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Omnomosaurus

British Theropod Bone?

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Omnomosaurus

Hey folks, got a big one to cross-check with everyone.

 

It's a partial....something.

 

Does this match any identifiable features seen on theropods, like the shape of a pubis or scapula?

 

Location: Oxfordshire, England

 

Size: 220mm X 221mm

 

5d003efee199d_megalosaurus-pelvis-5-1091-p2.thumb.jpg.79ee3755d084b04156010bf70c90a626.jpg

5d003f00a7cc8_megalosaurus-pelvis-4-1091-p2.thumb.jpg.8a3ca9b4b67ebb883a15908a1861e666.jpg

5d003efb7b9e8_megalosaurus-pelvis-2-1091-p.thumb.jpg.2d782a9c7b5cb6b1c3a724139d7e4098.jpg

5d003efd1702e_megalosaurus-pelvis-3-1091-p.thumb.jpg.4eafcf142e1e83af3b7132a29c8d33a5.jpg

 

Any help would be muchos appreciated. Cheers!

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Tidgy's Dad

Icthyosaur humerus ? 

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TqB

Ichthyosaur something probably, maybe coracoid?

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Omnomosaurus
11 hours ago, Tidgy's Dad said:

Icthyosaur humerus ? 

 

2 hours ago, TqB said:

Ichthyosaur something probably, maybe coracoid?

 

I was wondering if there was a risk it was Ichthyosaur or Plesiosaur, rather than theropod, as the seller was claiming. 

 

Coracoid seems like a good shout with the general shape!

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TqB
33 minutes ago, paulgdls said:

Plesiosaur pubis? 

 

Paul

 

 

Hi, Paul! 

 

( @Omnomosaurus This will be a much more likely ID than mine as Paul is far more familiar with this sort of material.)

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LordTrilobite

I'm not really getting a theropod vibe from this.

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Omnomosaurus
1 hour ago, paulgdls said:

Plesiosaur pubis? 

 

Paul

 

 

 

32 minutes ago, TqB said:

Hi, Paul! 

 

( @Omnomosaurus This will be a much more likely ID than mine as Paul is far more familiar with this sort of material.)

 

Thanks TqB and Paul! I was trying to decide whether it was worth buying as a punt, but it looks like this thing is almost certainly not theropod; especially not the "Megalosaurus Pelvis" it is advertised as, so I won't risk it.

 

25 minutes ago, LordTrilobite said:

I'm not really getting a theropod vibe from this.

 

I'm an absolute dunce when it comes to identifying bone (beyond "hollow bone with thick walls might mean theropod").

 

Is there is there a method you can use to help distinguish plesiosaur/ichthyosaur bone from dinosaur?

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LordTrilobite
4 minutes ago, Omnomosaurus said:

I'm an absolute dunce when it comes to identifying bone (beyond "hollow bone with thick walls might mean theropod").

 

Is there is there a method you can use to help distinguish plesiosaur/ichthyosaur bone from dinosaur?

I'm not much of a plesiosaur/ichthyosaur guy. But I don't recognise it as theropod at least.

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Omnomosaurus
3 minutes ago, LordTrilobite said:

I'm not much of a plesiosaur/ichthyosaur guy. But I don't recognise it as theropod at least.

 

Thanks @LordTrilobite. Without input from you and others, I would've had quite a collection of overpriced/misidentified pieces by now!

 

If you don't mind me asking, what would you usually look for to determine if something is from a theropod?

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LordTrilobite
16 minutes ago, Omnomosaurus said:

 

Thanks @LordTrilobite. Without input from you and others, I would've had quite a collection of overpriced/misidentified pieces by now!

 

If you don't mind me asking, what would you usually look for to determine if something is from a theropod?

For unidentifiable bones, like you pretty much said, see if they are hollow. Hollow bones are more likely to be theropod, bird or pterosaur. Different types of animals have different bone density. Especially pterosaurs have ridiculously thin bone walls.

 

Here's an example of a pterosaur cervical vertebra that broke in half during prep. I took a photo before I glued it back together. The bone wall is little more than a millimeter thick. So identifying a bone just on bone thickness can be done.

ptero_crosssection.thumb.jpg.0971ecb320563ede4f1ca800007c6793.jpg

 

 

But for bones that do have good features that make them identifiable, I find that it's just good to get familiar with the anatomy of the animal in question.

Buy a fossil that isn't too expensive. Do research and gather a database of images. See if the reference matches you fossil. And if it doesn't expand your search. Through this process you'll get more and more familiar with more groups of animals and after a while you will just recognise even small parts of bones because you've already seen the same bone many times on more complete specimens, be it on reference or your own specimens. I generally buy the fossils I think are cool and that I can get my hands on. With extensive research every next fossil becomes easier to identify. So having researched a bit on theropods (mainly Spinosaurids and Tyrannosaurids, but also Allosauroids, Abelisauroids and Dromaeosaurids) I hope I have a decent understanding of the bones.

And of course I can be wrong like anyone. And judging from a photo is far from ideal. But right now I don't recognise it as a specific theropod bone.

But in general it looks like it's most likely part of a hip or pectoral girdle. Due to the sediment filled dimple on the one side I think coracoid of a reptile is a good guess. But I am not familiar enough with plesiosaur or ichthyosaur hips and shoulders to make a proper judgement on that.

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Omnomosaurus
46 minutes ago, LordTrilobite said:

For unidentifiable bones, like you pretty much said, see if they are hollow. Hollow bones are more likely to be theropod, bird or pterosaur. Different types of animals have different bone density. Especially pterosaurs have ridiculously thin bone walls.

 

Here's an example of a pterosaur cervical vertebra that broke in half during prep. I took a photo before I glued it back together. The bone wall is little more than a millimeter thick. So identifying a bone just on bone thickness can be done.

ptero_crosssection.thumb.jpg.0971ecb320563ede4f1ca800007c6793.jpg

 

 

But for bones that do have good features that make them identifiable, I find that it's just good to get familiar with the anatomy of the animal in question.

Buy a fossil that isn't too expensive. Do research and gather a database of images. See if the reference matches you fossil. And if it doesn't expand your search. Through this process you'll get more and more familiar with more groups of animals and after a while you will just recognise even small parts of bones because you've already seen the same bone many times on more complete specimens, be it on reference or your own specimens. I generally buy the fossils I think are cool and that I can get my hands on. With extensive research every next fossil becomes easier to identify. So having researched a bit on theropods (mainly Spinosaurids and Tyrannosaurids, but also Allosauroids, Abelisauroids and Dromaeosaurids) I hope I have a decent understanding of the bones.

And of course I can be wrong like anyone. And judging from a photo is far from ideal. But right now I don't recognise it as a specific theropod bone.

But in general it looks like it's most likely part of a hip or pectoral girdle. Due to the sediment filled dimple on the one side I think coracoid of a reptile is a good guess. But I am not familiar enough with plesiosaur or ichthyosaur hips and shoulders to make a proper judgement on that.

 

22 minutes ago, Flx said:

Totally agree to what Lordtrilobite said. A few (somewhat stupid) extra points that may help to get started finding theropods:
- Check if the area/formation can contain theropod fossils. The layer must be mesozoic age, sedimentary rock and must not be exclusively marine.

- Limb bones: Usually hollow, long and slender

- Metatarsals/phalanges: Usually longish and slender

- Claws: Usually pointy and expensive :-)

 

Another point to consider:

If the fossils is fragmentary and cannot be identified it is most likely not a theropod. The reason is that there were less theropods than other animals in most ecosystems (such as non-theropod dinosaurs, turtles, crocs, ...). The Kem Kem beds in Morocco produce a fair amount of theropod fossils. This is an exception though. In most other places theropods are really rare.

 

 

Wow, thanks guys, that's some fantastic advice!

 

I mainly dabble with theropod teeth, and have a workable grasp of identifying different morphologies, but do get tempted when I see other potential theropod material for sale.

 

I'll take your ace advice @LordTrilobite and try picking up a few pieces to familiarise myself with some different anatomies. I'll also definitely double check the biodiversity of any formations I'm looking at too @Flx;)

 

I never realised how hollow pterosaur bones could be. It's crazy that the bones have survived intact for millions of years with such thin walls!

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Omnomosaurus

@LordTrilobite So I'm going to risk still looking the fool, and say that since this is a hollow bone with a thick internal wall, sourced from the Jurassic Kimmeridge Clay formation (Oxford, UK), then it could possibly be theropod?

 

juratyrant-tyranosaurid-bone--865-p.thumb.jpg.6bf7e1c4759d2123fce340a15e6e87d7.jpg5d018010dbdb5_juratyrant-tyranosaurid-bone--2-865-1-p.thumb.jpg.aa646e8df4abcace76defbe15a40ca6d.jpg5d01800da4ffe_juratyrant-tyranosaurid-bone--4-865-p.thumb.jpg.cddb724384c21e2185abe38f0fbda668.jpg

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LordTrilobite

That hollow inside looks more like erosion than a natural cavity to me. I don't think that looks like theropod bone structure.

 

But it's always good to ask questions when one is unsure of something.

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Omnomosaurus
19 minutes ago, LordTrilobite said:

That hollow inside looks more like erosion than a natural cavity to me. I don't think that looks like theropod bone structure.

 

But it's always good to ask questions when one is unsure of something.

 

So, this one's a dud too. I'll get there eventually! :ighappy:

 

I really do appreciate all the advice you've given....it sure is a complex old subject!

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Omnomosaurus
2 hours ago, paulgdls said:

Hello Tarquin.

 

@Omnomosaurus All I can say is that dinosaur material from the Kimmeridge and Oxford Clay formations is incredibly rare and theropod material even more so. 99.9% of bone is from marine reptiles but sometimes sold as dinosaur. Differentiating between the massive dorsal vertebral centra of pliosaurs and sauropods can be almost impossible and is often the subject of controversy. The limb bones of marine reptiles are not normally hollow although occasionally plesiosaurid humerii and femora do have narrowish cavities. The second bone you posted looks like a section of girdle bone from either an ichthyosaur or a plesiosaur. The first bone is a nice example. 

 

I have a massive section of bone which I collected from the Callovian of the Oxford Clay.  I still can't decide whether its from a huge pliosaur scapula or an ilium of a sauropod. The left hand photo below is the type specimen of Simolestes vorax scapula. If my find is a scapula it is from the biggest pliosaur ever found. 

 

regards

 

paul

 

 

Comparison with Simolestes vorax.jpg

scap in situ#2_1200.jpg

scap articular_1400.jpg

DSCF3350.JPG

 

Wow Paul, that's an amazing find, regardless of whether it does turn out to be sauropod or pliosaur!!

 

Thanks for the input; I have seen a few sellers with pieces of "dinosaur bone" for sale from the Kimmeridge Clay, so I think I will stay away from purchasing anything from that locality (or the Oxford Clay), just to be safe. You clearly know your stuff, and if it can be that difficult for an expert to be sure, then I have zero chance!

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JohnBrewer

That’s awfully large for an ichthyosaur coracoid 

 

@DE&i might know 

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paulgdls

@Omnomosaurus

 

Glad to be of some assistance. If you ever want an ID let me know and if its Kimmeridgian I'll run it past the world expert (Steve Etches).

 

Paul

 

 

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Omnomosaurus
11 hours ago, paulgdls said:

@Omnomosaurus

 

Glad to be of some assistance. If you ever want an ID let me know and if its Kimmeridgian I'll run it past the world expert (Steve Etches).

 

Paul

 

 

 

Aww thanks, Paul. I really appreciate that! :star:

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JohnBrewer

Dean Lomax would know too. He’s also an expert and has published several books and many academic papers. PM me if you want his email. 

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