are often moulds showing the interior structures. The shape and morphology of the actual shell can be recreated by using a rubber or silicone mould and then more replicas can be made.

—Written by Jeffrey H Robinson and Daphne E Lee