Disappointments, delights and a small surprise

You might have guessed, I’m currently spending some time prepping the finds from my last Yorkshire visit…

Here are a few updates on the fossils I’ve found and their prep status :
Lytoceras, no inner whorl :(

Lytoceras, no inner whorl 😦

The lower lias Lytoceras has become a disappointment,  as I was working around the whorl towards the inside of the nodule, several gaps in the shell appeared, where the whorl had broken apart, probably during the process of the fossilization.  The outermost part of the whorl is squashed, as I was “digging” for the inner whorls, nothing was there…
This is not unusual for luridum subzone Lytoceras, but they can be found with inner whorls preserved, as shown in the next picture of a specimen found ex-situ during another visit:
Lytoceras fimbriatum, 12 cm, with inner whorl :)

Lytoceras fimbriatum, 12 cm, with inner whorl 🙂

The Pleuroceras I´ve shown you earlier also  has become a disappointment after a promising start – there´s a big hole (more like half the whorl missing) in the outer whorl, the inner whorl is there, but it´s brittle Calcite. Oh well, another one for the graveyard of failed prep attempts aka the gravel patch beside our house…
Pleuroceras, whorl stops :(

Pleuroceras, whorl stops 😦

But there have also been delights and a small surprise…
An upper toarcian Ammonite that had recently fallen from the cliff and was just covered by a thin layer of soft mudstone went  directly to the air abrader, details that are usually lost when they roll around in the waves (or when they are embedded in hard mudstone nodules)  could be recovered, like the wonderful complete spines or this especially delightful small spiny Peronoceras (fragment ?) inside the aperture of the larger Peronoceras subarmatum.
Catacoeloceras subarmatum, 7 cm

Peronoceras  subarmatum, 7 cm

Aperture of the Catacoeloceras, with another small Catacoeloceras fragment inside

Aperture of the Catacoeloceras, with another small Catacoeloceras fragment inside

With some fossils, they may not look like anything when found but can yield surprises :
Peronoceras turriculatum, as found

Peronoceras turriculatum, as found

While roughing this Peronoceras turriculatum from the nodule, I noticed a small shelly fossil appearing after a matrix piece of about 1 x 1 cm size was dislodged by the airpen.  I stopped the airpen to take a closer look :
Peronoceras turriculatum, during preparation

Peronoceras turriculatum, during preparation

It’s a small aptychus, part of the ammonites jaw apparatus !
Apytchus inner mould, 10 x 7 mm

Apytchus inner mould, 10 x 4 mm

Since it is not inside the shell of the ammonite, it can not be safely concluded that it belongs to the ammonite, but form and size (may be a bit on the small side) seem about right, and it’s at least close to the aperture of the Peronoceras…
Peronoceras turriculatum, 7.5 cm, with aptychus

Peronoceras turriculatum, 7.5 cm, with aptychus

There is very little literature about Dactylioceratid aptychi, the only article I found is by Ulrich Lehmann describing remains of the jaw apparatus inside a Dactylioceras tenuicostatum
(Palaeonology Vol. 22, part 1, pages 265-271). He does notice that the jaw apparatus that was found inside that Dactylioceras was also smaller than expected.
Inside my prep box I then went looking for the bit of matrix that flew away (I did not see where it landed) because it took with it most of the actual shell of the aptychus. This was about half an hour after I started work on the Peronoceras and my prep box was filled with hundreds if not thousands of similar matrix shreds… While contemplating the time it would take going through the splinters one by one I picked up a few likely looking ones and after about 5 pieces I found it –  you have to lucky sometimes  !
Apytchus shell, 9 x 7 mm

Aptychus shell, 9 x 7 mm

This has been tweaked somewhat in Photoshop to better show the structure of the aptychus – the colors are not 100% exact.
In my experience, every time I come to Yorkshire to collect I usually get to take with me one special piece – this time, it´s got to be the ammonite with the aptychus !
And, as a little bonus, since this is my 30th post, here is one of the highlights of  the previous visit in April : A double Androgynoceras lataecosta, 6 & 7 cm –
what makes this one special is a Goniomya bivalve which with its v-shaped ornament sits decoratively on the whorl of the ammonite…
Androgynoceras lataecosta, 6 & 7 cm, with Goniomya bivalve

Androgynoceras lataecosta, 6 & 7 cm, with Goniomya bivalve

AndyS
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