Fossil Hunting at Picket Wire Canyonlands, Colorado
PROHIBITED
Not permitted at this location
Key Conditions
- Every one of the site's 1,900-plus dinosaur tracks is a vertebrate trace fossil, and the Paleontological Resources Preservation Act prohibits casual collection of vertebrate material from federal land without a research permit — there's no invertebrate-collecting carve-out here the way there is at most fossil sites on this list, because the exposed bedrock is essentially the trackway surface itself
- Access requires real planning, not a collecting permit: either an 11.2-mile round-trip hike, bike, or horseback trip from Withers Canyon Trailhead, or a reserved seat on a Forest Service-guided high-clearance 4x4 tour offered only on specific Saturdays in April, May, September, and October
- The tracksite sits in Otero County — some older regional write-ups place it in Las Animas County, likely because the broader Comanche National Grassland unit does extend across that county line about a mile and a half south of the trailhead
- The same observation-only standard covers the canyon's other historic features on the same route — a 19th-century mission and cemetery, Native American rock art, and the Rourke Ranch historic site — none of it is collectable
There's Nothing to Legally Collect Here — And That's the Point
Most fossil-hunting pages on this site describe a PRPA split: common invertebrate and plant fossils are open to casual collecting on federal land, while vertebrate material needs a research permit. Picket Wire Canyonlands doesn't offer that split at all. The exposed Morrison Formation bedrock along the Purgatoire River is the trackway — over 1,900 individual dinosaur footprints — and every one of those prints is a vertebrate trace fossil under federal law. There is no loose, invertebrate-bearing float to legally pick up here the way there is at most Morrison Formation sites; the entire draw of the location is the one category of material PRPA locks down hardest.
Why Tracks Count as Vertebrate Fossils
The Paleontological Resources Preservation Act (16 U.S.C. §§ 470aaa et seq.) defines vertebrate material broadly enough to cover trace fossils — tracks, trackways, burrows, and similar evidence left by an animal — not just bone or teeth. A dinosaur footprint pressed into ancient lakeshore mud, now fossilized limestone, is legally treated the same as a bone fragment for collecting purposes. That's the detail that surprises visitors who assume a footprint impression, being rock rather than a literal bone, might fall under looser rules than it actually does.
- No collecting of tracks, bone fragments, or any trace fossil material anywhere in the canyon
- No collecting of co-located historic material — mission/cemetery remains, rock art, or Rourke Ranch artifacts
- Self-guided access via 11.2-mile round-trip hike, bike, or horseback from Withers Canyon Trailhead only
- Guided auto tour requires visitor-owned 4WD, high-clearance vehicle — no AWD, ATV, minivan, or RV
- Horses permitted for general canyon access but not directly on the tracks
Source: USDA Forest Service, Comanche National Grassland, 719-523-6591, 1420 East 3rd St., La Junta, CO 81050
About 150 million years ago, during the Late Jurassic, a shallow lakeshore here recorded the footfalls of sauropods and theropods moving across soft mud that eventually hardened into the Morrison Formation limestone now exposed along a quarter-mile stretch of the Purgatoire River. More than 1,900 individual prints across 130 separate trackways survive in that bedrock — the largest concentration of dinosaur tracks documented anywhere in North America. Among them, researchers identified something more specific than raw scale: several sauropod trackways run roughly parallel to one another, evidence that's been used to support the conclusion that sauropods moved in groups rather than as solitary animals, a genuine data point in how paleontologists think about dinosaur social behavior.
The same canyon carries a second, entirely different layer of protected history along the same access route. A 19th-century Catholic mission and its associated cemetery, Native American rock art panels, and the remains of the Rourke Ranch — a historic homestead — all sit along the trail to the tracksite, each protected under its own framework, none of it collectable any more than the tracks are. Visitors making the 11.2-mile round trip pass through several centuries of human history on the same walk that ends at 150-million-year-old footprints.
Picket Wire Canyonlands vs. a Typical Morrison Formation Site
| Site | Formation | Invertebrate/Plant Collecting | Vertebrate Material | Primary Draw |
|---|---|---|---|---|
| Picket Wire Canyonlands | Morrison Fm. (Late Jurassic) | Not practically available — exposed rock is the trackway | Prohibited (PRPA) — this is the entire site | 1,900+ dinosaur tracks, observation only |
| Como Bluff, WY (published on this site) | Sundance/Morrison Fm. | Allowed, 25 lb/day BLM casual-use | Prohibited (PRPA), including all dinosaur material | Marine invertebrates + petrified wood, some legal collecting |
Verified against USFS and BLM sources, August 2026. Como Bluff represents the more typical Morrison Formation fossil-hunting experience on this site; Picket Wire is the exception where even the standard invertebrate allowance doesn't functionally apply.
Getting to Withers Canyon Trailhead
Verified against Recreation.gov and USFS Comanche National Grassland sources, August 2026.
Booking the Guided 4x4 Tour
- 1
Watch the release windows
Spring-date tickets (April, May tours) typically go on sale in early March; fall-date tickets (September, October tours) typically release in early August.
- 2
Book on Recreation.gov
Tours are capped at 40 participants and fill quickly — there's no on-site standby option if you miss the window.
- 3
Confirm your vehicle qualifies
Four-wheel-drive, high-clearance truck or SUV only. Contact the Comanche National Grassland office at 719-523-6591 if you're unsure whether your vehicle meets the requirement.
- 4
Pack for a full-day, remote trip
Minimum 2 quarts of water per person, rain gear, sun protection, personal medications, and a first aid kit — there's no services along the route.
Picket Wire Canyonlands at a Glance
1,900+
Track count
130
Trackways
~150 million years (Late Jurassic)
Age
No
Collecting allowed?
11.2 mi
Round-trip hike distance
Before You Go
- Decide between the self-guided 11.2-mile hike/bike/horse trip and the guided 4x4 tour before planning your date
- If booking the guided tour, watch for the early-March or early-August ticket release depending on season
- Confirm your vehicle meets the 4WD, high-clearance requirement if driving the guided tour
- Pack at least 2 quarts of water per person plus sun protection — no services along the route
- Plan to observe only — leave every track, artifact, and rock art panel exactly as found
Permits & Licenses
| Permit | Required? | Notes |
|---|---|---|
| Fossil/track collecting permit | No | Not offered for recreational or casual use at this site. Any legitimate excavation or collection here would require a formal PRPA research permit issued to a qualified institution — not something available to a recreational visitor. |
| Guided 4x4 tour reservation | Yes | An access reservation, not a collecting permit. Tours run specific Saturdays in April, May, September, and October, capped at 40 participants; tickets typically release in early March (spring dates) and early August (fall dates). Contact the Comanche National Grassland office, 719-523-6591, or book via Recreation.gov. |
Time & Seasonal Restrictions
- No collecting, removing, touching, or disturbing any track, bone fragment, or trace fossil anywhere in the canyon
- No collecting of the co-located historic material either — the mission/cemetery remains, rock art panels, and Rourke Ranch site are all separately protected
- Guided-tour vehicles must be visitor-owned four-wheel-drive, high-clearance trucks or SUVs — no all-wheel-drive cars, minivans, RVs, or ATVs permitted
- Horses are not allowed directly on the dinosaur tracks, even though horseback is a permitted way to reach the canyon generally
- Self-guided access requires the full 11.2-mile round trip from Withers Canyon Trailhead — there is no shorter public route to the tracksite
Equipment Notes
- None for collecting — this is an observation-only site regardless of what you bring
- Camera, minimum 2 quarts of water per person, and sun protection for either access method
- High-top hiking boots recommended for the self-guided hike over loose rock and uneven riverbed terrain
- For the guided auto tour: your own high-clearance 4WD vehicle, full-size spare tire, lug wrench, and jack
What People Find Here
- Nothing collectable — the tracksite itself, over 1,900 prints across 130 trackways spanning a quarter-mile of exposed riverbed, is the find, preserved in place rather than removed
- Sauropod trackways (large, rounded prints attributed to Apatosaurus) and theropod trackways (three-toed prints attributed to Allosaurus), both dated to the Late Jurassic Morrison Formation, roughly 150 million years old
- Parallel sauropod trackways at this specific site provided some of the original evidence supporting gregarious, herd-like behavior in sauropod dinosaurs — a genuine contribution to paleontological science, not just a scale of tourist attraction
Penalties for Violations
← Scroll to see all columns
| Violation | Statute | Penalty |
|---|---|---|
| Collecting or removing any vertebrate fossil material, including trackway rock, without a PRPA research permit | Paleontological Resources Preservation Act, 16 U.S.C. §§ 470aaa et seq.; 36 CFR Part 291 | Federal criminal penalties can apply for knowing violations, including fines and imprisonment, with additional civil penalties covering the resource's value and restoration cost |
| Operating an unauthorized vehicle type (AWD car, ATV, minivan, RV) on the guided tour route | USFS Comanche National Grassland guided-tour terms | Denied tour access; no refund |
Etiquette & Leave No Trace
- Walk around trackways, never across or directly on them, even where the route seems to lead over the rock
- Don't touch, chalk, or highlight tracks for photographs — oils and abrasion degrade the rock surface over time
- Stay on the designated route past the mission/cemetery and rock art panels — this canyon layers multiple protected resource types on a single trail
- Book guided-tour tickets the moment they release — early March for spring dates, early August for fall dates — they fill quickly with no on-site standby option
- Carry more water than the stated minimum; there is no water source, reliable shade, or cell service for most of the route
Frequently Asked Questions
Can I collect a piece of the dinosaur tracksite?
No, absolutely not. Every track is a vertebrate trace fossil, and the Paleontological Resources Preservation Act prohibits casual collection of vertebrate material from federal land without a research permit — a category of authorization not available to recreational visitors. This is a look-don't-touch site by law, not just by park etiquette.
Is Picket Wire Canyonlands in Las Animas County or Otero County?
The tracksite and Withers Canyon Trailhead are in Otero County. Some older regional sources place the site in Las Animas County, which likely traces back to the fact that the broader Comanche National Grassland unit does cross into Las Animas County about a mile and a half south of the trailhead — but the tracksite itself is Otero County.
How do I actually get to the tracksite?
Two ways: an 11.2-mile round-trip hike, bike, or horseback trip on your own from the Withers Canyon Trailhead, or a reserved seat on a Forest Service-guided high-clearance 4x4 auto tour, offered only on specific Saturdays in April, May, September, and October. There's no shorter or easier public route to the tracks.
What's the scientific significance beyond just being large?
Parallel sauropod trackways documented at this site provided some of the original evidence supporting gregarious, herd-like behavior in sauropod dinosaurs — meaning this isn't only the largest dinosaur tracksite in North America by track count, it also contributed real data to how paleontologists understand sauropod social behavior.
Can I just drive my own 4x4 out there instead of hiking or booking the guided tour?
No. The guided auto tour is the only motorized way to reach the canyon, and it requires a reservation and a Forest Service guide — you can't drive yourself in independently, even with a suitable high-clearance vehicle.
Is there anything else protected along the route besides the tracks?
Yes. The same trail passes a 19th-century Catholic mission and cemetery, Native American rock art panels, and the Rourke Ranch historic site — all separately protected and all observation-only, the same as the tracks themselves.
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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
- USDA Forest Service, PSICC — Picket Wire Canyonlands(accessed 2026-08-28)
- Recreation.gov — Picket Wire Canyonlands Guided Auto Tour(accessed 2026-08-28)
- Colorado Geological Survey — SP-40, Dinosaur Lake: The Story of the Purgatoire Valley Dinosaur Tracksite Area(accessed 2026-08-28)
- US Forest Service — Fossils: A Guide to Casual Collecting on National Forests and Grasslands(accessed 2026-08-28)
- eCFR — 36 CFR Part 291, Paleontological Resources Preservation(accessed 2026-08-28)
Last verified: 2026-08-28 · Last updated: 2026-08-28