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These two (partial) bones were collected two summers ago (2021) on private land in Weld County, Colorado. They’re from a super fossiliferous bit of exposure which, based on the Oreodont fauna, is likely to be part of the Poleslide Member, which dates to the early Oligocene. These bones have puzzled me since I collected them, and I had for quite a while hypothesized that they must be some sort of ungulate metatarsal. I decided to pull them out again tonight, and having more experience with osteology generally I have decided that these look decidedly avian - specifically, the proximal ends of a right tarsometatarsus. The White River Formation has a rather diverse formally described avifauna: Benton et al. (2015) lists six genera in five families along with several different morphologies of bird eggs in The White River Badlands: Geology and Paleontology, however only one family (the Bathornithidae) has more than one described genus. Bird fossils are well-documented from the WRF, and incidentally quite a few avian holotypes have been described from the White River Formation in Colorado, so perhaps the preservational bias favors them more in that general region. However, bird fossils are simply generally rare in the fossil record due to their delicate nature, so I thought I’d post on the forum before I make a (relatively) extraordinary claim. Now, these two bones aren’t in any way associated, but they’re the exact same sort of bone. They’re identical (with the exception of the shorter one being slightly larger) - same bone, same taxon (as far as I can tell, the shorter one has some weathering). This is what puts me off even more - what are the odds that not only did I come across bird fossils, but that I independently found the exact same end of the exact same bone from the exact same avian taxon in the same week? Tarsometatarsus bones do seem to be a fairly commonly preserved isolated element for fossil birds, many genera are described based of a single tarsometatarsus and the same summer I found these I happened to find an avian tarsometatarsus in the Hell Creek Formation. But it would still be odd. Here are the pictures: I should also add that these bones are in fact thin-walled and hollow, though getting the camera to focus on the broken ends is difficult. But that doesn’t automatically make them avian, bones are fairly frequently hollowed out by simple decay. Below is an image from Benton et al. (2015), with an illustration of the holotype tarsometatarsus of Badistornis aramus, an extinct relative of the living limpkin, for comparison: My bones actually compare quite well to this illustration, though there are differences so I wouldn’t assign them to this genus/species even if I could confirm that they are bird tarsometatarsi. I also don’t think that they’re Bathornithid bones, even though those are the most famous birds from this rock unit. Of the genera from the WRF only Bathornis has a known tarsometatarsus, and it’s both morphologically very different and much larger than my bones. I’ve also ruled out the Galliformes and Falconiformes (two bird orders with representatives in the WRF), again assuming these are avian bones. I think that it compares best with wading birds such as herons and, indeed, limpkins. But this is mostly informed speculation I admit. So does anyone have any thoughts? Is there a more obvious answer for what this bone could be, or does it truly have avian affinities in your opinion? Looking forward to hearing everyone’s thoughts. References: Benton, R. C., Terry, D. O., Evanoff, E. and McDonald, H. G. (2015). The White River Badlands: Geology and Paleontology. Indiana University Press.

Wondering if you can help me identify these fossils. They are all on the same slab of shell rock in southern colorado, near lake pueblo. The two pieces that look like bone or exoskeleton (approx the length of an adult hand) are on one side and the round object is on the other. The third image is the side of the round object. I took it to show how deep it goes into the rock. There are many mollusk-type shell fossils in the area, but I've never seen fossils like these. Thanks so much for any help you can give.

Hello I saw this tooth online. I am very confused by the shape of this tooth. Seller thinks it might be from a brachiosaurus. It looks more like a camarasaurus to me however. I've never seen a tooth like it before. It was collected in Moffat County Colorado and measures 1.49 inches..

Hello, I recently acquired these two chunks from a seller in Apache Junction, Arizona. He claims that they are from Colorado, but I was not able to get a more specific location. Can anything be known about these? The seller said the larger piece looked like a vertebrae, but I have no clue. Any insight would be appreciated!

I found this beautiful piece today along the Arkansas River bank in Colorado. I have a few other pieces of petrified wood but this is the largest that I've found and it almost looks to have been cut with something before hardening. Just curious if this is usual. The cuts are not very deep and I've tried to get the best pictures I can of them.

Hello all. I'm a rock and mineral guy but am becoming more interested in fossils and have been able to fossil hunt in a few states over the past two years. I was hunting on the Peace River after a business trip two weeks ago and The Fossil Forum kept coming up as I was discussing credible, well respected resources with a few experienced individuals in the river with me. I'm looking forward to increasing my fossil knowledge and plan to use this forum as one way to do that. Thanks in advance for everyone who is willing to share their knowledge, whether here or elsewhere.

I recently collected quite a few artifacts from a privately owned piece of property located in the Debeque Colorado area. I beleive most of the pieces (knives, drills, hand axes, projectile points, ect.) to be of late Paleo Indian Age. Specifically, Foothills Mountain Complex. A significant portion of the artifacts were knapped from source material that contains the fossil type represented in the photo. I cannot identify the species. I find it very interesting that tool stone containing this particular fossil was apparently utilized over the same material without this fossil. Tool stone containing this fossil is very difficult to find. Stone with no fossil is easily obtained. This could indicate they wanted their tools to have this fossil within them. Why? I would love it if someone could tell me what this thing is. The Geologic maps I can find online indicate the entire area could be the DeBeque\Wasatch Formation. Any information would be more than appreciated. I have numerous additional photos but this one is by far the most detailed. Thank You.

From the Rocky Ridge Sandstone unit of the Pierre Formation near Fort Collins, Colorado

Thank you for allowing me on here. I’m just learning so bear with me I’ll get the hang of it. Can Anyone give advice the best places in Colorado to fossil hunt?

Little slice of heaven near Fort Collins with some nice Inoceramus Clams. Usually try to not bust open big rocks like this and instead find ones that have already eroded out but this nodule had a crack running along really nice bivalve so I couldn't resist.

Never seen anything like this so far. I know it's an Inoceramid from the shell structure but I've never seen one in this shape before. I know there's a lot of variety with this species but I have a lot of experience collecting bivalves and I've never seen one like this.

Good day everyone, I was out over by the Ratone Plateau, not too far from the purgatory river, and came across these fungi like fossils. I have only heard that mushroom fossils were only found within amber but my father was thinking they were actual fungi fossils. What do you all think? They kind of look like the caps of mushrooms. Any help identifying what these are would be greatly appreciated. Thank you

Found in Douglas Pass Colorado decades ago. Revisited and unable to tell if it’s fossil or rock

A cool piece frozen in time from the day they were buried together. Also a decent size Inoceramus shell for the area and always fun to find an ammonite. This piece is from Boulder, Colorado.

Hello, Could I get some help identifying these two nautiloid steinkerns? Unfortunately no precise age/locality info on them but I think they might be from the Pennsylvanian or Permian of Kansas or Texas. They are both around 8-9cm wide. 1. 2. Referring to this: http://inyo2.coffeecup.com/kansasfossils/kansasfossils.html I think #1. might be Metacoceras and #2. might be Liroceras. @Missourian I believe you are referenced in that post and you seem to be experienced in this fauna? Thanks

I was wondering if there's anyone (preferably in Colorado) who can prepare fossils with an air scribe if sent to them and if so what there prices would be for a project. I have a plethora of fossils from the Pierre Shale still encased in matrix and a hammer and chisel is just not detailed enough and it requires breaking and glueing specimens. Hopefully one day I can get my own air compressor and scribe setup but for now I'm in a apartment and that's just not possible. Any feedback is appreciated.

I was really enjoying hiking around different spots in Boulder, Colorado and eventually I came across a beautiful outcrop of the Niobrara Formation. I thought it was so cool that there were shell imprints in the rock and nobody had ever taught me about the Geology of the area and it was really fascinating to see for myself that the whole area was once under the sea. I stumbled upon a massive Inoceramus and I knew I had to haul it home. Not bad at all for a first fossil hunt I don't think I ever found a Inoceramus as impressive as my first. Begginers luck.

I've had some beautiful little hikes around a sandstone outcrop and I've stumbled upon some very decent bivalves