Erbenochile
aff erbeni
Trilobites
Order Phacopida, Suborder Phacopina, Superfamily Acastoidea, Family Acastidae
Geological
Time: Lower Devonian, Upper Emsian
Size: Trilobite
is 60 mm long by 50 mm wide on a 75 by 110 mm matrix
Fossil Site:
Jebel Oudriss, Morocco
Code: 18128
Price: $1995.00
Description:
Elegant example of a member of the Order Phacopida, Superfamily
Acastoidea with many fine details present. Once known in the trade
as “Big Eye”, this one is actually Erbenochile, and
has recently become commercially available in limited quantities.
The most diagnostic features of this taxon are the high “eye-towers”.
Fortey and Chatterton described Erbenochile
erbeni in September 2003 from a single commercially- prepared specimen,
and it created a stampede among collectors. The “wrap around”
eyes gave a good panoramic view of the trilobite’s environment,
allowing it to keep alert for predator and prey alike. Since fish
had recently evolved true jaws, any advantage a prey species could
derive would place it at an advantage. This one has been prepared
with the genal and axial spines all freestanding, quite an achievement
from such hard matrix. Note the exceptional eye facets seen here,
a feature that is difficult to prepare well due to the matrix. About
10 years ago a second species Erbenochile issoumourensis was described
from Jebel Issoumour with the main differences being a lower eye
tower and lack of a sunshade. Early last year a third site at Jebel
Oudriss turned up a very few examples that while they looked like
E erbeni they had much more dramatic spinose tubercles to the genals
and thoracic segments. There is a progression in the robust nature
of these elements, being smallest in E issoumourensis and greatest
in the Jebel Oudriss material. I have included some in preparation
photos that demonstrate the spines are authentic to the specimen,
At this point it is not certain whether this material constitutes
a new species or not. I will play it safe and simply refer to it
as Erbenochile affinis erbeni for the time being.
A
specimen of the very rare Erbenochile
issomourensis may be seen here, and here is another Erbenochile
erbeni specimen.
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