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Laballidae sp. from 88 Valley, Wakefield
One of the most intriguing finds from the Triassic in the Nelson area is the specimen shown above and in the image to the right. It is one of two, collected from Highfield Farm, near Wakefield, and poses some fascinating questions. The specimen comes from what are believed to be upper levels of the Otamitan or Warepan beds, close to outcrops containing Monotis. The second specimen (shown below), which is corroded and incomplete, was from scree beneath lower Otamitan or Oretian deposits.
The fossil is clearly of a brachiopod, but with its conical ventral valve and its flap-like dorsal valve, it is highly unusual. When consulted, Hamish Campbell and Don Macfarlan both suggested that the specimens are members of the Laballidae - a family within the Spiriferinida. Previous finds of Laballidae in New Zealand have been attributed to three species. Psioidia australis, has been recorded in Otamitan deposits south of Wakefield. Zugmayerella taringaturaensis has been found in Warepan deposits in several localities in Southland. Lepismatina sp. has been found in Etalian stage deposits from thirty of more sites in both the Nelson and Southland regions. Other finds of Laballidae both in these locatlities and from New Caladonia have been non-specific. Without access to good comparative speciemns, I'm unable safely to identify these below genus level. |
Laballidae sp.
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A broken and corroded specimen of Laballidae sp. from Highfield Farm
Summary of description given by Don Macfarlan:
Specimen examined with nearly flat dorsal valve and high hemipyramidal ventral valve. Dorsal valve with straight hingeline about equivalent to valve width; rounded flanks and rounded anterior margin. No sulcus or fold seen. Maximum width at about ¼ distance from hingeline to anterior margin. Ventral valve high, hemipyramidal with well-defined triangular, nearly flat, apsacline interarea. Delthyrium open, with no indications of spondylium in specimen seen. High narrow median septum seen near apex only. Internal details apart from bases of spiralium not seen. Exterior unknown apart from interarea. |
Further Reading: Trechmann, C.T. 1917 The Trias of New Zealand. Quarterly Journal of the Geological Society 291, 165-246 (+ 10 plates). |