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Eboraciceras from Russia (I don't know the species) I don't know why it has this hole in the conch. I may have an idea but I want to be sure

Hello, I recently acquired an Edestus Heinrichi jaw fragment and wanted to draw an illustration of the animal. But all the images I can find on internet are so weird though.... How could it feed with such a jaw? It's so different from what we see today....From what I have read, it either used it's jaw like scissors or kind of like a hammer (like the sawshark ??) ? Also, how can paleontologist know how to reconstruct such a weird animal, no full skeleton can be found since they are mostly made of cartilage.

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:

Here is a fine way to spend 16 minutes. A wonderful (even if simplified) story of a gene at the top of the hierarchy of limb formation in tetrapods, and the identification of a mutation in the gene that causes a dramatic change in fish's morphology. It is remarkable that the mutation doesn't affect the protein sequence but the switch that turns it on or off in different tissues of the developing animal. Why would this be of particular interest to you? Because shown herein is the remarkable correlation with the fossil record of this small fish. So grab some popcorn, or better yet a beer or glass of wine and enjoy yet another page of how scientific research illuminates.

At work, I study convergent antibody evolution in response to COVID vaccination. When you have a chisel everything around you is shale, so during my internet endeavors in paleontology, I find a lot of questions coming up for me about trilobite convergent evolution, particularly between the Moroccan and North American species with which I am most familiar. This thread will be a few different posts of species which have really stood out to me as similar, and I would be delighted if others shared their own observations! For a little background which got me thinking on the topic- I'm in Boston, where the Braintree trilobites once were, (and currently exist as mostly as gravel in the harbor ). These Olenellus bugs are here because Boston was the little plug blocking up the straight of Gibraltar between Morocco and Spain, where the same species can also be found due to the shared origin, pre-continental drift https://www.jstor.org/stable/4094982 (Fletcher et al 2005, J Paleontology). So anyway below are some photo side-by sides and some very very amateur observations on convergent evolution after earlier speciation, or just half-way there divergent evolution after population separations. I'm interested to hear others thoughts, and if anyone knows of any good literature on this subject and better ways of distinguishing morphologically between Moroccan and North American Trilobites, and what niches these species filled which may help inform shared body structure. I'm holding out hope @piranha might have some insights if they are feeling generous :0 . The following critters are all Devonian in some capacity. Thanks for your input! (ALSO please let me know if this belongs in a different forum)

So, I have been doing more research on thelodont morphology, and I have a few questions regarding the branchial structure, and was hoping for some other people's understanding on this subject. Regarding the branchial structure, what is the most current research? I have read that the species Pezopallichthys ritchiei, Cometicercus talimaaae, Drepanolepis maersae, Sphenonectris turnerae, Turinia pagei, Furcacauda heintzae, and Furcacauda fredholmae, have shown themselves to be among the best preserved articulated thelodonts, with pretty well preserved branchial bars and openings. The picture below is of an excellent illustration of one of the species, from: Donoghue, P. C. J., Smith, M. P. (2001) The anatomy of Turinia pagei (Powrie), and the phylogenetic status of the Thelodonti. Transactions of the Royal Society of Edinburgh: Earth Sciences, 92. It shows a T. pagei, and the anatomy of this fish. However, it is still debated as to the exact nature of this structure. I have read that the general consensus on the matter is that the transverse ridges seen on these specimens are from the internal cartilaginous branchial skeleton. Each branchial opening is thought to have been covered by a flap of scales. Some specimens preserve black stains in the these openings, that are supposedly the remnants of the cartilaginous skeleton. I would appreciate anyone's insight on this matter, and their views on the structure of the gills of thelodonts - as well as any new research that I am unaware of. Another picture from the same paper, showing the holotype specimen under three different lighting conditions: And two more from a separate paper that details the morphology of Furcacaudiformes from Northern Canada: Wilson, M. V. H., Cladwell, M. W. (1998) The Furcacaudiformes: A New Order of Jawless Vertebrates with Thelodont Scales, Based on Articulated Silurian and Devonian Fossils from Northern Canada. Journal of Vertebrate Paleontology, 18(1). The first one is a reconstruction of F. fredholmae, the second is of P. ritchiei; an excellently preserved thelodont, with well preserved gill openings and branchial bars. Thanks everyone for reading this (lengthy) post! I look forward to seeing your thoughts. References: Donoghue, P. C. J., Smith, M. P. (2001) The anatomy of Turinia pagei (Powrie), and the phylogenetic status of the Thelodonti. Transactions of the Royal Society of Edinburgh: Earth Sciences, 92. Marss, T., Turner, S., Karatajute-Talimaa, V. (2007) "Agnatha" II, Handbook of Paleoichthyology, Volume 1B. (Schultze, H.-P., ed.). Pfeil, Munich, 143 pp. Stetson, H. C. (1931) Studies on the Morphology of the Heterostraci. The Journal of Geology, 39(2). - details the morphology and structure of the thelodonts Thelodus scotica (debated whether branchial bars are present), Thelodus planus, and Thelodus taiti (now Loganellia taiti). Turner, S. (1982) A new articulated thelodont (Agnatha) from the early Devonian of Britain. Paleontology, 25(4). http://www.ewyaslacy.org.uk/docs/nw_nwt_2002.pdf - details the similarities of T. pagei with the new specie N. milesi, discusses the branchial apparatus and other organs. Wilson, M. V. H., Cladwell, M. W. (1998) The Furcacaudiformes: A New Order of Jawless Vertebrates with Thelodont Scales, Based on Articulated Silurian and Devonian Fossils from Northern Canada. Journal of Vertebrate Paleontology, 18(1). Wilson, M. V. H., Marss, T. (2012) Anatomy of the Silurian thelodont Phlebolepis elegans Pander. Estonian Journal of Earth Sciences, 61(4). https://www.researchgate.net/publication/258421627_Anatomy_of_the_Silurian_thelodont_Phlebolepis_elegans_Pander - details the anatomy of P. elegans, also discusses the apparent absence of any trace of branchial bars or opening.

Hi I decided to make a quick guide on how to ID Tyrannosaur teeth from the Belly River Group of Alberta, and the Judith River, Two Medicine Formations. I got this information on a study on how to ID isolated Tyrannosaur teeth from Dr. Angelica Torices. I’ll start off on saying Albertosaurus and Gorgosaurus are extremely alike not much differences in the morphology Daspletosaurus is a little bit Different, the morphology of these two Tyrannosaurs (Gorgosaurus and Daspletosaurus) are probably do to similar evolutionary history Gorgosaurus could of been Albertosaurus ancestor. Now I’ll tell you how to tell these two Tyrannosaur teeth apart (Gorgosaurus and Daspletosaurus). Gorgosaurus has two denticles (serrations) per mm where’s Daspletosaurus does not. Albertosaurus also have two denticles per mm because of Albertosaurus and Gorgosaurus evolutionary history. Also one more thing only with Albertosaurus, juvenile teeth can be different not just in there size but in there morphology too to the Adult teeth where’s Gorgosaurus and Daspletosaurus juvenile and adult teeth always have the same morphology. And thats what I’ve learned about this topic hope it helps, enjoy!!.

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?)

I'm starting to sort through the trilobites I found at Oak Springs and need some help. My degree is in electrical engineering, which means when I was in college I never had to take any of those pesky courses in biology, zoology, etc. But that puts me at a disadvantage now as I read through the descriptions of the candidate trilobites and try to make sense of them. There are a fair number of papers published on the trilobites of the Cambrian in California and Nevada. To help identify what I have collected I'm using this one: Carrara Formation. Here is where I am having difficulty. The descriptions in this paper include features that don't appear on the diagrams I have of trilobite morphology. I have compiled one example here: Gilberti.pdf (reproduced as a low-res JPEG below). The color photo at the top is the specimen I'm trying to identify. I think it might be an Olenellus gilberti, so I have pasted that description below the photo, along with three photos of O. gilberti from the paper. (Below those photos is a diagram of trilobite morphology I pulled from the Internet.) The description of O. gilberti includes at least two features that don't show up on the morphology diagram: occipital ring (is this the same as occipital lobe?) and intergenal spine (I don't think this is the same as genal spine?). More concerning to me is this part of the description: "Glabella elongate, separated from frontal border by preglabellar area as wide or wider than anterior border." In my novice opinion, the examples in photos 6-8 from the paper show glabellas that extend pretty much all the way to the anterior border. In my specimen the preglabellar area is much wider, which would seem to be more consistent with the written description. Any help would be appreciated. Of course I'd like to identify the specimen, but what I'd really like are pointers on how to interpret the morphology descriptions. Maybe I've got an O. fowleri instead of O. gilberti, but if I don't understand how to interpret the descriptions I won't be successful in identifying it. Is there a book I should lay my hands on?

I am sculpting an ammonite which will be hunting through kelp fronds. The ammonite i want to use for this sculpture is crioceratites or something closely related. I like the spines and overall shape. My question is how many spines around each band of the shell? Five or six? Thanks for any help you might provide.

I bought this fossil mosasaur tooth. It came from Morocco, from some phosphate deposits. The size is very small about 2 centimeters I'm wondering if this tooth was from a juvinile. I have heard that each mosasaur has it's own tooth morphology even in species who's teeth are very similar like Prognathodon and Mosasaurus. The tooth is very unusual from others I have. It is very curved. Photo of tooth Other side

This is not an ID question, but more a morphology one to determine likely size. I can't recall where I once chanced upon a formula for judging what the full size of a trilobite (pending species) would have been on the basis of a fragment. This one would have been a fairly substantially sized bug, but not by any means the biggest. It is a typical Eldredgeops rana. It is likely just a moult, and perhaps there is a (very) slim chance I might be able to find the full one in the vicinity. Measuring to just at where the halfway point of the glabella is, I get a reading of 1.8 cm (0.71 inches) for a possible total width at the cephalon of approximately 3.6 cm (1.42 inches). Any experts have the "magic formula" for measuring this species so that I can perform this on some of my other specimens?

Here's a treat for the troops. These have been hidden from public and scientific view since they were acquired from the finder. I purchased them from a civil war relic hunter and collector, who claimed to have these found together, but he wouldn't divulge exactly where. I suspect coastal Charleston, north to possibly southern NC, based upon his distance of travel from the sale, which was the old Civil War Museum, located in downtown Myrtle Beach - Mid 90's.(A friend who worked there, alerted me of the seller's presence.) The owner also collected fossils and displayed these, so it was known as a place of trade and sale for both artifacts and fossils. When I first saw them, I immediately recognized the possibility that they were a pair, and likely land finds, but what I didn't expect to discover, was their curious potential axial relationship. Published relative axial ratios of known or suspected associated sets reveal similar math to what I've found in these Both appear to be from the same side of the jaw, which makes a reasonable argument for how they may have literally, come together in the first place. I've managed to contact one nationally recognized expert who seems intrigued. Unfortunately, there's probably no DNA remaining, but if you've ever watched Forensic Files on TV, more than just DNA is often used to establish beyond a reasonable doubt. I think this is also a good time for a poll, recognizing of course that you can't see these in person.