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Okay so I found this specimen at the Taughannock Falls in Ithaca New York. I found it at the edge of the gorge which consists of Shale, composed of slit and clay that fell onto lime mud and hardened into rock. I've done some research and it appears to be a Brittle star trace fossil formed by their arm grazing the sand floor. Although, these Brittle Star fish traces are known as "Pteridichnites biseriatus" and they have only been discovered so far in upper Devonian shales out in western and eastern Virginia. I'm not an expert but to my knowledge the Ithaca geological formation is Devonian and was slowly covered by sand. Is it possible that the Brittle Star fish once roamed in the ancient sea now known as "Taughannock falls" today? Because a research team is trying to find this specimen and they are wondering if anyone has discovered it. Edit: Im referring to the dotted trackway. check this link out for more information. http://www.wvgs.wvnet.edu/www/news/Pteridichnites.htm
baronrauhutezcurbrusatnaturedinosauLangerdbnormanat.2017.pdf Nature,november 2017,v.551 Untangling the dinosaur family tree. Max C. Langer, Martín D. Ezcurra, Oliver W. M. Rauhut, Michael J. Benton, Fabien Knoll, Blair W. McPhee, Fernando E. Novas, Diego Pol & Stephen L. Brusatte ARISING FROM M. G. Baron, D. B. Norman & P. M. Barrett Nature 543, 501–506 (2017); doi:10.1038/nature21700 0,470 Mb
Thought it would be nice to post an oldie(1922)** yakowecolinteractgastropcrinoidZoolAnzc1922_0291-0294.pdf The author "leans towards" Simroth's theory that commensalism (and/ or mutualism)evolved from "parabiosis*",because the gastropod can sometimes be found attached to the crinoid stele . *apparently:the simple phenomenon of attachment,without connotations about causes or substrate preference . The frequent (obligatory,almost?)co-occurence of the fossils is explained by the life-long interaction itself: when the crinoid dies,the gastropod dies. (probable naticid gastropod boreholes can be found on some "infested" crinoids) The attachment scar of the gastropod are concentric,the gastropod aperture has an excentric location,to keep the aperture covering the anal aperture of the crinoid. The erosion/(resorption?) of the anal proboscis may be due to the gastopod Small circular depressions are tentativel attributed to early ontogenetic failed predation attempts by juvenile gastropod **and I am aware of the more recent literature on this subject havent read yet