Uncle Siphuncle Posted December 28, 2008 Share Posted December 28, 2008 I found this tiny echinoid at an exposure of Duck Creek fm north of Fort Worth, TX last month. It came from a gray clay bearing pyritized ammonites and gastropods, along with a couple Goniophorus scotti echies. Big, wormy, smashed Macrasters were present as well as damaged adult Holaster simplex specimens. Anyone care to wager a guess on this one? I've never seen a tiny H. simplex so I'd love to hear from you more experienced echinoid guys. Scale in mm. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Guest bmorefossil Posted December 28, 2008 Share Posted December 28, 2008 I have no clue sorry, but it does have a really flat side does that help with an id? Link to comment Share on other sites More sharing options...
tracer Posted December 28, 2008 Share Posted December 28, 2008 couldn't tell from the photos if you'd prepped and examined characteristics of the 'noid. i assume you've seen as many as most people so unlikely to have revelations greater than your own from that angle. spatangoidea have free-swimming larval phases. i do not know where the larvae "settle" when they morph to the adult body style. it might be that the reason if one doesn't find all different sizes of urchins in one place has to do with each size having an optimal environment. but since they're burrowing creatures and don't seem to be as subject to the vagaries of predation as fish, maybe sometimes a small one lands in the same area as the big ones and burrows and thrives long enough get locked into a time capsule and cause wonderment a hundred million or so years later. Link to comment Share on other sites More sharing options...
LanceH Posted December 28, 2008 Share Posted December 28, 2008 Ya should have emailed me or Roz, we are in northwest Fort Worth. Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted December 28, 2008 Author Share Posted December 28, 2008 Well then maybe I will next time, Brutha Lance! But then again you probably know this site well... Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Mike Murphy Posted December 31, 2008 Share Posted December 31, 2008 Dan: It is hard to tell by the diminutive size of the echinoid and the lack of clarity of the ambulacral features. From what I can see (I think) of the unpaired ambulacra, they appear to be curved, non-petalloid and non-depressed and the pores appear to be slits. This would indicate that it is likely Holaster sp. In addition, the unpaired ambulacral sinus is shallow, which would fit Holaster. The periproct appears to be supramarginal, but this could represent its position in the juvenile forms. A lateral view of the test might help. From what I can tell, I would agree with your diagnosis of Holaster sp, probably Holaster simplex Shumard. Let me know when you make it up to North Texas again. I'm not that far from the metroplex. I would enjoy collecting with you (as long as I can go in front!) Regards, Mike Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted December 31, 2008 Author Share Posted December 31, 2008 Sounds good Mike, thanks. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
LanceH Posted January 24, 2009 Share Posted January 24, 2009 Hey Dan, Regarding the Duck Creek fm. quarry in Fort Worth.... Do you know of OR have found any Eopachydiscus ammonites there? I'm trying to work out the exact stratigraphy of the quarry. I'm pretty sure the bulk of the clay/marl of the walls is the mid-upper Duck Creek section (Kingena brachs are present around rim). I'm also thinking the "floor" of the quarry is the upper part of the Kiamichi formation which (in that region at least) is a hard blue-gray clay. In a trench cut into the floor a DPS member found a bit of the Oxy (Adkinsites) ammonite which is from upper Kiamichi at least. I'm thinking the Pachy zone (in the Duck Creek limestone) must be maybe 3-6 feet or so above the floor but everything near the bottom is obscured by fallen material. Have you found any evidence of Pachys near the floor? Also have you ever found any Kingenas in situ in the walls? This would help determine where the upper/lower Kingena zones are at (assuming Winton & Adkins did a good job with limited exposures 80 years ago around TCU) I still haven't determined if the uppermost limestone layers around the rim are still part of the Duck Creek OR actually Fort Worth formation. It's been written that it's hard to differentiate between the two where they meet anyways. I'm leaning toward Duck Creek but not sure. I climbed down to a ledge about 8 feet below the rim and found an interesting limestone layer that contained Amphidonte oysters, Lopha oysters, and Rastellums all mixed together. Some slabs can be found near the bottom of the quarry. Lance Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted January 24, 2009 Author Share Posted January 24, 2009 Lance I've never seen Eos there, but have seen some giant Idiohamites (Anisoceras?) taken from the floor. I've never taken Oxys there, nor have I paid attention to the Kingena. I was more after the Morts and Macs. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
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