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  1. Jared C

    Ptychodus whipplei

    From the album: Texas Coniacian (Cretaceous)

    Ptychodus whipplei Coniacian Texas
  2. Hi folks! I'm relatively new to the Dallas area (about 4 years now) and very new to rockhounding/fossil hunting. I've done some of the basic hunting in the fossil parks, but I'm looking to branch out and find new things. I keep seeing the Atco and Kamp Ranch names thrown around, but I have no idea how to actually locate them. I understand that they are part of larger formations, but as someone who doesn't have any training in natural sciences I'm not really sure where to look. The few times I've attempted to find somewhere off the beaten path I've been unsuccessful at finding anything besides calcite. If anyone is willing to share any helpful hints or trusty references I would appreciate it!
  3. Jared C

    Mecaster texanus

    From the album: Texas Coniacian (Cretaceous)

    Mecaster cf. texanus Coniacian (lower Atco fm) Texas
  4. Jared C

    Pycnodont tooth, cf. Acrotemnus

    From the album: Texas Coniacian (Cretaceous)

    Pycnodont tooth, cf. Acrotemnus lower Coniacian (basal Atco fm) Texas
  5. Hi everyone, my name is Gavin and I’d like to say hi. I am a Geology major that likes to dabble in the paleo world. My beginnings in fossil hunting were as a little kit with my parents but by the time I was in middle school I didn’t do it very often but after I got into a geology class in college I regained my passion for hunting and I’ve been going strong since last fall. I look forward to see what every one has to post! Posted below are some of my best sharks teeth finds so far.
  6. Hi there. I found this on a field trip to a private quarry in Midlothian , TX (just south of Dallas). It was in limestone / shale in the ATCO formation, where there’s lots of shark teeth and fish bones. I’m pretty sure it’s been compressed as most of the shark spines I’ve seen are much more round and this is pretty oval shaped. Does anyone have any guesses as to species? Thanks in advance!
  7. Jared C

    Ptychodus mortoni

    From the album: Texas Coniacian (Cretaceous)

    Ptychodus mortoni tooth Coniacian Texas
  8. Jared C

    Ptychodus whipplei

    From the album: Texas Coniacian (Cretaceous)

    Ptychodus whipplei Coniacian Texas Found in float, but definitely originating in the Atco member of the the Austin Chalk
  9. Jared C

    Ptychodus cf. latissimus

    From the album: Texas Coniacian (Cretaceous)

    Ptychodus cf. latissimus Coniacian Texas
  10. Hey everyone! Towards the end of my time down in Austin, I collected a dozen or so bags of matrix across three sites that covered the Bouldin Flags (Cenomanian), South Bosque (Turonian), and basal Atco (Coniacian) of Central Texas. Over the course of the last 6 months, I have processed and tried to identify everything that my sieve caught in order to complete this project of mine. I’m sure there are plenty of errors within this amateur study, but I hope that the overall information it provides will at least be of some use to my fellow hunters who are looking for a centralized place to figure out just what kind of tooth they stumbled upon in their local creek. I know that, especially in my first year of fossil hunting, the seemingly endless list of shark names looked like a mountain too tall to overcome. Perhaps this report might just help to demystify that obstacle. There were many expected finds and some total surprises. I learned a lot myself from this whole endeavor and am excited to share what I found. Special shoutout to @Jackito and @LSCHNELLE for so kindfully sharing their fantastic sites as well as their expertise. This could not have been done without their help! Also, if you have found a species of shark not mentioned in this report from the Bouldin Flags, South Bosque, or Atco of Central Texas, feel free to leave a reply with a photo and some info on your specimen! Enjoy! Abundant (), Common (), Uncommon (), Rare () Bouldin Flags (Cenomanian) The Bouldin Flags represents the end of the Cenomanian stage of the WIS in Central Texas. It carries much of the typical “Woodbinian fauna” that is often associated with Cenomanian sites from across the continent. The formation is “flaggy”, tending to split into layers. Much of the formation can be devoid of vertebrate life, but now and then, extremely rich layers may crop up and yield an extensive diversity of sharks, bony fish, and even reptiles to collect from. Processing the matrix can be difficult. I tried to process only the softest material I could find from productive layers as the harder parts were sometimes almost solid pyrite or totally cemented into an unbreakable stone. Even the parts that are soft tend to carry lots of grit that are rough on the hands and fossils. Nevertheless, the Bouldin Flags has some of the most diverse shark and reptile fauna as well as the richest layers, making it well worth the effort of locating. The majority of the collecting for this formation was done in the Lower Bouldin Flags, however, specimens that also occurred in the limited Upper Bouldin Flags sampling will be marked with an asterisk (*=Upper BF) Lamniformes *Carcharias saskatchewanensis Together with Cenocarcharias tenuiplicatus, these species make up the two most abundant sharks teeth to be found in the Bouldin Flags. They are typically only millimeters in size and tend to separate well from the matrix without breaking. C. saskatchewanensis can be easily differentiated from C. tenuiplicatus by its absence of fine striations on the labial faces of the cusps and cusplets. C. saskatchewanensis and C. tenuiplicatus are distinguished from Haimirichia amonensis by their significantly smaller size. I have also seen this species referred to as Microcarcharias saskatchewanensis. *Cenocarcharias tenuiplicatus A common tiny tooth found in the Bouldin Flags. They are easily identified by the presence of fine striations on the labial faces of their cusps/cusplets. Now and then, they may have an extra pair of cusplets. Cretalamna catoxodon Surprisingly rare given how abundant this genus usually is in other similarly aged strata of Texas. From the entirety of my material, I only came across one identifiable specimen in the final batch. Unlike mature Cretoxyrhina agassizensis, these teeth have a single pair of pointed cusplets and are usually more gracile. Unlike Cretodus semiplicatus, these teeth are more gracile and lack wrinkling on the base of the crown and cusplets. C. catoxodon is a relatively newly defined species within the genus Cretalamna and, to my knowledge, the only one documented from the Cenomanian. Cretodus semiplicatus One of the most coveted shark fossils of the Eagle Ford is the fearsome Cretodus. These are some of the biggest and most robust teeth to be found and can be spotted quickly by their size and diagnostic wrinkled crown bases on both the labial and lingual faces. To my knowledge, C. crassidens does not appear until the Turonian. C. semiplicatus, unlike Cretodus houghtonorum, typically exhibits a U-shaped basal concavity and U-shaped crown base border whereas C. houghtonorum is more of a V-shape in both departments. Both typically have gracile cusps. In my hunting at the Bouldin Flags site, I found one perfect tooth and a single, large broken off cusp to another tooth. Cretomanta canadensis This is one of the most interesting teeth to be had in the Bouldin Flags. Cretomanta has been interpreted as a planktivorous filter feeder. These teeth are sometimes confused with rostral denticles of Ptychotrygon triangularis, however the oral teeth of P. triangularis were not found at all in the Bouldin Flags Site. In contrast, the Atco Site (more on this later) did produce many of these oral teeth. I believe this suggests P. triangularis is likely not the culprit for the pictured specimens. Additionally, Cretomanta canadensis is commonly listed in faunas of other Cenomanian sites. Fairly recently in Northern Mexico, an amazingly preserved ray-like filter-feeding shark was discovered and named Aquilolamna milarcae. Sadly, no teeth were preserved, making it impossible to confirm synonymy between Aquilolamna and Cretomanta, but nevertheless there is a suspected connection between the two which future discoveries may one day prove. *Cretoxyrhina agassizensis On the right are the juvenile C. agassizensis ("Telodontaspis agassizensis") Cretoxyrhina are always a welcome sight and not all that rare for the Bouldin Flags. These are some of the larger teeth to be had and are generally well preserved. They typically do not have cusplets, however some specimens may have poorly developed ones as Cenomanian Cretoxyrhina were still in the process of diminishing them. C. agassizensis is a chronospecies of the genus Cretoxyrhina, representing the time period of the Late Middle Cenomanian to the Early Middle Turonian. Throughout the sifting process, I came across small, thinly cusped and distally curved teeth that somewhat resembled the larger Cretoxyrhina teeth I had as well. In researching possible IDs for these teeth, I came across the species Telodontaspis agassizensis which seemed like a decent match. However, Siversson makes the point that this taxon seems to appear only in places where larger, more typical Cretoxyrhina specimens also occur. It would seem that the two genera are synonymous and these smaller teeth instead belong to juvenile C. agassizensis. *Haimirichia amonensis Medium-sized teeth that are extremely abundant in the Bouldin Flags as well as many other Cenomanian deposits of Texas. A decent degree of heterodonty exists and lateral teeth may have many pairs of cusplets. This species was previously known as Carcharias amonensis, however the discovery of a new and well preserved specimen showed that it possessed enough morphological differences to warrant the creation of the family Haimirichiidae. I originally misidentified these teeth as Scapanorhynchus raphiodon which appears to not exist in the Bouldin Flags. *Squalicorax sp. Squalicorax is one of the most abundant teeth present. They are easily identified by their unique shape that highlights their generalist diet. There is currently much work to be done in properly separating the species of this genus across the Mesozoic, so I will simply refer to all teeth found as Squalicorax sp. Ptychodontiformes *Ptychodus anonymous The most common Ptychodus teeth found in both the Bouldin Flags and South Bosque. P. anonymous can be distinguished from other co-occurring Ptychodus teeth most easily on the basis of having a defined marginal area where the transverse ridges will merge instead of bifurcating and running all the way to the end of the crown. P. anonymous is known to have two distinct morphotypes (Cenomanian vs. Turonian), both of which are represented in this post. The Cenomanian morphotype is common in the Bouldin Flags and are typically smaller and more robust than their Turonian counterparts (however my Turonian specimens are just as small as my Cenomanian ones). Another key difference in the morphotypes is that Turonian teeth have an apparent concentric ornamentation of the marginal area whereas Cenomanian teeth have no such feature. It is possible, in the future, these differences may lead to the creation of a new species between the morphotypes. *Ptychodus decurrens This larger specimen in the lower 3 photos was misidentified. I now believe it to be a P. decurrens from the Upper Bouldin Flags. Ptychodus decurrens is a low crowned tooth that is also numerous in this formation. Like Ptychodus occidentalis, the transverse ridging gradually bifurcates to the edges of the crown as opposed to terminating at a distinct marginal area. These teeth are often broad and have the ability to get quite large in size. The bottom specimen shown was originally misidentified as P. marginalis. I have taken another look and now realize P. decurrens is a stronger ID. Despite it being a fragment, I do not think the tooth shows signs of a concentric orientation of transverse ridges and instead seems to follow the hooked on one side and straight on the other ridge pattern more typical of larger P. decurrens. Also, I initially misidentified the formation the tooth came from as being South Bosque based on visuals alone. After getting the chance to process the matrix for micros, it shares much of the same microfauna with the Lower Bouldin Flags and has little faunal overlap with the South Bosque outcrop. I now believe the location to be Upper Bouldin Flags. Ptychodus occidentalis Ptychodus occidentalis is rarer in the Bouldin Flags than the other Ptychodus. They can be identified by the bifurcating nature of their ridges as they travel through the marginal area of the tooth to the edge of the crown. The crown height tends to be higher than that of Ptychodus decurrens. In comparison to P. anonymous, P. occidentalis generally possesses finer and more numerous transverse ridges. This species is also capable of producing some very large teeth. Ptychodus rhombodus is a smaller-toothed species that commonly occurs in the Cenomanian WIS that also shares bifurcating ridge features. It has been suggested, however, that these may represent a juvenile form of P. occidentalis. Orectolobiformes *Cantioscyllium decipiens Common little teeth that belonged to a Mesozoic nurse shark. The teeth look similar to Chiloscyllium, but have striations present on the labial face. Sclerorhynchiformes *Onchopristis dunklei Although not the rarest to find, Onchopristis dunklei represents an order of sharks that hardly seems to be found in the Bouldin Flags. This species tends to preserve both oral teeth and rostral teeth. The rostral teeth are quite iconic, being best known for the multiple barbs decorating its edge. These teeth are fragile and rarely collected in one piece. From the Lower Bouldin Flags, I collected a handful of oral teeth and broken rostral specimens. In my small sample of Upper Bouldin Flags material, I only collected one O. Dunklei rostral and it happened to be the single complete one in the collection. Hybodontiformes Indet. Hybodontiformes Only a singular specimen of a Hybodontiformes tooth fragment was recovered. I don’t believe enough is present to make a confident determination as to whether it belongs to Meristodonoides or some other genera. It has striations on both sides of the tooth and a slight curvature. Other Fauna Amiid? A single, tiny arrow shaped fish tooth was collected. It is difficult to confidently lay down an identification, but Amiid is a candidate for this morphology. Coniasaurus crassidens Coniasaurus crassidens may be found in the Bouldin Flags on rare occasion. Most commonly, teeth, jaw fragments, and vertebrae are found disarticulated amongst shark teeth and shells. Because of their position within the order Squamata, Coniasaurus vertebrae share many visual similarities with larger mosasaur vertebrae from younger strata such as the Ozan. Although Coniasaurus teeth exhibit heterodonty, most of their teeth have a characteristically bulbous shape that distinguishes them from all co-occurring sharks and fish (though anterior-most maxillary teeth may be quite gracile in contrast). While Coniasaurus seems to be restricted to the Cenomanian in England, American specimens cross the Cenomanian-Turonian oceanic anoxic event (OAE 2) and reach the Middle Turonian with some reports even further beyond. Enchodus sp. Typical of just about every Cretaceous exposure in Texas is the saber-toothed Enchodus. The Bouldin Flags is absolutely filled with them. The teeth are generally quite small and vary in shape. Most commonly, they are flattened and take on a recurved shape. Sometimes they may be conical and completely straight. They may be smooth or have striations. Pachyrhizodus minimus These are very small and resemble miniature mosasaur teeth. They are smooth around their circumference and have a strong distal curvature. Pachyrhizodus is a genus known for having relatively large heads, similar to modern Grouper fish. Protosphyraena sp. Protosphyraena was a genus of fish that heavily resembled modern swordfish. Their teeth are common finds all over Texas. They generally take on a flattened shape and bear two cutting edges. They can sometimes have a slight curvature or stay completely straight. The ones I collected were among the larger fish teeth found. Known but missing sharks Pseudomegachasma comanchensis Despite not having personally collected one, Pseudomegachasma comanchensis is known from the Bouldin Flags. Similar to Cretomanta, these sharks are suspected to have been the oldest elasmobranch planktivorous filter feeders. The lingual protuberances on these teeth are so large, they almost look like backwards root lobes. Ptychodus marginalis Ptychodus marginalis is better known from the South Bosque, but has been previously found in the Bouldin Flags, though it is on the rarer end as far as Ptychodus go. They can get large, sometimes to the size of a golf ball. P. marginalis is distinct from other Texan species of the genera in that its ridges go on to form concentric rings as they travel towards the edges of the crown.
  11. These past few days, I've been running around North Texas to a handful of sites, some old some new. The reason for occasion was the arrival of a couple of our own forum members to the DFW metroplex, my current stomping grounds. I was excited to show off a few of my favorite sites and have the opportunity to explore something new in a short span of time. One of my first forum friends ( @Jackito ) had some work to do in Dallas along with a couple afternoons to kill for fossil hunting. I decided to take him to a couple of spots that had fossils unlike anything found down in Austin. Our first stop was at my new Woodbine outcrop one sunny evening. The pocket did not disappoint this time around and Carter found himself a nice Cretodus, Cretoxyrhina, and several croc teeth! I didn't have the most luck, but I've got a baggie of the rubble that is promising for micros or so I hope. We finished the final hour of sunlight at my ole Pawpaw site. I was hoping we could score a bunch of crab carapaces, but we got a bit skunked in that department. Plenty of complete Engonoceras ammonites and crab claws were had at least. I sent Carter off to a Kamp Ranch site for the following day. I haven't seen his finds from there just yet, but I heard it was a good hunt. Another forum member friend, @LSCHNELLE coincidentally visited DFW this weekend. Anyone familiar with him knows that he is the craziest ptychodus fanatic on the forum. He and I had been planning a Paraptychodus expedition for awhile and Saturday was set to be the day. Before that though, we made a visit to my Atco site in hopes of scoring some Early Coniacian Ptychodus. Sadly, we got completely skunked and almost had serious trouble when a giant tree limb fell just feet away from us. A Long Story Short Lee had some secret intel on a possible site where we could find the elusive Paraptychodus washitaensis, the oldest species of Ptychodontiformes. When we met up, I told him I had a good feeling about our chances to which he agreed. We spent the morning walking around the place looking for any indication that we were in the right area, but nothing seemed to match. After finding a whole lot of nothing three hours in, I could sense that we were both beginning to feel defeated. Instead of calling it quits there, however, we decided to change our focus and take a long shot at another spot. As we walked along the new outcrop, I searched the exposure while Lee poked through the talus. Things were going smoothly as we began to find the usual Duck Creek stuff including a pretty little shark tooth. The atmosphere was very serene, but that took a quick turn when I heard Lee excitedly shout, "PARAPTYCHODUS!". I almost couldn't believe it at first, but then I saw the unmistakable transverse ridges of the oldest Ptychodontiformes known to science. We were filled with a renewed energy and got straight back to hunting. Pretty soon I came across my own smaller Paraptychodus specimen and an extra half of a tooth on top. After a handful of smaller shark tooth discoveries we were nearing the end of Lee's visit as he had a long way to go back to Austin. We turned around and started making our way back the route we came. The majority of the fossils had been in the talus, but I took an ambitious path looking at the exposure. I focused on a darker spot of interest in the wall that I had initially written off as just another oyster. As I looked closer, I saw its wrinkled surface and hollered for Lee to come over. In my hands was a pristine and quite large Paraptychodus tooth! It was more than anything I could've hoped for! My best Paraptychodus washitaensis (mesial tooth) My first Paraptychodus washitaensis. Note the preserved root Posterior Paraptychodus washitaensis A vert I think is sea turtle? A strange fish jaw. Any ideas?
  12. Howdy y'all! Found these two tiny ptychodus teeth in my micro matrix from Midlothian. It's Atco formation and I am fairly sure the second one is P. latissumus (looking for confirmation) but the first one....is it too small to determine? If not, any suggestions as to species?? Thanks!! 1. Size 1/4 inch 2, Size 3/8 inch
  13. Mikrogeophagus

    Cretalamna sp., Atco

    From the album: Austin Chalk

    Cretalamna sp., Central TX Coniacian, Cretaceous Dec, 2022
  14. Mikrogeophagus

    Pseudocorax laevis, Atco

    From the album: Austin Chalk

    Pseudocorax laevis, Central TX Coniacian, Cretaceous Dec, 2022
  15. Mikrogeophagus

    Scapanorhynchus raphiodon, Atco

    From the album: Austin Chalk

    Scapanorhynchus raphiodon, Central TX Coniacian, Cretaceous Dec, 2022
  16. Mikrogeophagus

    Squalicorax sp., Atco

    From the album: Austin Chalk

    Squalicorax sp., Central TX Coniacian, Cretaceous Dec, 2022
  17. Mikrogeophagus

    Ptychodus mortoni, Atco

    From the album: Austin Chalk

    Ptychodus mortoni, Central TX Coniacian, Cretaceous Dec, 2022
  18. Mikrogeophagus

    Ptychodus whipplei, Atco

    From the album: Austin Chalk

    Ptychodus whipplei, Central TX Coniacian, Cretaceous Dec, 2022
  19. Mikrogeophagus

    Chiloscyllium greenei, Atco

    From the album: Austin Chalk

    Chiloscyllium greenei, Central TX Coniacian, Cretaceous Dec, 2022
  20. Mikrogeophagus

    Texatrygon hooveri, Atco

    From the album: Austin Chalk

    Texatrygon hooveri, Central TX Coniacian, Cretaceous Dec, 2022
  21. Mikrogeophagus

    Ptychotrygon triangularis, Atco

    From the album: Austin Chalk

    Ptychotrygon triangularis, Central TX Coniacian, Cretaceous Dec, 2022
  22. Mikrogeophagus

    Ischyrhiza schneideri, Atco

    From the album: Austin Chalk

    Ischyrhiza schneideri, Central TX Coniacian, Cretaceous Dec, 2022
  23. Mikrogeophagus

    Sclerorhynchus cf. S. priscus, Atco

    From the album: Austin Chalk

    Sclerorhynchus cf. S. priscus, Central TX Coniacian, Cretaceous Dec, 2022
  24. Mikrogeophagus

    Pycnodont, Atco

    From the album: Austin Chalk

    Pycnodont, Central TX Coniacian, Cretaceous Dec, 2022
  25. This past Sunday I had the opportunity to join in a Dallas Paleo Society sponsored trip to the Ash Grove quarry in Midlothian, Texas. As with other quarries in this area, they are mining the carbonates of the Austin Group and often expose the Atco Fm. (Upper Cretaceous / Coniacian aged) near the base of the operations. In this case, the fossiliferous rock was found in various piles that had been moved aside during their work and usually can be identified by its grey color, speckled with black bits (the black bits either being fossils or phosphatic "pebbles"). Thanks go out to DPS for organizing this and to the Ash Grove quarry for allowing us in. Due to recent rains inundating an area of the quarry containing previously quarried material, we went to a very new part of the operations, where the sought after rock had just been dug up in the last week or so. Unfortunately, fossil hunting in this case greatly benefits from the rock having had a chance to weather so fresh stuff was not necessarily ideal, but the weather was fantastic, so that was good. The Atco is a marine deposit, part of the large inland waterway that cut north/south-ish across North America during much of the Cretaceous. It is a lag deposit , although the exact details of its deposition are the source of much debate. For most of the collectors on this trip, sharks teeth are the primary target, but there are other fossils to be found in the rock. First off, a couple of pictures of the group (there were about 50 participants) getting organized, heading down into the quarry and out collecting. A picture of the rock we were primarily searching for: Here is what I found. The last quarry trip in this area I was on, I came away with well over 100 small, but nice, teeth. This time was quite different, I probably only have a half dozen complete teeth, but a couple of pretty nice ones, so I was OK with that. This one looked really nice when I found it in the rock. The color was fantastic, a nice brown (almost all the teeth here are black), a little over an inch long blade (most teeth here are quite small), and very sharp edges still present. I cleaned it up a bit when I returned home and put a scale on it (increments are CM's). Unfortunately the root on this Cretoxyrhina mantelli is a little punky I think due to pyrite or some other diagenetic change. During cleaning a nice little tooth showed up just underneath (see third picture below) that looks like a little C. mantelli or a small Scapanorhynchus raphiodon posterior The other nice find of the day for me was a Ptychodus atcoensis, my best and largest Ptychcodus by far (I don't see these a lot in my collecting) and a new species for me. I neglected to take a picture that showed the whole rock it was in, about a grapefruit sized chunk of limestone but here is a close up of what was peaking out. When I returned home, I put my air scribe to work to see if it was complete or not, luckily it was and is in great condition. I have opted to leave it in the matrix for now and have trimmed down the rock to a more reasonable size. Lastly here are a few of the other fossils I picked up. A couple of bivalves (probably Ostrea for the small one on the left and Lopha for the larger) and then a chunk of what would have been a large Inoceramus which are quite common in this material. The fourth picture is wood I am told (I'm not a plant guy) which also was quite common in the the rock. That is all for now, thanks for taking a look. Mike
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