Nimravis Posted May 2, 2019 Share Posted May 2, 2019 I collected this Dugong bone near Sarasota, Florida today and was wondering what would make this indentation/ boring? Link to comment Share on other sites More sharing options...
Brett Breakin' Rocks Posted May 2, 2019 Share Posted May 2, 2019 19 minutes ago, Nimravis said: I collected this Dugong bone near Sarasota, Florida today and was wondering what would make this indentation/ boring? Hi There, usually they are burrowing or boring clams that can make marks and holes in fossils like these. You can see similar marks in other bones, meg teeth etc ... Cheers, Brett Image Credit: MegaTeeth Dugong rib section - Peace River Image Credit: Galactic Stone and Iron Works Modern 'ship worms' a type of boring clam. https://www.smithsonianmag.com/science-nature/tunneling-clam-bedeviled-humans-sank-ships-conquered-oceans-180961288/ 3 Link to comment Share on other sites More sharing options...
Nimravis Posted May 2, 2019 Author Share Posted May 2, 2019 @Brett Breakin' Rocks Cool Brett- I appreciate the quick response. Link to comment Share on other sites More sharing options...
digit Posted May 2, 2019 Share Posted May 2, 2019 Yup. Bored dugong ribs make an appearance on this forum every once in a while. Here's my comments from a couple of years ago: http://www.thefossilforum.com/index.php?/topic/71805-peace-river-fossil-sirenian-rib/&do=findComment&comment=756096 And some information about the boring mollusks (which are, in fact, quite interesting): https://en.wikipedia.org/wiki/Pholadidae https://en.wikipedia.org/wiki/Pholad_borings Dugong bones are quite dense and do not have the spongy cancellous interior of many other bones. Dugongs (and modern day manatee) have developed these heavy bones to act as ballast to enable them to do more than just buoyantly float around on the surface. Sometimes you can quite clearly see the growth rings in the cross-section of a break in the bone--much like tree rings. Those layers are quite evident and display well in the beginnings of a boring in your specimen. That simple item comes packed with lots of stories to tell. Cheers. -Ken 3 Link to comment Share on other sites More sharing options...
Brett Breakin' Rocks Posted May 2, 2019 Share Posted May 2, 2019 8 hours ago, Nimravis said: Cool Brett- I appreciate the quick response. No worries... I'm a bit of a night owl. Cool piece. Link to comment Share on other sites More sharing options...
Bronzviking Posted May 2, 2019 Share Posted May 2, 2019 More on Shell Wars Boreholes. Gastropods and bivalves drill in other shells to eat them. Single, circular boreholes were likely eaten by a predatory gastropod. Oyster drills (Urosalpinx app.) leave a straight hole, whereas thick lipped drills (Eupleura caudata) leave a slightly beveled hole. Shark eye snails (Neverita duplicata) leave a countersunk hole, circular borehole that has a outer diameter twice the inner diameter. Reference: "Florida's Seashells A Beachcomber's Guide" by Blair and Dawn Witherington I've seen bore holes in rock so, I don't see why that can't drill in bone. Would you say yours is a beveled or countersunk hole? Link to comment Share on other sites More sharing options...
Nimravis Posted May 2, 2019 Author Share Posted May 2, 2019 6 minutes ago, Bronzviking said: Would you say yours is a beveled or countersunk hole? I would say beveled- though pics of beveled and countersunk holes look the same to me. Link to comment Share on other sites More sharing options...
digit Posted May 2, 2019 Share Posted May 2, 2019 Keep in mind that the predatory gastropods mentioned above (murex and shark eyes) drill tiny holes into the shells of other mollusks (usually bivalves) in order to breach the protective shell and feed upon the soft tissue within. These holes are usually much smaller than the larger boring holes made by burrowing pholad bivalves and shipworms. Here are some examples of the tiny predatory holes that are evidence the demise of these mollusks. Cheers. -Ken Link to comment Share on other sites More sharing options...
Bronzviking Posted May 2, 2019 Share Posted May 2, 2019 12 minutes ago, Nimravis said: I would say beveled- though pics of beveled and countersunk holes look the same to me. Can you measure the diameter of the hole? Thanks Link to comment Share on other sites More sharing options...
Nimravis Posted May 2, 2019 Author Share Posted May 2, 2019 12 minutes ago, Bronzviking said: Can you measure the diameter of the hole? Thanks I will go find that piece in a bit, but I believe that it is a tad over 1 cm. Link to comment Share on other sites More sharing options...
digit Posted May 2, 2019 Share Posted May 2, 2019 Which is much larger than the smaller drill holes that the predatory mollusks would drill into other shells. There would be no point for these predators to drill into dugong bones as it would not gain them any food. The larger holes would be the burrows of the pholad type mollusks. I've seen newbie fossil hunters on the Peace River who, upon discovering their first fossil gator teeth, try to convince themselves that the teeth fit nicely into the holes left in the dugong bones and must have come from gator predation. A classic mistake made by a simple assumption unencumbered by the thought process. Cheers. -Ken 1 Link to comment Share on other sites More sharing options...
Harry Pristis Posted May 2, 2019 Share Posted May 2, 2019 Pholadid clams (Fam. Pholadidae - "rock-boring clams") burrow into any hard substrate. Here's a fossil coral from South Florida with two pholadids still embedded. 2 http://pristis.wix.com/the-demijohn-page What seest thou else In the dark backward and abysm of time? ---Shakespeare, The Tempest Link to comment Share on other sites More sharing options...
Nimravis Posted May 2, 2019 Author Share Posted May 2, 2019 Link to comment Share on other sites More sharing options...
Nimravis Posted May 2, 2019 Author Share Posted May 2, 2019 2 hours ago, digit said: Here are some examples of the tiny predatory holes that are evidence the demise of these mollusks. I agree- and I like collecting them and have tons of examples of these. Link to comment Share on other sites More sharing options...
Bronzviking Posted May 2, 2019 Share Posted May 2, 2019 16 hours ago, Brett Breakin' Rocks said: Modern 'ship worms' a type of boring clam. https://www.smithsonianmag.com/science-nature/tunneling-clam-bedeviled-humans-sank-ships-conquered-oceans-180961288/ Don't ship worms just bore in wood and drift wood? Link to comment Share on other sites More sharing options...
digit Posted May 2, 2019 Share Posted May 2, 2019 11 minutes ago, Bronzviking said: Don't ship worms just bore in wood and drift wood? Likely. I expect that is their primary choice for burrowing into. I can see how these were a real pain back in the days when all boats were made of wood. Cheers. -Ken Link to comment Share on other sites More sharing options...
Bronzviking Posted May 2, 2019 Share Posted May 2, 2019 1 hour ago, Nimravis said: @digit So what your saying is these circles exposed by the boring pholadid clams is growth rings in the bone? At first glance it looked like a beveled hole made by boring shells. Link to comment Share on other sites More sharing options...
digit Posted May 2, 2019 Share Posted May 2, 2019 It is both--this hole is made by the larger boring pholad bivalves as a burrow and it is exposing the layers of the dugong bone since the bottom of the hole has a nice curvature to it. Cheers. -Ken Link to comment Share on other sites More sharing options...
Harry Pristis Posted May 2, 2019 Share Posted May 2, 2019 Shipworms and rock-boring clams are placed in the same Superfamily (Pholadoidea), but they are in two different Families, Teredinidae and Pholadidae, respectively. In other words, they are as closely related to one another as pronghorn antelopes are related to whitetail deer or as gomphotheres are related to mammoths. 1 http://pristis.wix.com/the-demijohn-page What seest thou else In the dark backward and abysm of time? ---Shakespeare, The Tempest Link to comment Share on other sites More sharing options...
Lee Jones Posted January 14, 2021 Share Posted January 14, 2021 On 5/2/2019 at 1:52 PM, Harry Pristis said: Pholadid clams (Fam. Pholadidae - "rock-boring clams") burrow into any hard substrate. Here's a fossil coral from South Florida with two pholadids still embedded. Nice pics Link to comment Share on other sites More sharing options...
Nimravis Posted November 12, 2022 Author Share Posted November 12, 2022 @scairp Check out this thread for your question. Link to comment Share on other sites More sharing options...
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