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Department of Paleobiology

Prehistoric Trackways National Monument, New Mexico

In the mid-1980s paleontologist Jerry MacDonald brought national recognition to the Robledo Mountains, located northwest of Las Cruces, NM, when he found abundant fossilized trackways of ancient vertebrates and invertebrates. These trackways belong to the Permian Period (299-252 million years ago), tens of millions of years before the dinosaurs, at the end of the Paleozoic Era (542 -252 million years ago). Research conducted by scientists from the New Mexico Museum of Natural History and Science (NMMNHS), in collaboration with researchers from around the world, has proven the Robledo trackways to be one of the most important examples of the life habits of Late Paleozoic terrestrial animals. The fossil record in the Robledo Mountains has given scientists a unique window hundreds of millions of years in the past and because of this it was dedicated as Prehistoric Trackways National Monument (PTNM) in March of 2009.

The PTNM also contains fossils of other types, equally important and of interest to a broad range of scientists. Among these are various remains of fossil plants, studied by scientists from the Smithsonian, University of London and University of California, Berkeley. The most common of these fossils are primitive conifers, some of which are the earliest of their kind yet found. (Continued below.)

During the Early Permian Period, the Robledo Mountains were located near the edge of the ancient Pangaean supercontinent, very close to the equator. In this area, deposits of oceanic rocks, mainly limestones and coastal-plain terrestrial rocks, especially shales and sandstones, were deposited as the shoreline oscillated in position through time. Consequently, in this area the marine and terrestrial rocks are interlayered, helping to link the mostly marine deposits to the south with the mostly terrestrial deposits to the north. Scientists from the NMMNHS, the University of Innsbruck, and the University of Illinois have been working on the geology of the area, linking it to other areas of the formerly western parts of Pangaea.

These videos about the Monument, filmed between February 28th and March 4th, 2011, document the research of the various scientists, working together and with staff of the Bureau of Land Management (BLM). The filming was done in partnership with faculty and students from the Creative Media Institute at New Mexico State University (NMSU), who agreed to record and produce these web videos.

This project was made possible in part with funds provided through a BLM NLCS Grant. The various activities were designed and carried out by Staff of the BLM PTNM, Smithsonian Institution, New Mexico Museum of Natural History and Science, NMSU Creative Media Institute, Illinois State Geological Survey- Prairie Research Institute, and Royal Holloway, University of London. The assistance and expertise of Mr. Jerry MacDonald of Las Cruces, NM was central to the success of this project; his long and tireless efforts on behalf of the Monument are gratefully acknowledged.

More information can be found at the Bureau of Land Management’s Prehistoric Trackways National Monument website.

The Videos

Ten individual videos make up this set, each focused on a different aspect of the Prehistoric Trackways National Monument. The videos are hosted by Lilia-Rosa Salmon.

Video 1: “Prehistoric Trackways National Monument Field Trip”. An introduction to the Monument, and a discussion with Jerry MacDonald.

Video 2: “Robledo Mountains Geology”. Geology of the PTNM and region discussed by Spencer Lucas, New Mexico Museum of Natural History and Science. Dr. Lucas explains the geologic forces that shaped the Monument and the ways in which geologists study and describe the exposures.

Video 3: “The Discovery”. Jerry MacDonald talks about the discovery of trackways in the Monument and the history of his work and that of collaborators within the PTNM, leading to its designation as a National Monument.

Video 4: “Red Rocks”. Jerry MacDonald and Spencer Lucas talk about how trace fossils are made, who the track makers were, and what this tells us about similarities and differences between coastal ecosystems of the modern world and those of the of the Early Permian world.

Video 5: “Prehistoric Trackways”. Lilia-Rosa Salmon and Jerry MacDonald discuss the various kinds of trackways found in the PTNM, the track-making animals, and the environments in which the trackways were preserved, including settings in which the animals walked over plant remains.

Video 6: “Permian Era Plant Fossils”. The plant fossils, particularly conifers, found in the PTNM, discussed by Smithsonian paleobotanist Bill DiMichele and Jerry MacDonald. Included are descriptions of the plants and how the fossils may have formed.

Video 7: “Ocean Front Property in New Mexico: Marine Fossils”. Spencer Lucas discusses the warm, shallow seas that occasionally covered the area that is now the Robledo Mountains, and the rich animal life that lived within them. He stresses the geological axiom that “the present is the key to the past.”

Video 8: “Fossil Curation”. Smithsonian staffers Dan Chaney and Skip Lyles demonstrate and discuss fossil collecting techniques and museum curatorial practices.

Video 9: “Earth’s History Book”. Scott Elrick hosts a conversation with Spencer Lucas, Jerry MacDonald and Bill DiMichele about life, paleogeography, and climate during the Early Permian Era on the western edge of the Pangaean supercontinent.

Video 10: “The Bureau of Land Management Perspective”. Lori Allen and McKinney Briske of the Las Cruces office of the BLM discuss the PTNM, its public importance, and plans for the future of the Monument. Pat Hester, BLM Regional Paleontologist, discusses preservation and multiple use.

Reading Suggestions

The history, paleontology and geology of Prehistoric Trackways National Monument and the general area is described in the following selected publications.

MacDonald, J. 1995. Earth’s First Steps: Tracking Life Before the Dinosaurs. Johnson Books, Boulder, Colorado. 290 pp. [This book tells the story of the discovery of the Robledo Mountain footprints and related fossils and discusses their significance.]

Lucas, S.G. and Heckert, A.B., editors. 1995. Early Permian Footprints and Facies. New Mexico Museum of Natural History and Science Bulletin 6. [This publication is available free as a PDF from the New Mexico Museum of Natural History and Science here. It contains many articles about the geology and paleontology of the Robledo Mountains and vicinity. For example: Lucas, S.G., Anderson, O.J., Heckert, A.B., and Hunt, A.P. 1995. Geology of early Permian tracksites, Robledo Mountains, south-central New Mexico. In: Lucas, S.G. and Heckert, A.B., editors, Early Permian Footprints and Facies. New Mexico Museum of Natural History and Science Bulletin 6: 13-32.]

Lucas, S.G., Estep, J.W. and Hoffer, J.M., editors. 1998. Permian Stratigraphy and Paleontology of the Robledo Mountains, New Mexico. New Mexico Museum of Natural History and Science Bulletin 12. [This publication is available free as a PDF from the New Mexico Museum of Natural History and Science here. It contains 10 articles about the geology and paleontology of the Robledo Mountains.]

Wahlman, G.P. and King, W.E. 2002. Latest Pennsylvanian and earliest Permian fusulinid biostratigraphy, Robledo Mountains and adjacent ranges, south-central New Mexico. New Mexico Bureau of Geology and Mineral Resources, Circular 208, 32 pp.

Lucas, S.G. and Hunt, A.P. 2006. Permian tetrapod footprints: biostratigraphy and biochronology. Geological Society, London, Special Publications 265: 179-200.

Mack, G.H. 2007. Sequence stratigraphy of the Lower Permian Abo Member in the Robledo and Doña Ana Mountains near Las Cruces, New Mexico. New Mexico Geology 29: 3-12.

Minter, N.J. and Braddy, S.J., 2009, Ichnology of an Early Permian intertidal flat: The Robledo Mountains Formation of southern New Mexico, USA: The Palaeontological Association, Special Papers in Palaeontology 82, p. 1-107.

Minter, N.J., Buatois, L.A., Lucas, S.G., Braddy, S.J. and Smith, J.A. 2006. Spiral-shaped graphoglyptids from an Early Permian intertidal flat. Geology 34: 1057-1061.

Seager, W.R., Kottlowski, F.E. and Hawley, J.W. 2008. Geologic map of the Robledo Mountains and vicinity Doña Ana County New Mexico. New Mexico Bureau of Geology and Mineral Resources, Open-file Report 509, available here. Hernandez, J.O. 2009. Misplaced trace fossils in unlikely environments. Geology Today 25: 71-74.

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