The Thorax of Zacanthoides Walapai
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Updated 7/2/17
The dearth
of literature and images of this species of trilobite indicates
the rarity of finding not only complete specimens, but even an
intact thorax. First reported from the Grand Canyon by Resser
in the 50s, Z. walapai is a very primitive trilobite in overall
morphology. The tapering thorax and very small pygidium is characteristic
of early and early middle Cambrian types. Therefore it is with
great pleasure we present to you this photo collection of our
thorax specimens from the SW locality up near Ashfork Arizona.
This site appears unique in several ways. First, it is the only
site outside the Canyon (south) that has this species. Second,
the preservation can be quite good, and very fine microscopic
details can be seen in many specimens. The site also contains
a large number of Hyolithids with articulated operculums, and
a peculiar colonial animal which we have not yet identified.
No Brachiopods were ever found here in thousands of shale slabs.
The basic features of a trilobite thorax can
be seen here. The size is about an inch.
A few articulated thorax sections:
( a selection of thorax / pygidium or connected ribs)
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Individual Ribs:
(More frequently found)
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Microscope shots, 10x
Still mastering the art of binocular microscope images. Bear with me...
