Unusual dagger, billfish or bone “blade”?

[werecow]

Originally Posted by Ian

ww, I suspect from the cross-section shown that this is an unusually long baculum or penile bone. The groove would have been where the urethra ran the length of the penis. The longest examples are reported to occur in walruses (up to 64 cm). The length and straightness of this one may explain why it has been preserved in this form.

Just so you guys know, I am exercising enormous restraint not making any of the dozens of puns that this thread provokes.

[Sajen]

Originally Posted by werecow

Just so you guys know, I am exercising enormous restraint not making any of the dozens of puns that this thread provokes.

[thomas hauschild]

Not a penis bone. ( I have one in my display)

This one is a „sword“ / Rostrum from a sword-fish (Xiphias gladius ) I used a piece for knifemaking with this kind of 2 nerve-holes

[Rick]

Originally Posted by werecow

Just so you guys know, I am exercising enormous restraint not making any of the dozens of puns that this thread provokes.

Mighty large for a baculum, Ian.
I used to get Swordfish bills from the Sword boats when I was working in Menemsha on a yacht summers many years ago. Although the material looks sort of like part of a swordfish bill; I don't think it is.

I too am biting my tongue.

[David]

Well, it certainly isn't too long to be a baculum, as walrus oosiks can be quite large, but it does seems far too straight for one and i do not believe that oosiks have nerve holes running through them as shown in the above photo.
A filed down swordfish rostrum makes more sense and as you can see in the cross section CT scan, the holes at the base correspond with the frontals in that illustration.

[Ian]

Hi David,

The baculum bone is an interesting structure that shows a high degree of variation in length and shape among the various mammal groups that have one. In several species, the baculum is actually a Y-shaped structure with two separate arms that unite into a singe longer bone. In others, the two arms may still be present but they appear fused together, as a widening at the proximal end of the bone. Basically the two arms fuse into a single bone. The two arms each have a medullary cavity (for bone marrow) and fuse to form a single such cavity more distally. Thus, the proximal end in cross section shows two central cavities. This is what drew me initially to think of a baculum for the example in the original post. Because the tissue in the canals is missing in the cavities shown in the OP, we don't know what may have been there, There is the suggestion of a membrane that may have lined the cavity, but not enough evidence to distinguish a "nerve cavity" from a "medullary cavity" in a long bone (at least as I look at it).

As far as straightness, some species (including the walrus) can have straight baculum. Attached is a picture of a walrus baculum that resides in the Medical Museum of the University of Melbourne not far from where I live now.

As I noted in my original comment, if this is a baculum, it is an uncommonly large and straight one, and would have had some carving done to produce an acute point. Then again it could be the bill of a swordfish.

Whether a walrus baculum or the rostrum of a swordfish, there is a nautical flavor to the item and I would opt for maritime SE Asia as its origin.
.

[Athanase]

For me it's clearly swordfish
I cut several thin sections from swordfish rostrum (Gladius) and the internal structure is really similar. There are 5 other species of swordfish and the Blue Marlin have a rostrum more round in section with tow canals in the rostrum.
On the rod the sharp edges of the rostrum have been trimmed to obtain a round section.
As for the baculum in the museum picture, I really have doubts about the identification. I've never seen any baculum that looks like that (and I work in a natural history museum, so I've seen those of many species).

I had some image of cut section of various fossil rostrums of Marlins (from Miocene and Pliocene of Panama).

[Ian]

Athanase, thanks so much for your reply here!!! I can't comment on the attribution of the item in the museum at the University of Melbourne. I can say that Melbourne University's School of Medicine ranks in the top two or three medical schools in the country. But anyone can make a mistake I suppose.

As a natural historian and scientist, can you tell us what the main tissue is that comprises the rostrum? I'm not seeing on your cross sectional diagrams where blood vessels are located and would be necessary to maintain a viable structure.

[Athanase]

The images show fossils; the diagrams only show the bone area without detailing the bone's porosity.
But in reality, bone is very porous, crisscrossed with very fine blood vessels, cartilage, and adipose tissue.
Here's a post that illustrates it well.

https://www.researchgate.net/figure/...fig1_271389341