cava.zachary Posted January 13, 2022 Share Posted January 13, 2022 I believe this is a Holmesina osteoderm (my first), but please correct me if you think otherwise. From a north Florida river. Thanks! -Zach 2 Link to comment Share on other sites More sharing options...
fossilus Posted January 13, 2022 Share Posted January 13, 2022 You are correct! 1 Link to comment Share on other sites More sharing options...
digit Posted January 14, 2022 Share Posted January 14, 2022 Yup. Holmesina sp. Cheers. -Ken 1 Link to comment Share on other sites More sharing options...
cava.zachary Posted February 19, 2022 Author Share Posted February 19, 2022 @digitI'm guessing it's not possible to distinguish H. floridanus from H. septentrionalis by the osteoderms alone? Link to comment Share on other sites More sharing options...
digit Posted February 20, 2022 Share Posted February 20, 2022 From the little I know, the two are chronospecies. Holmesina floridanus is Blancan and H. septentrionalis is late Irvingtonian to Rancholabrean. The larger H. septentrionalis which evolved from H. floridanus then spread to Mexico and Central America. Other than possible size and thickness differences, I'm not sure if there are any structural differences that can be used to distinguish the two species by isolated osterderms. I know someone who studies pampatheres at the FLMNH and I'll ask her if it is possible to assign a specific-level ID to an isolated osteroderm. Here is an old paper that might provide some interesting reading (though not the answer to your question): https://repositories.lib.utexas.edu/bitstream/handle/2152/29906/tmm-pss-40.pdf Cheers. -Ken 1 Link to comment Share on other sites More sharing options...
digit Posted February 20, 2022 Share Posted February 20, 2022 Quick response back from my inside source: I'm not sure if there is actually a size threshold that could be measured to differentiate species. Richard Hulbert and Gary Morgan wrote a paper on the size difference but I don't remember how much they focused on the osteoderms. I'll find the paper once I'm at the computer! Even so, I'm nearly certain that it is H. septentrionalis based on the large size and the location--even not being in situ. I'm not sure we ever find floridanus in the Peace and septentrionalis is just way more common anywhere. It's either a pectoral or pelvic buckler osteoderm and towards the front of the fingers would be towards the head in the pampathere. So it seems you can label this one Homesina septentrionalis. Cheers. -Ken P.S.: Here's a bonus. I learned this some time back when I wondered where the species name "septentrionalis" came from as I'd run into it several times in different taxa: https://en.wikipedia.org/wiki/Septentrional 1 Link to comment Share on other sites More sharing options...
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