Fossil Hunting in the Two Medicine Formation, Montana
ALLOWED
Permit required — see below
Key Conditions
- The realistic way most visitors dig Two Medicine Formation fossils is through the Montana Dinosaur Center's paid guided Fossil Expeditions in Bynum ($110 for a half-day site tour, $225 for an 8-hour day-dig, June–September), on the Center's own private/leased active sites — not free casual collecting on public land
- Egg Mountain, the formation's most famous locality and the site of the original 1978–79 Maiasaura nesting discoveries, is private property owned by the Museum of the Rockies (Bozeman) and closed to public access entirely — it is not open for a visit at any price, guided or otherwise
- No specific, mapped BLM Havre Field Office parcel with confirmed public casual-collecting access to Two Medicine Formation exposures was found for this page; the standard federal PRPA framework (invertebrate/plant collecting allowed, vertebrate material prohibited without a research permit) would apply on any genuinely open BLM land bearing this formation, but that's a general rule, not a specific named site
- Because the Montana Dinosaur Center's dig sites are on private or privately-leased ground, the federal PRPA vertebrate/invertebrate distinction that governs most fossil-hunting pages on this site doesn't directly apply there — the program's own rules, not federal land-management law, set the terms
- Bynum, Choteau, and Egg Mountain all sit in Teton County, not Glacier County — a mix-up that likely comes from the formation's general proximity to Glacier National Park, which itself is roughly 60 miles further northwest in Glacier and Flathead counties
The Fossil Everyone Knows Is Behind a Locked Gate
Egg Mountain, discovered by Bynum rock-shop owner Marion Brandvold in 1977 and developed into the site that gave the world Maiasaura — the first strong evidence that any dinosaur cared for its young — is not a place you can visit. The Nature Conservancy bought the 553-acre property in 1985 as part of its Pine Butte Swamp Preserve holdings, and sold it in 2004 to the Museum of the Rockies in Bozeman, which continues to use it as an active research property, closed to the public. If a page or map suggests you can wander up to Egg Mountain yourself, that page is wrong.
"Two Medicine Formation" Isn't One Place You Can Just Drive To
Unlike most fossil-hunting pages on this site, there isn't a specific, mapped BLM parcel here with confirmed casual-collecting access. The Two Medicine Formation outcrops across a broad swath of northwestern Montana, and the realistic, confirmed public access point is the Montana Dinosaur Center's paid guided dig program in Bynum — private land, private program, private rules. Treat any claim of free, open collecting somewhere specific in this formation with real skepticism until you've confirmed it directly with BLM's Havre Field Office.
- $110 half-day site tour / $225 8-hour day-dig, June through September
- Minors under 18 must be accompanied by a parent or guardian
- Reservations required — expeditions book quickly
- Program rules govern the dig, not federal PRPA vertebrate/invertebrate rules, since the sites are private
- Keep/retain policy for significant finds not confirmed by this page — ask when booking
Source: Montana Dinosaur Center, Bynum, MT, 406-469-2211
In 1978, Marion Brandvold — who ran the Trex Agate Rock Shop in Bynum and had found juvenile dinosaur bones on a hillside south of Choteau the year before — showed her discovery to a young paleontologist named Jack Horner. Working with Robert Makela through 1978 and 1979, Horner uncovered fourteen dinosaur nests at what became known as Egg Mountain, along with eggshell, hatchling bones, and adult material belonging to a previously unknown duck-billed dinosaur he named Maiasaura peeblesorum — "good mother lizard." The hatchlings showed worn teeth and underdeveloped limbs, evidence that they'd stayed in the nest and been fed or protected by an adult. It was the first strong evidence that any dinosaur cared for its young, and it reshaped how paleontologists thought about dinosaur behavior generally.
That discovery happened on what's now private, closed research ground, which is the central fact anyone researching this formation needs going in. The public-facing side of Two Medicine Formation paleontology in this area runs through the Montana Dinosaur Center a short drive north in Bynum — a separate institution running its own guided digs on its own sites, connected to Egg Mountain's legacy but not the same property, and not a source of unsupervised access to it.
The Three Ways People Try to Access This Formation
| Access Point | Status | Cost | Governing Rules |
|---|---|---|---|
| Egg Mountain | Closed to public entirely | N/A — not available | Private property, Museum of the Rockies |
| Montana Dinosaur Center (Bynum) | Open via paid guided program | $110–$225, Jun–Sep | Private program rules, not federal PRPA |
| General BLM Havre FO public land | Unclear — no confirmed specific site | Free, if genuinely open | Standard PRPA: invertebrate/plant allowed, vertebrate prohibited |
Verified against NPS, Museum of the Rockies reporting, and Montana Dinosaur Center sources, August 2026.
Getting to Bynum
Verified against Montana Dinosaur Center public information, August 2026.
Booking a Fossil Expedition
- 1
Choose your program length
A $110 half-day site tour for a lighter introduction, or a $225 8-hour day-dig for hands-on excavation time on an active site.
- 2
Book in advance
Reserve through the Montana Dinosaur Center's online system well before your travel dates — expeditions run only June through September and fill quickly.
- 3
Confirm details for minors
If bringing anyone under 18, a parent or guardian must attend — the Center won't accept guardianship responsibility.
- 4
Ask about the keep/retain policy
Confirm directly with the Center what happens to significant finds before your visit, since this isn't publicly documented in detail.
Two Medicine Formation at a Glance
83.5–70.6 Ma (Campanian)
Formation age
No
Egg Mountain public access?
$110
Bynum dig cost (half-day)
$225
Bynum dig cost (full-day)
June–September
Season
Before You Go
- Book a Montana Dinosaur Center Fossil Expedition well in advance if you want hands-on dig access
- Don't plan a trip to Egg Mountain itself — it's closed to the public
- Ask the Center directly about the keep/retain policy for significant finds
- If exploring nearby public land independently, call BLM Havre Field Office to confirm current status before assuming any spot is open
- Pack for outdoor badland-type terrain and full sun exposure
Permits & Licenses
| Permit | Required? | Notes |
|---|---|---|
| Montana Dinosaur Center Fossil Expedition | Yes | Not a government permit — this is a paid, guided program on the Center's own private or privately-leased sites. Reserve in advance; expeditions book quickly. What participants get to keep from a find was not confirmed for this page — ask directly when booking. |
| Egg Mountain access | No | Not available at any price for casual visitors. Egg Mountain is privately owned by the Museum of the Rockies and used for institutional research, not public digging or tours. |
| BLM casual collecting (surrounding public land, where genuinely open) | No | Standard PRPA framework would apply — invertebrate/plant fossils collectable, vertebrate material prohibited without a research permit — but no specific confirmed public Two Medicine Formation collecting site was identified for this page. Contact BLM Havre Field Office before assuming any particular parcel is open. |
Time & Seasonal Restrictions
- No public access to Egg Mountain under any circumstances — it is private research property, not a visitor site
- Vertebrate fossils cannot be casually collected from any genuinely open federal land in the region without a PRPA research permit, regardless of the Two Medicine Formation's fame for producing them
- At the Montana Dinosaur Center's guided digs, participants under 18 must be accompanied by a parent or guardian — the Center does not accept guardianship responsibility for minors
- Fossil Expeditions run June through September only; the program is not available year-round
Equipment Notes
- Provided by the Montana Dinosaur Center for its guided digs — excavation tools, brushes, and instruction are part of the program
- Sturdy field clothing and sun protection — digs take place outdoors on exposed badland-type terrain
- Water and snacks for a full-day session if booking the 8-hour dig option
- No personal excavation equipment has any legal use on BLM land here for vertebrate material regardless of what you bring
What People Find Here
- Maiasaura nests, eggshell, and hatchling material — the discovery that made Egg Mountain famous, first identified by Marion Brandvold in 1977 and developed by Jack Horner and Robert Makela starting in 1978, though this specific site remains closed to public digging
- Hadrosaur and other Cretaceous vertebrate material — documented across the broader Two Medicine Formation, most accessible to the public through the Montana Dinosaur Center's ongoing excavation program rather than casual collecting
- Common invertebrate and plant material — collectable under standard PRPA rules on any genuinely open BLM land bearing this formation, though no specific confirmed public locality was identified for this page
Penalties for Violations
← Scroll to see all columns
| Violation | Statute | Penalty |
|---|---|---|
| Trespassing onto Egg Mountain or attempting to collect there without authorization | Montana trespass law; private property rights of the Museum of the Rockies | Criminal trespass citation; any collected material subject to recovery by the property owner |
| Collecting vertebrate fossil material from genuinely open federal land without a PRPA research permit | Paleontological Resources Preservation Act, 16 U.S.C. §§ 470aaa et seq. | Federal citation; potential criminal and civil penalties for knowing violations, scaled to the resource's scientific value |
Etiquette & Leave No Trace
- Book Montana Dinosaur Center expeditions well in advance — they fill quickly during the June–September season
- Don't attempt to visit Egg Mountain on your own; it's private research property, and there's no unofficial way to see it
- Ask the Center directly, before booking, what happens to significant vertebrate material you help uncover — this page couldn't confirm the keep/retain policy from public sources
- If exploring general public land in the region independently, confirm current BLM Havre Field Office guidance before assuming any specific spot is open for even invertebrate collecting
- Respect that this formation's fame rests on carefully excavated, scientifically documented material — the value of a find here is largely in its context, which casual, undocumented digging destroys
Nearby Alternatives
← Scroll to see all columns
| Site | Distance | Notes |
|---|---|---|
| Hell Creek (BLM, Garfield County) | 250 mi | A genuinely open BLM casual-collecting site for invertebrates/plant material, unlike the largely private-access Two Medicine Formation |
Frequently Asked Questions
Can I collect fossils from the Two Medicine Formation on my own?
Not in any confirmed, specific way. The realistic public access point is the Montana Dinosaur Center's paid guided Fossil Expeditions in Bynum, on the Center's own sites. No specific BLM-managed public locality with confirmed casual-collecting access was found for this page — general PRPA rules for invertebrate/plant material would apply on any genuinely open federal land bearing the formation, but that's not the same as a mapped, known destination.
Can I visit Egg Mountain, the famous Maiasaura nesting site?
No. Egg Mountain is private property owned by the Museum of the Rockies, purchased from The Nature Conservancy in 2004, and it's closed to public access entirely — not open for tours, not open for digging, at any price.
How much does the Montana Dinosaur Center's dig program cost?
A half-day site tour runs $110, and an 8-hour day-dig on an active excavation runs $225, with the Center historically offering a 50% discount for Montana residents. The program runs June through September.
Do I get to keep what I find at the guided dig?
This wasn't confirmed from public sources for this page. Scientifically significant vertebrate material at active research digs is commonly retained by the institution running the excavation rather than given to participants, but you should ask the Montana Dinosaur Center directly when booking rather than assume either way.
Why can't I just collect vertebrate fossils on public land near Choteau or Bynum?
The Paleontological Resources Preservation Act prohibits casual collection of vertebrate fossil material from federal land without a research permit, and that rule applies regardless of how famous a formation is for producing that material. It's the same federal framework covered on other fossil-hunting pages on this site — the difference here is that this specific formation's best-documented public access point is a private paid program, not open BLM ground.
What's the scientific significance of this formation beyond Egg Mountain?
The Two Medicine Formation, Campanian-age (roughly 83.5 to 70.6 million years old), preserved not just the Maiasaura nesting colony but a broader record of Late Cretaceous hadrosaurs and other dinosaurs across northwestern Montana. Egg Mountain's 1978–79 discoveries provided the first strong evidence that some dinosaurs cared for their young, a finding that reshaped how paleontologists think about dinosaur behavior generally, not just this one species.
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Disclaimer
Information is provided for general guidance only. Regulations change frequently. Always verify current rules with the official jurisdiction before relying on this information for legal decisions. Permitted Pursuits is not a substitute for official agency guidance. Report an error.
Sources
- National Park Service — Egg Mountain, the Two Medicine, and the Caring Mother Dinosaur(accessed 2026-08-28)
- Montana Dinosaur Center — Program FAQ(accessed 2026-08-28)
- BLM — Collecting Paleontological Resources Under the Paleontological Resources Preservation Act of 2009 (Policy IM-2012-140)(accessed 2026-08-28)
- Helena Independent Record — Nature Conservancy Sells Dino Dig Site to Museum of the Rockies(accessed 2026-08-28)
Last verified: 2026-08-28 · Last updated: 2026-08-28