Researchers have documented more than 18,000 dinosaur tracks at a single site in Bolivia’s Torotoro National Park, making Carreras Pampa the largest dinosaur tracksite ever recorded. The study, published in PLOS ONE, cataloged 1,321 trackways and 289 solitary tracks across nine mapped surfaces in the Upper Cretaceous El Molino Formation, including 16,600 theropod tracks, 280 swim trackways totaling 1,378 swim traces, and multiple tail drag marks. The findings surpass the roughly 12,000 footprints previously counted at Cal Orck’o, Bolivia’s best-known dinosaur track locality, and offer direct evidence that scores of dinosaurs walked and swam along what was once a coastal shoreline.
Why the Carreras Pampa record reshapes Late Cretaceous behavior studies
The sheer density of tracks at Carreras Pampa is not just a numbers game. Across approximately 7,485 square meters of mapped rock surface, the research team identified bimodal trackway orientations, meaning the dinosaurs consistently traveled in two opposing directions rather than scattering randomly. That pattern points toward shoreline-parallel movement, the kind of behavior seen in modern animals that follow coastlines for feeding, migration, or water access. If these orientations correlate with tidal or seasonal cycles, they could reveal how Late Cretaceous ecosystems functioned along fluctuating water margins.
One way to test that idea would be to compare the track azimuths with microfossil salinity markers preserved in the same bedding planes. Salinity-sensitive microfossils, such as foraminifera or ostracods, can indicate whether water conditions shifted between freshwater and marine states over time. If the two dominant trackway directions align with distinct salinity regimes, that would support the hypothesis that dinosaurs adjusted their travel routes in response to changing tidal or seasonal conditions rather than simply wandering along a static shore. No such cross-referencing has been published yet, but the detailed orientation data now available from Carreras Pampa makes this kind of analysis feasible for the first time at a site of this scale.
Beyond movement directions, the mix of walking, swimming, and tail-dragging traces captures a snapshot of animals negotiating a dynamic shoreline. Theropod tracks dominate the assemblage, but the presence of swim traces and tail marks suggests repeated use of shallow water zones, perhaps as foraging grounds or low-risk corridors for crossing embayments. In modern coastal settings, birds and mammals often exploit similar nearshore strips where footing alternates between firm and partially submerged. The Carreras Pampa surfaces appear to record an ancient analogue of that behavior, frozen into the mud and later lithified into limestone.
Six years of fieldwork and the data behind the record count
The Carreras Pampa study drew on six years of fieldwork, during which researchers mapped nine discrete study sites within Torotoro National Park. The authors of the peer-reviewed analysis report 1,321 trackways plus 289 solitary tracks, with 16,600 of those prints attributed to theropods, the group that includes both small predators and large carnivores. The 280 swim trackways, comprising 1,378 individual swim tracks, are especially significant because swim traces are rare in the fossil record and difficult to preserve. Their abundance here suggests that water levels at this ancient shoreline were shallow enough for dinosaurs to touch bottom while partially buoyant, leaving distinctive scratch-like marks rather than full weight-bearing footprints.
Field teams documented track size, spacing, depth, and orientation using tape-and-compass measurements, drone-based photogrammetry, and high-resolution mapping of bedding planes. These methods allowed the researchers to distinguish true tracks from erosional features and to separate overlapping trails made at different times. Multiple surfaces, stacked vertically through the El Molino Formation, record repeated episodes of track-making rather than a single crowded day on the shoreline. That stratigraphic repetition strengthens the case that Carreras Pampa preserves long-term behavioral patterns rather than a one-off congregation.
The underlying measurements of track dimensions and orientations are compiled in a supplementary dataset referenced by the paper. These quantitative records allow other researchers to independently analyze the distributions, though the raw XLSX values have not been released as fully open data files separate from the journal’s supplementary system. That means independent verification of the aggregate totals currently depends on the authors’ summary statistics rather than a standalone, freely downloadable spreadsheet. For now, outside teams can check sampling methods and basic calculations but cannot easily run alternative statistical treatments on the full, original measurement matrix.
For context, Cal Orck’o in Sucre has long been Bolivia’s flagship dinosaur track locality. A comprehensive review of regional tracksites documented the history of that site and others in the El Molino Formation, establishing the baseline against which Carreras Pampa’s new totals are measured. Cal Orck’o’s roughly 12,000 footprints, spread across a dramatically tilted limestone wall, held the informal record for years. Carreras Pampa’s count exceeds that figure by at least a third, and the diversity of track types, from walking to swimming to tail dragging, adds behavioral dimensions that Cal Orck’o’s vertical exposure makes harder to study.
Open questions about track density, data access, and tidal signals
Several gaps in the evidence limit how far conclusions can be drawn. The PLOS ONE paper aggregates orientation and density statistics across all nine study sites, but per-site breakdown tables have not been published in a format that would let outside researchers test whether the bimodal pattern holds uniformly or varies between surfaces. If some surfaces show random orientations while others are strongly bimodal, the shoreline-travel interpretation would need to be refined. It could mean, for instance, that only certain bedding planes record peak-activity periods tied to specific water levels, while others capture more diffuse movement during stable conditions.
Another unresolved issue is how track density relates to the duration of track formation. High densities could reflect a brief but intense influx of animals-perhaps driven by drought, storms, or short-lived food pulses-or a moderate but steady flow of traffic over a longer window of time. Without independent age constraints between closely spaced bedding planes, it is difficult to distinguish between those scenarios. Sedimentological indicators, such as mud cracks, ripple cross-lamination, and bioturbation, may eventually help bracket the time represented by each surface, but such fine-scale temporal analysis has not yet been published for Carreras Pampa.
No direct statements from the lead authors appear in the available press materials beyond institutional summaries. That absence makes it harder to assess how the team interprets the swim trackways in relation to dinosaur physiology and behavior. For example, it remains unclear whether the authors favor an explanation rooted in energy-efficient travel-using buoyancy to reduce the cost of locomotion-or one emphasizing forced crossings of shallow channels. Both possibilities are consistent with the scratch-like swim traces, and distinguishing between them will likely require more detailed comparisons of track depth, stride length, and substrate consistency across the mapped surfaces.
Data access also shapes what outside specialists can do with the Carreras Pampa record. While the supplementary tables list track counts and some measurements, high-resolution photogrammetric models and georeferenced maps have not been widely distributed. Those products would allow independent teams to re-digitize trackways, test alternative orientation bins, and explore spatial clustering patterns such as potential herd structures or age-segregated pathways. Until such datasets are made more broadly available, many of the more nuanced behavioral questions will remain open, even as the basic numerical record stands.
Despite these limitations, the Carreras Pampa site marks a turning point for Late Cretaceous ichnology in South America. It demonstrates that the El Molino Formation preserves not only spectacular individual sites like Cal Orck’o but also laterally extensive, behaviorally rich track-bearing surfaces. As additional sections of the formation are surveyed with the same intensity, researchers may find that Carreras Pampa is part of a broader network of coastal corridors used repeatedly by dinosaurs over thousands of years. Future work that integrates sedimentology, microfossils, and high-resolution mapping could transform the site from a record-breaking track census into a detailed reconstruction of how dinosaur communities moved through a changing shoreline landscape.
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*This article was researched with the help of AI, with human editors creating the final content.
