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I am right now out in the field, attempting to extract a string of articulated reptile vertebrae in the lower Atco. It is in a soft marl bed just a few feet above the basal Atco. There seems to be articulated ribs associated with the specimen, and so far I have uncovered 14 verts. 9 of them were lose of the surface and bagged in ziplocks, but now I am trying to get the rest out. If anyone has any advice, I need it! The specimen also has articulated ribs. I want to get this thing home tonight, and not destroyed. This is is my first time attempting to extract vertebrae, and I want to do it right and get it home tonight. It is currently 8:54 p.m. here in North Texas. Here are some pictures of the bones when I found them and where the dig is now. I don’t know what exactly it is, but I am guessing juvenile Mosasaur. Age is Earliest Coniacian. 9 verts were on the surface, and at least 6 more uncovered with ribs. Pictures incoming: All 9 verts. @Uncle Siphuncle @erose
I found this Phlycticrioceras trinodosum heteromorph specimen in June of 2018 whilst hunting the middle/upper Coniacian Atco formation. It is the largest fragment of this species that I am aware of, having a whorl height of 51 mm as opposed to 47 mm of the largest fragment I've seen published. This genus is a bigger, rarer, and (mostly) younger cousin of Allocrioceras. I sent pictures of it to Keith Minor and he pointed out that there was also an echinoid sticking out of the specimen, something which I had totally missed! With much of the echinoid still stuck in the living chamber it is hard to get a definitive ID. But because it has such a shallow anterior ambulacra, which gives the anterior end a more smooth rather than definitive heart shape, he ruled out both Mecaster texanus and batensis. He suggested Micraster since the site has a strong European component in both the bivalve and ammonite faunas, and because the periproct side has the right shape. From finding other, although not as well preserved specimens that show similar morphology he appears to be right. I have yet to confirm this ID with Andrew Smith, but either way I think the piece is worth showing. And reading this thread got me thinking about how this could have happened and what effect it could have had on the echinoid's preservation. My thought is that because irregular echinoids lived and today still live most of their lives burrowing in the sediment it is unlikely that it would have crawled into the living chamber, but instead that it was blown into it post-mortem via currents that had dredged it out of the sediment. I already know that this site was a high energy environment from my other finds here so this seems the most likely possibility to me. But because of the fact there is still at least one spine still attached to the specimen it could not have been swept up from the sediment too long after death or all of its hairlike spines would have blown away. I do, however, find it interesting that it is positioned anterior first with its posterior towards the aperture, the position I would expect to see it in if it had indeed crawled into the shell. The specimen is also the best preserved echinoid from this site so far. Despite the ammonites being generally well preserved and not too crushed, most of the echinoids that I have from the site are terribly crushed, flakey, and often infested with rotting pyrite. I think being encapsulated in the chamber very much reduced those effects. Even though the ammonite and the echinoid are a bit crushed, the echinoid would have probably been worse off otherwise. The heteromorph fragment length is 70 mm and the whorl breadth, being a bit crushed, is 13 mm. I would think that this specimen, with its open planispiral coiling, would would have been at least over a foot in diameter when complete. It is the robust (female) morph of the species with a rib index of 5½. For comparison in Fig. 1 I pictured it with my most complete P. trinodosum specimen. From the part of the echinoid that is exposed I can measure 25 mm in length, 25 in width, and a thickness of 8 mm. I have also found abundant yet scattered fish remains at the site, so perhaps one day an ammonite-fish will come my way. But until then, anyone else got ammonite-echinoids to show? Fig. 1. Fig. 2.
Heteromorph posted a topic in Fossil IDAt a site where I have been finding heteromorphs, I have recently come across some vertebrate material. So far I have only found three vertebrate specimens; one bone fragment and two fish scales. I am hoping to get some information on their affinities. I am most interested in the fish scales, since it seems they would be the most easily identified. The site is in North Texas, the Austin Chalk group, Atco formation, upper Coniacian stage. For biostratigraphic reference, at this same site I have also found the ammonites Protexanites planatus, Phlycticrioceras trinodosum, Tridenticeras peramplum, Scaphites semicostatus, and Glyptoxoceras sp., among others. The bone (Figs 1-17) was found on Saturday the 14th of July. It is a small fragment from a more marly layer than the fish scales and most of the rare ammonites that I am finding are from, but still from the same site. The main part of it has 39 mm exposed length wise as shown in Figs 11-12 (some of it is still buried in the rock), and has a branch coming from the main part that is 22 mm long that forms a depressed canal structure in the rock (Fig. 14). The maximum thickness of the specimen that I can see is about 2 ½ mm. The branch begins to curve around when it meets the main part of the bone. The other end of the rock and the underside don't show much exposure of the bone except for a few bits poking through (Figs 16-17). I don’t know if the specimen came from a fish or some other vertebrate, but I would guess fish. If anyone can give more information on what kind of animal this came from and where this might have been located in the animal’s skeleton, that would be much appreciated. But I also know that due to its very fragmentary nature, a more definite identification may not be possible. The two fish scales (Figs 18-20) were both found on Friday the 27th of July over 100 yards from where the bone was found. These specimens are from a more chalky matrix than the bone, the same matrix that the rare ammonites are in. The first specimen (Figs 18-19) was found breaking open a large chunk of chalk. It is basically flawless and in excellent condition, and only has a little bit of obscuring matrix on the right side that could be prepped off. In the same chunk of rock that I cracked open to find this I also found a T. peramplum specimen. The fish scale is 5 ½ mm long by 5 ½ mm wide. The second fish scale I found (Fig. 20) was found within a few feet of the first one, possibly from the same fish specimen. It is a bit beat up and less complete than the first scale, but is larger from what I can see. It is 7 mm wide including the flatended area upon which the scale once was before it flaked away during excavation. The front part of it is still buried in the rock but could hopefully be prepped out. It is also in a chalky chunk of rock, not marly. I have noticed that these are less shiny than scales preserved in shales, though they still do glimmer a bit in direct light. They are also differently colored than most fish scales preserved in shales, with mine being on the red/brown spectrum while those in shale are usually black or dark gray. I am hoping that the distinctive symmetrical 7 way splitting shown on the first fish scale could narrow down the identification. I know that getting to the species or genus level could be very difficult, but could a family or order be at least possible? I have heard that identifying fish scales is challenging, but this paper indicates that it is not impossible. @oilshale, you’re a fishy guy (in a good way of course). Any ideas? Fig. 1.
dre464 posted a topic in Fossil Hunting TripsIn August, I received an invitation to join a group to hunt fossils and minerals at a cement quarry in Midlothian, Texas on September 10th. It was my very first field trip with a group, and I was extremely excited. I put my dad and my ten-year-old daughter on the list as well, and we figured we'd make a weekend of it. I had to be back on Sunday morning, so we figured we'd leave early Friday morning and squeeze two days out of the trip. After all, its a little bit of a drive to get to Midlothian from Kingwood (220 miles), and we would be passing some great sites that my dad had never visited. At 5:30 am, my dad met my daughter and me at our house, and we set out for College Station, Texas at 6:00 am. We arrived just after 8:00 am and headed out to the Whiskey Bridge for some Eocene fossils. We grabbed our gear and began heading down to the river. I glanced behind us and another fossil hunter was following us down (I'm sorry, but I can't remember his name!). We stayed on the south side of the train trestle, while our new friend moved to the north side. We found lots of great specimens, many larger than ones I had found on my previous two trips. I found two nearly complete Conus sauridens, which I have never had the fortune of finding. My only other specimen was just a fragment. The Conus specimens are below. The scale is in centimeters (as they will all be in this post). I also stumbled across some very large corals that I had never seen before . I believe that they are Balanophyllia desmophylum. My daughter managed to find a shark tooth as well. I'm not sure of the type. The root is missing, as well as the tip, but she was excited to find the first shark tooth of the trip, and her first shark tooth ever! After about an hour and a half of looking, I went over to see how our friend was doing. I showed him my two Conus specimens, and he said that he had found some as well. He reached into his bucket and pulled out a one gallon zip-lock bag with 10 or 12 HUGE Conus specimens. He had hit the jackpot, and piece after piece were coming out of the hillside. I congratulated him and told him where we were headed next, the Waco Research Pit. He had never been there and was interested. He told me he might meet us there. In fact, he told me he was an amateur fossil hunter who had just recently gotten back into the hobby, and he was looking around for possible sites where he could bring his kids. We also found out that he lives less than ten minutes from my dad. It's a small world! I really wish I could remember his name! We left the bridge and drove to Waco. After lunch at one of the amazing food trucks in town (we had the barbeque!) we headed out to the pit. It was hot in town, but we had seen nothing yet. We arrived at Army Corps of Engineers Office and signed in. As we were filling out the paperwork, in walked our friend from the Whiskey Bridge. He said he couldn't pass it up! We drove back to the site and trekked down the trail to the pit. There were few clouds and a very intermittent breeze. The heat was oppressive; the temperature had to be in the upper 90s. And they gray marl of the pit reflected the heat back up from the ground as well. My daughter lost interest very quickly, and found a small shady spot under one of the sparse cedars in the pit. Me and my dad braved the heat for several hours, as did our friend. We managed some very interesting finds. My favorite was a large shark tooth that I found, just gleaming in the afternoon sun. It was, in fact, the first shark tooth I have ever found in my fossil hunting experiences. The tooth, along with two smaller ones is below. We also found some echinoids parts and a spine... ...and, of course, the very common (at least in the Waco Pit) irregular ammonites, Mariella sp.... ...and regular ammonites, of many kinds... ...a curious coral... ...and finally, some small, but beautiful, Neithea sp. bivalves. Once we finally had all we could take of the heat, we bid farewell to our fossiling friend, who wanted to stay just a bit longer, and headed out of the pit. From Waco, we drove north to Midlothian and checked into a hotel for the night. We were exhausted, but happy with our finds so far. We were also excited about the possibilities of what we might find in the quarry the next morning. At 6:00 am the next morning, I awoke to the sound of rain hitting the window of the hotel. We had a cool front blow through the area overnight, and we were now concerned about the possibility that the quarry tour could be cancelled on account of the rain. Our group leader sent out an email saying that he was going to head that way, but that it might still be cancelled. We arrived a little before 8:00 am, and to our relief, the quarry opened their doors to us. We had about 20-25 people in the group. We were first taken into an area of the Atco Formation with deposits of dark, pebbly stone that was known to contain various types of shark teeth (including Ptychodus, which I really wanted to find), mosasaur bones and teeth, fish, and turtle bones and shell. The quarry had very generously allowed us to stay from 8:00 am to 12:00 pm. I made some very interesting finds, including fish and shark vertebrae and some bone material. I also found some shark teeth, but they were all damaged partials. Unfortunately, I didn't manage to find any Ptychodus. Below is some of the material that I found. My daughter stumbled across a very badly damaged, but still very interesting tooth. I'm not sure if it is mosasaur or plesiosaur, or something different altogether. It has a keel or ridge along one side and is rounded on the opposite side. Perhaps someone might be able to help identify it... My most interesting find in the quarry was a strange flat specimen, covered in pores, with a concave side and a convex side. I found it weathered out on the surface of a black piece of crumbled stone. The exposed side was bleached white by the sun. The underside, still in contact with the stone was black. As I picked it up, it began to crumble, much as the boulder was doing. I gathered all of the pieces I could find and brought it home, where, with the help of some cyanoacrylate glue, I put the jigsaw puzzle back together again, as best as I could. The complete specimen is below. The first is the sun-exposed, concave side. Notice the unusual shape. The two "lumps" on the left side of the image above, and then the curve outward at the top. I can only guess that the opposite side had a similar curve, but this portion is missing. The reverse side is below. It is much darker, having been against the dark rock matrix... The darker portions on the surface outline a convex bulge in the middle of the piece. Also, notice the "porosity" of the specimen. This is more visible in the next two pictures. Continued below...