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I've loved snooping around this forum for a while now and decided I would finally make an account. I'll be uploading some finds from around Colorado and hopefully some 3d models if I'm able to post them here.

I am heading to Pagosa Springs Colorado next week and would love to do some fossiling. I have a few sites to check out but I was wondering if there were any day trip fossil hunt guides that were in the South Colorado area. I haven't been able to find any on web search, so if you know anyone who leads half day or day trips, please PM me! Thanks!!

About a year ago I made a post where I made a post on the forum where I shared some of my more interesting fossil insects I had found at the Florissant Fossil Beds in Colorado. For those uninitiated, the Florissant Formation is an Eocene (Priabonian Stage, ~34 Ma) lägerstatte notable for exceptional preservation of plant and arthropod fossils. My original post can be found here: One of the fossils I showed off in that post was of an insect larva which I had interpreted as a fly (order Diptera) larva, speculating that it may be a botfly larva because it possessed setae which resembled those of a botfly. I had never been super confident in this interpretation, and over the last year I’ve showed the fossil to several knowledgeable friends, paleontologists, and entomologists. What has emerged is a different consensus that I am much more confident with (and is far more intriguing than what I had originally thought!): this fossil is in fact the dorsal view of a caddisfly larva (order Trichoptera). There are several anatomical characteristics present which I had failed to notice initially. To start, I was viewing the fossil backwards. I had interpreted that anterior end as the posterior end and vice versa. Once I had this corrected, it became clear that the insect’s head and thorax are both clearly definable and both eyes are visible on the head. Additionally, small portions of the legs are visible sticking out from the thorax as well. I originally did not see any legs which had informed my original interpretation, but in this fossil most of the legs are tucked underneath the body and not visible. Here’s the fossil. The anterior end faces to the left. Here’s a picture of a modern caddisfly larva sans its protective casing. It is oriented in the same fashion as the fossil, for comparison: Caddisflies are closely related to butterflies and moths (order Lepidoptera) but they have larvae which live in bodies of water. Many caddisfly species’ larvae build little casings out of silk and pebbles/debris to protect themselves, but this is not universal. The larva seen here is not within a casing, so it either died in a rare instance in which it was not in its case or it is of a species which does not build cases. Adult caddisflies have been reported from Florissant, as have fossils of isolated larval casings, but I was unable to find a description of a body fossil of a caddisfly larva. Not to say one doesn’t exist, they just seem to be obscure. So there you have it: a really interesting and unique find from this fossil locality. Just needed another half dozen or so sets of eyes to figure out what was actually going on there!

Hey there! I’m just wondering if anyone could give their opinion on whether or not this may be an impression of an ammonite? It was found face down in Colorado, USA. Thank you!

Hi this came from the Laramie fm if Marshall Colorado. It is dense and light and sticks to your tongue I have heard of people finding up there please correct me if I’m wrong. I also thought maybe petrified wood but to light and sticks to your tongue. I am exited to hear what you all think. Thanks -Daniel

Hello, I just acquired this specimen. It was listed online as dinosaur skin by the seller who found it on their property at the base of the rocky mountains in Colorado. I recently took it to online fossil retailer to try to get it identified but they couldn't give me a straight answer. One of their staff members thought it looked like Siderite but also said some aspects of it didn't line up with that kind of mineral. I also reached out to the Burke museum in Seattle and they said without more context (Formation, age, lithology) it is hard to say what the specimen you attach might be but they are still looking into it. Let me know if you have any thoughts on what this might be!

I found this in a rock pile in Northern Colorado. With that said The rockpile could have come from anywhere honestly because it was being used for landscaping. It's an extremely weird shape and I immediately thought of some kind of shoulder or hip bone but I really have no clue what this is. If anybody has any ideas I would appreciate it. Thanks

Here are some trilobites I found in Colorado’s Ordovician limestone.

Hello! I found this amazing fossil on my mom’s property in Pueblo, Colorado. I’ve tried to do some extensive research online to see what type of vertebrae animal/marine life this is. Could you please help identify? thank you so much!

Hello Good Folks from the Fossil Forum. We at Gofer Prospecting are precious Gemstones and Metals prospectors who have been tossed into fossils it seems! Started staking off a new acreage a few weeks back in S. Colorado and was surprised to see dinosaur eggs, Cretaceous Period! More looking showed us many fossils onsite! Hadrosaur is the best guess.

Found in Northeast Costilla County Colorado in the Sangre de Cristo Mountains at almost 10,000 feet elevation. From limited research I believe they may be brachiopods from late Paleozoic? There are shells and snail looking things. Found next to each other but not together in the same piece of rock rock. I was wondering what other kinds of fossils may be in this same area. Like fish or trilobites? Thanks

Hi I was on a friends property near Boulder and golden Colorado and found ripples from water. When I looked closer it looked like there were scratch marks possibly from a dinosaur. When I looked on a geologic map it said the age was creatacous. I’m just wondering if it could possibly be scratch marks from the beasts the used to wander the earth. I think the formation is the Dakota formation. Any help would be appreciated.

Well, this year we did not battle the gods of snow and mud. The temperatures were also not scorching this year, with a nice breeze and a hint of a drizzle coming into the area instead. This Baculite Mesa location is always a (WIPS) Western Interior Palentological Society favorite led by our respected leader Malcolm Bedell. Several experts on the site were in attendance, so good advice and information was graciously provided as always ... Looking toward the mesa. The helpers are READY ! .. they did a good job this time. The hike there and back took a good three hours of time. Exercising their little muscles for a dad win. Only have a few of those so they are treasured. Comon' dad, I wanna climb ! Ok, first, we must stop off and smell the flowers blooming in the desert this time of year. This is the typical presentation of the Baculites, usually as casts. Or eroding quickly out of the formation. We have had tons of rain and snow this year, so their scattered skeletons were everywhere. Generally I pick up a few as giveaways. Still some of the original shell on this one. A good example of what you will usually find in the area. I was most interested in exploring the Tepee Buttes this year. These carbonate deposits were created by cold methane seeps. These seeps, in turn, colonized by microbes that fix the chemical energy, supporting a vibrant marine community. There are at least half-a-dozen surrounding the local area. Inoceramus sp. are common at the vent sites. I believe these bivalves are Nymphalucina occidentalis and are common on the buttes. They often are filled with calcite crystals. A bit of Inoceramus sp. shell You can also find traces of the baculites in these formations as well. The climbing was the best part for the kids. Several of the baculite fossils found that day had these large round concretions attached. Our local resident expert indicated that these concretions hid crab predation marks. Large predation entry points created when the crab popped open the shell like a tin can, to feed on the baculites, as they came to rest on the sea floor. The second site was better this year. My daughter was the first to flip what she thought was a stone. Low and behold ! ... a male ammonite fossil. Dad found the female. Lying in a wash, an arroyo, at the second collection location. A few more finds .. nothing to write home about, but they will be great for schools and to give away to those future fossil hunters. Cheers, Brett

Hello, Can someone help ID the insects and other stuff on this plate? It's from the Eocene Green River Formation of Colorado, and the whole plate is about 12 cm long. I see some winged insects but have a hard time telling if they are crane flies or potential dragonflies/damselflies. Thanks.

Found this in San Miguel county, western Colorado. USGS layer says it's Dakota Sandstone and Burro Canyon formation out there. This stood out because it wasn't just a flat blocky rock. I thought it looked like it came out of one of those playdoh things where you squished the stuff through and got a star shaped rope or a bunch of spaghetti. But it's all sandstone and when I cleaned it up I see it's got some kind of mineralization on it. Whatever it is it's resting on a slightly different type of sandstone that I tried to show in the 2nd photo. Limb cast sandstone wood rreplacement?

I have zero fossil-finding experience but apparently this area is significant? Is it maybe an impression of something? Thanks and sorry if this is just a rock!

Hey there I wanted to introduce myself because I'm completely new to not only this forum/website but also entirely new to any field even remotely related this sort of stuff. Many many props to you pros on here like paleontologists, archaeologists and scientists because I would consider myself to be a fairly intelligent individual in general, but trying to self teach about fossils when you don't know the first thing is not the easiest lol I've always been pretty outdoorsy and love the idea of fossil hunting or rockhounding (new word recently added to my vocabulary). It wasn't until recently that I moved to one of the most perfect places for it... Northern Colorado. To be honest though, it still took a few years after moving here before I had the slightest clue of what amazing things are waiting to be found. Even still, I feel like I'm just barely cracking open the door to it all. In the past two or three years I've gotten more and more fascinated with Mother Nature and her ability to create things far more beautiful than I could even imagine. For the most part I've collected cool rocks I've seen here and there but because I've got an 8-year-old that loves to follow suit, it can be tricky to remember 100% where these rocks have come from. I can tell you for sure most of them if not all of them I would bet money came from the same place which just happens to be what I would imagine is as perfect as any for something like fossils really be at. So I've gone back and forth saying that it's totally possible to find a kick butt fossil but then I tell myself there's really just no way I'd be lucky enough and all I've got is a really pretty Rock I can put my garden. In the back of my mind I've wondered though for a long time now and so I thought that I'd come on here and ask for some advice from some of you guys if you wouldn't mind. I'm making three posts of my number three favorites I think is what I'm going to do and then cross my fingers. I'll expect there just rocks for my garden and hope for the best. If you could please let me know if you have any idea for sure if this might be any kind of a fossil or even a sOr even maybe a semi-precious Stone or interesting mineral. Anything would help at all and I do think you had a Time for your time

Hi I found this in Colorado while on a hike. On the hike there was what looked like an ancient ocean or river bed and had rivets from water moving. I was just wondering if it could be a jaw with no enamel or just a cool rock.

Hello Everyone, I picked up some Cretaceous fossil matrix (fossiliferous rocks) from an auction that our WIPS (Western Interior Paleontological Society) group held last year. I picked them up knowing I wanted to give them a nice Vinegar bath and pull out the teeth/fossils trapped in the matrix. So far it looks like it was a very vigorus marine environment. The teeth and fossils are fairly worn and broken. Lots of fishy bits and pieces. A few shark teeth, fish teeth etc... I'm going to share the finds as they drop out of the matrix. I pull the fossils out of the solution every day or so, and refresh the vinegar once or twice a week. I manipulate and move the fossils using a small paintbrush. With what I have so far being able to sit quite comfortably in a pencil eraser's footprint. 1) My question is, what are these round things ? They have bands of light/dark and they are water polished. They don't 'look' geological. But I'm not familiar with fossils/structures such as these. Average size is less than a mm. Maybe 0.5mm if I had to guess. I'm not familar with Ostracods .. but I thought they were more assymetrical in shape. See image below. These survived the Vinegar bath and I've probably noted 2 dozen of about the same size and shape. 2) The formation I am assuming is from Colorado? The member these fossil rocks belonged to was a long-time member here in Colorado. The fossils feel like they are lying in that Cretaceous timeframe and look familar to what I have seen before. Does anyone recognize this rock type/formation ? A selection of the finds so far: The Ptychodus is about 2mm Thanks, Brett

Prehistoric Chili Pepper Fossils Challenge Tomato Plant's Evolutionary History, Study Says The open access paper is: Deanna, R., Martínez, C., Manchester, S., Wilf, P., Campos, A., Knapp, S., Chiarini, F.E., Barboza, G.E., Bernardello, G., Sauquet, H. and Dean, E., 2023. Fossil berries reveal global radiation of the nightshade family by the early Cenozoic. New Phytologist. Open access paper Yours, Paul H.

Hi I found this near peublo Colorado on a private site. And I was wondering what it could be. I was just wondering if I could have some help for ID? This is what it came out of.

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.

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.

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!