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Havlicekia secans
Phylum: Brachiopod
Genus: Havlicekia Species: Havlicekia secans Location found: Baton River |
Havlicekia secans is a rare and somewhat unusual fossil from the Baton River deposits. Like others in the New Zealand Devonian, it has undergone various changes of name over the years, and has previously been known as Eospirifer secans and Spirifer secans. Its presence is important because it is a characteristic member of the early Devonian Emsian or Pragian stage in Eurasian faunas, and thus ties the age of the deposits to that stage.
Shirley (1938) notes the similarity between this species and Eospirifer togatus, so confusion between the two is possible, but H. secans can be distinguished by the presence of furrows bordering the dorsal fold, and two extra folds near to the umbo on both values. (Shirley's full description is presented in the panel to the right.) The specimen above displays the strong fold and associated furrows, and the straight hinge (partly obscured) that is slightly shorter than the maximum width. Further Reading: Shirley, J. 1938 The fauna of the Baton River Beds (Devonian), New Zealand. Quarterly Journal of the Geological Society 94, 459-506. |
Description (Shirley 1938): Outline transversely elliptical, hinge line a little shorter than the greatest width. Dorsal valve with prominent fold flanked by furrows; near the umbo two more furrows are developed but these disappear anteriorly. Ornament of fine ribs about 22 in 5 mm., increasing by bifurcation. Dorsal internal cast shows a divided hinge-plate carrying elongate dental sockets bordered internally by the crural bases; crura supported by short vertical plates exactly as in E. togatus . . . |