Dromaeosarid Foot (Bones and claw)

[Flx]

Hi 
I recently acquired some foot bones from a dromaeosaurid. Attached please find a sideview as well as a topview of the bones.
I was hoping that it is possible to:
1) identify the genus and 
2) identify which foot bones I have exactly

 

Location where the fossil has been found: North of Dupuyer, Montana, USA
Geological formation: Two Medicine - approx. 70M Years old

All bones have been found in the same micro-site in close proximity but not "associated". It is pretty save to assume that these come from the same animal though. Unfortunately no other bones have been found that would help identifying the genus. The guy who found the fossil thinks it could be Saurornitholestes.

 

My preliminary assessment (please note that I am not an expert at all):
- The long bone (top left) is one of the three metatarsals
- The weird shaped bone (top right) is a part of the ankle (lower end of the tibia)
- The claw (bottom left) is the claw that belongs to digit III or digit IV
- The other bones are probably digits From II, III or IV 
 

I am looking forward to your feedback. I realize that this is probably extremly difficult to ID the bones correctly. 
Thank you.

 

 

[Troodon]

Not sure you will be able to ID to a species but will need closer images of the claw top, side and bottom.  Like the same of the other digits but straight on shots not at an angle

 

That long bone is indeed a metatarsal poss digit III

[Flx]

Thank you for the quick reply. I will take some more pictures asap.

[Miocene_Mason]

I'm not convince these are dromaeosaur, could also be ornithomimid, right? Also, any idea of the formation these belong to?

[Kane]

1 minute ago, WhodamanHD said:

I'm not convince these are dromaeosaur, could also be ornithomimid, right? Also, any idea of the formation these belong to?

I think the OP stated the formation in the first post.  

[Miocene_Mason]

Just now, Kane said:

I think the OP stated the formation in the first post.  

Oh, sorry missed that.

[The Speeding Carno]

12 minutes ago, WhodamanHD said:

I'm not convince these are dromaeosaur, could also be ornithomimid, right? Also, any idea of the formation these belong to?

I am also a bit confused on what makes these dromaeosaur bones, could someone explain this to me?

[Miocene_Mason]

the straightness of the claw is my problem with the dromaeosaurid argument, the deinonychisaurs have more curve in there claws (everyone, not just the big one). Ornithomimids were cursorial animals that did a lot of running but not a lot of killing, so the claws straightened to allow better running. Here's a picture of ornithomimid foot

I hope that picture also can tell you which bones you have.

[Miocene_Mason]

I think you have either ornithomimus or struthiomimus.

[Troodon]

 

I think Saurnitholestes indet. is a good guess but like to see those closeup pictures.  There are other small theropods it could fit. That claw is odd why I need a closer image.   Here is an associated foot of a Saurnitholestes from Dinosaur Park that I took from the Royal Tyrrell Museum.  Your metatarsal is a good match D- III.   I don't see it being an ornithomimid the bones are too gracile.

 

 

. 

[The Speeding Carno]

Oh, so it depends on the shape of the bones. I guess that makes sense considering their different lifestyles.

[Miocene_Mason]

I agree that more photos are need. I'm still not sure about the raptor ID , it could just be variation in the species though. I will admit, I'm no expert at this. Maybe the claw is not associated, as assuming is never completely safe.

[Troodon]

17 minutes ago, The Speeding Carno said:

Oh, so it depends on the shape of the bones. I guess that makes sense considering their different lifestyles.

 

Isolated theropod foot digits are difficult to diagnose since they are very similiar.  Size and shape help reduce the possibilities.  In the end comparative analysis is the best way to try to get you at least to a family level but they are hard to find.   If you have an associated set with a claw you have a much better shot at an ID since they have more diagnostic features.  

[The Speeding Carno]

3 minutes ago, Troodon said:

 

Isolated theropod foot digits are difficult to diagnose since they are very similiar.  Size and shape help reduce the possibilities.  In the end   comparative analysis is the best way to try to get you at least to a family level but they are hard to find.   If you have an associated set with a claw you have a much better shot at an ID since they have more diagnostic features.  

Ok, thanks for the info!

[Flx]

Ok, I tried my best to get good pictures of the claw.

[Flx]

The length of the claw is 24mm (approx. 1 inch).

[Miocene_Mason]

Now that I see it up close, I can accept drmoaeosaurid.

[Flx]

I forgot to upload the bottom view.

[hxmendoza]

Possibly Dromaeosaurid, but can't completely rule out Troodontid either. It looks to be one or the other though. But I think it's too hard to truly tell with the pics and the apparent taphonomic distortion and preservation.

[Troodon]

The bones all have the same preservation, look comparable in size and were found in close proximity so I think its reasonable to suggest they are associated but one can never be certain.  I think it's a Dromaeosaurid now is it a Saurornitholestes, I cannot be sure because of similarity of bones in that family but I would lean that way with how similiar they are with the RTMP specimen.   Nice group of bones from a cool locality.   Other possibilities include Dromaeosaurus and adult Bambiraptor.   Other opinions welcomed.   Saurornitholestes skeletal elements have been found in the Two Medicine but it not described

 

Your claw, although weathered, seems to have some resemblance to Digit I of this Saurnitholestes foot from another RTMP specimen.

 

[hxmendoza]

17 minutes ago, Troodon said:

The bones all have the same preservation, look comparable in size and were found in close proximity so I think its reasonable to suggest they are associated but one can never be certain.  I think it's a Dromaeosaurid now is it a Saurornitholestes, I cannot be sure because of similarity of bones in that family but I would lean that way with how similiar they are with the RTMP specimen.   Nice group of bones from a cool locality.   Other possibilities include Dromaeosaurus and adult Bambiraptor.   Other opinions welcomed.   Saurornitholestes skeletal elements have been found in the Two Medicine but it not described

 

Your claw, although weathered, seems to have some resemblance to Digit I of this Saurnitholestes foot from another RTMP specimen.

 

 

That was my first impression too @Troodon. It superficially resembles the hallux claw. But then the straight on picture view of the articulating end didn't match up. 

All the Dromy hallux claws I've seen have a narrow elliptical articulating end. That includes Troodontid hallux claws. 

 

Its such a rounded sub-oval articulating end that it makes me doubt (not rule out completely though) that it's one of the other Dromaeosaur or Troodontid foot claws. 

Just about every Dromy walking claw I've seen has a more laterally compressed strong oval or dominantly teardrop shaped articulating end. The teardrop morphology being the more common morph. 

 

Definitely a tough one to call. 

[Troodon]

14 minutes ago, hxmendoza said:

 

That was my first impression too @Troodon. It superficially resembles the hallux claw. But then the straight on picture view of the articulating end didn't match up. 

All the Dromy hallux claws I've seen have a narrow elliptical articulating end. That includes Troodontid hallux claws. 

 

Its such a round articulating end that it makes me doubt (not rule out completely though) that it's one of the other Dromaeosaur or Troodontid foot claws. 

Just about every Dromy walking claw I've seen has a more laterally compressed strong oval or dominantly teardrop shaped articulating end. The teardrop morphology being the more common morph. 

 

Not easy is right.  I thought of Troodon and ruled it out because their metatarsals did not match the specimen in question so went to dromaeosaurid which fit the RTMP specimen 

 

Troodon tarsals

 

 

[Miocene_Mason]

Is it possible it does not fit into any existing taxon?

[Flx]

Thank you very much for the analysis. I highly appreciate it.
Recently a pretty complete fossil of a raptor was found in the US so maybe there will be more reference material soon. 

[hxmendoza]

26 minutes ago, Troodon said:

 

Not easy is right.  I thought of Troodon and ruled it out because their metatarsals did not match the specimen in question so went to dromaeosaurid which fit the RTMP specimen 

 

Troodon tarsals

 

 

 

Yep, I just finished looking around at some info. And the Talos foot photos too.

So I'm going to go the most conservative route for now, also.

 

I'm in agreement that it most likely is a Dromaeosaurid. 

 

But the foot claw is somewhat problematic. 

Maybe slight pathology?...

I just don't know.