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Veralum Trilobite


Malcolmt

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My friend QuarrymanDave here on the forum asked me to prep what looked to be an unusual trilobite from the veralum formation of Ontario. This is Ordovician . The prep is not finished, I still need to do the fine detail .

Even though this is just a cephalon , I think it is an amazing little fossil. It is 31.3 mm at its longest and 22.0 mm at its widest. I have certainly never seen this species in all the times I have been to the location he found it in.

It could very well be a rare paraharpes ottawaensis or equally rare dolichoharpes dentoni

Please jump in with your identification......

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I am currently leaning towards it being dolichoharpes dentoni

Edited by Malcolmt
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Wow; definitely not run-of-the-mill!

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The cephalic brim of Paraharpes is broad and flat with finely pitted ornament.

Dolichoharpes looks like the correct ID. Congrats on the great find and prep!

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Whittington, Harry B. 1949.
Dolichoharpes and the origin of the harpid fringe.
American Journal of Science, ser. 5, 247(4):276-285

Whittington, Harry B. 1949.
A Monograph of the British Trilobites of the Family Harpidae.
Palaeontographical Society, London 447:1-55

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What a beauty! Nice craftsmanship and the usual excellent scholarship from Piranha.

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Well done everybody, from beginning to end!

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That is certainly an unusual trilobite find! Nice prep too! B)

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Great find, and great prep job! I have never seen a trace of any harpid trilobite in the Verulam, that certainly is a rare find.

Don

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That is a beautiful Dolichoharpes cephalon!

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Nice find Dave and great job on the prep Malcolm! That is a really cool cephalon you got there.

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Quarryman Dave

So happy I found it. At 1st i almost dismissed it as a flexi or ceraurus but the genal spines were so different and striking that I had to give it to malcolm for prepping and ID. What an amazing prep job. thanks Malcolm

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Hi Dave,

I tracked down some useful research material for you. Dolichoharpes dentoni is evidently a dubious species as the type material has been lost. Presently It appears that Dolichoharpes aff. D. reticulata is the preferred ID for this trilobite. Attached for your files is a PDF of the description and figures from Chatterton & Ludvigsen. Congrats again on your spectacular find! happy0144.gif

Chatterton, B.D.E. & Ludvigsen, R. 1976.
Silicified Middle Ordovician Trilobites from the South Nahanni River Area, District of Mackenzie, Canada.
Palaeontographica Abt.A 154:1-106

Dolichoharpes.pdf

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Thanks Scott, this definitely is an excellent PDF for this fossil. Looking at the pictures and the comparing to the fossil in front of me I think we have a 100% match.

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Dolichoharpes is shown as occurring in the Verulam in Ludveigsen's volume on the trilobites of Ontario. On the other hand, the genus is not mentioned in B.A. Liberty's extensive faunal list for the Verulam in his GSC memoir on the geology of the Lake Simcoe area, though he does list it for the Bobcaygeon. If Liberty didn't find it, it's safe to say it's really rare in the Verulam.

Don

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Couple comments: 1) it's awesome that folks like Pirhana (scott) provide the type of info/materials that they do and 2) is it just coincidence that the pic Scott provided and Malcom's specimen are both missing the main body portion? Is that typical for that type of "rare" trilobite?

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Cephalons are always more common than whole specimens. In the case of Dolichoharpes and related trilobites, the sutures that split to let the trilobite molt are at the margins of the head part, so a molted cephalon looks complete in that it is not missing the free cheeks, unlike most other trilobites. The same is true of the Cambrian olenellids (Olenellis, Bristolia, etc), which is why those trilobites are also mainly represented by what appear to be intact heads. The body, on the other hand, is made up of a lot of pieces (thoracic segments, and the pygidium or "tail") that readily break up, so complete specimens require especially rapid burial. Harpids lived partially buried in the sediment on the sea floor, and were good at burrowing, so they may have had to be buried deeper than some other trilobites to smother them after a storm or turbidity flow. That last part is just speculation on my part, though.

Don

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Facial sutures are absent in the olenellids which is regarded as a primitive feature unique among trilobites except where they are secondarily lost (Treatise O 1997).

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Thanks Scott, I obviously didn't phrase that clearly with regard to the olenellids. My bad. My point was, with harpids and olenellids molted heads will look intact, unlike Flexicalymene (as one of many examples) where the free cheeks will be dissociated.

Don

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Quarryman Dave

Thank you Scott for your information regarding this species the PDF photos exactly matches this specimen

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