Fossils of the 2026 National Fossil Day Artwork

White Sands National Park: Following the Footprints

White Sands National Park, in New Mexico, is extraordinary in many ways, but what truly sets it apart is its unparalleled record of coexistence among people, plants, and animals on this landscape during the late Pleistocene and early Holocene. What appears today as a dry playa or desolate salt flat was once a vibrant system of wetlands and lake margins. These ancient environments are partially restored only during rare, heavy rains that return water to the Tularosa Basin every few decades.

At White Sands, scientists have identified more than 20 distinct sedimentary horizons, preserved over more than 10 vertical feet of sedimentary deposits, that record cycles of past water abundance as well as drought. Within these layers are remarkable trace fossils which have inspired the 2026 National Fossil Day artwork, including footprints of short-faced bears, large cats such as the American lion and saber-toothed cat, giant ground sloths, horses, and humans—providing rare insight into Ice Age life and interactions. Radiocarbon dating of these layers has revealed that people shared the land here with Pleistocene megafauna at least 23,000 to 21,000 years ago, making White Sands National Park the site of the oldest known human footprints in the region.

Today, we understand that White Sands is not alone in preserving these incredible records. Instead, it serves as a powerful analog for other Ice Age pluvial lake systems that have since transformed into salt flats and desert playas across the southwest region of the United States.

Treading New Ground

The unique geology of White Sands created a depositional setting suitable for trace fossil preservation, many of which have now been revealed by years of research at the park which is primarily known for the world’s largest gypsum dunefield. Around 280 to 250 million years ago, towards the end of the Permian Period, a shallow sea covered much of what is now the southwestern United States. As sea level changed over time, evaporite minerals such as gypsum were sometimes deposited when water evaporated from shallow basins. Over millions of years gypsum accumulated in layers. Much later, the shifting of tectonic plates in the Mesozoic and Cenozoic Eras built the Rocky Mountains and created fault zones. Around 30 million years ago, the San Andreas and Sacramento Mountain ranges split due to tectonic activity, and the Tularosa Basin formed between them. The Rio Grande River brought sediments into the basin and water was trapped at the basin’s lowest point, eventually forming the ancient Lake Otero.During the Pleistocene, the climate fluctuated between warm and cold many times. When conditions were warm, snowmelt from the surrounding mountains carried dissolved gypsum into the lake basin. Eventually the lake would shrink after the snows melted, becoming a dry lakebed, or playa, like what is seen at White Sands today. One such warming period began following the end of the last Ice Age of the Late Pleistocene, around 12,000 years ago. The drier climate transformed the area into the modern Chihuahuan Desert, and selenite crystals formed on dry portions of the lakebed known as Alkali Flat. Winds broke down and polished the crystal grains into the characteristic white color of the dunes.

Painting of a theoretical scene from Lake Otero, based on fossils found within what is now White Sands National Park in New Mexico

Artwork by Karen Carr

The wetter climate before the formation of the modern dunes offered a landscape of abundant vegetation, welcoming diverse Pleistocene fauna and their predators who left footprints along the soft ground of Lake Otero’s shores. Fossil prints were first discovered in the Tularosa Basin in the 1930s by a local resident and trapper, Ellis Wright, who believed he had found human tracks of unbelievable size. This was corrected when the tracksite was revisited in 1981 and 2001, and the tracks were identified as belonging to a mammoth and a camel. The new century saw the discovery of more tracksites, with varying degrees of preservation quality, in the basin and in White Sands National Park exposed by wind deflation.

Thousands of fossil tracks are delicately preserved in soft gypsum and carbonate sediment of the former lake shore. Track preservation may be of two types, either as upstanding pedestals or as true tracks, sometimes known as “ghost tracks,” which are depressed and invisible for parts of the year due to the presence of surface crust. If local moisture is high, texture differences between the infill of a print and the surrounding sediment are much easier to see. The ever-changing moisture conditions may create a buildup of salt around the edges as the tracks “disappear” and “reappear” over time. It is not possible to safely remove these fragile tracks, so they need to be studied in place. Methods such as magnetometry (detecting tiny changes in magnetic fields of different materials) and photogrammetry (using multiple overlapping photos of objects to create three-dimensional models) are used remotely and non-destructively to detect and document these ephemeral tracks. The raised prints are thought to be compressed sediments from beneath the track (like how footprints in melting snow are slightly more resistant to melting than the surrounding snow) and have been exposed due to wind erosion or other weathering. While many tracks are infilled with gypsum sand, some are composed of dolomite and are slightly more resistant. In the layers surrounding the tracks, some body fossils, hair, possible coprolites, and vegetation have been found. Radiocarbon dating of aquatic grass seeds and pollen grains of conifers found with the tracks have revealed an age range of 21,000 to 23,000 years ago.

The National Fossil Day 2026 artwork, featuring a theoretical scene from what is now White Sands National Park in New Mexico

Artwork by Studio105

A Thriving Pleistocene Ecosystem

The 2026 National Fossil Day artwork depicts a scene of Late Pleistocene fauna that were known to walk this former wetland environment. Large Ice Age animals roamed the area, leaving behind body fossils as well as trace fossils, such as the tracks seen in the corners of the logo, depicting giant ground sloths (top left), short-faced bears (top right), camels (bottom left), and saber-toothed cats (bottom right).

In the illustration, Columbian mammoths are observed from the background. They stood up to 14 feet tall at the shoulder and sought the area’s plentiful vegetation, such as the depicted shrubs, to satisfy their herbivorous diets. Numerous localities in and around White Sands have documented the presence of mammoth tracks, and the round to ovoid impressions are described as resembling those of living elephants.
Other animals in the artwork include western camels (Camelops hesternus), which looked like their modern relatives and grazed over large ranges, and a native North American horse that fed primarily on grasses and has a close relationship to modern zebras. Not included in this scene are such fauna as American lions, dire wolves, and saber-toothed cats, as well as smaller mammals, which are known to have also walked these lands.

Photograph of trace fossils of bear footprints found at White Sands National Park in New Mexico. Rectangles in the scale bar are 1 cm across.

NPS photograph

In the foreground is a family of short-faced bears, which were enormous omnivores that stood up to 11 feet tall on two legs. The bear family’s prints are left in the soft sediment and intersect with human footprints, representing similar examples found across White Sands of the coexistence of humans with these megafauna. One locality suggests humans were hunting a giant ground sloth, and prints of mammoths, camel, bison, and other taxa have been recorded stepping atop human prints, and vice versa. These prints have been recorded many feet above other human and megafauna prints laid earlier in geologic time, showing that they lived concurrently for thousands of years. The latest research and dating of the oldest human footprints found in the Tularosa Basin shows humans have been in this part of North America for at least 23,000 years, much longer than the 13,000–16,000 years previously scientifically estimated, though in keeping with indigenous accounts.

Much remains unknown of how these people interacted with the massive, extinct animals from the end of the ice age. Evidence of their coexistence, as well as of the habits of these humans, such as children crawling or playing, a mother carrying her child, or people dragging wooden poles, continued to be revealed by the shifting sands.

Related Links

• White Sands National Park (WHSA), New Mexico—[WHSA Geodiversity Atlas] [WHSA Park Home] [WHSA Npshistory.com]

• Learn more about National Fossil Day and the NFD Logos and Artwork.

• To download the National Fossil Day 2026-White Sands National Park artwork, click here.

• NPS—Prehistoric Life Coloring Book

• Geologic Time Scale

• Fossils through Geologic Time

• Rocks and Minerals

• NPS—Fossils and Paleontology