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In an anatomical discussion - Are there any extant "ornithshian" species? If not, did any "bird-hipped" species survive the K/T extinction?
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Greetings. I would like if possible a visual guide to understand the difference between Odontochile and Zlichovaspis, which most often get mistaken with each other. I have red the differences, but without a visual aid I am struggling to understand them.
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So...I have some questions about sclerotic rings. In addition to supporting large eyes, resisting pressure, etc. how do they work? I ask as I see four basic forms across species, extant and extinct. the first is a fixed ring fused to the frontal and zygomatics. the second looks to be a fused or partially fused ring that is around the iris the third is a ring of small plates held together by connective tissue and the fourth looks like a camera iris Where my confusion arises is with the third and fourth and some birds and fossils. Do these function as part of the actual muscles of the iris sliding/flexing the sclera, or are they purely support for the overall structure? For those unfamiliar:
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There are a lot of experienced dinosaur collectors out there but for the newbie I thought a topic on the anatomy of bones and teeth would be beneficial, in plain english. Avoids reading pdf's that are difficult to get through the technical terms. Orientation Skeleton The specific sketal structure of a dinosaur varies between theropod and herbivore but the major elements are typical. Skulls of dinosaurs are not comprised of a single bone but many elements See the osteology of a Trex skull on page 2 The holes in the skull are identified as follows Theropod Teeth Theropod teeth are widely collected let's look at their anatomy and nomenclature Tooth Orientation Apical- The direction from the cervix to the apex (Fig. 1C, E). Basal- The direction from the apex to the cervix (Fig. 1C, E). Mesial- The direction towards the jaw midline, center (Fig. 1C). Mesial can refer also to the surface facing the jaw midline, center. Distal- This term is used slightly differently for teeth versus denticles. For teeth, distal refers to the direction away from the jaw center and towards the posterior end of the jaw (Fig. 1C). For denticles, distal refers to the direction away from the crown, from the denticle base to the denticle apex (Fig. 1E). Proximal- From the denticle apex to the base, proximal refers to the direction towards the crown ( Fig. 1E). Labial- The surface or direction pointing from the skull outwards, thus towards the lips or cheeks ( Fig. 1D). Lingual- The surface and direction towards the skull midline, thus facing the tongue ( Fig. 1D). Tooth Situation and Position Isolated Tooth- Tooth shed or non-articulated with the toothbearing bone. This is what collectors typically purchase. Shed Tooth- Tooth lost while alive,, either falling out due to the eruption of the replacement tooth or when processing food (e.g., biting, impaling, shearing, chewing), and therefore only preserving the crown and the basal-most part of the root. In Situ Tooth-Tooth within the alveolus of the tooth-bearing bone. Erupted Tooth- Tooth that grew outside the tooth-bearing bone, thus fully visible in the mouth. Unerupted Tooth- Tooth within the alveolus and still inside the jaw, and therefore not visible or only partially visible in the mouth. Premaxillary Tooth - Tooth in front of the upper jaw, typically four would exist in a theropod Maxillary Tooth - Tooth in the upper jaw that follow the Premaxillary teeth. Dentary Tooth- Tooth in the lower jaw Tooth Anatomy Crown (co) Portion of the tooth covered with enamel, typically situated above the gum and protruding into the mouth Root (ro) Portion of the tooth beneath the gum and embedded in an alveolus or an open alveolar groove
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hi i try to reconstruct a spinosaurus skeleton, i miss some bones of course, lot of bones ares in privates collection,and it s difficult to access them. my idea is : if you have in your collection some cervicals vertebrae or dorsals , the size is not a problem, i look for 3D models of them. i look also for the 3D models bones of the front limbs. thanks for help in this project.
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What is the Ammonite with the greatest number of whorls? Which one has the least?
MeargleSchmeargl posted a topic in General Fossil Discussion
After looking at different pictures of ammonites for a hot minute this burning question hit me. I know that some ammonites have a greater number of whorls from keel to umbilicus than others, but which ammonites have the most/least number of whorls in their shells from keel to umbilicus? I haven't yet found any satisfying answer in my own searches and I know this is gonna be one of those questions that keeps me up at night. -
Hello, I just purchased this interesting-looking partial Gonioceras "internal cast" fossil originating from Rock County, Wisconsin. I had some questions regarding the anatomy of this specimen: (EDIT: I forgot to mention dimensions; the rock is about 9cm x 8.5cm) 1. From a quick internet search (https://equatorialminnesota.blogspot.com/2016/02/gonioceras-when-nautiloid-is-also.html) it seems the lateral edges of the shell chambers curve away from the body as the shell tapers towards the tip. From this information, in this photo of my specimen would the tip/apex be towards top-right and body towards bottom-left? 2. Toward the top-right of my specimen, there appear to be exposed cross-sections of portions of the apical chambers. Here I see holes aligned at the center of the chambers looking as if a narrow cylinder passed through them. I'm thinking these are the holes that the siphuncle went through in the animal. Is this a reasonable assessment? 3. I read that Gonioceras siphuncles are described as being "sub-central". Judging by the position of the putative "siphuncle holes", would that mean this photo of my specimen is looking at the ventral surface of the animal's shell? Or is this too much to infer from this specimen? Thanks!
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Hi! I got this Hadrosaur caudal vert from the two medicine formation. in Pondera County. I was wondering what part of the tail this bone would have come from? the seller says it is likely a proximal vertebra, but couldn't give any details on its placement. Is there any possible way you can tell what part of the tail this fossil belonged to? assuming a grown individual of the species. If exact placement isn't possible, Ill settle for general region. The centrum of the Vert is 2.7 x 2.3. x 2.2" and the process is 7.6" long in a straightline including the anterior points of articulation. As always I can provide more detailed pictures/measurements of requested parts of the specimen.
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Sloth Claws And Claw Cores: What's The Difference?
MeargleSchmeargl posted a topic in General Fossil Discussion
I've seen people collecting Megatherium claw cores on this site for a good while, but I never did get a good look at what a complete claw would look like (since judging by the fact that they're cores, there'd have to be more to those claws in life). What other components would make up the claws of animals like Megatherium, and what would a complete claw look like?- 3 replies
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Hello together, I am not entirely sure if the fossil ID section is the right place for this, but I am hoping for information on a fossil specimen, its not one I hold in hands, but a ct scan, and I think I may not post pictures because they are copyrighted. While looking for new inspirations for my model building I took a close look at this wonderful ct scan of a Simosuchus clarki skull. A pugnosed crocodile, how sweet is that? I wonder two things: -how is that bilateral bone called that in many crocodiles protrudes downwards from the skullbase reaching between the mandibles? -Could the fragile structure of the distal end of said bone hint at a juvenile animal? In recent croc skulls I have seen these bones seemed quite solid. The species description says several specimens in a range of sizes have been found, all below one meter and considered fully grown. on the Digimorph site there are videos showing rotation and cross-sections, the structure in question is best visible in the "roll"-vid: http://digimorph.org/specimens/Simosuchus_clarki/ Thanks and Regards, J
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This is the most recent complete list of trilobites described with appendages. Six trilobites have a complete record of the antennae and post-antennal limbs. table from: Zeng, H., Zhao, F., Yin, Z., & Zhu, M. (2017) Appendages of an Early Cambrian Metadoxidid Trilobite from Yunnan, SW China Support Mandibulate Affinities of Trilobites and Artiopods. Geological Magazine, 154(6):1306-1328 PDF LINK
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Hi I was wondering if anyone could help me identify some of the key anatomical features of the calyx of this crinoid (Apiocrinites elegans) and any anatomical features of this brachiopod (specimen unknown). I have trawled and searched but am having limited success so thought there might be a fair few people that would be able to lend a helping hand on here! cheers mark
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Hello evereybody, I dont know if this is the right place to post this but I would be interested to learn more about mosasaur skull three-dimensional anatomy. Do someone know where it is possible to buy accurate mosasaur's skull cast? I am looking for something more educational than decorative and ideally not too big. I know that there are plenty of interesting stuffs on the web but from my experience in human medecine nothing is as good as a three-dimentional model to understand complex anatomical structure like the skull. Thanks for helping!
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New detail of internal structure of trilobite eyes and implications of their location on the tree of life. https://www.nature.com/articles/s41467-019-10459-8
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7 ft tall Three toed tracks Walks flat on its feet, not on the sides of its feet Three fingered claw marks Osteoderms in skin Ancestor of cloepus, not bradypus Found in North America (do any known ground sloths have a smaller tail or even no tail at all?)
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