minnbuckeye Posted August 31, 2019 Share Posted August 31, 2019 During my recent visit to Bradenton, Florida, I collected many dugong rib bones to put into the fossil pit for kids at our local nature park. I pulled 3 out to keep. This one was lighter in weight and color to the others. My wife accidentally dropped it on the floor, breaking it. After looking at the damaged piece, I began to wonder if this was indeed a dugong rib. Any thoughts are appreciated. Mike Link to comment Share on other sites More sharing options...
Fossildude19 Posted August 31, 2019 Share Posted August 31, 2019 I am not seeing any schreger lines, so rib sounds right to me. 1 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
digit Posted August 31, 2019 Share Posted August 31, 2019 From the cross-sectional view, it does match my concept of dugong rib bone but the other surfaces are quite bizarre. I'm used to seeing taphonomic clues like pholad holes to indicate what the bone experienced after the death of the owner and before fossilization. I'm not sure what to make of this oddly textured surface. Likely some sort of bioerosion going on there but I can't recall seeing similar examples in the thousands (quite literally) of dugong rib bones I've seen (and usually tossed back into the river). An odd specimen. Perhaps @Sacha or @Shellseeker or @jcb might have more to say on this? Cheers. -Ken 1 Link to comment Share on other sites More sharing options...
jcbshark Posted August 31, 2019 Share Posted August 31, 2019 Definitely not tusk Mike Every once in a great while it's not just a big rock down there! Link to comment Share on other sites More sharing options...
digit Posted August 31, 2019 Share Posted August 31, 2019 I'd say definitely a dugong rib fragment but really weird texturing on the outside that I do not recall seeing before. Cheers. -Ken Link to comment Share on other sites More sharing options...
Rockwood Posted August 31, 2019 Share Posted August 31, 2019 Pathological ? It looks almost tumorish. Link to comment Share on other sites More sharing options...
caldigger Posted August 31, 2019 Share Posted August 31, 2019 Not wanting to deviate from the subject at hand, but why is it 99.9% of all things Dugong found are the ribs? Didn't these things have other bones?! You find fragile bones from other creatures of the same geologic age all around them. 1 Link to comment Share on other sites More sharing options...
daves64 Posted August 31, 2019 Share Posted August 31, 2019 Outer surface looks like it was a worm buffet. Similar to what you see in wood, usually under the bark. 1 Accomplishing the impossible means only that the boss will add it to your regular duties. Link to comment Share on other sites More sharing options...
jcbshark Posted August 31, 2019 Share Posted August 31, 2019 22 minutes ago, caldigger said: Not wanting to deviate from the subject at hand, but why is it 99.9% of all things Dugong found are the ribs? Didn't these things have other bones?! You find fragile bones from other creatures of the same geologic age all around them. From what I understand Doren it’s because their ribs were solid unlike most bones so they wouldn’t float. Being so dense makes them almost indestructible so they very plentiful Every once in a great while it's not just a big rock down there! Link to comment Share on other sites More sharing options...
Brett Breakin' Rocks Posted August 31, 2019 Share Posted August 31, 2019 47 minutes ago, caldigger said: Not wanting to deviate from the subject at hand, but why is it 99.9% of all things Dugong found are the ribs? Didn't these things have other bones?! You find fragile bones from other creatures of the same geologic age all around them. Trust me .... I feel the same way about horses. Those guys were just dropping teeth everywhere. Haha B Link to comment Share on other sites More sharing options...
Harry Pristis Posted August 31, 2019 Share Posted August 31, 2019 51 minutes ago, caldigger said: Not wanting to deviate from the subject at hand, but why is it 99.9% of all things Dugong found are the ribs? Didn't these things have other bones?! You find fragile bones from other creatures of the same geologic age all around them. Which fragile bones from other creatures are you referencing? Dugongs are marine, so those bones would be from other marine animals. We do find odontocete bones (usually vertebrae). Shark skeletons are not well preserved, being cartilage, but there are plenty of shark remains (teeth) to show that they were present. Bony fish scraps are present. The marine remains are not nearly as diverse as the terrestrial fauna. But, as to your original question, all the dugongid bones are dense, but particularly the ribs (as jcbshark points out). The ribs are also brittle as fossils. Take the number of ribs of a fossil dugong and multiply that by, say six. Six being the number of fragments the rib contributes. Compare the resulting number to the number of each other dugongid parts: skull-cap - one; humerus - two; molars - twelve; periotics - two; etc. You can see the odds are great that your next dugongid find will be a rib fragment. 4 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...
Rockwood Posted August 31, 2019 Share Posted August 31, 2019 If it had spent time in onshore deposits maybe root feeding would leave this behind. The texture has an etched look perhaps ? Link to comment Share on other sites More sharing options...
Harry Pristis Posted August 31, 2019 Share Posted August 31, 2019 1 hour ago, daves64 said: Outer surface looks like it was a worm buffet. Similar to what you see in wood, usually under the bark. Maybe gastropod feeding on a green bone. Just an impression. 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...
minnbuckeye Posted September 1, 2019 Author Share Posted September 1, 2019 Thanks for all of the thoughts!! Read up on Dugongs and did not realize they still exist today. My understanding was they were precursors to the manatee. And more surprising was that manatees and dugongs are close relatives to elephants!!! For all of us that find dugong rib pieces, there is a reason why they are so dense: Like other sirenians, the dugong experiences pachyostosis, a condition in which the ribs and other long bones are unusually solid and contain little or no marrow. These heavy bones, which are among the densest in the animal kingdom (Waller et al. 1996), may act as a ballast to help keep sirenians suspended slightly below the water's surface (Myers 2000). Link to comment Share on other sites More sharing options...
digit Posted September 1, 2019 Share Posted September 1, 2019 19 hours ago, Rockwood said: If it had spent time in onshore deposits maybe root feeding would leave this behind. The texture has an etched look perhaps ? This thought had crossed my mind as well. Most of these bones likely came to rest in a marine (or brackish) environment and were subject to things like the pholad clams which make the very common borings in these rib fragments. I wondered what might happen if (by some means) some bone fragments found their way to dry land and were subject to different taphonomic processes resulting in this unusual texturing. 2 hours ago, minnbuckeye said: Like other sirenians, the dugong experiences pachyostosis, a condition in which the ribs and other long bones are unusually solid and contain little or no marrow. I've described this to hundreds of folks passing down the river in canoes while we are hunting for fossils. The brief story (yes, unusual for me but canoes don't wait long ) is accompanied with gifts of solid dugong bones for all the kids (and often parents) in the canoes. I call them "paleo paperweights" and figure enough of the story may stick to make the fossil an interesting curiosity for them which may open the door to more of an interest. I've added "pachyostosis" to my vocabulary (but I promise I won't toss it around here too much ) and now have a succinct word to describe this bone densification. A small amount of research into the term has added the fact that this condition is also shared in plesiosaurs (likely for similar reasons) and, of course, in the thick skulls of one of my favorite dinosaurs--Pachycephalosaurus wyomingensis. I also turned up information on a group of animals I never new existed--semiaquatic ground sloths! Learning is fun! https://en.wikipedia.org/wiki/Thalassocnus Cheers. -Ken 1 Link to comment Share on other sites More sharing options...
minnbuckeye Posted September 1, 2019 Author Share Posted September 1, 2019 @digit Look at all we have learned just because my wife dropped and broke a fossil!!!!! Link to comment Share on other sites More sharing options...
digit Posted September 1, 2019 Share Posted September 1, 2019 That's pretty much indicative of how I aggregate my fossil knowledge. Cheers. -Ken Link to comment Share on other sites More sharing options...
LONGOF Posted September 2, 2019 Share Posted September 2, 2019 Similar questions of pictured dugong ribs. Are they really ribs or corals (Pliocene Age, Caribbean) Link to comment Share on other sites More sharing options...
digit Posted September 2, 2019 Share Posted September 2, 2019 No polyp structures to suggest corals. I've seen some dugong material from the DR before that looked similar to this. They are so different from the river-polished and phosphate-blackened dugong ribs that we see here in Florida. Cheers. -Ken Link to comment Share on other sites More sharing options...
LONGOF Posted September 2, 2019 Share Posted September 2, 2019 4 hours ago, digit said: No polyp structures to suggest corals. I've seen some dugong material from the DR before that looked similar to this. They are so different from the river-polished and phosphate-blackened dugong ribs that we see here in Florida. Cheers. -Ken Thanks a lot Ken for your support. Have you noticed that all of those have Manganese-like small spots on surface ?? Is it common ???? Thanks again to all in advance! Link to comment Share on other sites More sharing options...
digit Posted September 3, 2019 Share Posted September 3, 2019 Those are so different from what we see here in Florida that I cannot say if the spotting is at all common--could be for the preservation you have in the DR. Cheers. -Ken Link to comment Share on other sites More sharing options...
siteseer Posted September 3, 2019 Share Posted September 3, 2019 This is what a fossil dugong tusk looks like. This one was collected in the 80's or maybe the 70's from a phosphate mine in Polk County, Florida. it's about 2 1/2 inches long with that small enamel crown being the part that stuck out. Jess 1 Link to comment Share on other sites More sharing options...
digit Posted September 3, 2019 Share Posted September 3, 2019 Cool! Can't say I've ever seen one of those before. I think Mike's title on this topic was meant to mean a dugong rib that now appeared different enough to suggest a tusk of something proboscidean like mammoth/mastodon (which the lack of Schreger Lines precludes). Interesting bonus facts for the day: Dugongs belong to the order Sirenia named for the sirens in Greek mythology who lured sailors to their demise (most notably in Homer's Odyssey). The fact that dugongs and manatees were once thought to be beautiful sirens or mermaids meant that sailors really needed less time on ships and more shore leave. Both the hose-nosed proboscideans (elephants/mammoths/mastodons) and the sirenian orders are thought to share a common clade (grouping) called Tethytheria. The third member of this clade is an odd extinct group called the Embrithopoda which has come wild looking animals from the Eocene-Oligocene. https://en.wikipedia.org/wiki/Embrithopoda Cheers. -Ken 1 Link to comment Share on other sites More sharing options...
Plax Posted September 3, 2019 Share Posted September 3, 2019 Perhaps one of those burrows that has a sleeve like outer membrane? Have only seen these ribs in NC and none I've seen decorticate like this. Keep in mind that I'm possibly or even probably wrong about this latter characteristic! Very limited experience. Link to comment Share on other sites More sharing options...
minnbuckeye Posted September 3, 2019 Author Share Posted September 3, 2019 29 minutes ago, Plax said: Perhaps one of those burrows that has a sleeve like outer membrane @Plax, I am not sure what you mean by this. Sorry!! Mike Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now