Tiny Fossil Gives Clue To Age Of Rocks

Press, Volume C, Issue 29632, 30 September 1961, Page 5

Tiny Fossil Gives Clue To Age Of Rocks

A tiny fossil, no bigger than a finttenuul, found *IB rocks. These argillites wera wobably laid down to the years-ago.. ’ "</' .:•* The fossil is the "aptycX Xilfish. was a chitinous flap held over the open end of the sheß when the antoial retraewd into safety.. Many modern coiled shellfish have similar '‘stoppera,” known as operculums which are the any discs or flat cones often seen bn peaches mixed ' shells and other The jiptyehus is in the shape dt a' segment of a sphere. The cut-off plane of -he sphere is smooth, but the convex 'surface has lines on it as if a fingerprint had been impressed on the inside. Fossils are rare in the greywackes and argillites of :he Southern Alps. The only o'her aptychus found in the South Island in rocks of a similar age was a single specimen discovered in the Morley gorge in western Southland.

The newly - discovered aptychus was found in argillites associated with greywackes, in Cascade Glen on the south bank of the Rakaia

- opposite Lake Coleridge and I belovr Redcllffe HUI. In i ! the fossil worm-tube Ter-'e-l beilinik There Terrebelllna ■ are generally bonjpdwed to i BMli&'iM the Swmry of the ammonite aptychus in • association with them gives i confirm»tlon of their age. > The beds were laid down Ito sea wter, although i whether deep or shallow is r The aptychus is now in ■ the reference collectum of r the Geological Survey head i office in Lower Hutt The i ammonite from whldh it I comes is not definitely r known, but there seetns to be some relationship to a > genus known as Arcesies.