Sifting for small Jurassic fossils in Fili Park

[RuMert]

Hi all!

Here I describe how we sift for Late Jurassic fossils in Moscow Fili Park, in continuation of 

Fili Park evokes mixed feelings. In fact, now it is the main place for Jurassic fish and reptile teeth. Nowhere else in our Jurassic will you be able to say casually: "I'll go find some teeth", here it is possible. Even in Ulyanovsk, with all its skeletons and verts, teeth have to be searched for a very, very long time. For Muscovites, Fili Park is literally close at hand (for me, for example, it takes a little over half an hour to get there). In addition, Fili Park introduces hobbyists to all types of paleo-activities: excavation, sifting, preparation, stabilization, gluing, varnishing, water management, sorting out micro-matrix, etc.

 

On the other hand, it's the most difficult site I have seen in our Jurassic and certainly not a place for a pleasant pastime. Cold, mud, mosquitoes, nettles, everything is flooded with water, everything crumbles and collapses, pouring water and mud on you, while you try to get out your boots gone knee-deep in mud. There are few holes, and digging another is complicated. The place is full of stones, branches and debris, and over the years everything has been so dug up and down that the likelihood of making your way through tons of dirt, debris and old dumps in vain is very high. Excavation and operation of a hole is not a matter of one day or even one person. Dozens of people dig and sift in one hole for a month, with the number of interesting finds combined counted on the fingers of one hand.
This year's holes:

 

Unlike Cretaceous sites, micro-matrix in Fili does not consist of teeth in any way. You will not find 60 teeth from a bucket of mud in any wash fraction. In addition, it contains an annoying amount of pseudo-fossils, including those similar to teeth: seeds, twigs, insects, modern shells, black phragmocons and serpula fragments, shiny pebbles, etc. In this regard, there are also objects like this:

 

As far as I understand, these belong to modern insects, if not, please correct.

 

With all this being said, the small size of the location is surprising: all the adventures of recent years have taken place on a small area of 50 by 20 m. 

I once witnessed guys complaining they could not find teeth by sifting mud. Naive folks! They did not realize the tooth layer was a meter UNDER the stream bed. And the latter is by the way the lowest point of the site.

The nikitini zone begins with a thick layer of belemnite shell rock, reminiscent of a concrete lid. After getting through, the matrix becomes soft again, and the pink fulgens fossils get replaced by the black and white palette of nikitini layer. I would call large brachiopods of the genus Mosquella its marker.

 

 

Instead of smooth kachpurite ammonites, ribbed epivirgatites begin to appear, and rare large (up to 40 cm) lomonossovellas become visible.

 

Each trip for nikitini fossils takes about three hours to clear the old hole. That's why it is important not to postpone the excavation, but keep it within one day, arriving at dawn. Any hole crumbles constantly before the eyes, all the abomination from rubbish and glass to the walls of the fulgens zone slides right into the center of the hole and sinks to the very bottom. Do not try to reinforce the walls with branches and stones, or later you'll have to get all of this out of the target layer. Instead, try to divert as much water as possible from the excavation. See where the streams come from and cut new channels for them. Try not to splash on the walls and do not allow the scooped water to flow back into the hole. The walls collapse where the water flows. Do not make vertical walls, obtuse angles prevent the edges from collapsing.

A typical pit in a pit, the smaller hole's edges are formed by the walls of the nikitini belemnite shell rock:

 

For better understanding. Shovel, buckets, sieves, chair. The water has been drained out. The stream is to the right:

 

First of all, in an old (any not freshly dug) hole, you'll have to scoop out several hundred liters of water (the procedure will have to be repeated several times a day). A regular bucket works best here. Unfortunately, the pumps cannot cope with the job. They are either submersible or designed for clean water, etc. Basically a weak surface fecal pump is needed, but there are none for sale. Last time, amateurs in ordinary rubber boots (lol) asked us how we had "drained the hole". With our own hands, getting there in waders up to the max

At the second stage, you will need to scoop out all the dirt and debris, a medium-sized fishing scoop helps here (in my opinion, better than a shovel). It is useful when clearing a hole, quickly scooping out water and working with mud. 

"Awesome" Fili slurry, aka the matrix:

Edited December 26, 2021 by RuMert

[RuMert]

And now the know-how. To work in Fili, I use a set of groundbait sieves, which you can conveniently use and automatically categorize the sifted mix.

 

A feature of my work this year (and in the past I had already vowed to not return there) was a sieve with a mesh of 0.8 mm, with which I hoped to sift out the teeth shown on this site. It turned out though those specimens were actually larger (4-6 mm) and were easily caught with a 2 mm screen. However, the 0.8 mm one does have advantages, which unfortunately come at a price. 

 

The sieves are like this:

which as a whole form a complex like this:

 

The advantages of such a system are that the sieves are strong, round in shape (which allows you to sift by spinning), of the optimal size for the Fili Park creek and are nested into each other, automatically sorting out the sifted matrix. 

 

The mesh size of the first sieve is 6 mm, which is quite OK. Bigger mesh would have even large reptile teeth fall through. The second sieve mesh is 2 mm, which is also acceptable. I bought a third round metal sieve with a mesh of 0.8 mm, which fits the other two (I wasn't sure if I should use 0,5 or 1 mm). Teeth of 2-3 mm fall into such a sieve ( for elongated specimens 2-4 times the mesh size). A larger mesh is undesirable, while a smaller one would significantly increase both the resulting mix volume and the complexity of photographing the finds. As you can see below, I managed to sift out some interesting teeth with this mesh. But are such teeth abundant, inaccessible to an ordinary prospector due to the large size of the sieve mesh? Find out below.

 

The mix that got into the fine sieve, I called micro-mix, the one in the large sieve, respectively, macro. Meso for the medium sieve. In fact, it was also possible to distinguish super-large mix (concretions, ammonites, belemnites, brachs) and ultra-fine (less than 0.8 - should have been washed out, but stuck to the rest). Sorting out the latter gave too few finds, so I chose to abandon it.

 

Mix by type.
The best finds get into the macro-mix: large reptile teeth, rooted sphenodus, large shark spines, centimeter-sized vertebrae. In principle, you can even limit yourself to that, especially since you don't have to take anything home, everything can be looked through on the spot.  Didn’t find anything cool? That's OK. In return, did not ruin your vision nor reason.
Typical mix:

In recent years, there have been only a few interesting finds in the macro: about five reptile and sphenodus shark teeth, a couple of small reptiles fell in the middle fraction (Fili and Mnevniki).

 

 

 

 

 

Edited December 28, 2021 by RuMert

[RuMert]

Meso-mix is what we usually call mix in the narrow sense of the word. It can be better looked through at home, although it's also possible in the field. An ordinary magnifying glass is enough, the pieces are quite large and looked through with pleasure, they are quite suitable for children. This includes typical Fili Park finds: fish vertebrae, otoliths, unrooted sphenodus teeth, sets of crinoid stem segments, teeth of the second order (gars, synechodus, small reptiles). I would say that otoliths are a marker here, nowhere else are they so abundant (but still not more than 2-3 per handful of mix)

 

There are much more vertebrae than in the small fraction too.

 

In general, it looks like this (here are also a couple of finds from the large mix fraction):

 

 

gar?

 

picnodont?

 

And, finally, micro-mix. So far, I have only managed to sort out the micro-matrix from one joint trip, in which, according to my calculations, we sieved 15 8-liter buckets. Thus, given that I worked a little longer, this is 8*8, i.e. 6.5 ten-liter buckets of primary slurry from the target layer. Above was shown the middle mix, and the micro one is like this:

 

I had to sort it out at home with jeweller's glasses of 10-15 times magnification. According to my estimates, the volume of the fraction is about the same as the volume of the middle one, but, as you understand, a 0.8 cubed, compared to 2 cubed, gives 15 times more particles (in fact, even more, since particles adhere more closely to each other). There are small teeth there indeed, but on average one micro-tooth of 2-3 mm length falls on a ten-liter target slurry bucket. Here you can find small teeth, crinoid segments, crayfish coprolites, pyrite, etc.

 

What I've managed to find so far:

? (some shark)

 

Squatina?

 

Sphenodus? Looks a bit different both in shape and color

 

Synechodus?

 

Quite a lot of type 1 objects

 

and type 2

(there are doubts that these are teeth).

Interestingly, there are a lot of crinoid stem segments,

 

some of which are 3-7 pieces in articulation (pyritized).

It was interesting to compare the finds in the micro-nikitini with about the same volume of micro-mix in the fulgens layer I collected in summer. Here they are:

Strange as it may seem, the fulgens micro-mix turned out comparable to the micro-mix of nikitini, with about the same number of teeth and interesting bones (fulgens is not usually considered rich in vertebrate remains). Otoliths though were almost absent. At the same time, the middle fulgens fraction was much poorer: only three vertebrae, one tooth fragment and one otolith.

 

? (partial shark tooth)

 

Conclusions:
The main conclusion is the confirmation of micro-mix's productivity for teeth, the price of which, however, is a proportional increase in the number of microparticles viewed and labor spent. There are teeth indeed, but they are by no means abundant. The second conclusion is that the fulgens micro-mix in terms of productivity was not radically inferior to that of nikitini, which should appeal to those who dislike mud and large-scale excavations. However, further observation is required. Thirdly, besides teeth and very few interesting bones, there are almost no unusual finds. Finally, pyrite, which is usually not associated with Fili Park, is significantly present in the micro-mix. It is a pity that it did not affect ammonites.

Edited December 28, 2021 by RuMert

[RuMert]

Thanks for reading!

[FossilDAWG]

Thanks for the super informative posts.  That is some hard core collecting!

 

Don

[pachy-pleuro-whatnot-odon]

Wow! Though those are spectacular finds, it requires, as Don said, some pretty heavy-duty collecting to get to it. In an fully imagine that the uninitiated would find it difficult to make this spot productive. I've been at and worked on a few archaeological digs and palaeontological sites, but nothing as rough as this. Makes my favourite beach site hunting grounds look like going out for fine dining in comparison, even if done in winter. And while at my favourite nearby site the payoff's about five "meso"-fossils (including teeth) per five litre bucket, and a five litre bucket per half day of digging (which then takes a week more to sort through, but I'd still recommend over sorting in the field, as the latter will result in a much lower yield), with people having used the site for a dumping ground to (i.e., now overgrown with nettles and spiny bushes, bits of glass and other trash, occasionally mosquitoes and ticks), it still feels like a much easier site to quarry than what you're describing here, if only for the water... I admire your persistence!

[Mainefossils]

That is beautiful! I did not know such amazing sites like this existed in Moscow. I especially like the claw-like fossil that is the 7th photo in your second reply. Do you happen to know what that is? I think that the sand tubes belong to sedge larvae. They use grains of sand and organic material to build a shell around themselves. 

 

Thanks for posting! 

[RuMert]

2 hours ago, pachy-pleuro-whatnot-odon said:

but nothing as rough as this

it's not as hard as it may seem, just usual digging in mud Hard for typical hobbyists, but for hardened fans and professionals it should feel like a walk in the park (in both senses)

This year I just used holes dug by others, sifting fulgens in one of them and deepening the other to the nikitini layer. As I said, same holes are used by many people

 

[RuMert]

1 hour ago, Mainefossils said:

That is beautiful! I did not know such amazing sites like this existed in Moscow. I especially like the claw-like fossil that is the 7th photo in your second reply. Do you happen to know what that is? I think that the sand tubes belong to sedge larvae. They use grains of sand and organic material to build a shell around themselves. 

Thank you very much

This thing was believed to be shark or ratfish spine, while it does also look like pincer

[pachy-pleuro-whatnot-odon]

2 minutes ago, RuMert said:

This year I just used holes dug by others, sifting fulgens in one of them and deepening the other to the nikitini layer. As I said, same holes are used by many people

 

Same goes for the site I frequent the most (the one I described above), though it's fun that people there tend to claim holes Still, if I see how others go at their search for fossils sometimes, I wonder whether I'm not still just a hobbyist

[pachy-pleuro-whatnot-odon]

1 minute ago, RuMert said:

This thing was believed to be shark or ratfish spine, while it does also look like pincer

 

I definitely see the resemblance to a pincer, but would indeed also have said shark spine...

[RuMert]

18 minutes ago, pachy-pleuro-whatnot-odon said:

it's fun that people there tend to claim holes

If I'd just dug a hole, went for a walk and came back to find someone working in it, I'd probably claim it too But this never happened, especially as you know holes shouldn't be left unattended. With old holes I'm OK with sharing it, it's usual practice

[pachy-pleuro-whatnot-odon]

20 minutes ago, RuMert said:

If I'd just dug a hole, went for a walk and came back to find someone working in it, I'd probably claim it too But this never happened, especially as you know holes shouldn't be left unattended. With old holes I'm OK with sharing it, it's usual practice

 

Ah, "my" site isn't even frequented that much. I've yet to bump into another collector (that I didn't come with) there. So the claims last over days or even weeks, and that goes even if it's an old hole In the case of Fili Park, I can fully understand with the effort involved in getting to the right exposure  And while it takes some work to find and get to the correct exposure at "my" site as well, it can easily be done in a couple of hours. No need for standing claims, in my opinion

[Coco]

16 hours ago, RuMert said:

 

I’m also thinking of a shark thorn. Very nice !

 

Coco

[FossilNerd]

Awesome post as usual @RuMert! Thanks for taking us along on the hunt. I can almost feel the mud on my boots.
 

You had some spectacular finds. I can’t help but admire the crinoids segments. They remind me of snowflakes. 

[RuMert]

6 hours ago, FossilNerd said:

 I can’t help but admire the crinoids segments. They remind me of snowflakes. 

They are also very small. Spirit of Christmas

[jpc]

Great report, rumert.  This looks like a great fossil adventure site.  Thanks for taking us along.  Can this be dug in winter like your ammonite site?

[digit]

Spectacular report! Thanks for taking us along to a place that we'll likely not get a chance to see in person.

 

 

Cheers.

 

-Ken

[Nimravis]

You put together an outstanding report and I love all of the pictures and finds.

[RuMert]

Thank you, gentlemen. The site strangely could be dug in winter, though it seems kind of perversion to me. We'll probably try it with friends in the coming weeks just for laughs

Edited December 29, 2021 by RuMert

[digit]

The water will come out easier? as blocks of ice.

 

 

Cheers.

 

-Ken

[pachy-pleuro-whatnot-odon]

8 minutes ago, digit said:

The water will come out easier? as blocks of ice.

 

 

Cheers.

 

-Ken

 

But make sure to take a water boiler and a small generator to run it on, so that you'll still be able to melt the muck you scoop out

[RuMert]

They say frozen ground doesn't crumble as much

[Crusty_Crab]

On 12/25/2021 at 5:38 PM, RuMert said:

In addition, it contains an annoying amount of pseudo-fossils, including those similar to teeth: seeds, twigs, insects, modern shells, black phragmocons and serpula fragments, shiny pebbles, etc. In this regard, there are also objects like this:

 

As far as I understand, these belong to modern insects, if not, please correct.

 

 

Very cool report. I agree, these appear to be caddisfly larvae cases. 

[grandpa]

@RuMert I always enjoy your posts.  Thank you for posting this trip and please keep them coming.  BTW, awesome finds on this outing; what fun!