Distal portion of a canid humerus?

[TXV24]

Hi, 

 

I was out this morning doing some collecting at Bouldnor Cliff (thought I'd mix it up from Hamstead for a change) and came across this distal portion of a mammal humerus lying on a mudflat. I'm regular collector along the north coast and know the vertebrate taxa and stratigraphy like the back of my hand but this humerus is unlike anything I've found before mammal-wise. I noticed straight away that it has a supratrochlear foramen, which from my own knowledge and some online research is a feature often found in canids. Material from amphicyonids like Cynodictis and Amphicyon have been found from the Bouldnor Formation (Rupelian aged, and spans 34.0 - 32.5 mya) but I'm unaware of any canid material, so I was looking to perhaps get a second opinion on whether this is canid, and/or whether the supratrochlear foramen is a reliable indicator of canid/carnivoran material.

 

 

Any help is much appreciated.

 

 

[Harry Pristis]

 

 

AFAIK, this foramen is limited to canids.  It is not present in amphicyonids.  Your specimen has so much damage, are you confident that this is a natural foramen?

 

 

[TXV24]

@Harry Pristis Thanks for the reply, it's difficult to say for certain, but as far as I can tell the foramen looks natural as there are no areas of abraded or cancellous bone around it that would suggest it has been produced through weathering/erosion. 

[jpc]

There are other critters with this foramen... rabbits come to mind, but this seems a bit large for a bunny.  

[Harry Pristis]

 

Yes, as I read it, sometimes rabbits and sometimes humans (most commonly a left, female humerus) have these foramina.  This is not a true vascular or neural foramen.  In life, it is covered by connective tissue.  It is located in an area of thin bone that, in a few species, feathers to nothing, a hole, a foramen.

 

This foramen is an unusual phenomenon in mammals.  It does not appear routinely in carnivores, with the exception of canids.  It seems to appear most consistently in canids.  Thus TXV24's question.  My opinion, for what it's worth, is that TXV24's specimen does not display a natural foramen.  The hole seems too regular to be a feathered edge, or even to be the result of erosion.  My guess is that this hole started as a puncture by a canine.  This guess is supported by the considerable damage (from gnawing?) to the head of the bone, though I don't see other bite damage . . . tooth marks may be beach-polished away.

 

What's your guess?

 

 

[TXV24]

@Harry Pristis That's an interesting idea that I hadn't considered. Turtle material has been found along the coast with puncture marks and embedded tooth fragments attributed to crocodilians so it's a possibility. However the damaged head is most likely the result of abrasion produced by being washed around by the tide and surf, rather than gnawing. I've passed some images on to the NHM in London so I should hopefully hear back from them soon. Thank you for your help.