Allosaurus Posted September 1, 2014 Share Posted September 1, 2014 (edited) This is a rib that comes from the Two Medicine Formation in Montana. Its outside lengthwise measurement is approximately 33 inches long. I've done some research on rib identification, but haven't come up with too much. I'm probably quite wrong, but I was thinking it might be a mid-dorsal from a ceratopsian. Thoughts? *EDIT* It was found partially sitting out exposed, with the rest of the fossil in very loose dirt. Many clams and corals have been found at this site, including the same level. Edited September 1, 2014 by Allosaurus Link to comment Share on other sites More sharing options...
Auspex Posted September 1, 2014 Share Posted September 1, 2014 I dithered with the image a bit: "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Opisthotriton Posted September 1, 2014 Share Posted September 1, 2014 Coral? In the Two Medicine Formation? That's very...odd... What type of sediment was the rib weathering out of? Black shale, grey mudstone, sandstone? As for the rib ID, ribs can be tricky. It is fairly stout, more robust than a hadrosaur rib, so ceratopsian seems like a good hypothesis; mid-dorsal is likely too. Link to comment Share on other sites More sharing options...
Troodon Posted September 1, 2014 Share Posted September 1, 2014 Welcome to the forum. Ribs are typically very difficult to ID but I agree with Opisthotriton the most plausible candidate is Ceratopsian. Much too beefy for a hadrosaur. I was hoping to attach a picture of one from Marsh's 1907 Monograph on Ceratopsians but as luck would have it its one of few bones not illustrated. The plates are beautiful but I need you to find one of the other bones Link to comment Share on other sites More sharing options...
Allosaurus Posted September 1, 2014 Author Share Posted September 1, 2014 (edited) Horn Coral yes. Let me check on the sediment in my notes. I've been to so many sites these past few weeks I want to be sure. Also, there was another rib recovered about 18 inches away from the above rib. I apologize for the poor photo; when I removed the rib this one was extremely fragile so I packed it up immediately before taking any pictures. This pic was taken before the rib's removal. When I finish prepping this smaller rib I'll post a photo of it up here. (we estimated this one's size to be about 12 inches in length) Troodon, thank you for the welcome. As far as finding other bones go, I will be going back to the site this weekend so with luck I might find something more. Edited September 1, 2014 by Allosaurus Link to comment Share on other sites More sharing options...
Opisthotriton Posted September 2, 2014 Share Posted September 2, 2014 Horn corals realllllllly shouldn't be the same age as the Two Medicine Formation...they went extinct in the Permian. Plus their depositional environment is completely different. But, it's near the mountains and lots of rocks get smushed together. Mountains are annoying that way. As are glacial deposits. Link to comment Share on other sites More sharing options...
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