Bone from near Whitby ID

[Holly Barber]

I found this fossil which looks like bone at Saltwick Bay, near Whitby on the Yorkshire Coast. I have been told it maybe ichthyosaur and someone said it maybe a fish bone from a Gyrosteus. Can anyone help me with an ID? The rocks where I found it are definitely Jurassic and I also found lots of ammonites and belemnites in the area. Thanks Holly

[TqB]

Maybe a bit of ichthyosaur jaw. It does look reptile to me rather than Gyrosteus. There are people on one or two local social media groups who could say for sure.

 

The age will be Upper Lias (Lower Jurassic) - lower Toarcian Stage.

[pachy-pleuro-whatnot-odon]

The line-patterning on the bone (black lines running the length of the bone) doesn't look particularly marine reptile to me. Much rather they remind me of a Chondrosteus fossil from Lyme Regis I saw online recently: 

 

Lower Jurassic in age too, though obviously the Lyme Bay specimen would be older, dating, as it does, to somewhere between the Hettangian and Sinemurian. But if Gyrosteus is anything like this,.it might be worth consideration.

[pachy-pleuro-whatnot-odon]

Photographs from the reverse and sides may aid identification, by the way. Right now there doesn't seem to be a lot to go on...

[TqB]

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

The line-patterning on the bone (black lines running the length of the bone) doesn't look particularly marine reptile to me. Much rather they remind me of a Chondrosteus fossil from Lyme Regis I saw online recently: 

I don't think the surface texture is a problem - I was thinking of something like this one of mine (actually, also a Charmouth specimen). (Just over a foot long.)

 

It could still be Gyrosteus though (which is indeed a close relative of Chondrosteus). But I think Gyrosteus is usually a much lighter brown than reptile bone from around Whitby - certainly all the ones I've seen (or recognised anyway) are. And the internal structure is more coarse.

Here's a selection of typical Gyrosteus bits from around Whitby (Yorkshire), including Saltwick, where it all derives from the same bed. Many collectors don't keep much of it - the fish didn't have a mineralised skeleton for the most part so you only ever find the parts that were.

[pachy-pleuro-whatnot-odon]

56 minutes ago, TqB said:

I don't think the surface texture is a problem - I was thinking of something like this one of mine (actually, also a Charmouth specimen). (Just over a foot long.)

Oh wow! That's an impressive specimen! Did you find it yourself? I could only ever dream of finding something like this...! Ichthyosaurus communis?

 

However, apart from the supposed similarities I saw concerning the stripes running across the fossil discussed and those on the Chondrosteus-fossil I shared, my reason for me proposing Gyrosteus was mostly based on the fact that I don't see any marine reptile in the piece of bone posted - although it would obviously need to be if not fish, especially if colouration would also suggest reptile. Working on an exclusionary basis, I think bones (whether ichthyosaur, plesiosaur, or pliosaur) like vertebrae, ribs, phalangae, and coracoids can be excluded. This leaves skull parts, scapulae, pelvic parts and podials as potential options. Of these, ichthyosaur propodial was one of the first things to cross my mind. But for that, the piece is way to longitudinally straight and too irregular around the flat surfaces - that is, not sculpted as you'd expect for muscle attachments.

 

I don't really have clear samples of marine reptile scapulae, so can't comment on that. Could it be an ichthyosaurian ischiopubis then - such as the one from Holzmaden, pictured below? The problem with that would be that the posted fossil looks too thick to be an ischiopubis, unless - maybe - part of a truly huge animal.

 

But I think not. Same goes for skull-parts: the bone is just too thick for most of them. This leaves, as you pointed out, the rostrum - in which case this would need to be a mandible and the shown top-surface the lingual side of it. However, in that case I'd expect to see a groove in the cross-section to mark where the teeth would've gone. May be a part towards the back of the jaw then, behind the dentary? There seems to be a bit of a waist to the fossil, which might indicate it's placement there. But not too sure about that either...

[TqB]

@pachy-pleuro-whatnot-odon I'm no vertebrate anatomist and all your points seem very reasonable! 

 

The rostrum is part of a partial skeleton I found a long time ago, when collecting belemnites from the Belemnite Marls for a university dissertation. So it's Lower Pliensbachian, where ichthyosaurs are rare. Probably a juvenile Temnodontosaurus sp., confirmed by a couple of specialists. I eventually prepped it a lot more recently and put it in a case on my fossil room wall.  (The rostrum is inverted for display as the teeth are better this side!)

Edited July 17, 2020 by TqB

[pachy-pleuro-whatnot-odon]

On 7/17/2020 at 7:11 PM, TqB said:

@pachy-pleuro-whatnot-odon I'm no vertebrate anatomist and all your points seem very reasonable! 

 

The rostrum is part of a partial skeleton I found a long time ago, when collecting belemnites from the Belemnite Marls for a university dissertation. So it's Lower Pliensbachian, where ichthyosaurs are rare. Probably a juvenile Temnodontosaurus sp., confirmed by a couple of specialists. I eventually prepped it a lot more recently and put it in a case on my fossil room wall.  (The rostrum is inverted for display as the teeth are better this side!)

Wow! That's an amazing specimen, @TqB! A find to be envious off! I can only imagine how it must have felt to uncover it. And to be able to prep it and hang it on your wall... I'm quite, quite jealous

Anyway, Temnodontosaurus sp. sounds about right for an ID, just based off of the teeth: I already thought I spotted some carina typical of T. platyodon on your earlier photographs of the rostrum, but then checked the size and thought it would be too small. I didn't consider juvenile, though, and this seems quite possible. Too bad the paddles aren't really preserved, as this would've been an equally telling feature, but the right humerus seems like a potential match for Temnodontosaurus...

 

Once again, awesome find. And thanks for sharing!

[TqB]

1 hour ago, pachy-pleuro-whatnot-odon said:

Wow! That's an amazing specimen, @TqB! A find to be envious off! I can only imagine how it must have felt to uncover it. And to be able to prep it and hang it on your wall... I'm quite, quite jealous

Anyway, Temnodontosaurus sp. sounds about right for an ID, just based off of the teeth: I already thought I spotted some carina typical of T. platyodon on your earlier photographs of the rostrum, but then checked the size and thought it would be too small. I didn't consider juvenile, though, and this seems quite possible. Too bad the paddles aren't really preserved, as this would've been an equally telling feature, but the right humerus seems like a potential match for Temnodontosaurus...

 

Once again, awesome find. And thanks for sharing!

Thank you, and for the diagnostic remarks. I have the McGowan & Motani Ichthyopterygia handbook but am rather rusty on all this.   A few of the paddle bones are notched which helps a bit. Judy Massare and Dean Lomax had a good look at it a while ago, along with a headless small juvenile I. cf. communis  that I later found a bit higher up which was the first thing I ever posted here!

Pliensbachian ichthyosaur

Edited July 20, 2020 by TqB

[pachy-pleuro-whatnot-odon]

3 hours ago, TqB said:

Thank you, and for the diagnostic remarks. I have the McGowan & Motani Ichthyopterygia handbook but am rather rusty on all this.   A few of the paddle bones are notched which helps a bit. Judy Massare and Dean Lomax had a good look at it a while ago, along with a headless small juvenile I. cf. communis  that I later found a bit higher up which was the first thing I ever posted here!

Pliensbachian ichthyosaur

That must've been a really lucky period for you, finding two such excellent specimens so near in time to each other. Like most other commentators in the other thread, my own finds from the Lyme Bay area are hardly worth writing home about, with us having found but a couple of verts and a very worn section of tooth-less jaw when my wife and I last were there, and only a single tooth from all the years I went there with my parents as a child

 

Yeah, I have the same volume of the paleoherpatologists' handbook, but no need to check that, as far as I'm concerned. I've got a couple of excellent jaw sections and individual Temnodontosaurus-teeth, as well as a nice section of paddle to compare against But I guess it must've been a special find if it attracted the attention of Judy Massare and Dean Lomax. Great to be able to validate my own diagnosis against theirs Also very interesting to see the propodials on your other specimen, which has allowed me to confirm that the couple of them I have lying around here should then also be Ichthyosaurus communis.

Need to get back to Lyme Regis again, see if I'll eventually get lucky... *dreams* First up is a trip to northern Normady, though