Kem Kem Bone Spike/Horn?

[LordTrilobite]

I recently bought a whole bunch of chunkosaur pieces. Most unidentifiable. But there was some interesting stuff in there as well. This piece in particular looks interesting.

At first glance it looks like just a chunk of bone. But then I noticed that most sides still show the outside cortical bone without much damage. The two main sides which are both subtly rounded, are vertically straight and seem to converge into a point. The whole thing is roughly cone shaped. Viewing it from the pointed end it is roughly oval shaped. There is a flat bit on the "underside" of the cone. The bone structure is very dense on one side and very rugose and open near the tip and the other side of the bone, indicating possible fast growth or remodeling. The broken inside also shows a lot of open spaces and air pockets.

 

Now the problem is, that this looks to me like some kind of spike or horn. But I don't know of anything in the Kem Kem beds that has these kinds of structures. Crocodiles have scutes and such, but this piece doesn't resemble armour as it doesn't seem dense enough. Ankylosaurs have spikes, but those aren't present in Kem Kem and their armour is denser as well. The closest thing I could find with a similar shape, was the brow horn of Carnotaurus, which is also not present in Kem Kem. It's a really weird shape that I can't seem to place.

 

Any ideas?

 

Side and "top" rounded surface with dense bone.

 

Other side view and the other rounded side.

 

Cross section of dense bone. "bottom". And broken tip of the "spike".

 

Details.

 

[Troodon]

Very hard to get the same perspective you're getting holding the peice, this is where photos fall short.   My initial reaction was the same as your first one, chunk of bone.  Couple of questions.

On your top pictures the one on the right looks flatish,  is it?  Could it just be a fragment of limb bone?

Also trying to understand your cone(spike).  The right image is the view looking down correct.  The area I marked in white does not look like outside bone but fragmented, to many open pores.  Do you have a photo of that side? Is it the bottom right one?

 

 

[LordTrilobite]

The area you marked white is definitely the outside of the bone. It is not broken apart from two scratches that are likely tool damage from finding the fossil. That side is visible in the fourth photo in my first post.

 

I'll try to make some drawings to try and make the shape a little more clear. I agree that it's very hard to tell from just the photos.

[Troodon]

Perfect, I was going to suggest that since you're very skilled at it.

[LordTrilobite]

Okay here are some notes over the same pictures. It basically has three main sides. Two sides of the point and an underside. The two sides of the point A and B are rounded and meet on the sides in a fairly pronounced edge. The tip is broken off but it is still very clear that the A and B sides would meet in the middle to create such a point.

 

Side A is the dense side and the most bumpy. It has a nice flowing curve from one edge to the other. It gets more rugose towards the missing tip.

Side B has two parts. There is an indented shelf on the left (B1) and a large bump that covers the rest of the B side (B2). Between B1 and B2 there is a vertical furrow that starts subtle near the top and goes deeper towards the bottom side (C).

Side C is the underside. It's mostly a flat surface. Its unclear how much the bone would have extended from the A and C area.

[Troodon]

Beautiful job....need to study it.

[Troodon]

I've looked at several different times and have not made any progress.

 

Let's just take this photo.  I'm struggling to see a real edge.  My white line is the outside surface A  but where my X's are appear to be open pores.  That "edge" appears to be a broken edge.  That edge is key in your theory of what this is.

[LordTrilobite]

Okay so some extra info. I checked it from under the microscope again. The side you marked has almost no damage at all. I might have exadurated the edge a tiny bit. On the photo you marked. There is an edge that follows my dotted line. It starts fairly sharp near the top. And it becomes softer as it goes down. Half way down there isn't much of an edge, it's just rounded. So on the bottom half of the edge A and B2 blend together to form a round bulge instead of a sharp edge. So the edge is only sharp near the tip.

 

Besides the obvious missing chunks. There is very little damage to the surface of the bone. All sides have the general shape intact. The bone is just incredibly rugose. The most surface damage is in the middle of the B2 side. There are some scratches. Otherwise even that surface is intact.

 

Short version. Very little surface damage. The edge is just softer near the bottom.

 

 

Going off the Carnotaurus horn idea, even though it's not present in Africa. It does seem a bit similar if A is the top of the horn and B the bottom based on these images. The top seems smoother while the underside seems bumpier. Of course it could still be something totally different.

https://www.researchgate.net/publication/232691183

[Troodon]

Okay, I see where you are coming from and the bone you comparing against.  There are some similarities but respectively I cannot agree.  You have the specimen and a much better visual on it.  Anyone at a local museum that is qualified to look at it?

[LordTrilobite]

Oh I'm not saying it's definitely that. I'm just trying to figure out what it is. Since it isn't just a non-descript bone, but has some odd features. I really want to try and figure out the mystery.

I did already take it to Naturalis. But no clear results yet. The Netherlands isn't exactly the hotspot for Theropods. I'll keep trying though.

 

Thanks for the responses.

[LordTrilobite]

I took it to the museum Naturalis in Leiden again. The comments I got was that it does look like something that was covered with keratin like a horn or nail due to the bone structure.

[Susan from PA]

1 hour ago, LordTrilobite said:

I took it to the museum Naturalis in Leiden again. The comments I got was that it does look like something that was covered with keratin like a horn or nail due to the bone structure.

Thanks for sharing!  Just goes to show that you never know what might be discovered in the Kem Kem!   

[LordTrilobite]

The thing is though. That nothing there is known to have horns, as far as I know. And it doesn't seem to resemble any unguals or armour I compared it to. Sauropod nails might be the right size but those seem to have a different shape and texture.

[Troodon]

Very nice thanks for giving us an update.  Question now what is it.  Titanosaurs/Diplodocid had that size in the terminal phalanx

A lot older but here is a jurassic Diplodocid 

[LordTrilobite]

Well there is of course a Sauropod present in Kem Kem. Rebachisaurus, which is a Diplodocoid.

 

I've looked through some good examples. Here that of Camarasaurus.

http://palaeo-electronica.org/content/2015/306-559/1301-manus-and-pes-of-camarasaurus-figures#f4

https://www.researchgate.net/publication/270157661_Pathological_Phalanges_in_a_Camarasaurid_Sauropod_Dinosaur_and_Implications_on_Behaviour

 

Alamosaurus example

https://www.researchgate.net/publication/232869159_A_Sauropod_Dinosaur_Pes_from_the_Latest_Cretaceous_of_North_America_and_the_Validity_of_Alamosaurus_sanjuanensis_Sauropoda_Titanosauria

 

But the shapes don't seem to match up. My fossil seems a lot fatter at the base. The point is also very straight. Not curved like the typical Sauropod claws. The Sauropod claws also seem a lot flatter laterally. The one flatter side may have some superficial similarities. But the other side on my fossil is rounded and way more bumpy. The texture of Sauropod claws also seem more smooth with much denser bone.

 

I also looked at Ankylosaurs and Stegosaurs. The plates of stegosaurs seem to have similar structure, but are way thinner. The spikes of Stegosaurs are way denser in structure. Also Stegosaurs in the cretaceous would be weird. Ankylosaur would make more sense. But those are also unknown here. Ankylosaurs have spikes in all shapes and sizes. But all the examples I could find all have way denser structure. So that seems like a dead end as well.

 

So far there are only two things I found that come close. The horns of Carnotaurus and the horns of Kaprosuchus. Neither of which is presently known in Kem Kem. The little horn-like structures on the back of the skull of Kaprosuchus seem a bit similar in shape and structure. It seems to be similar in texture. But in side view the base of the horns on Kaprosuchus are thinner. I also don't see any weird bumps like my fossil has. Niger, where Kaprosuchus does have a fairly similar ecosystem though.

 

But the best match I can find is still Carnotaurus. With the top of the horn being fairly smooth and the bone fibers are parallel just like my fossil. The underside has a rounded bump and a notch on one side just like my fossil. The base is smoother and the tip is more rugose just like my fossil. From the side view the angle is very similar. From the front view the angle is very similar.

Though there's one thing I can't really see very well on the images on Carnotaurus. It's difficult to see if front and back edges of the horns are rounded or sharp. Since my fossil has one harder edge and one more rounded softer edge. The main thing that I see that is different in my fossil compared to Carnotaurus is that my fossil seems to have a sharper point. The horns of Carnotaurus seem just slightly fatter and more rounded towards the tip.

[Sagebrush Steve]

Just to cover all the bases, are you sure it is Kem Kem?  You say you bought it with a lot of chunkosaurus pieces, could the seller have mixed in pieces from other localities?

[LordTrilobite]

Good point actually.

 

It was labeled as a Kem Kem bunch. Basically the Kem Kem reject pile. Broken teeth and chunks of bone. Pretty much all with the typical Kem Kem preservation. 3D with chunks of matrix stuck to it in the form of pebbles and sometimes iron rich crusts. I hadn't thought of the possibility. But I don't see any reason to assume any of the pieces are not from Kem Kem. This piece as well has also has the typical Kem Kem preservation as well as the same matrix.

[Troodon]

I'm sure you've looked at this paper but just in case.

 

 

Coria, Rodolfo A. (1990). "Carnotaurus sastrei Bonaparte, the horned, lightly built carnosaur from the Middle Cretaceous of Patagonia" (PDF). Contributions in Science. Natural History Museum of Los Angeles County. 416.

[LordTrilobite]

I have indeed. But, thank you anyway.

 

Here's what that paper says about the horns of Carnotaurus.

Quote

"The horns of this species are formed by the frontals. They project laterodorsal and are relatively short and very thick, with the dorsoposterior surfaces rather flat. They show a system of shallow grooves, lateromedially directed, that make the surface very different from the rugose nature of the muzzle. The structure of the horns is not very different in appearance from the horn cores present in bovids, although they are certainly not identical to the latter. the horns may have had a corneous covering, which would have made the horns much longer in life."

 

This description seems fairly similar. Though I can't really judge how shallow those grooves on Carnotaurus are since the photos aren't of the best quality. Another thing that seems to be different is that I don't really see a flat surface on either sides of the "top" that could be the dorsoposterior. My fossil has a more rounded shape anteroposteriorly when the fossil is set in the same orientation.

 

And still one bigger difference is that the Carnotaurus horns are longer and less sharp at the point as I said earlier. Still, Carnosaurus horns are the only thing that seems to come close in shape. I dunno what I should think of this.

[Troodon]

Not sure what to tell you, it's difficult comparison.  Your looking at a Maastrichtian age dinosaur, thats around a 25m year difference from the Kem Kem, what's changed.   The other issue is that there has been no evidence of any large Abelisaurid type teeth in this fauna.  With the large number of teeth that come out one would expect a few to surface and that would make news.  I think you would be better served if you focus on what we currently know in theropods or sauropods.  

[LordTrilobite]

Indeed it is a big time gap. Though this fossil isn't actually that big. It it were attached to an Abelisaur skull it really wouldn't be that large.

 

Whatever it is. It sure is a good mystery.

[westcoast]

Just erect a new genus. Problem solved   . Thanks for sharing your thoughts so openly and clearly. Where do you get your key kem material?

[LordTrilobite]

All over the place. I just buy any Kem Kem stuff that looks interesting. random chunks of bone are generally cheaper and more interesting than teeth I find.

[LordTrilobite]

So I want to revive this thread because I now have a proper scan of this piece. So I can more easily show of the actual shape of this bone since it didn't translate well into 2D photos. I've also done some more research but I've really gotten no further. The experts I've spoken to all agree that this looks like a horn or some type that probably had a keratinous covering on it. And I have still not found anything else that matches other than the horns of Carnotaurus.

I have gotten around to comparing it some with some better reference of Carnotaurus, and there are some differences in shape. Carnotaurus has a bit longer horns that are a little fatter at the point. But the general shape and structure is very similar. A dense smoother top and a more rugose bottom side of the horn that is rounded with a bump and a vertical groove on one side. But even if this has nothing to do with a relative of Carnotaurus. It still seems to be a horn from an area where no horned animals are known.

 

@Troodon, perhaps this will help to show what the actual shape of the bone is.

[Troodon]

Ha ha why I'm not surprised to see this pop up again, very nice.  Great 3D image and it does give a better perspective.  It has some similarities to Carnotaurus but there are differences like you said.  Having said that we do not know what the frontals look like on Abelsaurids in the Kem Kem, they do exist,  so it's possible.   

 

 I attached images the skull of the Carnotaurus holotype skull so others can see what is being discussed.