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Hey all! When I went on a collecting trip in the Hell Creek Formation in Montana, there were many iron concretions, and I've noticed that some specimens from there appear to be iron-stained. This makes me wonder if pyrite could be among the minerals involved in fossil preservation there. Are some of the bones found in the Hell Creek pyritized, and how could those be distinguished from others preserved differently? If so, do those Hell Creek specimens ever develop "pyrite disease," and what would be the warning signs to look out for? Thanks so much for sharing your knowledge!

Purchased this piece in 2018, but now have concerns about its authenticity. Main area of concern is the base of the horn where the outer layer has chipped away to reveal a white-ish interior that looks a bit like cement/plaster. There is a slight glint to the white material. Any help is much appreciated + can upload more photos if necessary!

Hello, Can someone help me identify these two Didymoceras pieces to the species-level? They are from Montana and both were repaired from a few fragments, though neither is said to be composite. From what I can tell they are in the 10-15cm range in terms of size. 1. This one seems to be part of the inner whorl, and based on how close the coil is I think D. cheyennense might be excluded, which leaves either D. stevensoni or D. nebrascense? Also in the 3rd photo there is a strange mismatch between the fragments...a poor fit or composite perhaps? 2. This looks like a section of the inner whorl lower closer to the living chamber. Any help would be appreciated, thanks!

Hello everyone, I recently finished preparing some ribs that I posted in the fossil preparation category and am having some trouble IDing them. One is fairly complete and the other 2 are fragments. They were found grouped together in Garfield County, Montana on a ranch. I think they resemble some Thescelosaurus ribs that I've seen in some papers but not enough to be confident in assigning an ID. Here are front and back views of each rib individually. I also found numerous bits of other bones in the jacket one of them being what I think is a carpal of something but haven't had time to do much digging. Here are some top and bottom views. I know you've said ribs are tricky to ID @Troodon but if you have any insight it would be very appreciated. Thank you all for your time and help.

I recently had the opportunity to purchase some jacketed fossils from a ranch in Garfield County, Montana in the hell creek formation. I bought 2 jackets, one with several small ribs present that I am currently working on. Another containing a single bone that I think is a hadrosaur pubis. One thing that surprised me was the wealth of smaller bits of bone present in the jacket I'm sure this is an amazing microsite I would love to see first hand. There were some really small bones that I don't think are identifiable but regardless very cool. This one with a really interesting convavity so maybe a joint in a small vertebrate? I also found what I think to be a ceratopsian spitter? It's very worn but it looks like some I've seen on the forum. And then another possible tooth? That unfortunately I was heavy handed in brushing off some sand before I consolidated it and it shattered. I also found what I think to be tiny petrified twigs, as well as what I think to be a piece of turtle shell that looks like trionychida to me but I'll know better when I get it cleaned off. There was also these pieces that vaguely resemble some carpals I've seen but are incredibly worn and not fully cleaned off yet. There were other various bits of bone as well that are waiting to be cleaned on my messy tray as well as a piece of coprolite? That I need to look at closer with a microscope. I got to the back side of the ribs without too much effort and that is where things started to get difficult, while I would love an ARO I'm fresh out of college and can't justify the purchase of that and an air compressor to my wife haha. So I am working with dental picks and some sculpting tools from my ceramics hobby. And a magnifying visor from yoctosun that I quite enjoy using with my glasses. The ribs were very generously coated in glue to stabilize them and about 2cm of matrix in any direction so I've slowly but surely picking off the sediment and softening it with brushed on acetone. I still have a long way to go before I even start the pubis and suspect that to get them where I wanted I might have to wait until I have a better set up to get some of the really stubborn bits off. The rancher thought they might be pachycephalosaur ribs which is possible, I know that ribs are tricky to ID. I have been having a hard time finding articles that describe hell creek ribs, let alone some that have pictures. It doesn't help that they aren't complete either so I am not comfortable assigning a species to them yet. I am very excited to start working on the pubis it will probably take awhile but my wife is leaving on clinical rotations, so I'll be alone for 6 months leaving me ample opportunity to prep after work. Thanks for reading, if you have any suggestions I would love to hear them.

Hi @Troodon, I've got one more for you. It's from the Hell Creek formation, Power River co, Montana. It's 7/8" long, but might have been more like 1.5" long if complete, since the point looks like it'd get very slender and long. Potentially with left blood groove swinging up around the top. (The blood grooves are very asymmetrical in trajectory.) Thanks!

Hope everyone has a good weekend coming to them. Any thoughts on these claw pieces? 1: Hell Creek formation, South Dakota 1 1 1 1 1 2. Hell Creek formation, Garfield county, Montana 2 2 2 2 2

I recently bought this ammonite from montana, any idea on its genus, There are baculites within the matrix surrounding the ammonite, so its Cretaceous, probably from the Bearpaw Formation? but I cant decide what genus it might be? a few candidates ive seen are Holoscpahites, rhaeboceras etc, any help on narrowing it down?

Hello! I have these 3 claws. The big one was identified as strutiomimus but I don't know the id of the other 2... The small hand claw has restoration on the base (not very good restored) They are from Garfield county. Thank you so much!!

Hello, I am making a great of in-situ pictures of my fossil hunting trips for this year. We now have a foot of snow in the ground so fossil hunting season is over. ☹️ These pictures occur in Wyoming, Montana, South Dakota and North Dakota. Mostly Cretaceous aged sites but some Eocene from ND. They are mostly tooth related. I hope everyone likes in-situ pics as much as I do!

Hello, is this a fish scale? It is about 1 cm wide at the widest point. It is complete and very nice looking. Any help will be appreciated! Found in the JRF with crocodile, fish verts/teeth, turtles, and some dinosaur related fossils. It is very thin with the enamel (correct term for this?) present on the one side. Thx!

I know next to nothing about radioactivity-- enough to know licking fossils is inadvisable, although I'll admit that wasn't terribly disappointing news. What I'm wondering is whether specimens not radioactive enough to endanger a person are capable of damaging other specimens. Is there a need to segregate displays here, or am I just confused about the mechanics of this? My specific reason for asking is that at the moment I'm planning for my current favorite mineral specimen (which I am babying forever), an almandine garnet from Broken Hill, New South Wales, Australia, to share a small shelf area with a tooth from the phosphate deposits in Oulad Abdoun Basin, Morocco and a few dinosaur bone pieces from the Hell Creek Formation of Montana (one from Dawson County) and Lance Creek Formation of Niobrara County, Wyoming. The shelf is not enclosed, by the way. Thanks for your help!

Edited 6/20/23: added Furcatoceratops elucidans More and more dinosaur material is becoming available from the Judith River Formation. I see lots of misidentified material and some with questionable localities that might fit other deposits. I would like to summarize what I believe is currently known and published. If you see any omissions or errors, please let me know. Not a lot of good maps out there to show the formation but here are two. In general, the exposures are in North Central Montana. Horner describes the formation on the western end is near the east end of the Sweetgrass Hills (very thick about 152 meters) and thins to less than 3 meters to its eastern edge Saco, MT. Bound by marine deposits Claggett Formation beneath and Bearpaw Fm above. More important, for collectors buying material is to be aware of the counties that have the majority of exposures they include but not exclusive to: Hill County, Blaine County, Phillips County, Western Part of Valley County, Fergus County, Wheatland County, Northern Valley County, Western Part of Garfied County, Big Horn County .You can see by the maps why a good provenance is vital to an ID. Stratigraphic range: Late Cretaceous, Middle to Upper Campanian 79.7 - 75.2 Ma Red _ Judith River Fm in Montana Faunal List: Updated 10/22/2022 (excludes Avialae) Lots of changes in recent years so older hard copy books are most likely out of date e.g. Dinosauria 2nd edition. This list was developed based on looking at a number of different reference sources, not Wikipedia, and like most lists some paleontologists or collectors may have different opinions, which is fine. The Judith deposit is very similar to those of the Belly River Group however you would not guess it by the variety of different dinosaurs that are described in this list particularly with the herbivores. Denver Fowler has even questioned if there is any justification to calling it Judith anymore since its continuous with Canadian Units. Will leave that for a different discussion since it probably will never happen. Edited 11/25/22 Tyrannosauridae: - Tyrannosaur indet. (Tom Holtz 2021) - Daspletosaurus wilsoni (Warshaw & Fowler 2022) - Aublysodon mirandus - nomen dubium Dromaeosauridae: - Dromaeosaurus albertensis (Matthew & Brown 1922) - Saurornitholestes sp. - Dromaeosaurid? - Zapsalis abradens (Although included on most faunal list this tooth morphology was shown to be a premaxillary tooth of a Saurornitholestes (DPF) (Currie & Evans 2019) it is therefore not valid Theropods: - Troodon formosus (Leidy 1856) - cf Richardoestesia gilmorei - cf Paronychodon lacustris - Ornithomimid indet. (spp.) - Ornithomimid large bodied (PO & Longrich 2007 DPFm) - Cenagnathid indet (Personal Observation) - Theropod indet Pachycephalosauridae: - Pachycephalosaurid indet. - Colepiocephale lambei (Sternberg 1945) Ankylosauria: - Nodosaurid indet (cf Edmontonia) - Zuul crurivastator (Arbour & Evans 2017) - Ankylosaurine ? Ceratopsidae: - Avaceratops lammersi (Dodson 1986) - Judiceratops tigris (Leidy 1856) - Medusaceratops lokii (Ryan et al. 2010) - Mercuriceratops gemini (Ryan et al. 2014) - Spiclypeus shipporum (Mallon et al. 2016) - Furcatoceratops elucidans (Hiroki Ishikawa et al. 2023) - Ceratopsid indet. - Leptoceratopsid indet? Hadrosauroidae: - Probrachylophosaurus bergei (Fowler & Horner 2015) - Brachylophosaurus canadensis (Sternberg 1953) - Hadrosaurinae indet. - Lambeosaurinae indet. - Corythosaurus sp. (Takasaki et al. 2022) Other Ornithischians: - Orodrominae indet? PO- Personal Observation in my collection Reference - Takasaki, Ryuji; Chiba, Kentaro; Fiorillo, Anthony R.; Brink, Kirstin S.; Evans, David C.; Fanti, Federico; Saneyoshi, Mototaka; Maltese, Anthony; Ishigaki, Shinobu (2022-10-23). "Description of the first definitive Corythosaurus (Dinosauria, Hadrosauridae) specimens from the Judith River Formation in Montana, USA and their paleobiogeographical significance". The Anatomical Record. doi:10.1002/ar.25097. ISSN 1932-8486 -Tom Holtz Theropod guild structure and the tyrannosaurid niche assimilation hypothesis: implications for predatory dinosaur macroecology and ontogeny in later Late Cretaceous Asiamerica (2021) Canadian Journal of Earth Science -Mallon JC, Ott CJ, Larson PL, Iuliano EM, Evans DC (2016) Spiclypeus shipporum gen. et sp. nov., a Boldly Audacious New Chasmosaurine Ceratopsid (Dinosauria: Ornithischia) from the Judith River Formation (Upper Cretaceous: Campanian) of Montana, USA. PLoS ONE 11(5): e0154218. doi:10.1371/journal.pone.0154218 -Sahni A. The vertebrate fauna of the Judith River Formation, Montana. Bull Am Mus Nat Hist. 1972; 147: 321–412. -Schott RK, Evans DC, Williamson TE, Carr TD, Goodwin MB. The anatomy and systematics of Colepiocephale lambei (Dinosauria: Pachycephalosauridae). J Vert Paleontol. 2009; 29: 771–786 -Longrich NR. Judiceratops tigris, a new horned dinosaur from the middle Campanian Judith River Formation of Montana. Bull Peabody Mus Nat Hist -Ryan MJ, Russell AP, Hartman SC. A new chasmosaurine ceratopsid from the Judith River Formation, Montana. In: Ryan MJ, Chinnery-Allgeier BJ, Eberth DA, editors. New perspectives on horned dinosaurs: the Royal Tyrrell Museum Ceratopsian Symposium. Bloomington: Indiana University Press; 2010. pp. 181–188 -Freedman Fowler EA, Horner JR (2015) A New Brachylophosaurin Hadrosaur (Dinosauria: Ornithischia) with an Intermediate Nasal Crest from the Campanian Judith River Formation of Northcentral Montana. PLoS ONE 10(11): e0141304. doi:10.1371/journal.pone.0141304 -Rogers RR. Sequence analysis of the Upper Cretaceous Two Medicine and Judith River formations, Montana: nonmarine response to the Claggett and Bearpaw marine cycles. J Sediment Res. 1998; 68: 615–631. -Fowler DW (2017) Revised geochronology, correlation, and dinosaur stratigraphic ranges of the Santonian-Maastrichtian (Late Cretaceous) formations of the Western Interior of North America. PLoS ONE 12(11): e0188426. https://doi.org/10.1371/journal. pone.0188426 -Dinosaurs under the Big Sky, Jack Horner, 2001 Mountain Press Publishing Co.

Hi I am going to Wyoming, Montana and maybe South Dakota with my brother in late May and very early June 2023. And we would of course like to look for dinosaur fossils. We know we are not allowed to collect on "State land". But can anyone help with contact to a private owner of land with dinosaurfossils. So we can pay for a couple of days and bring a few things home to Denmark. (I know of Paleoadventures). Hope someone can help us. Thank you and kind regards Torben

Hello, I am going to post a tooth I found a few days ago. I will try to follow the theropod tooth description post on the photos and info. Letme know if I am missing anything. Thanks for any help. It was kind of hard to miss! Fmtn: JRF State: MT County: Hill County CH: 33 mm

Picked up a vert, supposedly found in Montana in Hell Creek formation. It's a little crushed but otherwise intact. Any reason to think it's not Edmontosaurus?

My son picked this up while visiting his grandpa. We aren’t sure but know it’s probably a concretion. Would love it to be a real egg!

‘Alien goldfish’ may have been unique mollusc, say scientists Nicola Davis, The Guardian, September 22, 2022 New clue found in 'alien goldfish' suggests it may have been a mollusk by Bob Yirka , Phys.org The open access paper is: Conway Morris, S. and Caron, J.B., 2022. A possible home for a bizarre Carboniferous animal: is Typhloesus a pelagic gastropod?. Biology Letters, 18(9), p.20220179. Another paper: Conway Morris, S., 1990. Typhloesus wellsi (Melton and Scott, 1973), a bizarre metazoan from the Carboniferous of Montana, US A. Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 327(1242), pp.595-624. Yours, Paul H.

Hello everyone, I am not incredibly new to this forum, but realized I had never introduced myself. My name is Alex and I'm currently living in Billings, MT with my wife while she's doing her masters program. After that I will pursue a PhD in microbiology. My love for fossils was reawakened after I found a partial femur of a probable thescelosaur on my brother in-laws ranch in the hell creek range. It's been lovely working with you all so far, and I'm looking forward to continuing that work for many years to come.

Hi all, A bulk purchase of channel deposit material from the Judith River Formation of Montana has yielded these teeth, each of which appears to have some ankylosaurian affinities. I have read @Troodon’s guide on this very topic, but alas I still would like a second look at some of these teeth. I do not have the capacity to take very good macro photos, but I hope that these are passable at least for an initial glance. The scale of each tooth. The numbering on the bottom is centimeters while the numbering on top is in inches Tooth 1: I’m 99% sure this one is ankylosauridae Tooth 2: Might actually be Ceratopsid, but the presence of “denticles” is what’s making me post this one. Tooth 3: Ditto for this tooth, may be Ceratopsid, but we’ll see. Tooth 4: 80% sure this one is Nodosauridae with feeding wear. The opposing side has the distinctive “shelf” that gives the tooth a mitt look. Let me know if a picture of the other side is needed. Tooth 5: Also thinking nodosaur on this one, fairly confident Thanks everyone!

I obtained this tooth on a dig back in early June close to Jordan, Montana and was immediately told it was definitely a raptor tooth and was content with that. But more recently I’ve gotten curious and done some reading to try to figure out what exactly it was. From what I’ve read and seen online, it is pretty much a token Acheroraptor tooth with the very apparent ridges and larger serrations on one side while the other has small or none, but I wanted to double check with someone more familiar with the teeth to make sure. I’ll post any pictures requested, thanks! (also, please don’t tell me this tooth is fake or super restored because it is 100% not. I discovered and prepared this tooth myself and the only damage its had is a break that was glued back together near the root. It feels like this should be common sense after saying I found this myself in the post already, but I've already had people tell me I'm posting fake fossils [and arrowheads, but thats a different story])

More and more dinosaur material is becoming available from the Two Medicine Formation. I see lots of misidentified material and some with questionable localities that might fit other deposits. I would like to summarize what I believe is currently known and published. If you see any omissions or errors, please let me know Not a lot of good maps out there to show the formation but here are two. The TMF is about 650 meters thick and is the western equivalent of the Judith River Formation. Most of the sediments were deposited in streams, rivers and lakes. It overlies the Virgelle Sandstone and underlies the Bearpaw Formation. More important, for collectors buying material to be aware of the counties that have the majority of exposures they include but not exclusive to: Glacier County, Teton County, Lewis and Clark County and Pondera County Faunal List: 9/13/22 (excludes Avialae) Lots of changes in recent years so older hard copy books are most likely out of date e.g. Dinosauria 2nd edition. This list was developed based on looking at a number of different reference sources, not Wikipedia, and like most lists some paleontologists or collectors may have different opinions, which is fine Tyrannosauridae: - Daspletosaurus horneri (Carr et al. 2017) - Gorgosaurus sp. Dromaeosauridae: - Dromaeosaurus indet. - Saurornitholestes indet. - Bambiraptor feinbergorum (Burnham et al. 2000) Theropods: - cf Troodon formosus - cf Richardoestesia sp. - cf Paronychodon? Ankylosayria: - Scolosaurus cutleri (Nopcsa 1928) - Edmontonia rugosidens (Sternberg 1928) Ceratopsidae: - Rubeosaurus (Styracosaurus) ovatus (Gilmore 1930) - Einiosaurus procurviconis (Sampson 1994) - Achelosaurus hornei (Sampson 1994) - Prenoceratops pieganesis (Chinnery 2004) Hadrosauroidae: - Maiasaura peeblesorum (Horner & Makela 1979) - Prosaurolphus maximus (Brown 1916) - Gryposaurus latidens (Horner 1992) - Hypracrosaurus stebingeri (Horner & Currie 1994) Thescelosauridae: - Orodromeus makelai (Horner & Weishample 1988) Pachycephalosauridae: - Stegoceras sp. Caenaganathidae: - Chirostenotes pergracilis (Gilmore 1924) References: - Dinosaurs under the Big Sky, Jack Horner, 2001 Mountain Press Publishing Co. - Rogers RR. Sequence analysis of the Upper Cretaceous Two Medicine and Judith River formations, Montana: nonmarine response to the Claggett and Bearpaw marine cycles. J Sediment Res. 1998; 68: 615–631. - McDonald AT (2011) A Subadult Specimen of Rubeosaurus ovatus (Dinosauria: Ceratopsidae), with Observations on Other Ceratopsids from the Two Medicine Formation. PLoS ONE 6(8): e22710. doi:10.1371/journal.pone.0022710 - Caleb Marshall Brown , David C. Evans , Michael J. Ryan & Anthony P. Russell (2013) New data on the diversity and abundance of small-bodied ornithopods (Dinosauria, Ornithischia) from the Belly River Group (Campanian) of Alberta, Journal of Vertebrate Paleontology, 33:3, 495-520, DOI: 10.1080/02724634.2013.746229 - Michael J. Ryan , Robert Holmes & A. P. Russell (2007) A revisionof the late campanian centrosaurine ceratopsid genus Styracosaurus from the WesternInterior of North America, Journal of Vertebrate Paleontology, 27:4, 944-962, DOI:10.1671/0272-4634(2007)27[944:AROTLC]2.0.CO;2

Hi! I bought this piece a few months ago and just wanted to make sure it is what they tell me it is. Apparently it's a Triceratops horridus vertebra pedicle from the Hell Creek Formation of Dawson County, Montana.

Hi folks, Anyone have any bright ideas on what this is and what species it might be from? 8 inch limb bone(?) fragment. According to the seller it's from the Montana portion of the Hell Creek formation. Both ends appear broken off, but I'm not sure if the bone features on the inside of the curve can help with ID at all?