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Frostedoddity

Dugong rib predation marks?

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Frostedoddity

I noticed that fossil dugong rib bones from Florida often have boring worm holes in them, though these are not predators per se, and have heard that shark marks can be found. Any other kinds of marks I should look out for? How common is it to find shark bite marks on the ribs?

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Bone Daddy

Here is a rib I found with possible predation marks on it. In this case, there are two evenly-spaced and parallel marks in the bone.



 

rib-marks-1.jpg

rib-marks-2.jpg

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Harry Pristis

Those borings on the dugongid ribs are from rock-boring clams, Family Pholadidae.

 My experience is that tooth marks are rarely as prominent as on Bone Daddy's example.  I've posted images of two specimens on which teeth seem to have been dragged lengthwise along the bone.

dugongrib.jpg

dugongribborings.JPG

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Frostedoddity

Thanks for the examples guys! I see clam borings all the time, but nothing like the scrapes in Harry's examples. I'll be checking more carefully though as it seems at first glance one might mistake some scrape marks for the natural surface of the rib.

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Bone Daddy

I would suspect that predation marks would vary according to what predator made the marks. Also, the marks may be different depending on when they were made - either at the time the prey was killed by the predator, or afterwards when the remains were set upon by scavengers.

 

Given that one of the major predators of dugongs was the megalodon, one would expect megalodon predation marks to be prominent and large - similar to the marks seen on the rib I posted photos of.

 

Smaller marks could be the result of predation or scavenging.  Here is a photo of some smaller bones I found that appear to have "gnawing" marks on them -

 

 

bone-mark-2.jpg

bones-pred-1.jpg

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Bone Daddy

Of course, without an analysis by professionals, there is little way to know for sure. It's mostly speculation on the part of amateurs like myself who find bones with markings on them and try to explain those markings.

 

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doushantuo

instructive,to say the least..

7526-6409-1-PB.pdf

 

edit:would that be the p-cubed article?

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Boesse

@doushantuo yes it is - and that jacobsen and bromley article was a most welcome addition to the literature, finally offering ichnotaxonomic names for bite marks.

 

 

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doushantuo

I will just have to exercise patience,then:P

 

 

 

 

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Doctor Mud

Hi Bobby,

 

Can you provide a reference to your paper with Ewan.

 

I hear what you are saying about being careful. Unless the marks are matrix filled and found by the observer (not the guy from Fringe for sci fi fans) you have to be careful. Sometimes a difference in bone patina inside the grooves may provide evidence that these are not coeval with death or deposition, but not a guarantee.

 

Speaking of serrations:

 

Heres my favourite bite mark from New Zealand. Note the serrations. Most likely C. Angustidens given the age of the sediments

 

image.jpeg

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Boesse

@Doctor Mud here's the link to the paper: http://onlinelibrary.wiley.com/doi/10.1111/let.12108/abstract

email me if you'd like a pdf.

 

Is that specimen from the Kokoamu Greensand or lower Otekaike LS? preservation looks right! The whales and penguins in the Otago collection are riddled with bite marks.

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Brett Breakin' Rocks
On 1/15/2017 at 0:28 PM, Boesse said:

Hey all - I've attached some figures of various types of bite marks. They can be quite common, though the only unequivocal way to demonstrate that they are bite marks - which is admittedly easier for amateurs than prof paleontologists - is to see the trace emerge on the bone surface as you remove the matrix yourself, and photograph it. If you see specimens with possible tooth scrapes in a museum drawer, you have no idea if they are dental pick scrapes.

 

Sometimes the bite marks can be very fine and short - in Boessenecker and Fordyce below, we reported bite marks that criss-crossed bone eating worm "pockmarks" where the roots of the worm were concealed by a thin veneer of bone, and a small shark, skate, or bony fish came and bit into the rotten bone to consume the worms.

 

The Collareta et al. figure (published this week!) shows that serrations can have some sort of expression as well. And the Boessenecker et al. image shows various sorts of bone modification, including a little tiny fur seal femur fragment with evidence of bite marks AND partial acid digestion.

Collareta 3.jpg

Boessenecker et al.jpg

 

 

Wow, this is some amazing visual reference ... thank you.

 

Cheers,

B

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Doctor Mud
10 hours ago, Boesse said:

@Doctor Mud here's the link to the paper: http://onlinelibrary.wiley.com/doi/10.1111/let.12108/abstract

email me if you'd like a pdf.

 

Is that specimen from the Kokoamu Greensand or lower Otekaike LS? preservation looks right! The whales and penguins in the Otago collection are riddled with bite marks.

Thanks Bobby,

 

Yes, lower Otekaike LS. Rescued from getting turned into dust in a lime quarry.

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Doctor Mud

I was thinking about predation marks on bones today (as you do!) I was thinking that some predation marks will be from predators attacking prey when alive and some will be from predators scavenging floating carcasses.

I wonder if there would be characteristic bite marks for a kill - and some that are more likely scavenging, or at least post-mortem. The killing bite may be somewhat  opportunistic, or like a cheetah taking down a gazelle a most efficient or preferred death bite occurs.

 

it is probably hard to differentiate and you would need special circumstances to tell what was the fatal wound.

 

@Boesse might have read something about this? I guess you might be able to perform "paleo forensics" if you had a complete, well preserved skeleton....

 

Heres a cool article on Great Whites scavenging a sperm whale carcass 1 km off the coast of Australia. 

 

The the sharks sometimes approach on their back to get a better angle for biting.

 

 

http://www.smh.com.au/environment/whale-watch/closeup-footage-shows-sharks-feasting-on-whale-carcass-off-coffs-harbour-20150703-gi4ci1.html

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Doctor Mud

I was thinking in terms of the example provided, a Great White probably wouldn't  kill a Sperm Whale, so unlikely predator prey relationships might be evidence for scavenging. Great White bite marks on whale bones vs Meg bite marks on Whale bones for example.

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