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  2. King Butler's Collection

    I may have to travel to Lyme Regis and find a beautiful ammonite like that for myself!
  3. Bands in Marine Mammal teeth

    Comments on mammal tooth development. Dentin and cementum are deposited within the crypt in a complicated progression: a kernel or "shard" of dentin is the first step. enamel, then orthodentine, more dentin, then cementum. The softest of these different materials, cementum, is often lost in fossil teeth, and sometimes death intervenes to interrupt late-stage tooth development. The timing of cementum deposition could cause confusion. It is the enamel epithelial sheath, which encloses the enamel crown, that must be breached before cementum can be deposited. That breach takes place at the cellular level. That is a different thing from the tooth erupting from the alveolar crypt. Beginning with a sieve-like penetration by mesodermal cells, part of the enamel epithelial sheath breaks down. Cementum-producing osteoblasts ("cementoblasts" of some authors) from surrounding tissue then deposit cementum on the now-available crown enamel. Dentin continues to be deposited on the interior (pulp cavity). Then, osteoclasts open the bone which protects the crypt. In the case of a premolar, the osteoclasts also attack the roots of a deciduous antecessor. The tooth emerges under hydrostatic pressures. Once the tooth crown emerges from the crypt, the "cementoblasts" are no longer supported and are finished with their work on the crown. The fact that there are to be found rootless, hollow enamel shells of teeth is an accident of when the animal died in this sequence of tooth development. ref. Bernhard Peyer's COMPARATIVE ODONTOLOGY as translated and edited by Rainer Zangerl with a forward by A. S. Romer. Maybe there is newer, better information published now.
  4. Interesting selection! Based on your last picture: teeth on the right are likely ichthyosaurs, while rightmost tooth in the bottom row of the first picture is a plesiosaur (it is just 1/2 of the tooth right? if it is strongly labio-lingually compressed it is an elasmosaurid). Ichthyosaurs survived until Cenomanian-Turonian boundary. Bony fish teeth in both pictures are a combination of Ichthyodectidae (it is incorrect to refer them to Xiphactinus because there were many species of this family with indistinguishable tooth morphology and contemporaneous - look at Aidachar, Cladocyclus or Ichthyodectes for instance), Protosphyraena and Pachyrhizodus (second from top in the second row from the left on the second pic). Also bottom tooth in the leftmost row on the second pic looks interesting, do you have any close-ups? The terminal phalanx is really cool! I suspect it is a manual ungual right? Looks very similar to Ornithomimidae hand claws but not sure what Hesperornithid claws looked like.
  5. Dinosaur skin impression or mummy skin

    I will buy it with return privileges. So this red mark is not the line between the matrix and probably skin? The seller not tell nothing about a mummy skin... for he is only a impression but I think he is only a reseller.
  6. Painting epoxy putty

    I have been using acrylics. Specifically the brand Ceramcoat by Delta Creative. Some of the other acrylic brands don't seem to adhere well.
  7. Dinosaur skin impression or mummy skin

    I cannot tell from that picture. What I looking for is to see a layer of skin on top of matrix that would say its mummified. If it was an impression the matrix and impression would be similar. I would go back to my prior statement that says buy it with return privileges
  8. King Butler's Collection

    A nice, varied collection. Thanks for sharing.
  9. King Butler's Collection

    Great collection! Especially the cave bear paw.
  10. Hello everyone. I saw this green river stingray bidding for much less than it is worth on an auction site. I will likely not bid on it, but in case I do I wanted to check it’s authenticity. I know these are not really faked, but it would be quite a large purchase so I just wanted to make sure everything was in order with it. Thank you all!
  11. Bone or stone?

    agree with Rockwood Chlorellopsis
  12. Today
  13. King Butler's Collection

    My collection at this moment. Sorry about the quality of some of the photos. A Spinosaurus Tooth Partial Mammoth Tooth Whale Tooth (Stated to be a Basilasaurus) Glossotherium Tooth Carcharodontosaurus Tooth Insect Exoskeleton (stated to be Arthropleura) Megalodon Tooth Edmontosaurus Partial Rib Cave Bear Paw Rebbachisaurus Tooth Whoolly Rhino Bone The best Ammonite I found at Lyme Regis Toe Bone (Stated to be Achelosaurus) Bone Fragment (Stated to be Agujaceratops) Centrosaurus Bone Fragment Plesiosaur Tooth Triceratops Tooth Saltasaur Eggshell Ankylosaurus Scute T. Rex Bone Fragment Polished Iguanodon Bone Bone Fragment (Stated to be Maiasaura) Prodeinotherium Tooth Gomphotheres Tooth Glyptodon Armour
  14. Bands in Marine Mammal teeth

    Very few mammal teeth will grow, mostly tusks. No. The enamel forms all at once.
  15. 400 Million years in 4 hours

    Nice to find 3 time periods in 10km range with such picturesque atmosphere. Fossil hunting at its finest.
  16. These are always my favorite clams and I still call them Edmondia or “Clam-Clam”. There is a vacant area near Reed Road that Walter and I would collect. This area had some barren patches several yards long and wide and every concretion contained at least one clam and many contained multiple clams. The area is still vacant, but because of the area being covered by grass nothing erodes out. Hopefully one day there will be some construction there and I will one again snatch these favorites up.
  17. Dinosaur skin impression or mummy skin

    I will do that. He send me one photo more... it seems that any photo costs 100$ hahahah
  18. Spinosaur jaw section?

    Awesome, thanks:) well, ITS not awesome, but the heads-up sure is:)
  19. White River Oligocene Prep - Leptictis

    looks really nice!
  20. French Mosasaur Teeth

    Et tu n'y perds pas au change : il vient d'un endroit méconnu pour ses oursins (et complètement inconnu de la majorité des Français). C'est donc un specimen très rare. And you won't lose out : it comes from a place little known for its urchins (and completly unknown by the majority of French people). Therefore, it's a very rare specimen.
  21. 400 Million years in 4 hours

    Thanks for the trip report Southern Germany is amazing for it's abundancy in different Sites and ages Have you tried cutting and polishing any of those favosites? Best Regards
  22. In the Journal of Vertebrate Paleontology, Vol. 7, No. 1, 19 March 1987, there is a note by Jiri Zidek concerning "...Syntax in Taxonomic Statements." There follows a response from Richard Estes. Zidek argues (among other things) that "cf." and "aff." are synomymous. Estes disagrees. Estes, the Editor of the JVP at the time, says the following: Lucas (1987) also discussed the usage of the qualifiers aff. and cf., stating that "most vertebrate paleontologists understand the meanings of aff. and cf." My discussion with vertebrate paleontologists, and also my reading of their manuscripts, suggests that this may not be the case. Zidek (1987) believed the two qualifiers to be interchangeable. If he is correct, one of them should probably be abandoned. I think that they often have, and should have, different meanings. If I have a fossil element that does not differ structurally from that of a particular species, and also does not display diagnostic character states of that species or genus, I may wish to indicate this similarity in a structural sense (there may be stratagraphic and geographic reasons for this as well). The use of cf. in this case indicates a conservative identification, i.e. simply "to be compared with." To me [Estes], the use of aff. indicates a greater degree of confidence. Perhaps I have a specimen that has most of the diagnostic character states of a taxon, or has one or two that differ very slightly, such that I have some minor doubts about referring it directly to that taxon. In this case I use aff. as an indication that I believe this specimen to be very close to the taxon concerned. Obviously, there is intergradation in these two concepts. and it is certain that different workers will not apply it in exactly the same way. But if there is an attempt to follow such usage consistently, I believe that the author's degree of confidence in the identification is more accurately represented. Because both [aff. and cf.] are an "alias for tentative identifications" (Zidek, 1987) information content may not be increased; again it is a matter of taste.
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