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Name: Asaphus delphinus
(double)
Age: Middle
Ordovician
Size: mm (25.4mm=1
inch): 100 & 85, respectively; shale is 215 x 120
Location: Asery level,
St. Petersburg region, Wolchow river, Russia
| This
is a double of a rare trilobite from the Ordovician strata near St.
Petersburg, Russian. Ocurring in the Middle Ordovician, Asaphus delphenus
was the end of one of two evolution lines of Asaphus from the region
that branched from Asaphus lepidurus in the Lower Ordovician. Delphinus,
with its distict morphology was preceeded in a linear progression
by proginitors Asaphus lamanskii, raniceps, and major. This double
is a natural, as it occurred in the matrix with no remounting. The
smaller delphenus is folded with the Hypostome (the anchor for trilobite)
mouthparts fully visible, a rare preparatory achievement. |
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