Fossil dugong relative or whale - tusk or tooth?

[siteseer]

I thought I would bring in the forum on a difference of opinion among a few collectors.  Attached are views of a specimen identified as a Metaxytherium tusk (late Miocene, Bone Valley Formation, unnamed phosphate mine, Polk County, Florida) by one experienced Florida collector and another collector familiar with a range of marine mammal fossils.  Two other experienced Florida collectors leaned toward an ID of whale tooth.  The specimen resembles one in Domning (1988: p. 409, fig. 7) which was identified as a Metaxytherium tusk.  The specimen in question is straight like a tusk with an enamel-coated crown with a constriction toward the tip as in the figure.  I've looked for a similar specimen labelled as a whale tooth in various publications (Richard Hulbert's "Fossil Vertebrates of Florida; the Lee Creek volume that covers mammals, etc.) but couldn't find one.

 

Metaxytherium was a "sea cow" or dugong relative that lived during the Miocene - a time when sea cows were more diverse and widespread than they are today.

 

The Florida collector who thought it was a Metaxytherium tusk pointed out the enamel texture and its laterally-compressed overall form was the same as a tusk.  The other Florida collectors didn't point out any particular feature to count it out as a Metaxytherium tusk - just didn't look right to them.  I can understand having difficulty articulating an overall impression.  Those two guys know Florida fossils so I respect their opinions.

 

I'm interested in reading what other collectors think - especially all the Florida/Bone Valley collectors out there.  I'll try to get a scan of the figure in the Domning article and attach it - couldn't find a pdf in a quick search.

 

Thanks,

 

Jess

 

Domning, D. P. 1988.

Fossil Sirenia of the West Atlantic and Caribbean region. I. Metaxytherium floridanum Hay, 1922. Journal of Vertebrate Paleontology 8:395–426.

 

[Miocene_Mason]

Well I’m not from there and I’m not sure about all this Metaxytherium tusk business (I didn’t know they had tusks) but that look a lot like a whale tooth to me. If there is someone to settle the matter I suppose it would be @Boesse

[Harry Pristis]

 

Anything helpful here?

 

dugongid_dentition.pdf

 

 

[doushantuo]

a while back I posted an excerpt from this:

[doushantuo]

 

 

from 1994(edit:I'll let it stand,although it might be considered (minor)threadjacking)

 

 

[doushantuo]

[Boesse]

This looks dugongid to me, and the flattened root - with flattening of the crown in the same plane - makes this resemble sirenian tusks.

[doushantuo]

[siteseer]

5 hours ago, Harry Pristis said:

 

Anything helpful here?

 

dugongid_dentition.pdf

 

 

 

Thanks for the paper, Harry.

 

Jess

 

3 hours ago, doushantuo said:

 

 

Thanks for posting the figure, Doushnatuo.  

 

Jess

 

[siteseer]

1 hour ago, Boesse said:

This looks dugongid to me, and the flattened root - with flattening of the crown in the same plane - makes this resemble sirenian tusks.

 

 

Thanks for taking a look, Bobby. 

 

There's a shot of sirenian fossils on page 20 of the mainstream guide, "Manatees and Dugongs of the World" by Jeff Ripple.  It's a photo of a fossil dugong molar and tusk plus a manatee tooth.  The specimens are not identified to genus nor are the localities noted.  The tusk appears rather large - roughly 3 inches long and maybe 1 3/4 - 2 inches wide.  Maybe you recall the photo.  The tusk does not look like the same form figured by Domning.  Do the tusks differ that much from genus to genus?  I would assume some variation even within a species (some tusks longer; some more robust) but the tusk shown looks more probiscidean to me. 

 

Jess

[doushantuo]

[doushantuo]

maybe,given the specific use of sirenian tusks,there might be distinctive attrition ("dental wear")patterns.

meanwhile

 

edit: before i forget: recommended,althought the taxonomy might be obsolete

Outtake:

 

edit two: And also available in Fruitbat's library,I belatedly noticed(AFTER i posted this).

As always kudo's to Joe  

 

 

[doushantuo]

also recommended:

[doushantuo]