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Education in BLM>Learning Landscapes>In the Spotlight>National Fossil Day 2011>Prehistoric Trackways NM>Science at PTNM
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Scientific Discoveries at Prehistoric Trackways National Monument

280 million years ago the area of Las Cruces, New Mexico, was located near the equator. It was a tropical environment, a coastal area located next to an inland sea. The vegetation was thick with trees that had broad, bamboo-like trunks and conifer-like leaves. Fern-like plants grew densely from the ground. Large amphibians and reptiles were at the top of the food chain. Smaller amphibians and reptiles fought for survival. Various insects made their homes amongst them in the swampy landscape. This was a time tens of millions of years before the dinosaurs and hundreds of millions of years before humans.

At Prehistoric Trackways National Monument this world has been caught in red mudstone. From tracks to mudcracks and gas bubbles, hundreds of fossil sites in and around the Monument preserve different parts of this ancient ecosystem.

Marine fossils tell of times when the sea took over parts of the land and then receded, leaving shells, corals, and microscopic organisms behind in thick slabs of limestone. Multiple layers of petrified wood laid out and buried (some even burnt and turned into petrified charcoal) show a picture of violent weather causing blow downs. Both plant fossils and plant impressions display what the botanical environment was like. Miles of tracks, from tiny amphibians to large reptiles, show where animals roamed, what they ate, how they walked, and how they lived. Even insect and invertebrate tracks and burrows display how these small creatures roamed around.

This incredible fossil record has received worldwide recognition. It continues to be studied by scientists, museums and research facilities from all over the world. Because it was established by Congress as a national monument it will be protected for perpetuity. Present and future generations will be able to learn, discover, and explore this ancient, lost, extinct period in the earth’s history.


Scientists Recognize the Importance of Prehistoric Trackways National Monument

“Acre for acre, this is one of the best fossil records on the planet. The number, the quality, the diversity is amazing, and we’re still finding new things. Scientists have come from all over the world to study them.”

Spencer Lucas, PhD.
Paleontology Curator
New Mexico Museum of Natural History and Science


“Plants from the Robledo Mountains are primarily representatives of groups that we believe to have grown in seasonally dry habitats - commonly including conifers and an extinct group known as peltasperms, as well as other less abundant forms. Most of the plants grew along the margins of stream channels or in swampy lowlands, which is what permitted their leaves and branches to be buried quickly and in environments where they were removed from the effects of decay.”
Bill DiMichele, PhD.
Curator of Fossil Plants
Smithsonian Institution


“The 280 million year old fossil tracksite from the Robledo Mountains represents the most diverse and abundant Paleozoic terrestrial trace fossils in the world. The scientific significance of the Robledo Mountain tracksite is without question. It represents the most significant advance in our understanding of terrestrial trace fossils to date. It is now recognized as the standard for vertebrate trackways.”

Simon Braddy, PhD.
Invertebrate Paleontologist
University of Bristol, UK


“Petrified wood abounds in the National Monument. These fossils provide important clues about the conifer woodlands that covered New Mexico, 280 million years ago. At that time, the state was lying on the equator and had a hot, dry climate like East Africa today. Across this dry landscape, fires periodically burned out of control as indicated by pieces of fossil charcoal found in the rocks. The fossil conifer trees are preserved in amazing detail.”

Howard Falcon-Lang, PhD.
Senior Lecturer and NERC Advanced Fellow
Department of Earth Sciences
University of London, UK

Conifer  Branch Impression - Found in Apache Canyon

Dimetrodon and Amphibian Track Walking Side by Side; Photo Courtesy of Sebastian Voigt

Dimetrodon Track

Petrified Wood Log; Photo Courtesy of Jerry MacDonald