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pachy-pleuro-whatnot-odon

Ichthyosaur paddle digit (Wimereux): hit or miss

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pachy-pleuro-whatnot-odon

Hi all,

 

Found this stone at Pointe aux Oies in Wimereux two days ago, amongst the pebbles collected next to a shelve down towards sea from the spot where I had found an ichthyosaur vertebra (on matrix) two days before this find. I picked it up because 1) the stone is unusually flat; 2) has exactly the right shape and thickness to it for an ophthalmosaurid ichthyosaur paddle bone (see picture below); 3) has certain ornamentation top and bottom; 4) seems to be of a different type of stone than I've generally come across in the area; and 5) has some weight to it. It vaguely reminds me of paddle bones found in the Oxford Clay at Peterborough. Yet, what makes me doubt, though, is that there is no clear radial ornamentation on either top or bottom of the piece, as would by typical for an ichthyosaur paddle bone. A friend of mine, more familiar with fossils from the region, suggested it could be a crocodile scute, as the ones found further up the coast, but this, to me, seems unlikely, as 1) the ornamentation on my find differs significantly from what's typical for crocodilians; 2) the underside is not flat as it would be for crocodile; and 3) the piece seem to thick for a scute.

 

Size is about 4.4 x 3.4 x 1.4 cm (1.7 x 1.3 x 0.6 ")

 

image.thumb.png.562170c7d1f45ecaf880155db2b11763.pngBrachypterygius extremus paddle from Ichthyosaurs: a day in the life...

My piece reminds me of the radius.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Now my question is:

  1. Is this just a rock - i.e. am I seeing things because I really want to - or is it an actual fossil?
  2. Is this an ichthyosaur paddle bone/phalange or something else?

 

20200828_102510.thumb.jpg.92aa6f41de80ae311653764bba2213f0.jpg20200828_102517.thumb.jpg.6ff7731d960cf66a3574f4d3733e4a57.jpg20200828_102524.thumb.jpg.92d56bfc5b95d2397053f8d908b2a15d.jpg20200828_102530.thumb.jpg.d5107ecb218b2391d275b3e2a2df2317.jpg20200828_102532.thumb.jpg.8bc16f4e9603e087ddd6c9f172eb0060.jpg20200828_102540.thumb.jpg.330f1c1a1bd3c663b10134bc9e06d927.jpg20200828_102550.thumb.jpg.cb2944cf1768bcf6a9e7ede628717afe.jpg

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DatFossilBoy

Unfortunately I’m not seing any bone structure...

Let’s see what others say.

Regards

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pachy-pleuro-whatnot-odon
19 minutes ago, DatFossilBoy said:

Unfortunately I’m not seing any bone structure...

That's indeed by biggest concern as well. I mean, the piece matches the criteria in all other respects, but the bone texture. To give an example of what is typical for the area:

 

5f4a21a8db079_OphthalmosaurulnaWimereux06.jpg.5d7fcaee82f9a42971f9f6f14644f1f0.jpg5f4a21a698007_OphthalmosaurulnaWimereux04.jpg.e402e9f66a756ebe7db1c16be3db08ae.jpg5f4a21a49aaf3_OphthalmosaurulnaWimereux02.jpg.96d8b826dc4409bc0104d0d9826f6f53.jpg

 

However, that's why it reminds me more of the paddle digits found in the Oxford Clays of Peterborough. There you'll frequently also not see a(s) clear (a) bone texture. Some examples from there:

 

5f4a226e04e1d_Ophthalmosaurussp.paddledigitOrtonPit01.thumb.jpg.004b3b687d5448069c9a89aa26dfac3d.jpg5f4a227108eb4_Ophthalmosaurussp.paddledigitOrtonPit02.thumb.jpg.94917df2038a27ce023dd833a810a3bf.jpg5f4a2273b9a1e_Ophthalmosaurussp.paddledigitOrtonPit03.thumb.jpg.a16a6e4ecf5f11f04194fb1ad1afd547.jpg

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Paleoworld-101

Pretty sure yours is just a rock. 

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BellamyBlake

It seems to be a rock 

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pachy-pleuro-whatnot-odon

Looks like the verdict is clear...

 

Thanks for the help, guys! Sometimes you just need someone to help you out of a dream inspired by desire ;)

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pachy-pleuro-whatnot-odon

As my original contact for the region is quite convinced it's bone, but cannot further identify it: can I ask your opinion on the matter here, @sjaak, seeing as your also very familiar with the region and its material?

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RuMert

No need super expertise for bone structure: it should have honeycomb and plantlike pattern. If it doesn't, no form will help - we remember numerous "preserved dino heads" and "giant beaver fetuses"

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pachy-pleuro-whatnot-odon

Time to stop making a fool of myself then... It's just that this guy has quite a bit of local experience with bone and remains so convinced.

 

From my part I had already given up, as, indeed, I know how this stuff works - I've found enough bone to know what it should look like by now (at least in most cases). But marine reptile bone can sometimes be very dense (lacking the honey-comb structure altogether), while fossil dinosaur bone sometimes simply doesn't show a clear honey-comb structure on the outside at all (have found various pieces like this on the Isle of Wight for instance, which were confirmed as bone by experts from the local museum).

 

So there not being a clear honey-comb structure would not be a good indicator in this case. In fact, if you look at the above images of confirmed paddle bones, you'll also not see this pattern. What you will, however, see instead is pitting, similar to on the rock I found (albeit somewhat more prominent on my piece).

 

Hence, what I actually feel would be the greatest discerning difference is the absence of the bone-growth structures visible on the two sample paddle-bones, though with a little intent such a radiating pattern can be seen on one side of my pebble too...

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sjaak

I don’t see any bone structure. Unfortunately, I have to agree it’s just a rock.

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pachy-pleuro-whatnot-odon

Okay, thanks guys!

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