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In Reply to: Found Fossil posted by Marion on August 13, 1998 at 21:21:28:
Well, the ID is almost final. Everything points that Marion found a Jurassic-Cretaceous Cycadeoid or similar trunk piece. Marion was given a geological map of the area (left). The J-K outcrops are shown in yellow, and she identified the area where she found the fossil as being in that region. Also, on her behalf, I have been having discussions in the sci.bio.paleontology newsgroup and there is an unanimous consence that the fossil has cycadeoid morphology. Also, it looks that it maybe something new (e.g. a new species). Will keep doing research and will keep all interested informed in this forum. Below are excerpts of what it was discussed during the last week. Peter --------------------- ...By the way, Yale Peabody Museum has the worlds' finest collection of cycadeoids. Earlier today I looked them over. I am no expert on cycadeoids, but the specimen looks to me a lot like some of the cycadeoid material at YPM. 8/25/98 ...The stratigraphic evidence for a mesozoic age for the specimen is very strong. I would accept it. The morphological evidence for a cycadeoid identification is fair to good. You could improve on this with a bit of library research. 8/26/98 ...that said, I am leaning toward a cycadeoid ID too. I just want to encourage a bit more rigor than "yeah, it looks similar". I am very, very unhappy with the standard method of teaching students to ID specimens by leafing through textbooks. There are analytic methods involved (as I have tried to outline here), but it often seems that students are expected to discover these methods all by themselves. Analysis isn't something that only a graduate student or PhD is capable of; children can do it, if someone shows them how. 8/28/98 Una Smith Department of Ecology and Evolutionary Biology ---------------------------- http://www.gtlsys.com/images/cycad3.jpeg...is indeed suggestively similar to the specimen in question. ...And it could possibly some other group altogether, perhaps something unknown... ...Tree ferns all completely lack the axillary buds that are so prominent in this specimen. The same is true for the true cycads, AFAIK. Palms do form axillary inflorescences, but those inflorescences would have a few large spathe-like bracts & not the numerous small scales seen in this one, and palms would also have broadly sheathing foliage leaf bases, not the narrowly discrete ones here. So I'd say it's not a palm or true cycad or a tree fern. That doesn't mean that a cycadeoid is the only other possibility, of course [other plants could have large stems with crowded leaf bases and scaley axillary buds], but it does show a general resemblance in organography to identified cycadeoids like that in the figure cited above [which differs in having relatively much larger axillary fertile shoots, but the overall arrangement is persuasively similar]. 8/27/98 Mel Turner Botany Department Duke University mturner@snipthis.acpub.duke.edu |
Posted by Peter on August 28, 1998 at 16:06:41: