Angulaticeras – or Schlotheimiinae part 2

No, you did not miss anything, I just decided to do part 2 before part 1,
because it fits so nicely with my previous post – a few of the ammonites for this
post was actually found on th e same day as the Bifericeras from the last post !

The whole set will be in 3 parts, part 1 will be about the Schlotheimia species
that can be found in Yorkshire only as erratics, but we will of course include
the Redcar & Cleveland Schlotheimiids (with some gaps).
Part 3 will take longest, because many of the ammonites from this part still
require careful (re)preparation and more research -part 3 will cover the genus
Phricodoceras, for which there is mounting convincement that it does not
belong, as previously thought, to the Eoderoceratidae, but to the S chlotheimiidae.

But back to Angulaticeras…

There are 2 species of Angulaticeras that I can show you, one is an early bucklandi
subzone species, that I plucked out of Byron‘s unprepped Redcar box a few years ago
for a good price, and the other a relatively rare  denotatus subzone species from
Robin Hoods Bay.

Angulaticeras often has a thin ventral groove created by rib ends projecting over
the venter line. This ventral groove is most often lost on larger specimen.
In contrast to Schlotheimia, Angulaticeras shows secondary ribbing,
i.e. bifurcating ribs, from very early on in the development.

But let‘s start with the bucklandi subzone one from Redcar :

Angulaticeras cf. charmassei (D´ORBIGNY, 1844)

Angulaticeras cf. charmassei, 9cm / 3.5 " diameter, bucklandi sz, Redcar

Angulaticeras cf. charmassei, 9cm / 3.5 ” diameter, bucklandi sz, Redcar

A big, robustly ribbed species. Angulaticeras can get quite big, I‘ve seen Somerset
specimen well above half a meter.

The next one is the denotatus subzone species from Robin Hoods Bay :

Angulaticeras sulcatum (SIMPSON, 1843)

I found the first fragmentary specimen of this species in 1996 as a small pyritic inner
mould, only a mere sliver of an ammonite:

First Angulaticeras fragment found in Robin Hoods Bay in 1996, diamater 1.6 cm

First Angulaticeras fragment found in Robin Hoods Bay in 1996, diamater 1.6 cm

I discovered my second specimen when formatting a little bit of matrix with an Eparietites
and found that there was a very small 7 mm Angulaticeras at the back :

Specimen of Eparietites denotatus, 4 cm, see next picture for what´s on the other side...

Specimen of Eparietites denotatus, 4 cm, see next picture for what´s on the other side…

Reverse of the previous specimen with small Angulaticeras sulcatum, 7 mm diameter

Reverse of the previous specimen with small Angulaticeras sulcatum, 7 mm diameter

Detail of small Angulaticeras sulcatum, 7 mm diameter

Detail of small Angulaticeras sulcatum, 7 mm diameter

Since then I‘ve been checking every likely nodule very carefully when splitting it and at
the day as mentioned above, found more signs of  ammonites :
Split nodule as found with 4 small Angulaticeras, one spilt in the middle...

Split nodule as found with 4 small Angulaticeras, one spilt in the middle…

The nodule showed signs of 3 ammonites, unfortunately one had been split in half.

I prepped the ammonite on the small bit of rock first, and discovered a tiny
Pleurotomaria gastropod sitting on it as a bonus !
Prepping the first Angulaticeras, if you look carefully you see that there´s also a gastropod...

Prepping the first Angulaticeras, if you look carefully you see that there´s also a gastropod…

Prepped Angulaticeras sulcatum, 2 cm diameter, with small Pleurotomaria, 4 mm diameter

Prepped Angulaticeras sulcatum, 2 cm diameter, with small Pleurotomaria, 4 mm diameter

The 2 remaining pieces of the nodule with the split ammonite were glued together again
after marking the position of the ammonites carefully.

Parts of nodule that contains 2 Angulaticeras glued together again and with ammonite locations marked.

Parts of nodule that contains 2 Angulaticeras glued together again and with ammonite locations marked.

The matrix was prepped down very carefully with the air pen and finished with the air
abrader once the smallest signs of ammonites showed themselves, revealing 2 small
further gastropods in the process :
The prepared specimen with two Angulaticeras sulcatum, 2 cm and 5 mm, an two small gastropods

The prepared specimen with two Angulaticeras sulcatum, 2 cm and 5 mm, an two small gastropods

The crowning specimen came along when in discussions on the Yorkshire fossil
hunters group on facebook, Mark Hawkes posted a much larger fragment of a
Robin Hoods Bay ammonite that was also identified  as Angulaticeras and which
Mark thankfully sold to me (also for a good price, thanks again Mark !).

Fragment of big Angulaticeras sulcatum, 10 cm wide

Fragment of big Angulaticeras sulcatum, 10 cm wide

This specimen is about 10 cm in width and includes inner whorls and part of a
still fully chambered next whorl, I would estimate it would have been more than
20 cm in diameter including the missing body chamber. It is very finely ribbed,
the ventral groove, being present in the juvenile, is now fully closed.
The matrix looks very much the same as the one for the smaller specimen, so it is
assumed it comes from a similar range of beds.

The Schlotheimiinae are known for large size differences of microconch [m] and
macroconch [M], and this is what we may see here as well, allthough the small
specimen show no signs of being mature, so could be juveniles as well.

What makes this specimen even more remarkable, besides its large size and
rarity, is the sharply localized, round holes in the shell, which are also
complemented by similar holes on the other side of the ammonite…

Since there´s a lot more to this specimen, it´s well worth another blog post
so we´ll explore this a bit(e) more in the near future, taking this to a
whole new dimension 😃

AndyS

Literature :

Schlegelmilch, R.,Die Ammoniten des süddeutschen Lias,
2nd revised and extended edition, Stuttgart & New York 1992

 

Howarth, M.K., The Lower Lias of Robin Hood´s Bay, Yorkshire,
and the work of Leslie Bairstow, Bulletin  58/2
of The Natural History Museum, London 2002

 

Edmunds,M., Varah, M., Bentley, A., The Ammonite Biostratigraphy
of the Lower Lias ‘Armatum Bed’ (Upper Sinemurian – Lower Plieansbachian)
at St. Peter´s Field, Radstock, Somerset, Proceedings of the
Geologists´ Assocation 114, 2003

 

Sheltered

For me the best fossils are the ones that surprise you when you prep them, because they turn
out so much better than you expected…
This specimen is one of those, this is how it was found in Robin Hoods Bay in July 2017:
Specimen as found

Specimen as found

It looked to me like a quarter section of a large Oxynoticeras, where some (I could see two)
Gagaticeras had been washed into the body chamber.
There was a little bit left of the inner whorl of that ammonite, and I decided that this might
potentially look nice when done.One additional specimen had crumbled off the relatively
brittle stone, it had lain a while in the water already.

At home, this was put on the back list of fossils that I would occasionally take another look
at, certainly not top priority. When I was air abrading another specimen, I tested the broken
off specimen, it abraded relatively easily, allthough the matrix was very sandy
(that should have told me something in the first place…).

I instantly saw that this was no Gagaticeras when the first spine appeared :

Bifericeras bifer (QUENSTEDT, 1845)

Broken off Bifericeras, diameter of ammonite = 3 cm

Broken off Bifericeras, diameter of ammonite = 3 cm

Bifericeras bifer is a very rare ammonite in the beds around Robin Hoods Bay, or,
to be more precise it is rarely found.
In all the years since 1989 I had only found Bifericeras bifer in 2016, after a cliff fall cut
through the specific beds of the bifer biohorizon.

The beds where Bifericeras bifer occurs are difficult to find in the reef, so one is
dependent on cliff falls, and of course on luck. to be there at the right time and place…

The ammonites in that fall were contained in highly pyritic lenses, unfortunately
neither very well preserved nor easy to prep.

Pyritic lens with multiple, badly preserved Bifericeras, diameter of biggest ammonite = 3 cm

Pyritic lens with multiple, badly preserved Bifericeras, diameter of biggest ammonite = 3 cm

So seeing this specimen from 2017, I was deligthed to have another Bifericeras bifer,
which had not been in my collection from Robin Hoods Bay yet, and more easily to
prep as well !

The specimen instantly went to the top of my prep list.
Preparation was not as easy as I had thought at first, the sandy matrix was made up
of harder and softer layers on the milimeter scale so I had to  alternate between air pen
to remove the harder layers and the air abrader to remove the softer layers which
were luckily mostly around the fossils.

I had finished the ammonite that is visible on the first photo and another one to the right
and was already smoothing the matrix between them, when I noticed another ammonite,
and while air abrading that one, even another one, better and bigger than all the previous
ones…

After about 6 hours of total prep time, this is the end result :
The finished specimen with 4 Bifericeras bifer within the body chamber of a large Oxynoticeras sp.

The finished specimen with 4 Bifericeras bifer within the body chamber of a large Oxynoticeras sp.

Detail of the better preserved ammonites - biggest Bifericeras bifer diameter = 3.5 cm

Detail of the better preserved ammonites – biggest Bifericeras bifer diameter = 3.5 cm

The ammonites were washed into the body chamber of the larger ammonites and were
sheltered there from compaction or getting  otherwise damaged before or during
fossilization, the shells all seem to be complete to the mouth border, though they are
most likely not adult.

They must have lain in a jumble right on the inside of the shell of the large ammonite‘s
body chamber, because there is very little matrix left at the other side, which necessitated
it being stabilized with liquid super glue to avoid accidently breaking through…
Note that the Bifericeras ammonites are all preserved with shells, so look slightly
different to those usually found elsewhere, e.g. in Gloucestershire, as pyritic inner
moulds from clay exposures, due to the preserved shell the spines are more pronounced
and seen on earlier whorls.

The most diagnostic characteristic for Bifericeras bifer is the double row of spines,
the spines being connected through a rib and the inner ones
often pointing inwards towards the center of the ammonite.  The innermost whorls up to
between 7—10 mm are smooth.

The 5 ammonites washed into the body chamber already show that there seems to be
quite some variation in spines and whorl width.
Detail of Bifericeras bifer showing double spines connected through a rib

Detail of Bifericeras bifer showing double spines connected through a rib

There are two more species of Bifericeras that occur in Robin Hoods Bay :

Bifericeras vitreum (SIMPSON, 1855) and

Bifericeras donovani DOMMERGUES & MEISTER, 1992

I do actually have a single Bifericeras vitreum, a small sharp shell preserved specimen
contained in a very similar sandy matrix as the Bifericeras bifer shown above.

Bifericeras vitreum, diameter = 2 cm

Bifericeras vitreum, diameter = 2 cm

View of the venter of Bifericeras vitreum with sharp ribbing, convex across the venter

View of the venter of Bifericeras vitreum with sharp ribbing, convex across the venter

Bifericeras vitreum has rather sharp ribs that run across the venter in a slightly convex manner.
This specimen has also been carefully prepped with air abrasion.

Bifericeras donovani from the base of the taylori subzone has so far eluded me,
allthough from the Wine Haven paper (see literature below) it appears they are
relatively abundant.

The only question now remains is : Is the ammonite that „provided shelter“
to the Bifericeras in it‘s body chamber really an Oxynoticeras or more likely
to be a Gleviceras ?

Section of Oxynoticeras sp with sutures showing, width = 9 cm

Section of Oxynoticeras sp with sutures showing, width = 9 cm

There really is not much to go from, but the venter seems to be very sharp and the
whorl lacks the fine ribbing characteristic for Gleviceras, so I‘d go for a late
Oxynoticeras grp. oxynotum, which with the sandy matrix lithology nicely fits
with (Hesselbo & Jenkyns numbering) beds 44-49 of the bifer biohorizon and their description
in PAGE 2004.

Detail of biggest Bifericeras bifer

Detail of biggest Bifericeras bifer

So in the end, that „ugly duckling“ of an incomplete ammonite has (been) transformed into
a stunning „swan“ of a multi ammonite, multi species specimen with a story to tell.

On the same day I found this specimen, two other, no less interesting ammonite
specimen were found, more about these soon…

AndyS

 

Literature:
  • Schlegelmilch, R.,Die Ammoniten des süddeutschen Lias, 2nd revised and extended edition,
    Stuttgart & New York 1992
  • Howarth, M.K., The Lower Lias of Robin Hood´s Bay, Yorkshire, and the work of
    Leslie Bairstow, Bulletin  58/2 of The Natural History Museum, London 2002
  • Meister/Eberhan/Blau/Dommergues/Feist-Burkhardt/Hailwood/Hart/Hesselo/Hounslow/
    Hylton/Morton/Page/Price,
    The Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian
    Stage (Lower Jurassic), Wine Haven, Yorkshire, UK, 2006
  •  Page,K.N., Normanby Stye Batts – Miller´s Nab (Robin Hood´s Bay),
    North Yorkshire (NZ 972 025- NZ 952 075), in : British Lower Jurassic Stratigraphy,
    Geological Conservation Review Series, JNCC Peterborough 2004, pp. 250-262

The lost Arnioceras or The hunt for a name

There are specimen that are appear unremarkable when you collect them, and you don´t
have high hopes for them,  but you take them home anyway.

 

Nodule with ammonite in3 pieces as found

Nodule with ammonite in3 pieces as found

This was very much the case for this specimen shown as found ex-situ in
Robin Hoods Bay this March. It just showed the section of an ammonite
on the side of the nodule, when formatting the rock, the part containing the
ammonite also fell into 3 pieces due to natural cracks.
I think there might have been a moment when I thought of chucking the
bits into the sea,  but the breaks were clean and promised to be simple to
glue so it went into the bag…

For one of the final stages of prepwork, which the air abrading usually is for me,
I often accumulate a few specimen that have been previously roughly prepared
with a big pen, then fine prepped with a small pen and just need that little bit of
extra cleaning with the air abrader – preparations before and cleaning up after
air abrading take some time and I usually don’t do that for single specimen.

I had glued the parts of the small nodule back together again, and after finishing
my other specimen to be abraded,  I had a bit of powder still in the tank and
decided just to test the ammonite to see what it was.
With nodules that have been weathering or a while that usually works, even if
the nodule itself is not completely abradeable due to increasing hardness of the
matrix when the weathered layer is off.

To my surprise, I could just keep on abrading…
The matrix was soft enough to be abraded at a relatively low pressure (3.5 bar),
the ammonite´s shell was beautifully preserved in dark grey calcite, and the
ammonite had a very strong undamaged keel.

I had initially wondered if it could be an Arnioceras, and that seemed to be the
correct genus identification.

 

Arnioceras sp., 5 cm diameter

Arnioceras sp., 5 cm diameter

BUT: I had never found a Yorkshire Arnioceras that could be air abraded from the matrix.
I don´t think even a very weathered semicostatum  matrix e.g. from the Holderness Coast
ever becomes abradable.
AND it looked different from all the species I had described in an earlier blogpost (link).

The innermost whorls up to about 1 cm are relatively smooth just like in Arnioceras semicostatum,
but the ribbing is more straight and finishes almost abruptly at the edge of the venter.

 

Arnioceras sp., 5 cm diameter, view of keel

Arnioceras sp., 5 cm diameter, view of keel

 

The keel on the venter is very strong, similar to Arnioceras falcaries, but
it´s whorl section is more rectangular.
It also has less ribs per whorl than the species mentioned : about 25 ribs / whorl at 5 cm diameter.

 

Arnioceras sp., 5 cm diameter, view of keel & whorl section

Arnioceras sp., 5 cm diameter, view of keel & whorl section

So I started getting out the books…(which in these days most of the time is
starting the full text database on the computer)
First candidate I found was Arnioceras oppeli GUÉRIN-FRANIATTE, but while whorl
section,  style of ribbing and keel was a good match,  the count of ribs/whorl of my
specimen was lower, and A. oppeli seems to not have smooth innermost whorls.

 

Arnioceras bodleyi (J. BUCKMAN), 7 and 5 cm diameter, Kilve/Somerset

Arnioceras bodleyi (J. BUCKMAN), 7 and 5 cm diameter, Kilve/Somerset

I then remembered the purchased Kilve/Somerset Arnioceras specimen I have in my
collection, which is Arnioceras bodleyi (J. BUCKMAN, 1844).
(incidentally it was James BUCKMAN, not SS BUCKMAN, who “founded” this species
(in the words of his son Sidney Savoury BUCKMAN, of “Yorkshire type ammonites”
fame)).
Very good match with the strong keel, style of ribbing, but again slightly less ribs/whorl
in my specimen, and maybe less compressed than the Kilve specimen, and no keel
furrows.
I was ready to call it a close enough match at this point in time. But I still had that
nagging thought that you have when something does not completely fit…

As a final check I consulted with some friends from the facebook Yorkshire fossils
collectors group if they had seen a similar Arnioceras from a soft matrix –
and Dave showed me a perfectly matched specimen from Redcar, in a very soft matrix !

Now two occurrences of Arnioceras in soft matrix make a pattern, so I scanned
HOWARTH´s summary of Bairstow´s collection again for Arnioceras from
Robin Hoods Bay – and found mentions of Arnioceras above the semicostatum
subzone, in the turneri zone, birchi/brooki subzone !

Ammonites from these subzones in Robin Hoods Bay show exactly the same style of
preservation and “abradebility”, unfortunately HOWARTH does not figure them,
the brooki subzone Arnioceras from the Bairstow collection are mentioned as
“?Arnioceras sp. indet. 1,lost”, and I unfortunately don´t remember from my last visit
what the two specimen from the birchi subzone housed in the collection looked like.

So back to the database…what species of Arnioceras occurs above the semicostatum
subzone ?

Kevin Page´s paper “The lower Jurassic of Europe: its subdivision and correlation”
delivers a hint on Arnioceras hartmanni from the brooki subzone, but no figure…

No luck in the Palaeontological Association´s “Fossils from the Lower Lias of the
Dorset Coast”  either – “not figured“.

But finally Alpheus Hyatt´s “Genesis of the Arietidae” has a figure (Plate II, fig. 17)  –
and it´s a perfect match and he also mentions that it can be found in the Whitby area !!!
Similarly fitting is D’ORBIGNY´s specimen of “Ammonites kridion” which was revised to
“Ammonites hartmanni” by OPPEL which I found after a bit of internet research in the
Paris Muséum National D’Histoire Naturelle’s online collection (very nice !)

It is still somewhat “circumstancial evidence”, since the ammonite was found ex-situ,
and of course therefore I cannot with absolute certainty know that this ammonite
really is from the brooki subzone but I think it´s close enough to give it a name,
at least with a “cf.” :

Arnioceras cf. hartmanni (OPPEL)

So if anyone has a Caenisites brooki together with an Arnioceras from Robin Hoods Bay,
please let me know, for final proof 🙂

Anyway, who would have thought that you can spend this much fun time on a rainy
weekend prepping and digging through palaeontological history on this (only seemingly)
unremarkable little ammonite ?
The excitement of the fossil hunt becomes the hunt for a name, which to me can be
almost as exciting.

AndyS

Literature and Links :

Paris Muséum National D’Histoire Naturelle’s online collection, “Ammonites kridion” :
Schlegelmilch R. (1992), Die Ammoniten des süddeutschen Lias, 2nd Ed,
Gustav Fischer Verlag
Howarth M.K. (2002),  The Lower Lias of Robin Hood´s Bay, Yorkshire, and the work of
Leslie Bairstow, Bulletin of The Natural History Museum Geology Series Vol. 58/2, London
Oppel  A. (1856), Die Juraformation  Englands,  Frankreichs  und des südwestlichen Deutschlands.
Jahreshefte  des  Vereins  für  vaterländische  Naturkunde  in Württemberg
Hyatt, A. (1889), Genesis of the Arietidae, Smithonian Contr. Knowl., Washington
Page, K. (2003), The Lower Jurassic of Europe: its subdivision and correlation,
Geological Survey of Denmark and Greenland Bulletin 1

A prickly ammonite and it’s spine-less partner – Xipheroceras and Promicroceras

Glorious Xipheroceras ziphus, width 8 cm, venter view, with spines mostly intact. Purchased from Mike Marshall.

Glorious Xipheroceras ziphus, width 8 cm, venter view, with spines mostly intact.
Purchased from Mike Marshall.

Since approximately the 1800s there have been single observations (d’Orbigny, … ),
since the 1960s (Makowski 1962, Callomon 1963),it was scientifically recognized that
there are certain ammonite shells, found in the same beds, that may be showing
signs of sexual dimorphism – usually with these specimen, the most inner whorls are
the same for the dimorphs, after that growth of the partners diverge, with one partner,
today assumed to be the female (= macroconch) showing continued growth and/or
changes in the sculpture of the shell, while the other, assumed to be the
male (= microconch) , remains relatively small with little sculptural changes.

One of the most obvious potential (we shall never know for sure…) dimorphic pairs is
Promicroceras / Xipheroceras.

Xipheroceras ziphus, width 8 cm, with spines mostly intact.

Xipheroceras ziphus, width 8 cm, with spines mostly intact.
“Promicroceras” early growth stage clearly visible.

Promicroceras planicosta 23 mm. In this view the flattening of the ribs at the venter can be seen.

Promicroceras planicosta 23 mm. In this view the flattening of the ribs at the venter can be seen.

For about the first 15-20 mm, the whorls of Promicroceras and Xipheroceras are
indistinguishable, after that, Xipheroceras as the macroconch develops broader whorls,
strong spines and a change in ribbing, attaining sizes up to more than 30 cm
while Promicroceras as the microconch does not grow much beyond 30-40 mm,
never changing its sculpture.

The following species have been found at Robin Hoods Bay:

Xipheroceras ziphus (ZIETEN, 1830)
Cluster of 2 Xipheroceras ziphus, both 4 cm. This one has a spine nearly fully preserved.

Cluster of 2 Xipheroceras ziphus, both 4 cm.
This one has a spine nearly fully preserved.

Cluster of 2 Xipheroceras ziphus, both 4 cm

Cluster of 2 Xipheroceras ziphus, both 4 cm

Xipheroceras ziphus, 5 cm. Not all specimen come as beautiful preserved as the other ones shown - this was found on the bottom of a 20 cm deep seawater puddle...

Xipheroceras ziphus, 5 cm.
Not all specimen come as beautiful preserved as the other ones shown –
this was found on the bottom of a 20 cm deep seawater puddle…

Small 22 mm specimen of Xipheroceras ziphus. When prepping, I thought this was a Promicroceras - until I found the first spine !

Small 22 mm specimen of Xipheroceras ziphus.
When prepping, I thought this was a Promicroceras – until I found the first spine !

Small 22 mm specimen of Xipheroceras ziphus, venter view. Broadening of the ribs on the venter clearly visible, also the first spine & widening of the shell

Small 22 mm specimen of Xipheroceras ziphus, venter view.
Broadening of the ribs on the venter clearly visible, also
the first spine & widening of the shell

On the first 15-20 mm the ammonite develops just like a Promicroceras, after
which the shell shows strong spines at about every 30-40 degrees and an otherwise
weakening of the ribs inbetween.
Spines stop at about 50-70 mm, only the weak ribbing continues.

Xipheroceras dudressieri (D´ORBIGNY, 1844)

Xipheroceras dudressieri, 6 cm. Holderness coast specimen, D. Pearson collection

Xipheroceras dudressieri, 6 cm. Holderness coast specimen, D. Pearson collection

Xipheroceras dudressieri, 6 cm, keel view. Holderness coast specimen, D. Pearson collection

Xipheroceras dudressieri, 6 cm, keel view. Holderness coast specimen, D. Pearson collection

Xipheroceras dudressieri, 8 cm. Somewhat crushed and oyster encrusted specimen from RHB

Xipheroceras dudressieri, 8 cm. Somewhat crushed and oyster encrusted specimen from RHB

In contrast to X. ziphus, the ribbing of X. dudressieri continues well beyond the
“Promicroceras” stage, and the spines are nowhere near as strong, but on every rib .
EDMUNDS et al suggested a potential synonymy with X. planicosta as a
junior synonym, see literature.

Promicroceras planicosta (SOWERBY, 1814)

Promicroceras planicosta in typical nodule, ammonite diameter 22 mm

Promicroceras planicosta in typical nodule, ammonite diameter 22 mm

Promicroceras (2 small specimen), Xipheroceras (specimen in middle, 2 cm ) and Asteroceras blakei (6 cm)

Promicroceras (2 small specimen), Xipheroceras (specimen in middle, 2 cm ) and Asteroceras blakei (6 cm)

Promicroceras is relatively common and can be found associated with Asteroceras and
of course Xipheroceras.
Promicroceras planicosta has about 24 ribs/whorl at 3 cm, and a characteristic
broadening/flattening of the ribs on the venter.

Promicroceras capricornoides (QUENSTEDT, 1884)

From a lower level (birchi – lower obtusum), occurs at RHB but has not been found by me yet –
it is characterized by less ribs/whorl (19 @ 3 cm vs 23-24 for planicosta) and a less pronounced
broadening/flattening of the ribs on the venter – something to go looking for next year !

Marston Magna specimen

Promicroceras and Xipheroceras from Marston Magna area. Xipheroceras approx 4 cm in width.

Promicroceras and Xipheroceras from Marston Magna area. Xipheroceras approx 4 cm in width.

Xipheroceras and Promicroceras have been described in great detail from an excavation
in the Marston Magna area recently by
EDMUNDS,WHICHER, LANGHAM, CHANDLER (see literature).

This specimen was obtained through ebay as a comparison example for Promicroceras,
the later discovery of a well spined Xipheroceras was an added bonus !
Rarity (I´ve found less than 10 specimen in 27 years) and a potentially stunning
preservation make up the appeal of these ammonites, and there is certainly much still
to be learned about their evolution.
The beds in Robin Hoods Bay are not exposed often, and are protected as an
SSSI – only responsible collecting is allowed.

AndyS

Literature :

Callomon J.H. (1963), Sexual dimorphism in Jurassic ammonites // Trans. Leicester Liter., Philos. Soc. Vol. LVII. P. 21-56.
Makowski H. (1962), Problem of sexual dimorphism in ammonites // Paleont. Polonica. no.12. 92 p.
Makowski H. (1971), Some remarks on the ontogenetic development and sexual dimorphism in the Ammonoides // Acta geol. Pol. V.21. no.3. Р.321-340.
Palframan D.F.B. (1969), Taxonomy of sexual dimorphism in ammonites: morphogenetic evidence in Hecticoceras brightii (Pratt) // Int. Union of Geol. Sci. Ser.A. no.1. P.126-154.
Rollier L. (1913), Sur quelques Ammonoïdes Jurassiques et leur dimorphisme sexuel // Arch. Sci. Phys. et Natur. Geneve. Sér.4. T.XXXV. P.263-288.
Schlegelmilch R. (1992), Die Ammoniten des süddeutschen Lias, 2nd Ed, Gustav Fischer Verlag
Cope J. (1994), Preservation, sexual dimorphism and mode of life of some Sinemurian
ammonites // Palaeopelagos Special Publication I, Rome
Howarth M.K. (2002),  The Lower Lias of Robin Hood´s Bay, Yorkshire, and the work of Leslie Bairstow, Bulletin of The Natural History Museum Geology Series Vol. 58/2, London
Edmunds M., et al. (2016), A systematic account of the ammonite faunas of the Obtusum Zone (Sinemurian Stage, Lower Jurassic) from Marston Magna, Somerset, UK. Proc. Geol. Assoc.

“Show me the keel, please” – or : A nodular mystery

When I´m asked to identify an ammonite from a picture, I often have to say
“show me the keel, please”,  because especially with liassic ammonites, a safe
identification of an ammonite cannot be done without  having a view of the keel.
The following example illustrates this best…

 

The mystery nodule with a partially prepared ammonite

The mystery nodule with a partially prepared ammonite

This nodule with a partially prepped ammonite was shown by David in the Yorkshire
Fossil Hunters group on facebook a while ago.

The fossil was found on the Holderness Coast as a glacial erratic, so age wise this can
basically be anything – from lower jurassic to cretaceous.
The keel of the ammonite was not prepped at this state, so identification was pure
speculation –  Schlotheimia and Caenisites were proposed candidates.

Intrigued by the nodule and the mystery, I offered David to try and prep this ammonite.
We met this summer in Robin Hoods Bay, exchanged the ammonite, and David also
allowed me to photograph another beautiful and rare ammonite,
a Xipheroceras dudressieri, which you will see in another blog post soon…

The matrix the ammonite is embedded in – a greyish-brown, relatively hard clay ironstone
like concretion – did not aid a lot in the identification – it could still be
hettangian (Schlotheimia), sinemurian (Caenisites), or even pliensbachian (Pleuroceras)
or some non-liassic formation unknown to me.

When I returned home after my vacation, I started prep work on the ammonite.
The matrix was still just soft enough to be air abraded using iron powder,
so my first check was wether this ammonite actually had a keel
(Caenisites, Pleuroceras,…) or just a furrow (Schlotheimia..).

After about an hour of carefully working towards the keel, first with an air pen, and then
with an air abrader, it was clear that the ammonite does actually have a keel, so it had to
be Caenisites – but wait, the keel is relatively strongly crenelated – could it be a Pleuroceras ?

Counting the ribs it would have to be a Pleuroceras apyrenum, and there is a bed that actually
produces nodules like these, so I went on based on this assumption…

Is this a Pleuroceras keel which I see before me ?

Is this a Pleuroceras keel which I see before me ?

Seing the beautiful preservation of the ammonite
(a milk cholcolate brown shell on a solid calcite core –
doesn´t that make your mouth water 🙂 ), I decided to completely prep the side
of the ammonite still completely hidden in the  concretion as well.

It is never without risk to prepare an ammonite from both sides, the ammonite might
break, or the innermost whorl might just blow through.

Since the concretion had some calcite-filled shrinkage cracks as well which might be
breaking points, I had to prep it most carefully and as vibration free as possible, so I
did most of the work with the air abrader, after securing the innermost whorl with a
drop of super glue, from the other side, just to be safe 😉

Keel of ammonite with deep furrows

Keel of ammonite with deep furrows

A few hours on, the furrows on the side of the keel I exposed got deeper and deeper…
Back to the books – no, there is no Pleuroceras where the furrows are that deep, even
taking into account that this specimen has shell preserved.

That means, it has to be a Caenisites after all, more specifically a Canisites turneri .
I had previously only seen smaller specimen without shell, so the crenelated keel
on larger whorl sizes is new to me.

After about 10 prep hours, here in it´s full beauty :

Caenisites turneri BUCKMAN 1925, 65 mm, found Holderness coast, D. Pearson collection

Caenisites turneri BUCKMAN 1925, 65 mm, found Holderness coast, D. Pearson collection

In summary, I think this shows how difficult it is to identify an ammonite without
having full view of all the diagnostic characteristics.

It´s been an absolute pleasure to prepare this ammonite
(but remember : Don´t ask me, I will ask you…), and of course it yielded a few more
good pictures of this species for the book and this blog.
The ammonite will be returned in the next couple of weeks to David, with special thanks .

AndyS

Robert´s Hammatoceras – a Yorkshire first ?

After I had met Robert for the crinoid & starfish block (see here), he also showed
me an ammonite he had found at Blea Wyke in situ on facebook :
Hammatoceras ammonite in situ, picture courtesy of R. Taylor

Hammatoceras ammonite in situ,
picture courtesy of R. Taylor

It came from the Grey Sandstone beds of the Grey Sandstone member of the upper lias,
?dispansum Zone.

We had briefly discussed it over facebook and consensus was that it could be a
Hammatoceras. I offered to prep it as well, price as usual – a photo for the book.
Unfortunately we had at that time already left Yorkshire again, so Robert posted
the ammonite to me, and after arrival  I could confirm that it is actually a
Hammatoceras.

I took a good look and did some exploratory prep of the inner whorls on one side.
Unfortunately it did not look so good, no inner whorl became visible, there were
only slight brown discolorations so I put it on side for a while.

All literature available to me did not mention any Hammatoceras from Yorkshire
so I contacted the Zoé Hughes, curator for ammonites at the NHM,
and Crispin Little, senior lecturer at Leeds University who had a project
cataloguing some finds of a student of his from the Ravenscar area,
but both confirmed they had not seen a Yorkshire Hammatoceras.

So when the time came to do the final prep on the ammonite
(I had promised to give it back to Robert this summer 🙂 ),
I decided to check the other side, where a part of the inner whorl was visible.

Hammatoceras ammonite as found, picture courtesy of R. Taylor

Hammatoceras ammonite as found,
picture courtesy of R. Taylor

Since most of the outer whorl on this side was eroded away, it was an easy decision to
remove the remnants of the outer whorl, bowling it out so it could still be seen from
the other side.

After about 10 hours total this is how it looks now :

Hammatoceras cf. semilunatum, 10 cm inner whorl

Hammatoceras cf. semilunatum, 10 cm inner whorl

It was relatively difficult to prep, what is preserved of the shell is mostly sideritic, at the
surface probably converted to limonite,  but overall very soft and brittle. The innermost
whorls are mostly not there.

But at  it´s still a very nice and especially rare ammonite – looks like a Yorkshire first !
Hammatoceras cf. semilunatum, 15 cm, keel view

Hammatoceras cf. semilunatum, 15 cm, keel view

Diameter of the inner whorl is 10 cm, including the crushed outer whorl it is about 15 cm.
I would tentatively put this towards Hammatoceras cf. semilunatum (QUENSTEDT, 1885)
– it has about 46 ribs on the whorl, and an umbilical width of about 30 %, which fits nicely.

Congratulations to Robert on this rare find – just goes to show what still can be found by
persistent collecting and a bit of luck !

And of course thanks very much for the opportunity to prep & photograph this ammonite !

AndyS

Addendum :
It looks like it was not actually the first Hammatoceras found in Yorkshire 😦 – Tate & Blake mention finds by Wright and Leckenby (from the Holderness coast), Wright describes finds from both the Grey and the Yellow sandstone beds at Ravenscar, but does not figure them. Since none of the newer literature mentions this, these finds may have either not been entered into a collection, lost or insufficiently documented.

Pleuroceras – the other amaltheid ammonite

Pleuroceras paucicostatum, 90 mm, Hawsker Bottoms

Pleuroceras paucicostatum, 90 mm, Hawsker Bottoms

The Yorkshire ammonites of the genus Pleuroceras have for some reason given me more
of a headache than other genera (not as much as the Aegoceras/Androgynoceras though !),
over the years I’ve made multiple attempts to get my head around the differences between
the species, but only the most recent and most thorough attempt has resulted in an
understanding satisfactory to me. At first glance, the species seem to be very similar, and
only when you dig deeper into morphological measurements such as rib count, relative
whorl height/breadth and most importantly, their stratigraphical position and  appearance
of their surrounding matrix, their differences and development become clear.

As M.K. Howarth noted in his 1958 monograph about the Amaltheidae, some of the
species appear to have evolved in Yorkshire and therefore, transitional specimen are
common, which adds to the difficulty distinguishing some of them.

The following species occur in Yorkshire :

  • P. solare
  • P. solare var. solitarium
  • P. apyrenum
  • P. hawskerense transient elaboratum
  • P. hawskerense
  • P. paucicostatum
  • P. birdi

For completeness, I’ve added one more species, which does occur in Britain,
though due to a non-sequence in the relevant beds, not in Yorkshire :

  • P. salebrosum
There potentially is a small overlap between genera Amaltheus and Pleuroceras,
but again it is  relatively unlikely to find those genera together due to a non- sequence,
i.e. missing beds in Yorkshire – find a list of all Amaltheus and Pleuroceras species and
the bed numbers for Hawsker Bottoms (compiled from Howarth 1958, Page 2004)
below :
Occurrence of Amaltheidae in Yorkshire

Occurrence of Amaltheidae in Yorkshire

This post also took longer to create due to the fact that I re-prepped a large portion of
the specimen, which predominantly have been found more than 10 years ago – that´s
not to say that chances to find specimen like these are lower today for most species,
though probably in no way as good as they were when M.K. Howarth wrote his
Amaltheidae monograph in 1958.
I had tried to air abrade a specimen that had a lot of fractured and torn light brown
shell and the result was so convincing (and addictive) that I did most of the specimen
in my collection.  Here is an example of the transformation :
Pleuroceras paucicostatum, 60 mm, before and after air abrading with iron powder

Pleuroceras paucicostatum, 60 mm, before and after air abrading with iron powder

But let´s get to the description of the different species, ordered more or less in ascending stratigraphical order.

Pleuroceras solare (PHILLIPS)

Pleuroceras solare, 80 mm, Hawsker Bottoms

Pleuroceras solare, 80 mm, Hawsker Bottoms

Pleuroceras solare for me is a rare species – I´ve only got one in my collection,
and I´ve only realized I´ve had it during the research for this post.
It is significantly bigger than the neotype shown by Howarth, which added to
the difficulty in correctly assigning it. Preservation is markedly different from all
the other species, most significantly the matrix it is embedded in is oolitic,
typical for Hawsker bed 25, and the internal mould is preserved in
light brown / light grey calcite.
Pleuroceras solare, detail of ribs & keel

Pleuroceras solare, detail of ribs & keel

Ribs are sharp and swing forward at the edge of the venter, they do not meet the even
on the internal mould strongly crenulated keel, smooth areas at the side of the keel
remain. On the bigger outer whorls of this specimen the ends of ribs at the are slightly
heightened.
Rib density appears to be relatively constant, the cast of the neotype I´ve procured
from GeoEd (see also here) has the same 28 ribs as myspecimen at almost double
the size.
Pleuroceras solare, 40 mm, cast of neotype, Hawsker Bottoms

Pleuroceras solare, 40 mm, cast of neotype, Hawsker Bottoms

Perceived rarity of these ammonites may also have something to do that Hawsker
bed 25, the “Pecten Seam” is only about 40 cm thick – my find did not come from
in situ, note to myself : Goal for 2016 = find bed 25 in situ…

 

Pleuroceras solare (PHILLIPS) var solitarium (SIMPSON)

Pleuroceras solare var. solitarium, 41 mm, Kalchreuth/Germany

Pleuroceras solare var. solitarium, 41 mm, Kalchreuth/Germany

This ammonite, though it should occur in Yorkshire, has not (yet) been found by me,
so I´ve procured a specimen from the german Kalchreuth quarry.
The only difference between this one and P. solare is that the var. solitarium has
larger tubercles on the inner whorls, and therefore a lower rib density up to 25 mm.
A specimen in the Whitby museum is displayed here :
http://www.whitbymuseum.org.uk/type/grp11/wm500.htm

 

Pleuroceras paucicostatum HOWARTH

Pleuroceras paucicostatum, 80 mm, with slight pathology, Hawsker Bottoms

Pleuroceras paucicostatum, 80 mm, with slight pathology, Hawsker Bottoms

P. paucicostatum has less dense ribs than P. hawskerense, especially visible on
the inner whorls. Ribs are straight and strong, there is a sharp bend forward
at the edge of the venter, the keel is strong and almost smooth on the internal
mould. Especially on the inner whorls the ribs are a little thicker and slightly
raised on both ends.
I my collection this appears to be the most common species, but I´m sure this
is due to severe collecting bias – once you know what nodules from Hawsker
bed 33 look like, and that they often contain ammonites, you´re more likely
to look for them again…
Detail of Pleuroceras paucicostatum, showing sutures and ribbing

Detail of Pleuroceras paucicostatum, showing sutures and ribbing

 

Pleuroceras birdi (SIMPSON)

I have not yet found P. birdi, which is very similar to P. paucicostatum in everything
except whorl breadth – the whorls of P. birdi are significantly thicker.
Only 2 specimen were known at the time of writing of Howarth´s monograph,
one from Hawsker Bottoms, one from Raasay.
The holotype is in Whitby museum (WM278) and can be seen on their website at

I have to look at that specimen “live”, from the picture there appears to be a bit of a
bend at about 1 o´clock in the shell and a successive increase in whorl thickness –
a possible parasitic growth on the shell and  potential cause of a forma aegra augata ?
The specimen seems to be preserved on one side only, the other side appears
to be eroded – if indeed the specimen is pathological, a possible structural
compensation cannot be estimated.

 

Pleuroceras salebrosum (HYATT)

Pleuroceras salebrosum, 60 mm, Holderness Coast (coll. A. Tenny)

Pleuroceras salebrosum, 60 mm, Holderness Coast (coll. A. Tenny)

Pleuroceras salebrosum is unlikely to occur in Yorkshire – both the transiens and
salebrosum zonules appear to be missing in the beds (PAGE 2004).
Nevertheless, a magnificent specimen has been found by A. Tenny
(superb prepwork by M. Marshall) on the Holderness coast – it´s pre ice age origin
is unclear.
Many thanks to Andy Tenny for letting me photograph this great specimen.

 

Pleuroceras apyrenum (BUCKMAN)

Pleuroceras apyrenum, 81 mm, cast of holotype

Pleuroceras apyrenum, 81 mm, cast of holotype

I´ve shown the GeoEd cast of the holotype before,  the main reason to procure
this cast was of course to verify identification of my Hawsker specimen
of P. apyrenum. Over the 27 years of collecting on the Yorkshire coast,
not many specimen of P. apyrenum have found the way into my collection,
and it is the Pleuroceras species I´ve had the most trouble of getting it
identified to an acceptable degree of probability.

With P. apyrenum, there appear to be 2 variants; one where the ribs get reduced
to a fine striation from up to 30-40 mm, and another one where this does not
happen, like in the holotype. I have so far at Hawsker only found specimen up
to 60 mm and a large fragment, where no reduction of the ribs takes place,
and some smaller specimen with an early reduction of ribs.

Measurements of P. apyrenum specimen

Measurements of P. apyrenum specimen

All specimen have been measured and fall into the variation breadth of P. apyrenum.
One specimen is somewhat closer to Pleuroceras quadratum, especially to the
specimen on table VIII, 4a,b which unfortunately has no measurements listed in
Howarth´s monograph and was not available as a cast.

Some of the specimen are also available on GB3D at http://www.3d-fossils.ac.uk/,
a great initiative making museum specimen available as high-resolution 2D and 3D
pictures.

At the moment I´m not totally convinced that P. quadratum is only occurring outside
of Yorkshire, or for that matter that some of the specimen listed in Howarth´s
monograph  as P. quadratum should not really be P. apyrenum.

A note for my continental readers who wonder about what P. apyrenum looks like in the UK –
the continental “version” of the same age indeed looks slightly different,
and often develops tubercles which are unknown in the Yorkshire population.

 

Pleuroceras hawskerense (YOUNG & BIRD)

Pleuroceras hawskerense, 107 mm

Pleuroceras hawskerense, 107 mm

The Hawkser Pleuroceras – an iconic ammonite, evolved in Yorkshire – so truly
born and bred Yorkshire !
P. hawskerense has characteristic densely ribbed inner whorls, strong radial
ribs and a stong keel, rib density is always bigger than P. paucicostatum apart
in large body chambers of both species. P. hawskerense is best preserved in
bed 42 (shown here (link)) and 43 at the top of the hawskerense subzone,
the specimen pictured above is from bed 43.
These beds, especially bed 43, where exposed, have been more or less exploited
over the centuries, so that well-preserved new finds are rare.

 

Pleuroceras hawskerense (YOUNG & BIRD) transient elaboratum (SIMPSON)

 
Pleuroceras hawskerense transient elaboratum, 82 mm, Hawsker Bottoms

Pleuroceras hawskerense transient elaboratum, 82 mm, Hawsker Bottoms

 
P. hawskerense transient elaboratum, in newer literature just P. elaboratum,
is a Pleuroceras population ancestral to P. hawskerense, specimen have the
same densely ribbed inner whorls, but higher rib density
(30 – 38 ribs instead of 25-30 in P. hawskerense) on whorls of more than
40 mm. Both the specimen in Whitby museum (WM:SIM302) displayed here :
and the specimen in my collection display a slightly sunken in keel on the
outermost whorl.
Pleuroceras hawskerense transient elaboratum, 130 mm, Hawsker Bottoms

Pleuroceras hawskerense transient elaboratum, 130 mm, Hawsker Bottoms

 

Summary of measurements
All measurements for the Pleuroceras species mentioned here, both for the specimen in Howarth´s monograph and the specimen in my collection
can be found here :
Measurements of Pleuroceras species

Measurements of Pleuroceras species

Rib density curves showing the complete variation of the species´rib density based
on ammonite diameter can be found in Howarth´s monograph.

So far this has been the blog post I invested the most work in – both in terms of
re-prepping specimen in my collection, and the amount of research needed until
I myself was happy with the result.
I´ve got a feeling that Pleuroceras is somewhat under-represented in Yorkshire
collections, may be because the ironstone nodules containing the ammonites
can be excruciatingly hard and tough – the name “ironstone” already says it,
I´ve many times given up on large nodules myself.
Therefore they rarely “pop open” with a perfectly preserved fossil, and
subsequently require significant work to prep the fossil – if at all possible,
when the inner whorls are preserved in a single “crystal” of solid calcite.

I hope I´ve shown that the result can be well worth the effort –
Pleuroceras is a stunning ammonite and some species are more or less
unique for Yorkshire.

AndyS

 Addendum Feb. 26, 2017 :

 Well, the Holderness coast has again delivered a surprise…
A friend who has recently visited the coast, sent me a picture today for identifiction.
The ammonite shown is a large, 140 mm diameter specimen and judging by the keel, is a
Pleuroceras – but it has massive thorns on the inner whorls !

Pleuroceras cf. yeovilense, 140 mm, Holderness Coast

Pleuroceras cf. yeovilense, 140 mm, Holderness Coast

 The only Pleuroceras species that has thorns like this is Pleuroceras yeovilense, not usually known from this high up,
below the GeoEd cast of the holotype :

Cast of holotype of Pleuroceras yeovilense, 60 mm diameter

Cast of holotype of Pleuroceras yeovilense, 60 mm diameter

Congratulations to the finder and thanks for sending me the picture !

Literature

M.K. Howarth : The Ammonites of the Jurassic Family Amaltheidae in Britain, Palaeontographical Society London, 1958
K.N. Page : Castlechamber to Maw Wyke, North Yorkshire in : British Lower Jurassic Stratigraphy, JNCC Peterborough, 2004

Gemmellaro*´s ammonite – scratch one off the “Wanted” list !

Gemmellaroceras rutilans (SIMPSON, 1843), diameter 40 mm

Gemmellaroceras rutilans (SIMPSON, 1843), diameter 40 mm

 

In May this year, Byron messaged me a picture of an ammonite which had been found
by Ricky at Ravenscar (presumably the side towards Robin Hoods Bay, i.e. Wine Haven),
asking me for an identification.

The small ammonite has a diameter of exactly 40 mm and is preserved as a somewhat
pyritic internal mould on a small block of shelly matrix.

Significantly, this matrix also contains pieces of Pinna bivalves which is usually indicative
of the jamesoni zone, taylori subzone, of the lower lias – so no guessing necessary for
identifying the stratigraphy, which can be a big bonus when identifying ex-situ ammonites
from the Yorkshire coast.

At that point I was prepping another small specimen from this zone with an Apoderoceras
so I figured it had to be the same thing and identified it as such…

A few days later Byron put this ammonite up for sale and (you know me) I could not resist….
The ammonite was picked up from Byron´s shop in Whitby this summer and went home
with me. Usually, ready-for-drawer ammonites like this one queue up on my desk for final
identification and a label.

A few months later, until this weekend in fact, it was still sitting on my desk for
identification…It had turned out that identification was not as easy as I had hoped,
it was not an Apoderoceras, no nodes on the thin ribs, and from the small remaining
bits of shell it looks like the ribs would barely be visible under the shell…

The ammonite at 40 mm diameter is a mostly complete adult, as the crowding of the sutures
suggests, and has about half a whorl of body chamber preserved.

Trifid lateral lobe of the suture (marked L) and crowding of sutures towards the aperature, indicating an adult specimen

Trifid lateral lobe of the suture (marked L) and crowding of sutures towards the aperature, indicating an adult specimen

I had identified a possible match with Epideroceras sociale, especially with the style of
ribbing on the inner whorls, but since Epideroceras is getting much larger and develops
much thicker whorls when adult, this match fell through…

Having about half an hour to kill before lunch would be ready this Sunday,  I was
browsing Howarth´s 1962 “The Yorkshire Type Ammonites and Nautiloids of YOUNG
and BIRD, PHILLIPS, and Martin SIMPSON”, looking for something entirely different
and stumbled across the pictures of Polymorphites rutilans (SIMPSON, 1843)
(now Gemmellaroceras rutilans) on table 15 – a perfect match with the crenelated keel
of my ammonite.

The ribs crossing the venter created a crenelated keel

The ribs crossing the venter created a crenelated venter

I had not had Gemmellaroceras on my list assuming they would only be much smaller
(like Gemmellaroceras tubellum), but reading HOWARTH´s
“The Lower Lias of Robin Hood´s Bay, Yorkshire, and the work of Leslie Bairstow” again,
found that this is indeed the larger species and can be found,
(how blind can one sometimes be…)  explicitly mentioned, in Bairstow bed 530,
associated with Pinna folium…

There is another subgenus which is apparently similar, just stratigraphically slightly
older – Leptonotoceras – in which the lateral lobe of the suture is only split twice
(bifid) instead of three times (trifid) as in Gemmellaroceras – the lateral lobe is trifid
in this ammonite so we´re also clear about this.

So that´s about enough to round up this identification, and it´s also a species that can be
scratched off my “Wanted” list – done !

Scratched off the "Wanted..." list !

Scratched off the “Wanted…” list !

Now let´s see if I have the smaller species of this genus, G. tubellum, hiding in my collection
somewhere…

AndyS

* Gaetano Giorgio Gemmellaro (1832-1904) was an italian paleaontologist and geologist,
founder of the Palermo Geological museum and researcher, among many other topics,
on sicilian pygme elephants. Alpheus Hyatt named the genus after him in 1900, presumably
to reciprocate for an honour which  Gemmellaro had bestowed upon him in 1887 by naming
a permian ammonite genus (Hyattoceras) after him…

Crinoid and starfish travel for a prep and a loan

Crinoid unprepped, picture courtesy of R. taylor

Crinoid unprepped, picture courtesy of R. Taylor

Another fossil travel story – but this time a crinoid and some associated starfish.

The story began when Robert posted a picture of a crinoid he found on the Yorkshire coast
in the Yorkshire Fossil Collectors facebook group. It looked very large and quite interesting,
so I asked him if we could meet when I would come to Yorkshire for our summer holidays
and take a “live” look. We agreed on a date and Robert came visiting with his crinoid,
see a pre-prep picture of it above.

Robert had protected the surface of the fossil with a thin coat of paraloid, but I could
instantly see the potential of this fossil, and also that there might be more in the rock –
starfish !

The surface of the slab was relatively soft, I could scratch it with a fingernail, which is a
good sign that this fossil can be easily prepared using an air abrader with iron powder
as an abrasive. I offered to prep it for Robert without charge and give it back to him on
our next visit to Yorkshire.

Now don’t get me wrong here – I neither do preparation as a business, nor do I encourage
readers to ask me to prep something for them -if I see a fossil that I see potential in and
I’m sure I can prep it well, I will offer to do so. So don’t ask me, I will ask you…

Anyway, Robert agreed to my offer and I took the fossil home to Germany with me at the
end of our holidays.Preparation commenced relatively soon after our return from
Yorkshire and it was as simple as I had hoped, the matrix covering the fossil melted
like butter under the low pressure stream of the abrasive.

When I first directed the abrasive across the crinoid remains, I was somewhat taken
aback because the crinoid arms suddenly appeared in a creamy white when the matrix
and the paraloid covering it were removed – I feared they would be soft crystallized
calcite, but they turned out to be stable and just fine.
Crinoid and starfish prepped
Crinoid and starfish prepped
Additionally, as suspected, the slab also contain the remnants of up to 6 starfish, with
two very decayed ones on top of the crinoid and 4 on the side of it. When most of the
matrix and paraloid was removed, which took about 4 hours of prep time,
I sent some pictures to Robert.

In September, Robert went to the Scarborough Fossil Festival at the Rotunda and
showed the pictures to Dr. Timothy Ewin, senior curator for Echinoderms at the
London Natural History Museum, who, in Robert’s words, got “very exited” seeing
the pictures and asked if he could see more detailed pictures of the crinoid and
of the starfish.

The Rotunda in Scarborough

The Rotunda in Scarborough

I sent some more pictures and an e-mail discussion between the 3 of us ensued with
the result that the crinoid has tentatively been identified as a large Isocrinus robustus
and the starfish needing a detailed inspection on the “live” specimen to identify them.

Since my family and I had planned a visit in London in October anyway,
I offered (of course conditional on Robert’s agreement to do so) to take the specimen
to London for Dr Ewin to see it.

Robert and Dr. Ewin agreed, so I finished the preparation of the specimen in an
additional 2 hours and packaged it very safely for the journey
(I luckily still had some foam left from the Ichthyosaur donation…)

Packaging material
Packaging material
Crinoid ready to go
Crinoid ready to go

The transport was relatively straightforward, of course you get the
“what the heck have you got in there ?” question from the x-ray folks at the airport,
but after opening the case and allowing a swab for explosives,the crinoid went
on the flight to London.

Natural History Museum, London
Natural History Museum, London

Later in the week, we met with Dr. Tim Ewin in the Natural History Museum, and after
a quick inspection we agreed that this was indeed a very complete and large
Isocrinus robustus, and the starfish were not Tropidaster, but maybe Uraster or
something similar but that would require further detailed inspection.

The material is surprisingly similar to the legendary Mickleton tunnel fossils,
which I could see later on in the collections.
Specimen will be on loan to NHM and be given back to Robert, maybe on occasion of the
next Fossil festival ? According to Dr Ewin, there’s  a good chance you might see this
specimen pictured in the upcoming Yorkshire Lias guide…

 

Many many thanks to Robert for entrusting  me with his crinoid, both for the preparation
and the transport to the NHM, it was a pure pleasure to prep. Many thanks to
Dr. Timothy Ewin for keeping the important contact with us collectors and of course
for the tour of the NHM crinoid and starfish collections 🙂

And the next post will again be an ammonite one, I promise 🙂

AndyS

An ichthyosaur travels…and finds a new home

Ichthyosaur paddle bones laid out on a piece of foam for taking measure

Ichthyosaur paddle bones laid out on a piece of foam for taking measure

It was in March 1995, Klaus and I were searching the lower lias reefs at Robin Hoods Bay
for ammonites when I stumbled across something exposed at the surface of the shale that
looked like a hand… it turned out to be an Ichthyosaur paddle.

We spent a few hours excavating the mostly disarticulated bones, before the upcoming tide
chased us away. Unfortunately I do not have a picture of how the bones looked like when in
situ – this was pre-digital, and my wife had the camera with her…and we did not want to
wait another day to return with the camera, risking we would not find the bones again.
In hindsight that probably was a good decision – there was a bit of a storm the night and we
barely found the place again next day for checking if we had left any bones !

In the end there was one mostly complete paddle, a few vertebrae, some jaw sections partly
with teeth, some isolated teeth and an isolated hind fin femur.

Ichthyosaur paddle fitted in to a box and the piece of foam

Ichthyosaur paddle fitted in to a box and the piece of foam

A cover of bubble wrap for additional protection

A cover of bubble wrap for additional protection

A sheet of foam on top ...

A sheet of foam on top …

...and a lid on top and this one´s ready to travel !

…and a lid on top and this one´s ready to travel !

The ichthyosaur remains stayed mostly unprepped, only the paddle and two jaw sections
(I gave one to Klaus for his help salvaging the bones) were prepped.
The preparation was somewhat tricky since it could only be done mechanically – the bones
are not embedded in any kind of nodule and are relatively soft, so no air abrasion was
possible.

Ichthyosaur jaw parts and teeth laid out waiting to be packed...

Ichthyosaur jaw parts and teeth laid out waiting to be packed…

Fast forward almost exactly 20 years (doesn´t time fly ?)…

Discussing bones in the Yorkshire Fossil Collectors Facebook group, I mentioned the
finds we made in 1995 and was persuaded by a collector specialized on bones
(that´s you, Mark !) to post a few pictures.
Dean Lomax and Nigel Larkin expressed an interest in the fossils due to their rarity
(ichthyosaur material from the lower lias is a lot rarer in Yorkshire than from the
upper lias), so I mentioned that I would be happy to donate these (I´m really more
of an ammonite collector, you might have guessed), if they could come up with a
museum which would take them.

Contact was made with Sarah King, curator at the Yorkshire museum in York and
after a few e-mails back-and-forth a meeting on August 24 was arranged to hand
the fossils over to Sarah.

Klaus kindly donated his jaw section back to me, so the bones were again complete
as found.

...laid out on a thick sheet of foam for getting measured...

…laid out on a thick sheet of foam for getting measured…

To get the fragile ichthyosaur bones back to Yorkshire (talk about carrying owls to Athens…)
boxes were fitted with several layers of foam, one at the bottom for cushioning, one with a
cut-out of the fossils shape in the middle, and one at the top to cover.

...foam is being cut out ...

…foam is being cut out …

...the jaw parts fitted in (and you know the rest)

…the jaw parts fitted in (and you know the rest)

An afternoon of cutting foam later, the bones were safely packaged up in four boxes and
one bag (for associated bits of shale without bones).
To be able to carry the bulky (though not heavy) boxes, two large blue bags from a well
known swedish furniture chain were utilized.

All ready in the box & ready to go !

All ready in the box & ready to go !

On August 24, the bags were packed into our car and the bones made their journey to
the Yorkshire museum at York.  Sarah was met in her office, I gave her a bit of a tour
of the boxes with the bones and she in turn gave us a tour of the fossil collection
rooms in the museum.

Final hurdle was a donation panel decision in September and that was positive as well,
so everything was set.
The museum catalog number for the ichthyosaur remains is  :
YORM : 2015.618, just in case anyone needs to look it up…

Yorkshire Museum in York

Yorkshire Museum in York

Although I´m really specialized in ammonites, I can´t help myself from finding
other “stuff” 🙂 from time to time. These days, if I´d find something rare like this again,
I´d probably engage the help of Pro´s like Mike Marshall or Mark Smith to
professionally collect the bones – these guys are much better equipped and experienced
to deal with finds like this.

I´m letting this find go with one crying and one laughing eye.

One crying eye because of course one gets attached to a rare find – but it´s much better
to give it to someone much more suited to take care of this find properly and provide
access for scientific study.

One laughing eye because this frees up two large drawers for more ammonites !

Thanks to Dean Lomax and Nigel Larkin for providing the contact , to Sarah King and
the Yorkshire museum for taking care of this find and of course to the members of the
Yorkshire fossil collectors Facebook group for the many good discussions…

AndyS