Rare and re-bedded

Phymatoceras rude, 1.4 cm

Phymatoceras rude, 1.4 cm

This wee little 1.4 cm diameter ammonite that came off an eBay auction is a big rarity both in terms of species and in terms of where it was found : Port Mulgrave.

The species isthe ultra-rare Phymatoceras rude (hurray, another species from my “wants list” down !), and it usually comes from the striatulum subzone of the upper lias, the Peak Mudstone member at Ravenscar, where the beds were protected by the downthrow of the Peak Fault from the erosion that everywhere else at the end of the upper toarcian eroded a lot of the uppermost toarcian.
Now wait, you will say, if these beds were eroded everywhere else, then how come this ammonite can be found at Port Mulgrave ?
There are two possible theories (and I think I can trust the data given by the seller, who wasn´t even selling it as a Phymatoceras, so that excludes the third option that the seller tried to make a bit of extra money by selling a rare ammonite that comes from somewhere else…) :
  1. When you look closely at the ammonite, you see a rusty brown sandy substance in the umbilicus.
    I think this is middle jurassic sandstone, and that the ammonite was naturally eroded from the striatulum subzone and then re-bedded when the aalenian sandstone was sedimented. I have seen small badly eroded fragments of ammonites in these sandstones before, but never a recognizable ammonite.
    I think somebody even told me about a nautilus from the sandstones as well…
  2. Somebody found this ammonite at Ravenscar and lost it at Port Mulgrave. Much less interesting…
I like theory 1 best, what do you think ?
AndyS
P.S.: If you are the seller of this ammonite : I know you might think that the sales price was a little low now that you´ve read this.
Console yourself with the tought that you´ve earned yourself a copy of the book once it´s ready !
Edit 09.08.2012 :
I’ve updated this post with a new set of pictures of the Phymatoceras and during our holiday in Yorkshire these last 2 weeks I’ve made of few pictures “on location” that provide some evidence for my theory number 1 :
A large aalenian sandstone block with a re-bedded layer of toarcian pebbles, including what looks like a rounded fragment of an upper toarcian Grammoceras !
I’ve looked at many of these blocks during my last collection trip and almost every one of them showed some ammonite fragments !
Aalenian sandstone block with reworked pebble layer, the tip of the hammer pointing to a Grammoceras fragment

Aalenian sandstone block with reworked pebble layer, the tip of the hammer pointing to a Grammoceras fragment

A view through the chambers or Translucent ammonites

On the Yorkshire coast, most ammonites are most usually preserved mud-infilled or pyritized. Calcite preservation of a significant part of the whorls is relatively rare, but does occur occasionally, in my experience for example with

  • Psiloceras
  • Arnioceras
  • Euagassiceras
  • Pleuroceras
  • Eleganticeras
There are rare calcite preserved ammonites where the calcite is so translucent that you can almost look through it – I´d like to show you 2 examples :
The first one is a Psiloceras erugatum from the glacial drift (more on the lower lias ammonites from the glacial drift later) :
Psiloceras erugatum, 3 cm

Psiloceras erugatum, 3 cm

I photographed it against the light on my light table and pulled up the contrast in Photoshop to maximum to show the most of the translucent chambers.
The second is an Eleganticeras elegantulum that you might have seen earlier in one of my Christmas postings on the UKGE forum,
the resemblance of the sutures with Christmas trees was just too tempting…
Eleganticeras elegantulum, width of ammonite 4 cm

Eleganticeras elegantulum, width of ammonite 4 cm

With this one I did a little HDR setup, photographing it with a number of exposure settings and combined the pictures with a software later to capture the maximum dynamic range.
Of course beside the right preservation you also have to prep the ammonite completely free of matrix to see the light shine through – with the two examples shown I was lucky with the Psiloceras, it “jumped” off a multi block matrix free, the Eleganticeras was a lot more work involving air pen, diamond cutter and air abrader to remove all the matrix surrounding it without braking the fragile calcite inner mould.
AndyS

“Wants list” upper lias

The upper lias is  for many collectors a firm favourite.  There is a bit of a problem with some of the ammonites on the “wants list”, especially the Dactylioceras genus : Many of those have been described by the great Sydney Savoury Buckman, in his “Yorkshire Type Ammonites” – but not many times afterwards.  So some of these may not be “real” species…

What do you do if you think you have one of the ammonites on the list ?

Simple : Post a comment in the specific post (you have to leave your e-mail address but noone else but me can see it) and I will contact you !

So here´s the upper lias list : Some of these are real rarities, some may not even occur in Yorkshire, but please surprise me !

AndyS

Brodieia pingue (Simpson)
Catacoeloceras dumortieri (Maubeuge)
Catacoeloceras foveatum (Simpson)
Collina mucronata (d’Orbigny)
Dactylioceras annuliferum (SIMPSON, 1855)
Dactylioceras attenuatum  (SIMPSON, 1855)
Dactylioceras consimile (Buckman)
Dactylioceras crassescens (Simpson)
Dactylioceras delectum (Simpson 1855)
Dactylioceras praepositum (Buckman)
Dactylioceras temperatum (Buckman)
Dactylioceras vermis (Simpson)
Dumortieria levesquei (D`ORBIGNY, 1845)
Harpoceras serpentinum (SCHLOTHEIM, 1813)
Harpoceras subplanatum (OPPEL, 1856)
Haugia beani (Simpson)
Haugia jugosa (Quenstedt)
Haugia obliquata (Young and Bird)
Hildaites forte (BUCKMAN, 1921)
Hildaites murleyi (MOXON, 1841)
Hildaites subserpentinus BUCKMAN, 1921
Hildoceras semipolitum BUCKMAN, 1902
Meneghiniceras lariense
Nodicoeloceras dayi (Reynes)
Nodicoeloceras fonticulus (Simpson 1855)
Nodicoeloceras incrassatum (Simpson)
Pachylytoceras crenatum (Buckman)
Pachylytoceras gubernator (Simpson)
Phylseogrammoceras dispansum (LYCETT, 1860)
Phymatoceras fabale (Simpson)
Phymatoceras rude (SIMPSON, 1843) – found on eBay, see post “Rare and re-bedded” !
Porpoceras vorticellum (Simpson)
Protogrammoceras (Protogrammoceras) paltum (BUCKMAN, 1922)
Trachylytoceras (syn. Lytoceras) fasciatum (Simpson)

“Wants list” middle lias

The “Wants list” of the middle lias is relatively short (that may have to do something with the fact that I´m collecting in these beds quite often) :

Amaltheus (Amaltheus) reticularis (SIMPSON, 1843)
Amaltheus (Pseudoamaltheus) engelhardti (D`ORBIGNY, 1844)
Canavaria cultraroni (Fucini 1931)
Pleuroceras birdi (SIMPSON, 1843)
Pleuroceras hawskerense (YOUNG & BIRD, 1828) transient elaboratum (SIMPSON,1884)
Pleuroceras spinatum (BRUGUIÈRE, 1789)
Protogrammoceras (Protogrammoceras) turgidulum (Funcini 1904)
Pseudogrammoceras latecens (Simpson)

Some of these are real rarities, some may not even occur in Yorkshire, but please surprise me !

What do you do if you think you have one of the ammonites on the list ?

Simple : Post a comment in the specific post (you have to leave your e-mail address but noone else but me can see it) and I will contact you !

AndyS

 

 

“Wants list” lower lias

The next three posts will be quite dull – no pictures, just lists of ammonites I´m looking for to photograph for the book.

Let me re-iterate the conditions :

  • Found on the Yorkshire coast  – or –
  • Found on the Redcar & Cleveland coast (Redcar, Marske,…)  – or –
  • Found in the quarries around Scunthorpe

The first post is the lower lias one.

Bear with me if the list is not completely perfect – I´m still sorting through it to weed out the ones that are synonyms, have only ever been found or pictured once, etc.
If you have any information to that effect, please also let me know !

What do you do if you think you have one of the ammonites on the list ?

Simple : Post a comment in the specific post (you have to leave your e-mail address but noone else but me can see it) and I will contact you !

So here comes  :

Aegasteroceras crassum SPATH, 1925
Agassiceras decipiens (Spath, 1923)
Angulaticeras densilobatum (POMPECKJ)
Apodoceras sinuatum (Simpson)
Bifericeras donovani DOMMERGUES & MEISTER, 1992
Caloceras belcheri (SIMPSON, 1843)
Caloceras convolutum (SIMPSON,  1855)
Caloceras wrighti SPATH, 1924
Coeloderoceras panula (Bremer)
Coeloderoceras sociale (Simpson)
Coroniceras (Arietites) alcinoe (REYNÈS, 1879)
Coroniceras (Arietites) cf. planaries (REYNÈS, 1879)
Coroniceras (Arietites) obesulus (BLAKE, 1876)
Coroniceras (Arietites) radiatus (SIMPSON, 1843)
Coroniceras (Primarietites) schloenbachi (Reynes)
Coroniceras (Primarietites) vercingetorix (Reynes)
Crucilobiceras obsoletum (BLAKE)
Cymbites laevigatus (SOWERBY, 1827)
Echioceras aureolum (Simpson 1855)
Echioceras cereum (Simpson 1855)
Echioceras exoratum (Simpson 1855)
Echioceras intermedium (Trueman & Williams, 1925)
Echioceras raricostoides (VADASZ, 1908)
Eoderoceras anguiforme (Simpson)
Eoderoceras armatum (SOWERBY, 1815)
Eoderoceras hastatum (YOUNG & BIRD, 1828)
Eparietites bairstowi HOWARTH 2002
Epophioceras landrioti (D`ORBIGNY, 1849)
Gemmellaroceras peregrinum (Haug)
Gemmellaroceras rutilans (SIMPSON, 1843)
Gemmellaroceras tubellum (SIMPSON, 1855)
Gleviceras doris (Reynès, 1879)
Hyperderoceras mamilllatum (Simpson)
Hyperderoceras nativum (Simpson)
Hyperderoceras retusum (SIMPSON, 1855)
Hyperderoceras validum (SIMPSON 1855)
Liparoceras (L.) naptonense SPATH, 1938
Macrogammites antiquatum (SIMPSON, 1855)
Microderoceras scoresbyi (SIMPSON,1843)
Paltechioceras regustatum BUCKMAN, 1914
Paracymbites dennyi (SIMPSON, 1843)
Paraoxynoticeras salisburgense (HAUER, 1856)
Parinodiceras parinodum (Quenstedt, 1884)
Phricodoceras nodosum (QUENSTEDT, 1846)
Platypleuroceras aureum (SIMPSON, 1855)
Platypleuroceras brevispina (SOWERBY, 1827)
Platypleuroceras obsoleta (SIMPSON, 1843)
Platypleuroceras ripleyi (Simpson 1843)
Polymorphites bronni (ROEMER, 1836)
Polymorphites caprarius (QUENSTEDT, 1856)
Promicroceras capricornoides (Quenstedt, 1883)
Psiloceras sampsoni (PORTLOCK, 1843)
Psilocras (Caloceras) bloomfieldense (Donovan)
Radstockiceras sphenonotum(MONKE, 1888)
Saxoceras aequale (SIMPSON, 1855)
Tragophylloceras ibex (QUENSTEDT, 1843)
Tragophylloceras loscombi (SOWERBY, 1817)
Tropidoceras futtereri (Spath 1923)
Tropidoceras masseanum ((d’Orbigny) var. rotundum ((Futterer, 1893)
Uptonia jamesoni (SOWERBY, 1827)
Uptonia lata (QUENSTEDT, 1845)
Uptonia obsoleta (Simpson 1843)
Vermiceras multanfractum (SIMPSON, 1855)

AndyS

20 posts or Who photographs the photographer

My little studio

My little studio

20 posts so far – that calls for a little excursion into photography and some reflection about my general workflow…
As you can see, this is my little studio where I photograph the fossils, with the “ensemble” of the Amaltheidae post still present.
It´s just a little Novoflex macro table, that I´ve put onto another table to reach comfortable working height. There are 2 flexible lamps with 5400 °K permanent light from above and another from below the slightly transparent table to provide a little contour light from below. There´s another led spot clamped to the table if I need it for a special spotlight etc. In front of the table I have positioned a sturdy tripod with a 3D geared head that holds the camera with a 150 mm macro lens which gets me to 1:1 size if I need to.  The geared head makes precisely framing the shot very easy, I find it a lot more suited to the task than a normal ball head. Depending on the size of the fossil I photograph, I move the tripod closer or further away from the table – the maximum size fossil I can do with this kit is about 30 x 30 cm.
If I photograph fossils for any post I´m planning, I will always do a lot more pictures than you actually get to see in the post. One reason is that I obviously do several different photos where I vary lighting, sharpness points, positioning of the fossil etc to get the best shot possible. The other reason of course is that I do not photograph only for the post – there are a lot more detail photos and shots of additional fossils that I get to be used later for the book !
I normally research the ammonites I´m planning to write about first, so the text usually comes before the pictures.
For writing the text I use a software called Evernote (it´s a free editor that saves the texts etc in the cloud) – It allows me to continue writing on my texts even if I´m not at home or not at my main computer.  Once the text is about ready, I select the fossils from my collection and do a photo session. Today´s photo session for the Amaltheidae took about 5 hours (while outside a thunderstorm with torrential rain & hail was going on…).
As the thunderstorm subsided, I switched my computer back on and began editing the photos. I run the pictures through a software called DXO first – it does a lot of automatic corrections for colour, white balance, sharpness, lens distortion etc for me. After that is done I do the masking, cropping and combining of pictures in Adobe Photoshop. If the picture will get used in the book I save it uncompressed for maximum quality in Photoshop´s own format so I can later use it without further problems in Adobe InDesign, the publishing software I´m going to use for the book. If it gets used in the blog as well, it will be re-sized for web use, marked with a copyright notice (If you like my pictures and would like to use them – contact me) and saved as a jpeg file, in a setting optimized for both size and visual quality of the picture.
Once text and photos are complete, I upload the picture files to the WordPress media library, add any pictures comments and paste the text for the new post from Evernote into the WordPress editor. I then add the links to the pictures in the media library, do a final spell & visual check – and publish the post !
This workflow has worked quite well for me so far, I feel that writing the blog posts gives me an intermediate goal that continues to drive my work for the book.
With over 2000 views to date (not much for a blog, but this is also a very specialized topic with a small target group), you readers out there seem to enjoy it as well
 – thanks for reading, wherever you are  !
  AndyS

Blog visitor statistics 07.07.2012

Blog visitor statistics 07.07.2012

Amaltheidae – One of my favourite ammonite families

Amaltheus stokesi, completely septate, 13 cm

Amaltheus stokesi, completely septate, 13 cm

It must be the beautiful braided keel that most of the members of the family Amaltheidae show that makes it a favourite amongst collectors.
The Amaltheidae family of ammonites includes the genera
  • Amaltheus, with it´s subgenus Pseudoamaltheus
  • Amauroceras, which we´ve already looked at in an earlier post
  • Pleuroceras
Amaltheus (Pseudoamaltheus) is supposed to occur in Yorkshire. I think I´ve seen a badly preserved, flattened one on a crumbling block at Hawsker once, but I´m not sure since large Amaltheus margaritatus can also sometimes show sections with spiral ornamentation. But I´ve never seen one in a collection – If you have one from Yorkshire – let me know !
We´ll deal with the Pleuroceras genus later, so this article will be about the Amaltheus genus.
In the middle lias of the Yorkshire coast, Amaltheus is not particularly rare, although nice specimen can be hard to come by. As with many Yorkshire ammonites from the various beds of the lias, the best preserved Amaltheus ammonites come from nodules.
In the order of (perceived, ascending) rarity of occurrence the species are :
  • Amaltheus stokesi
  • Amaltheus wertheri
  • Amaltheus subnodosus
  • Amaltheus striatus
  • Amaltheus bifurcus
  • Amaltheus margaritatus
  • Amaltheus laevigatus
  • Amaltheus gibbosus
  • Amaltheus gloriosus
  • Amaltheus reticularis
This order of course is just perception, not based on any well founded statistics. Of the 3 first species I have more than 10 specimen in my collection, of the next group of 3 species up to 5 specimen in my collection, the last group of 4 species I have only one or none. This might give you some idea about chances of finding them…
The first one, Amaltheus stokesi, is also the largest, I have found specimen up to 22 cm / 9″.
The shown specimen is almost complete including the body chamber, there seems to be a predetermined breaking point (when eroding) between body chamber and phragmocone, because most specimen are found as just the phragmocone. It does often occur together with A. wertheri and A. bifurcus.
Amaltheus stokesi, almost complete specimen, 20 cm

Amaltheus stokesi, almost complete specimen, 20 cm

Amaltheus  wertheri in constrast is one of the smaller Amaltheus species, I´ve never seen specimen exceed 4 cm. It’s an almost smooth species with just a slight crenelation of the keel and a very pronounced constriction at the aperture.
Comparison of small Amaltheus : A. bifurcus (left), A. wertheri (top), A. stokesi (right), all approx. 2.5-3 cm

Comparison of small Amaltheus : A. bifurcus (left), A. wertheri (top), A. stokesi (right), all approx. 2.5-3 cm

In the subnodosus subzone the species A. subnodosus is the naming index species. it’s got an inner whorl with strong ribs, each crowned with a little tubercle.  Ribs stay strong on larger whorls, while tubercles fade away at around 2 to 3 cm. Strong keel.
Amaltheus subnodosus : Side view, keel view, aperture view (from left)

Amaltheus subnodosus : Side view, keel view, aperture view (from left)

Amaltheus striatus starts similar to A. subnodosus, ribs & tubercles on the inner whorls are not as strong and fade away until at around 2-3 cm the shell becomes almost smooth apart from fine shallow ribs. Strong keel.
Amaltheus striatus, 4 cm

Amaltheus striatus, 4 cm

Amaltheus bifurcus is a rarer Amaltheid from the stokesi subzone, occurring together with A. stokesi and A. wertheri. Similar to A. stokesi, but stronger ribbing at similar sizes, thicker whorls. Usually specimen do not get much larger than 6-8 cm, I do have a very eroded (doubtful) specimen at about 10 cm.
Amaltheus bifurcus, 6 cm, completely septate

Amaltheus bifurcus, 6 cm, completely septate

Amaltheus margaritatus is the index fossil of the margaritatus subzone. It does not overlap with A. stokesi, is seen as the direct descendant from A. stokesi and can grow to similar sizes. The more differentiated keel is the main difference between A. margaritatus and A. stokesi, but since the species do not overlap and the rocks they´re found in in Yorkshire are rather distinctive (ironstone nodules = A. margaritatus, grey limestone nodules = A. stokesi), mixing up of the two species ist almost impossible.
It is often found together with A. subnodosus and A. striatus.
Large A. margaritatus 7cm, A. striatus (below) 3.5 cm, A. subnodosus (left) 4 cm

Large A. margaritatus 7cm, A. striatus (below) 3.5 cm, A. subnodosus (left) 4 cm

Amaltheus laevigatus is almost smooth on the inner whorl and develops fine ribbing after about 1 cm.
Rather rare, I’ve found only 1 specimen in more than 20 years.
Amaltheus laevigatus, 2.5 cm, not a replica !

Amaltheus laevigatus, 2.5 cm, not a replica !

Amaltheus gibbosus  is very rare in Yorkshire – I only have a specimen that I purchased from M. Marshall / M. Forster that came from Staithes.

Amaltheus gibbosus, 3 + 3.5 cm

Amaltheus gibbosus, 3 + 3.5 cm

Both Amaltheus gloriosus and Amaltheus reticularis are apparently extremely rare (or I have not been looking in the right places) – I have not found a specimen of these.
I do have a replica Amaltheus reticularis that I´ve shown you in a previous post.
As a bonus (this is my 20th post !) here´s another picture of a combination of the 3 stokesi subzone Amaltheus :
Large A. stokesi 14 cm, 2 small A. wertheri 2 cm, A. bifurcus in aperture 5 cm

Large A. stokesi 14 cm, 2 small A. wertheri 2 cm, A. bifurcus in aperture 5 cm

AndyS

Old beliefs proven wrong or Young and Old Oxynoticeras

Oxynoticeras simpsoni, 9 / 5 / 3.5 / 2.5 cm

Oxynoticeras simpsoni, 9 / 5 / 3.5 / 2.5 cm

You might have wondered why I called the Oxynoticeras in one of the last posts Oxynoticeras simpsoni and not Oxynoticeras oxynotum. I did actually have that one labeled as O. oxynotum originally, more or less assuming that this was the more common species and not looking for the differences. I had only the large Oxynoticeras where you could not overlook it’s typical O. simpsoni characteristics labeled as such. So when I looked through my collection, I actually found that I had only one potential O. oxynotum, all the other ones were O. simpsoni, just different growth stages !

This picture shows the O. cf. oxynotum , found in 1990, a lucky split, inner whorls as they could be prepped then (with a prep needle).

Oxynoticeras cf. oxynotum, 3.5 cm, 1990 style prep

Oxynoticeras cf. oxynotum, 3.5 cm, 1990 style prep

Today I gave it a little re-prep with the air abrader, just a 5 min job.
Oxynoticeras cf. oxynotum, 3.5 cm, re-prepped today

Oxynoticeras cf. oxynotum, 3.5 cm, re-prepped today

Here is a similar sized Oxynoticeras simpsoni :
Oxynoticeras simpsoni, 3.5 cm

Oxynoticeras simpsoni, 3.5 cm

So here are the main differences between the species : O. oxynotum has a smaller umbilicus at larger sizes, the whorls do not get as thick, the whorl section is more oval with a sharp keel,
there is a bit of a soft wave-like ribbing that almost vanishes at the point where the ribs bend forward towards the keel,  while O. simpsoni has a larger umbilicus, thicker whorls, and the whorl section thins out towards the venter, making it more lanceolate. O. simpsoni has very fine ribbing that continues towards the keel and can produce a crenelated keel. In comparable beds around the world, Oxynoticeras seems to be more common without shell, e.g. pyritized. I wonder if the authors describing the different species ever saw them with shell ?
At small sizes, with the shell on, they´re almost identical.
This is a “classical” larger Oxynoticeras simpsoni, 9 cm, an inner whorl of a larger, eroded specimen, the largest I have with almost complete shell on :
Oxynoticeras simpsoni, 9 cm

Oxynoticeras simpsoni, 9 cm

Both O. oxynotum and O. simpsoni apparently get very large : HOWARTH 2002 describes specimen between 25 and 40 cm !
As usual: If you do have a large specimen like that, let me know !
I have a small Oxynoticeras specimen with a crenelated keel – SCHLEGELMILCH lists this as a characteristic of another 2-3 cm small species O. bucki, which HOWARTH 2002 later lists as a synonym of O. simpsoni – I tend to agree with that, allthough since this one has its complete shell preserved, the other characteristic of O. bucki, as SCHLEGELMILCH describes it – a very simple suture – cannot be seen.
Oxynoticeras "bucki", 2 cm

Oxynoticeras “bucki”, 2 cm

AndyS