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LordTrilobite

Spinosaurid Vertebra with gnaw marks?

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LordTrilobite

I have this anterior dorsal Spinosaur vert from the Kem Kem beds. But I noticed these small vertical marks on one side of the vert and figured they might be gnaw marks. They definitely seem pretty worn down so I don't think they are recent. Any ideas what could have made these marks?

Vertebra overview.

post-3991-0-09412400-1471215564_thumb.jpgpost-3991-0-09252200-1471215570_thumb.jpg

Scratch detail.

post-3991-0-67267700-1471215575_thumb.jpgpost-3991-0-04415200-1471215582_thumb.jpg

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sagacious

Cool piece. I'm not an expert on dinosaur bones, but the short, largely unidirectional scratches on your specimen appear to my eye to be the scratches made by whoever removed the adhering matrix from the bone surface, over which a coat of varnish/consolidant/etc was then applied, which also has the effect of making the scratches appear less visible.

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Troodon

Theropod predation would leave a deeper gouge and there would be a lot fewer. Just looks like there are too many to be gnaw marks but I cannot tell. What's odd is that they are all from one direction but that could be the curve of the vertebra. Don't know.

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LordTrilobite

Cool piece. I'm not an expert on dinosaur bones, but the short, largely unidirectional scratches on your specimen appear to my eye to be the scratches made by whoever removed the adhering matrix from the bone surface, over which a coat of varnish/consolidant/etc was then applied, which also has the effect of making the scratches appear less visible.

Maybe, there is no coat though. And they weren't hidden. when I bought it there wasn't a whole lot of matrix on it. Just natural stuff. Nothing was added at any rate.

The problem is that I don't remember if there was natural matrix on some of the marks as well since it's been in storage for a while. And I occasionally go back to this piece to clean it some more as there are some really tough conglomerates on there that I want to remove. Two can be seen at the top in teh second picture.

Theropod predation would leave a deeper gouge and there would be a lot fewer. Just looks like there are too many to be gnaw marks but I cannot tell. What's odd is that they are all from one direction but that could be the curve of the vertebra. Don't know.

The marks roughly all have the same direction. Most are vertical slightly diagonal. The marks appear exclusively on the one side. It follows the curve of the centrum from bottom to top but seems to stop at the neural arch.

The main reason I lean more towards the marks not being prep marks is because the bone is really hard and the marks are seem fairly worn. When prepping this myself I did not leave any marks. I figure that if the are mechanical prep marks the damage would be more visible and leave a light discolouration.

I would agree that the marks seem way too small for Theropods though. Could they be fish bite marks maybe?

Edited by LordTrilobite

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Troodon

A couple of thoughts and a cool mystery to solve since I have not seen this on other bones from the region. If they were tool marks it would not be limited to one area and the scratches would not be in the same direction. So I'm shying away from preparation being the cause. Unless, the bone was not stored/transported correctly and was rubbing against some rocks which can easily cause the scratch marks. Fish definite possibility but they why would it be limited to that one area and all in the same direction. No answers just thoughts.

Edit

A mystery that may never be solved but is always asking the question HOW did they occur

Edited by Troodon

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doushantuo

Might be fungi..

Edited by doushantuo

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Canadawest

Gnaw marks are somewhat rare. If you think about an animal that is predated upon, it has much less chance of being preserved than one covered quickly in a flash flood, falling into a sinkhole, in the depths of a cave, etc. A predated animal is likely on the surface and the integrity of the body compromised...quick decomposition and bones fracturing.

Although rare, we do find some predation marks in Alberta dinos. There are lots of bones with various scratches but what tips the scale to predation? The main one is the marks need a bit of depth..obvious marks and not surfaces scratches. A dozen things can cause surface scratches. Secondly the marks are the same preservation as the bone...not lighter or darker in colour as they have undergone the same preservation. Thirdly, predated marks, in my experience, tend to be in parallel. A single gouge might be caused by lots of things but a few parallel marks are less likely to be random.

Anyways, when we walk through our badlands we could find a few 'probable' predation marks. However, we would need to pick up a few hundred bone chunks and really give them a good look. Might find a couple in a day ( if that was the focus) or even none.

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sagacious

Maybe, there is no coat though. And they weren't hidden. when I bought it there wasn't a whole lot of matrix on it. Just natural stuff. Nothing was added at any rate.

The problem is that I don't remember if there was natural matrix on some of the marks as well since it's been in storage for a while. And I occasionally go back to this piece to clean it some more as there are some really tough conglomerates on there that I want to remove. Two can be seen at the top in teh second picture.

Ok, yes, I see there's no coating applied.

Since the marks are all roughly the same length and depth and width, and distributed fairly evenly over wide areas, one might initially suspect they're prep marks. That the marks are largely unidirectional strengthens that suspicion, as one generally works along the smooth bone surface in one direction when removing tightly adhering matrix, generally along the curve of the short axis -- as on your piece, and not by stabbing at random angles into the matrix. The marks may have been made while the bone was still part of a much larger, unwieldy block of matrix, making unidirectional marks even more likely. On a simpler note, the scratches may be largely unidirectional simply because that's how the prep guy preps fossils, or because the matrix needed to be removed that way.

To my mind, you've solved the mystery of the marks with the phrase "really tough conglomerates on there," as one might expect hurried prep of a Kem Kem fossil bone with really tightly adhering, tough conglomerate matrix would result in a lot of scratches. Perhaps you can remove the remaining matrix, and check for the presence or absence of similar marks underneath. Had the bone never been prepped, then one could simply exclude prep marks.

I find a lot of bone in the formations I hunt, and perhaps like you, I scrutinize every piece for predation/scavenging marks, because of course, there's a thrill involved with finding a bone revealing traces of an ancient story of some predator/scavenger activity. That may certainly be what your piece is, but either way, it's still a very cool piece.

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LordTrilobite

Okay, so it's definitely an interesting mystery.

I've rechecked the vert under the microscope again. And I'm now 99% certain the marks are prefossilisation. The marks are pretty worn. And the main thing is that there are some marks that go across breaks that have happened in the fossilisation process. Cleaning some more of some of the cracks, what little natural matrix is left, the marks seem to extend under said matrix.

So the marks were made, and then the vert was slightly crushed in fossilisation, breaking apart some of the marks.

Here's a rough area where the marks appear.

post-3991-0-37840000-1471298704_thumb.jpg

So the marks appear only in that area. I've rechecked all sides of the vert and no where else does it show those marks.

Most of the marks are vertical with some variation within 20 degrees maybe? Then there are a few exceptions. There is a set of three larger deeper marks at around 20 degrees.

There is a bit of difference in the depth of some of the marks too. Most are subtle but clear scratches. A few are slightly deeper and there is also some that are less deep. These less deep marks appear to be at a different angle. The majority of the marks appear on the convex curve on the side of the vert. Of the affected area the top part is fairly similar to the middle. The bottom has fewer marks.

As far as I can tell all the marks have been slightly worn and have smooth-ish edges mostly. Some edges are harder than others. None of the marks have the lighter colour that is associated with damage elsewhere on the fossil.

And this might just be me seeing patterns where there are none. But some marks look like they might come in pairs.

What I think I'll do is make some more photos tomorrow and maybe also make a map drawing of all the marks I can find to see if there's a discernible pattern anywhere. And that will also allow you guys to properly see where the marks are.

Edited by LordTrilobite

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Troodon

Good detective work

The Kem Kem was semi-aquatic it's possible that this bone was caught in a stream and subjected to pre-fossilization turbulence which caused the marks.

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LordTrilobite

That's an interesting idea. I suppose it's possible that if the vert was partially burried only the "gnawed" area would have been exposed. More photos coming.

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LordTrilobite

Wel I made a proper image now since I removed the remaining ugly conglomerates there were left. And here are also some more detail photos of the marks.

Photos of the main marks. Most of these marks are pretty much vertical with a few exceptions that are at a slight angle. Some of these marks seem paired. But that is just my interpretation. The amount of wear on the mark edges is also fairly visible here.

post-3991-0-70718400-1471451055_thumb.jpgpost-3991-0-54967100-1471451060_thumb.jpg

Top view with a different set of marks at a different angle. These also seem to be at a different scale. On this photo a number of marks can be observed that cross the breakage in the fossil that occured during fossilisation. All of the smaller marks seem to be at roughly the same angle. All of these small marks are exlcusive to this area.

post-3991-0-99988000-1471451066_thumb.jpg

Notice the semi horizontal three marks on the lower right of the photo. The third mark is a bit hard to see on this photo but it is below the 2 clear marks. These marks are also slightly deeper.

post-3991-0-17669300-1471451072_thumb.jpg

gallery_3991_1190_2991810.jpg

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Troodon

Great pictures. With that one new photo I'm inclined to believe that the marks were there at the time of fossilization. I'm still hung up with the number of marks that they are directional and because of that still leaning away from predation. The other characteristic that I see is that the depth of a good number are about the same which would support non predation. Can be easily swayed.

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siteseer

I've been looking at this thread for days now. My first impression was definitely prep marks especially since many are parallel to each other - an indication of a preparator working from the best angle as Sagacious noted (there might have been more bone attached and was difficult to secure during prep - later broken and too fragmented to put back together cleanly). They look like cuts from a scalpel or a sharpened dental tool but I would expect the marks to indicate more of a slicing action than a downward cutting action. You would be trying to pop off individual pebbles and sand clusters. A preparator might later sand the bone down a bit to diminish the depth of the marks and shine it up a little.

Your observation that the cuts still appear under matrix that you have removed is evidence against prep. More evidence against the prep work idea is that a dealer probably wouldn't want to put too much time/money cleaning up a piece of a bone. I would squirt on some acetone onto the matrix to see if any glue comes up. That "matrix" could have been applied to cover up some of the marks if they were prep marks. Some glue might have been applied to stabilize the piece so even if some comes up, that's not damning evidence of prep marks.

I don't know of any gnawing animals from the Kem Kem beds. There were multituberculate mammals at the time. They had gnawing teeth like rodents but I don't know if a tooth has ever been reported from that time and place. The marks look more like cuts than repeated gnawing actions. A variety of fish bits are found there - perhaps a rather large scavenger in the fauna.

Wel I made a proper image now since I removed the remaining ugly conglomerates there were left. And here are also some more detail photos of the marks.

Photos of the main marks. Most of these marks are pretty much vertical with a few exceptions that are at a slight angle. Some of these marks seem paired. But that is just my interpretation. The amount of wear on the mark edges is also fairly visible here.

attachicon.gifvert06.jpgattachicon.gifvert07.jpg

Top view with a different set of marks at a different angle. These also seem to be at a different scale. On this photo a number of marks can be observed that cross the breakage in the fossil that occured during fossilisation. All of the smaller marks seem to be at roughly the same angle. All of these small marks are exlcusive to this area.

attachicon.gifvert08.jpg

Notice the semi horizontal three marks on the lower right of the photo. The third mark is a bit hard to see on this photo but it is below the 2 clear marks. These marks are also slightly deeper.

attachicon.gifvert09.jpg

gallery_3991_1190_2991810.jpg

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LordTrilobite

Thank you for the in depth post.

I can't really do that kinda of acetone test because there really isn't any matrix of note left as I've already cleaned it completely. But during the course of prepping, I've found zero evidence of any tampering or prepping before I started. Even the large crack in the middle of the vertebra showed no evidence of having been glued. It seems at least that the parts have never separated. I've used a lot of cyanoacrylate on the whole thing to prevent such things from happening in the future though. I have maybe around 30 or 40 Kem Kem fossils with varying quality and amount of matrix on them. Several of the fossils had been tampered with. Pieces glued back together, partial teeth constructed from different parts etc.

So by now I think I have a decent understanding of some of the typical states Kem Kem fossils are generally in and the amount of fakery that goes on. This is one of the few Kem Kem verts I have that had zero reconstruction and appeared to have no prep work done on it either (not counting the scratch marks). Generally parts that have fake matrix or are filled in artificially tend to have a different structure and colour. None of that was present here.

The tiny amount of damage I have done to the surface of the cortical bone of the vertebra is very different from the scratches. The bone is very hard but brittle and when damaged it breaks. It seems very scratch resistant. Although I haven't exactly tried to make scratches on the surface. :P

When popping off some pebbles of matrix with too much force and possibly damaging the bone. It either didn't make a mark at all or it left a white mark similar to some of the break lines. It seems to want to chip instead of making "clean" scratches.

There wasn't really anything "hidden" on the piece. Most of the cortical bone was clean to begin with. Just a few seemingly random chucks and pieces of martix here and there. Just what I would expect from something that wasn't cleaned.

But the main thing that makes me think that it's impossible for these to be prep marks. Is that several individual scratches perpendicularly cross the break lines that were caused during fossilisation. There is no extra damage on the edge where the scratch meets the break. It's very clean and continues on the other side. Which to me is a strong indicator that the scratch was made before the fossil was slightly squashed causing it to break.

I should still make a map of the marks to see if there's a discernable pattern...

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JohnBrewer

If the marks are from a scavenger/predator wouldn't the marks have an initial deeper part as it sank it's teeth in at one end then tail off as it removed it's mouth?

Absolutely stunning photography.

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siteseer

The average scavenger doesn't have heavy, bone-cruncher type teeth especially the small-medium-sized forms. They are going for chunks of flesh with rather thin (laterally-compressed) teeth occasionally scraping bone.

If the marks are from a scavenger/predator wouldn't the marks have an initial deeper part as it sank it's teeth in at one end then tail off as it removed it's mouth?

Absolutely stunning photography.

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Troodon

The marks would also be random from a scavenger these appear to be generally in one direction.

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LordTrilobite

What about snail gnaw marks? I've seen some that seem fairly similar.

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Troodon

Never seen those kinds of marks, can they get that deep and be so directional.

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LordTrilobite

Most I've seen are deeper and sometimes appear in horizontal bands with vertical marks that have roughly the same direction.

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LordTrilobite

Okay so it's been a while. But I finaly made a map of the scratch marks. I had a hard time stretching out the surface of the bone in one picture so I could trace the scratches.

I might have missed a few marks (especially some of the small ones). But this should be mostly accurate.

 

What becomes clear is that there are two main patterns present at two different scales and angles. The three larger sub horizontal three marks on the right seem like an anomaly. These three are also by far the deepest cuts. Black lines are scratch marks. Grey is outline and major breaklines on bone.

marks_map01.jpg

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Canadawest

It helps to visualize dinosaurs as part of a larger ecology. 

 

If an Elk is killed by a Cougar, the cat will rip open the carcass...feeds . Meanwhile a Grizzly smells the kill, wanders over and claims the carcass and literally tears it apart. A fox, Ravens, Jays, are hanging around getting scraps, etc.  The carcass is scattered about. The cougar reclaims part of the kill and  runs off with a leg...chews on it...her older kittens bite on it. Its left somewhere.  A Raven yanks away more meat. A weasel scrapes off some more.  The bare bone isn't finished as squirrels, voles, etc will gnaw on it for minerals.

 

A dead dino, if exposed was a big buffet. Tyrannosaurs, raptors, various reptiles like crocs and champsosaurs, , pterosaurs, birds, small mammals, etc. all would have joined the feast if they had the opportunity.

 

Anyways, if a predated bone is preserved,  it can may have a variety of marks. Perhaps different sizes are made from adult and their young...or by completely different types of animals.

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JohnBrewer

Great map Olof!

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Canadawest
6 minutes ago, JohnBrewer said:

Great map Olof!

Ha! It may be a fossil treasure map leading to a complete T rex skeleton. Perhaps Captain Kidd dug up a dino and reburied it but the pirate met his fate before he could  reclaim it.  Arg!

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