Another odd one

[Metopolychas]

Another odd one! It's the same kind of surface I've found before, tiny spikes and bumps, and the previous one was suggested as some kind of lichid. 

[Metopolychas]

This is the negative, there are small spikes left in it. 

[Metopolychas]

[Metopolychas]

Cross section seems to be an oval. 

[Metopolychas]

The arrow shows a groove that I suspect runs along the edge of this thing. Could be the border between head and thorax?

 

There's more still in the stone, some bits that looks to be smooth but I don't dare remove more in fear of destroying it since I only have very basic hand tools. 

[Rockwood]

Looks like a heliolitid coral encrusting something.

[Wrangellian]

It looks like you should be able to use a pin to carefully pry up this piece and glue it onto where it fits on the other piece...

Then you might be able to tell better what it is. Doesn't look like a coral to me but I would be afraid to hazard a guess as to what it is.

 

[Tidgy's Dad]

I'm thinking it's maybe a part of one of the bizarre stalked echinoderms, a rhombiferan, diploporate, something like that. 

The circled piece could be stem? 

[Rockwood]

6 hours ago, Wrangellian said:

Doesn't look like a coral to me

If the fifth photo down is a sectioned view of the inside, (didn't catch it last night) definitely not.

[Kane]

I wouldn't rule out that this is indeed another lichid fragment, possibly the median lobe of the cranidium. The relatively regular pattern of tubercles seem to suggest this, as well as the arcing feature just left of the arrow and beneath the lobe. The bulbous shape shown in cross-section is another potential clue, as is the pinching/narrowing at the posterior of the lobe, possibly indicative of where the lateral lobes would have been. 

 

If it were tipped forward, imagine your piece appearing as the middle/median lobe of the cranidium. Just an illustrative example of the morphology here (not a suggestion on genus and species): 

 

[Metopolychas]

A better look at that edge I mentioned. 

 

And yes Rockwood, I think it's a cross section. 

 

It really would be fun if this was a trilo, even a partial one. With how well it seems to be preserved (even if the fossil itself is mudrock) I'm pretty sure I should be able to find a complete one at some point. 

[minnbuckeye]

18 hours ago, Metopolychas said:

 

Definitely an interesting piece. Can't help with an ID, but what I notice on this picture, when enlarged, is that the larger bumps look like they have been broken off. Does it have that appearance in person? 

 

Mike

[Metopolychas]

19 minutes ago, minnbuckeye said:

 

Definitely an interesting piece. Can't help with an ID, but what I notice on this picture, when enlarged, is that the larger bumps look like they have been broken off. Does it have that appearance in person? 

 

Mike

Yeah, the larger 'spikes' (tubercles?) broke off and is left in the negative part. They're mostly less than a millimeter wide at the base, some of them may with some good will reach two millimeters. 

[minnbuckeye]

My question isn't the width, but how long would they be? This would aid in formulating an ID.

 

Mike

[Metopolychas]

3 hours ago, minnbuckeye said:

My question isn't the width, but how long would they be? This would aid in formulating an ID.

 

Mike

I haven't found any that's more than maybe 3 millimeters long. 

[Metopolychas]

In case it might help, as far as I know the layer is the ordovician layer, and so far I've only found trilobites there, nothing else from what I've been able to determine and the tubercled bit was attached to an initial fossil (I didn't see the tubercled one at first). 

 

 

[Metopolychas]

Found in the same area, within a few meters. 

[Metopolychas]

Possibly a small mussel? Also within a few meters. 

[Metopolychas]

Been go ogling, could it be a deiphon trilo? 

[Kane]

23 hours ago, Metopolychas said:

Found in the same area, within a few meters. 

This one is definitely an asaphid, albeit somewhat exfoliated. And I'll double down on that very first one being a lichid.

[Metopolychas]

34 minutes ago, Kane said:

This one is definitely an asaphid, albeit somewhat exfoliated. And I'll double down on that very first one being a lichid.

Oh, nice! Asaphid. I think there's a lot of these there. 

 

I've looked up pics of lichid and do agree they look a lot the same, it's just the shape of the oval that throws me off. It looks like almost a complete oval and I can't wrap my head around how that would fit on a trilobite. Oh, another clue might be that I'm finding a lot of pygidiums, many very fan-shaped, a few less so. 

[piranha]

This pygidium matches well with: Niobe frontalis

 

 

figures from:

 

Wandås, B.T.G. 1983
The Middle Ordovician of the Oslo Region, Norway, 33. Trilobites from the Lowermost part of the Ogygiocaris Series. Norsk Geologisk Tidsskrift, 63:211-267  PDF LINK