aek Posted June 26, 2020 Share Posted June 26, 2020 I'm curious what may have caused this burrow-like hole in dalmanitid eye? The eye popped off while I was prepping it availing a look inside. Microbes, worms, decay? Link to comment Share on other sites More sharing options...
DPS Ammonite Posted June 26, 2020 Share Posted June 26, 2020 The photos are fuzzy. If the holes are white inside like the photos appear then they probably are made out of a painted white manmade material. My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
aek Posted June 26, 2020 Author Share Posted June 26, 2020 6 minutes ago, DPS Ammonite said: The photos are fuzzy. If the holes are white inside like the photos appear then they probably are made out of a painted white manmade material. This is dolomitic steinkern type preservation. Link to comment Share on other sites More sharing options...
Kane Posted June 26, 2020 Share Posted June 26, 2020 Very intriguing. The lenses seem to curve around the hole, which might suggest post-ecdysis healing after being damaged. Or, possibly a pathology. 4 ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
jpc Posted June 26, 2020 Share Posted June 26, 2020 cool specimen. Link to comment Share on other sites More sharing options...
aek Posted June 26, 2020 Author Share Posted June 26, 2020 @Kane Thanks for your interesting interpretative observations. Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted June 26, 2020 Share Posted June 26, 2020 In the top photo, the damage clearly runs along inside the base of the eye. I think this is post-mortem, maybe even after fossilization. 3 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
aek Posted June 26, 2020 Author Share Posted June 26, 2020 @Tidgy's Dad interesting. What indicators point towards post-fossilization? Any ideas as to the cause of damage? 1 Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted June 26, 2020 Share Posted June 26, 2020 2 hours ago, aek said: @Tidgy's Dad interesting. What indicators point towards post-fossilization? Any ideas as to the cause of damage? No clue whatsoever. I just feel it is unlikely, and I've certainly never seen it before, that something burrowed into the trilobite's eye while it was alive and continued to burrow in a sort of bend. The lenses don't continue after the initial hole, but it looks like rock is missing, I'm not sure we're seeing the whole picture. Goodness, I know nothing at all, just stating my opinion from observation alone. 3 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
aek Posted June 26, 2020 Author Share Posted June 26, 2020 @Tidgy's Dad lol, I have no idea either, just interested to hear yours and others thoughts. I agree, likely post mortem . Thanks for your take on it. The eye was completely uniform until a piece flew off while prepping. There are tiny flecks of pyrite mingled with the dolomite crystals in the tube which might suggest bacteria or maybe worms ? 1 Link to comment Share on other sites More sharing options...
DPS Ammonite Posted June 26, 2020 Share Posted June 26, 2020 I guess that I was trying to focus of the bright spots instead of the tubular structure. Are the bright spots pyrite cubes? Pyrite usually indicates an anoxic environment. You mentioned that this is a steinkern. If you mean an internal mold then what is now a hole may have been an impression of a solid part of the trilobite. Does anyone know if there are tubular hard parts inside of a trilobite eye? Anyone find a diagram with internal structures of an eye from a similar trilobite? We probably know much more about the exterior of a trilobite than interior parts. My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted June 27, 2020 Share Posted June 27, 2020 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
Kane Posted June 27, 2020 Share Posted June 27, 2020 We actually know quite a bit about trilobite eyes through thin-sectioning. This image from: Torney, C., Lee, M.R., and A. W. Owen (2014). Microsctructure and growth of the lenses of schizochroal trilobite eyes. Palaeontology 57.4: 783-99. 3 ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
aek Posted June 27, 2020 Author Share Posted June 27, 2020 Yes, thanks for info . Since we're on the topic , thought I would share an attempt i made at thin sectioning a holochroal eye of a Isotelus. The matrix was soft so it worked pretty well with basic tools. You can see individual corneas which I think is pretty cool. 2 Link to comment Share on other sites More sharing options...
piranha Posted June 27, 2020 Share Posted June 27, 2020 20 minutes ago, aek said: Yes, thanks for info . Since we're on the topic , thought I would share an attempt i made at thin sectioning a holochroal eye of a Isotelus. The matrix was soft so it worked pretty well with basic tools. You can see individual corneas which I think is pretty cool. Schizochroal eye lenses have individual corneas. Holochroal eyes have a single corneal membrane: These holochroal eyes (Fig. 1A) may consist of up to several thousand lenses and their visual units are covered by one common cornea, which is a thin sheath of calcite. Among the Ordovician to Devonian phacopid trilobites exists another type of eye, the so-called schizochroal eye (Fig. 1B). Here all lenses are much larger and less numerous than those of holochroal eyes, and are separated from each other by intralensar sclera, made of the same cuticular material as the rest of the exoskeleton. Each lens has its own individual corneal membrane, which is prolonged proximally, through the sclera, to form a membranous capsule below the lens (Clarkson 1967; Schoenemann et al. 2008a). Schoenemann, B., Clarkson, E.N.K. 2011. Light Guide Lenses in Trilobites? Transactions of the Royal Society of Edinburgh: Earth and Environmental Science, 102(1):17-23 Link to comment Share on other sites More sharing options...
aek Posted June 27, 2020 Author Share Posted June 27, 2020 @piranha Ok, great. Thanks for clarifying this. Link to comment Share on other sites More sharing options...
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