Please help identify rock found - man made or naturally made
25th Apr 2012 17:42 UTCSteve Tguiri
Knut, with all due respect, you are not very close on this. I have not been able to confirm the existence of a gastropod having such form during the Cretaceous. Moreover, there have never been any gastropods having a circular aperture. That hole is somewhat irregular, and you seem to be trying for a “freebie” to claim it was something that it does not resemble. The hole in the rock is not part of the outline (the “numeral” 6 or 9), so I am mystified as to how you connected those, anyway. I dispute that such an approach is good science. That would be tantamount to saying that a smoothly rounded crystalline material someone asked about is orthoclase, and the fact that it lacks cleavage is a result of abrasion or solution, so lack of visible cleavage doesn’t matter in its identification.
The figure on that rock is an involute cephalopod. I include illustrations of them below. Note that there is a plan view and a cross-sectional view for each one (nautiloid and ammonoid). I also show an involute planispiral gastropod for comparison. It looks OK, except that is an archaic type from the Paleozoic to Triassic (most lived during the earlier part of that time span).
This information is not secret. You can find it in any good geology library. I referred to these sources:
1. Arkell, W. J., et al., 1957, Treatise on Invertebrate Paleontology, Part L, Mollusca 4 (Ammonoidea): Geological Soc. America and Univ. of Kansas Press, 490 p.
2. Shimer, H. W., and Shrock, R. R., 1944, Index Fossils of North America: Cambridge, MA, M.I.T. Press, 837 p. (for the gastropod illustration; a dated reference but readily available and comprehensive enough for amateurs).
3. Teichert, C., et al., 1964, Treatise on Invertebrate Paleontology, Part K, Mollusca 3 (Nautiloidea, etc.): Geological Soc. America and Univ. of Kansas Press, 579 p.
When using those, you have to be sure that the form you choose for the correct identity lived during the proper time (e.g., Early Cretaceous as opposed to Tertiary, etc.) and that it lived in the correct region (e. g., North America rather than Europe or Asia (today’s lands, of course, may have not been so far apart in the past–that needs to be taken into consideration).
So, again with all due respect, I don’t think people (especially those on the Mindat management team) should pretend to be expert commentators on subjects in which they are not particularly knowledgeable. We should give other sciences all the respect they deserve. While it may be true that mistakes in paleontology may not come back to “bite” you (like they might in chemistry or thermodynamics when discussion mineralogical issues), such mistakes may mislead the person who posed the paleontological question. They also suggest we think it is not important to be correct in what we say in other fields. As for me, I think we should provide state-of-the-art commentary in all scientific fields. If we cannot, then we should not risk confusing things with poorly-advised opinions. Any commentary should be left to those who have appropriate expertise.
The figure on that rock is an involute cephalopod. I include illustrations of them below. Note that there is a plan view and a cross-sectional view for each one (nautiloid and ammonoid). I also show an involute planispiral gastropod for comparison. It looks OK, except that is an archaic type from the Paleozoic to Triassic (most lived during the earlier part of that time span).
This information is not secret. You can find it in any good geology library. I referred to these sources:
1. Arkell, W. J., et al., 1957, Treatise on Invertebrate Paleontology, Part L, Mollusca 4 (Ammonoidea): Geological Soc. America and Univ. of Kansas Press, 490 p.
2. Shimer, H. W., and Shrock, R. R., 1944, Index Fossils of North America: Cambridge, MA, M.I.T. Press, 837 p. (for the gastropod illustration; a dated reference but readily available and comprehensive enough for amateurs).
3. Teichert, C., et al., 1964, Treatise on Invertebrate Paleontology, Part K, Mollusca 3 (Nautiloidea, etc.): Geological Soc. America and Univ. of Kansas Press, 579 p.
When using those, you have to be sure that the form you choose for the correct identity lived during the proper time (e.g., Early Cretaceous as opposed to Tertiary, etc.) and that it lived in the correct region (e. g., North America rather than Europe or Asia (today’s lands, of course, may have not been so far apart in the past–that needs to be taken into consideration).
So, again with all due respect, I don’t think people (especially those on the Mindat management team) should pretend to be expert commentators on subjects in which they are not particularly knowledgeable. We should give other sciences all the respect they deserve. While it may be true that mistakes in paleontology may not come back to “bite” you (like they might in chemistry or thermodynamics when discussion mineralogical issues), such mistakes may mislead the person who posed the paleontological question. They also suggest we think it is not important to be correct in what we say in other fields. As for me, I think we should provide state-of-the-art commentary in all scientific fields. If we cannot, then we should not risk confusing things with poorly-advised opinions. Any commentary should be left to those who have appropriate expertise.
