Fred Posted January 26, 2016 Share Posted January 26, 2016 (edited) Let's start the next live preparation project with a small game. Trilobites are often found as cross sections. Here, we have a little more than that, but it still requires some insight in trilobite morphology to guess the correct genus. Can you guess the trilobite? I'll narrow the options down a bit. The specimen is from the Pragian of Morocco. Edited January 26, 2016 by Fred Paleo database, information and community Link to comment Share on other sites More sharing options...
xonenine Posted January 26, 2016 Share Posted January 26, 2016 I'm thinking a Harpes... "Your serpent of Egypt is bred now of your mud by the operation of your sun; so is your crocodile." Lepidus Link to comment Share on other sites More sharing options...
Ptychodus04 Posted January 26, 2016 Share Posted January 26, 2016 Regards, Kris Global Paleo Services, LLC https://globalpaleoservices.com http://instagram.com/globalpaleoservices http://instagram.com/kris.howe Link to comment Share on other sites More sharing options...
GerryK Posted January 26, 2016 Share Posted January 26, 2016 Kettneraspis? Link to comment Share on other sites More sharing options...
Fred Posted January 26, 2016 Author Share Posted January 26, 2016 (edited) Hey Gerry, that is a very good guess! I would likely say that it's a Leonaspis. But since the difference between Kettneraspis and Leonaspis is close to none, and even subject to discussion, Kettneraspis is close enough. They are so much alike, these genera. Edited January 26, 2016 by Fred Paleo database, information and community Link to comment Share on other sites More sharing options...
Fred Posted January 27, 2016 Author Share Posted January 27, 2016 Some more info. The specimen is likely an as of yet undescribed Leonaspis from the Maharch section near Jebel Mrakib. The separation between rock and bug seems quite ok judging from the way the split already exposed part of the trilobite. But I know from experience it can be very variable in these layers, so we'll see. It is a very nice split: you can see almost the entire trilobite, from the pygidium, thoracic segments, to the cephalon. The right free cheek is visible, and it is right where it's supposed to be. This increases the chance of the left free cheek also being in place. The head it bent downwards, making the genal spines point upwards. This is something to take into account. Therefore, I will first prep my way over the central part of the cephalon to the front of the trilobite, and then follow the cephalic margin to locate the genal spines. Once these are located, it will be very clear how the trilobite is positioned in the rock. 1 Paleo database, information and community Link to comment Share on other sites More sharing options...
Fred Posted January 28, 2016 Author Share Posted January 28, 2016 Time for an update. The first phase of the prep is about locating the contours of the cephalon. From the cross-section it is clear that the head is tilted forwards, and that the right librigena is more or less in place. This gives me a fair idea about where the right genal spine is located in the rock. The left genal spine however, can be anywhere depending on the position of the left librigena. The 'safest route' to take is to prep up to the occipital ring (i.e. the 'back of the head'), then over the glabella to the front of the cranidium. The is basically what you can see me do in these two pictures. The tricky thing with Leonaspis here is the position of the eyes. They stick out, and are positioned on the back of the cephalon. So one needs to be careful not to hit them. Again, safest thing is to locate them before proceeding. In the fist picture you can see that I have just located the right eye. It is well-preserved and I can see the individual lenses under the microscope. Leonaspis has holochroal eyes, so a lot of small lenses. 1 Paleo database, information and community Link to comment Share on other sites More sharing options...
Manticocerasman Posted January 28, 2016 Share Posted January 28, 2016 Quite a start of the prep Fred Keep up the excellent work growing old is mandatory but growing up is optional. Link to comment Share on other sites More sharing options...
Malcolmt Posted January 28, 2016 Share Posted January 28, 2016 Looking good!!!! Link to comment Share on other sites More sharing options...
Ludwigia Posted January 28, 2016 Share Posted January 28, 2016 Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Fred Posted February 1, 2016 Author Share Posted February 1, 2016 (edited) Another milestone, another update. Part of the cephalon is now prepped. I worked my way to the front, and then along the cephalic margin up to the edge of the fracture. The shell is mostly smooth with a small number of pronounced tubercles. Up to this point, the quality of preservation is excellent. I leave the typical spoon-like protrusions on the cephalic margin in the matrix for now. To free them will be one of the last steps in the preparation process. Nice details are the complex shape of the glabella, with many furrows, and the neat row of tubercles on the cephalic margin. At this point, it is a good idea to put both halves of the stone together again. Edited February 1, 2016 by Fred Paleo database, information and community Link to comment Share on other sites More sharing options...
Fred Posted February 1, 2016 Author Share Posted February 1, 2016 (edited) After putting both pieces together and letting the glue harden out overnight, it is time to remove a lot of excess matrix to make room for the next preparation steps. Meanwhile, I also follow the genal spine all the way to the tip. Halfway, however, the properties of the stone change, becoming much harder. The matrix becomes more 'sticky', and little fragments are left on the spine (hence the whitish color). The tip of the spine is less well preserved. The transition is very abrupt. The third picture is taken in line with this transition line, you can clearly see the color difference between the left and right parts. It is not uncommon to find such variations in one rock. Edited February 1, 2016 by Fred 1 Paleo database, information and community Link to comment Share on other sites More sharing options...
Ptychodus04 Posted February 1, 2016 Share Posted February 1, 2016 Very cool!!! Regards, Kris Global Paleo Services, LLC https://globalpaleoservices.com http://instagram.com/globalpaleoservices http://instagram.com/kris.howe Link to comment Share on other sites More sharing options...
Malcolmt Posted February 1, 2016 Share Posted February 1, 2016 Still looking good!!!! Link to comment Share on other sites More sharing options...
Ludwigia Posted February 1, 2016 Share Posted February 1, 2016 :popcorn: Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Fred Posted February 9, 2016 Author Share Posted February 9, 2016 So, very lucky to see the left free cheek or 'librigena' emerge. It is all there and in place. You can see it emerging in the first picture. Next, I cleaned the second genal spine. Now both genal spines demarcate the extend of the trilobite. All pleural spines are normally found in between the two genal spines, but deeper into the stone. The following phase is cleaning the thoracic pleurae. 1 Paleo database, information and community Link to comment Share on other sites More sharing options...
Ptychodus04 Posted February 9, 2016 Share Posted February 9, 2016 You sir are an artist! Regards, Kris Global Paleo Services, LLC https://globalpaleoservices.com http://instagram.com/globalpaleoservices http://instagram.com/kris.howe Link to comment Share on other sites More sharing options...
Fossildude19 Posted February 9, 2016 Share Posted February 9, 2016 Fantastic! Doing a spectacular job! Thank you for the updates. Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Fred Posted February 16, 2016 Author Share Posted February 16, 2016 I'm working on the pleural spines now. Because of the curved posture of the trilobite, I have to remove quite a bit of stone to get to the spines. It is a good strategy to work from the outside towards the inside to locate the spines. The preservation is highly variable, in general it is very good, but some small patches show very poor preservation, often associated with a rusty coating. The variable preservation makes progress very slow, and I often have to consolidate small parts with glue. It looks a bit messy, but believe me, it will be beautiful when finished. Paleo database, information and community Link to comment Share on other sites More sharing options...
Ptychodus04 Posted February 16, 2016 Share Posted February 16, 2016 Regards, Kris Global Paleo Services, LLC https://globalpaleoservices.com http://instagram.com/globalpaleoservices http://instagram.com/kris.howe Link to comment Share on other sites More sharing options...
Fred Posted February 22, 2016 Author Share Posted February 22, 2016 And yet another progress shot. It is mostly following the spines at this stage. The pygidium is located, it will require some digging to free the pygidial spines. Paleo database, information and community Link to comment Share on other sites More sharing options...
Ludwigia Posted February 23, 2016 Share Posted February 23, 2016 It's looking really good, Fred! Have you been counting the hours? Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
fossilized6s Posted February 23, 2016 Share Posted February 23, 2016 Thanks for the update. I can't wait to see it done. ~Charlie~ "There are those that look at things the way they are, and ask why.....i dream of things that never were, and ask why not?" ~RFK ->Get your Mosasaur print ->How to spot a fake Trilobite ->How to identify a CONCRETION from a DINOSAUR EGG Link to comment Share on other sites More sharing options...
Fred Posted February 23, 2016 Author Share Posted February 23, 2016 Hi Ludwigia, Having a full time job and a young family, very little time remains for fossil preparation nowadays. I'm not logging the hours, but as a rule of thumb, there are usually a couple of hours of work between the steps I show here. Paleo database, information and community Link to comment Share on other sites More sharing options...
Fred Posted February 26, 2016 Author Share Posted February 26, 2016 Starting the finishing phase... mainly removing small bits of matrix, cleaning the edges, using needles and some very careful blasting. Lots of work still to be done. But check out that row of tubercles on the cephalon. This was one cool bug. I wonder whether it was brightly colored. 1 Paleo database, information and community Link to comment Share on other sites More sharing options...
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