New Backyard Site

[Kane]

Averaging about 20 hours a week at this site. It's nice to be able to run into nature on the way there and back...

[Kane]

This is the typical stuff in the more prosperous layers of the rock, and here are the usual tools needed for the task. Some of the rocks are boulder-sized, and tend to break vertically more often than horizontally (when they don't just simply shatter). 

[Kane]

Today was a good day as I found what I assume are two examples of lichids. 

 

The first is a pygidium that I'll still need to uncover with the scribe. Acanthopyge contusa?

 

[Kane]

The second is my first hypostome find at this location (part of what takes me so long apart from actually wrestling and breaking the rocks is inspecting them very carefully).

 

Possibly the hypostome of a Terataspis grandis? Comparing here with Whitfield's illustration. @piranha?

[FossilNerd]

46 minutes ago, Kane said:

Averaging about 20 hours a week at this site

I don’t think I get 20 hours a year out in the field! 

 

Very cool finds! I see why you are spending so much time there. 

[Kane]

Thanks, Wayne.  It helps that the site is near my house, and that I have Wednesdays and Fridays off (until student papers start coming in next week). 

[piranha]

5 hours ago, Kane said:

The second is my first hypostome find at this location (part of what takes me so long apart from actually wrestling and breaking the rocks is inspecting them very carefully). Possibly the hypostome of a Terataspis grandis? Comparing here with Whitfield's illustration. @piranha?

 

 

 

Congrats!  What is the size?  This hypostome from the ROM measures 7.5 cm in width:

[Kane]

Just now, piranha said:

 

 

Congrats!  What is the size?  This hypostome from the ROM measures 7.5 cm in width:

 

Like all the other Terataspis fragments I find in these rocks, it is quite small; about 1 cm! 

[piranha]

It appears you have stumbled upon a "Terataspis Kindergarten".  At least that improves the odds for finding a complete specimen! 

 

The first pygidium was great, and now a spectacular hypostome to go with it! 

[Kane]

Thanks, Scott! I hope you're right about finding a full one before I run out of viable material. 

 

Today's expedition netted three Acanthopyge partials, but one of them (a pygidium) was a negative with no trace of the positive. But I was able to collect two other examples, which were both a fetching orange hue:

[FossilDAWG]

 

No more complete Pseudodechenella?

 

Don

[Kane]

Just now, FossilDAWG said:

 

No more complete Pseudodechenella?

 

Don

Sadly, no.  And despite very abundant Crassiproetus, none complete of those either! I think that complete Pseudodechenella was a lucky fluke. Very little outside of brachs, bryozoans, coral, and rostroconch seem to preserve whole. 

But I suppose finding partial lichids is a close runner-up.  

[FossilDAWG]

2 hours ago, Kane said:

But I suppose finding partial lichids is a close runner-up.  

I would say so!

 

Don

[Kane]

Another three hours at the spot, and possibly another baby Echinolichine fragment. This one looks like a genal spine, specimen is split on two sides of the rock:

[Malcolmt]

Wonder where exactly that fill came from........

[aek]

Nice genal spine! Getting closer...

[Kane]

19 minutes ago, Malcolmt said:

Wonder where exactly that fill came from........

The nearest quarry for this stuff would be Ingersoll, but that's just a guess.

19 minutes ago, aek said:

Nice genal spine! Getting closer...

Thanks! I think the odds of finding a complete one are astronomical, but perhaps one day I'll have a complete one between all the fragments.  

[FossilDAWG]

20 minutes ago, Malcolmt said:

Wonder where exactly that fill came from........

My guess would also be the quarry at Ingersoll.  I don't know of any other place where the Anderdon is stripped off the Lucas and discarded (or used for fill).  The Anderdon is too sandy to use for cement production.

 

Don

[Scylla]

On 9/25/2019 at 1:08 PM, FossilDAWG said:

My guess would also be the quarry at Ingersoll.  I don't know of any other place where the Anderdon is stripped off the Lucas and discarded (or used for fill).  The Anderdon is too sandy to use for cement production.

 

Don

One man's trash is another's treasure

[Kane]

Yesterday's six hour visit netted a larger number of lichid fragments than usual, although nothing has yet to emerge complete. These are just a few, and best, of yesterday's finds:

 

1. Pygidium of Acanthopyge contusa, slightly above average size for this diminutive lichid

[Kane]

2. Crassiproetus pygidia are common, but I had to keep this one on account of its size: about 4 cm x 3.5 cm. Not shown would be the side view where it is fully inflated to the convex egg-like proportions the species is known for.

[Kane]

3. This may make my fifth example of Terataspis grandis. Like all the others, these are quite wee, and likely juveniles. The fragment shown here is another genal spine. Why I am hesitant to declare it with certainty would be on account that I've not seen what the genal spine for Acanthopyge contusa looks like, and none of my sources seem to picture or describe what that would look like.

[Kane]

And this oddball. This appears to be a glabella, possibly belonging to a proetid, but the raised bit (possibly a tubercle, but may be an artifact of preservation or an encrusting organism) poses a bit of an identification problem. The proetids in this material (Crassiproetus and Pseudodechenella) have glabellas that are either entirely effaced or possess some furrows. If it is a trilo fragment at all... The condition on this is quite poor, so diagnostic detail is a bit lacking.

 

If only that was the only mystery. There are faunal elements that show consistency with the Amherstburg (Formosa Reef) and Bois Blanc formations, but also inconsistencies in both. Relying on Ludvigsen's (and to a lesser extent Fagerstrom's) work on the Formosa reefal complex, there are some wide deviations. In Ludvigsen's work on the Formosa (1986), his tabulation of trilobites from this strata on the basis of 139 collected specimens yields this in terms or relative abundance:

 

Crassiproetus 51.7%

Mannopyge 30.2%

Mystrocephala 13.6%

Acanthopyge 3.5%

Harpidella 0.7%

 

Trilobites remain a distinct minority in these sediments, as they are generally dominated by corals (tabulate, rugosa), stromatoporoids, bryozoans, rostroconchs, and brachiopods. This compares favourably with the material from my site. However, the trilobites do not. Not counting the beds with disarticulated single segments in mass profusion and focusing on more identifiable fragments in identical layers, based on several hundred individuals I get these approximate values:

 

Crassiproetus ~55%

Pseudodechenella ~35%

Acanthopyge ~8%

Terataspis ~2%

 

Although the Crassiproetus relative abundance is within the range of the Formosa reef / Amherstburg strata, this proetid is a poor index given its stratigraphic range (ditto can be said of Pseudodechenella, which is not reported in the Formosa). Also, not even a whisper of any of the other trilobites aside from Acanthopyge appear. Of note would be the fact that Acanthopyge is only reported in the Amherstburg/Formosa reef, and Terataspis is only reported in the underlying Bois Blanc formation, and yet both have appeared together in the same rock at least once at this location, which might suggest gradational contact between the two formations... or not. If these were Bois Blanc, then the absence of even a single trace of the common dalmanitid Anchiopsis anchiops is conspicuous, but would explain the presence of Pseudodechenella. So could this be Lucas, Anderdon Member? According to the literature on hand, Crassiproetus is the sole represented trilobite reported from that formation. 

 

Of course, attempting to pin this precisely bumps up against the plain fact that these are imported from a quarry (this bears out on account of finding spent blast fuses!). However, with a focus on layers that are identical to each other for comparison purposes (usually sitting above/below the coral zones), as well as non-trilobite faunal associations in the same type of matrix, this narrows things down considerably. The only outlier was the first near complete Pseudodechenella that appeared solo in an otherwise blank matrix type that did not resemble the source material of all the other specimens. 

 

[Ludwigia]

You sure are coming up with some very interesting stuff in this fill.

[Kane]

47 minutes ago, Ludwigia said:

You sure are coming up with some very interesting stuff in this fill.

Thanks, Roger.  Maybe next year when you're on this side of the pond I can take you there (if not another possible spot I have my eye on that is an actual outcrop in the lower Devonian). As long as the fill continues paying out like this, I may as well keep digging at it.