Click on the image to zoom
An impression of Aparimella apteryx (LPC6_91) from Highfield Farm
As fossils are re-examined by different workers in different generations, their cassification and names tend to change. Sometimes a species may be split into two more new apecies; at other rtimes different species become grouped into one.
This species has had something of a chequered career - variously classified as Daonella indica, Daonella apteryx and, now, Aparimella apteryx. The description (right) was done under the name Daonella apteryx, by Marwick (1953). As this indicates, the species is typically rounded to oval in outline, and marked by slightly flared and fine ribs (radials), which divide towards the margin of the shell. In profile, it is relatively flat, but the folds (growth-rings) hive a somewhat stepped appearance, and the shell tends to flatten towards the rim. The umbo is rather small and pimple-like, standing low above the central growth rings. It is generally a fairly distinctive species, but can be confused with species of Halobia. A. apteryx, however, is confined to Kaihikuan strata and often occurs with the brachiopod Alipunctifera kaihikuana; Halobia only occurs in later strata, of Oretian and Otamitan age. Further Reading: Marwick, J. 1953 Divisions and faunas of the Hokonui System (Triassic and Jurassic). Paleontological Bulletin 21, Wellington: New Zealand Geological Survey. Trechmann, C.T. 1917 The Trias of New Zealand. Quarterly Journal of the Geological Society 291, 165-246 (+ 10 plates). |
Aparimella apteryx
|