In 2014, first fossil hunt for a freshman in New Mexico’s San Juan Basin led to a new mammal species, which gave science its first new multituberculate in over 100 years, and proved even well-dug fossil sites still hide surprises

First-time fossil enthusiasts usually assume they will gain basic field experience. However, few think they could take part in finding an animal species that was not known to humans. This is precisely what happened to a first-year undergraduate student, Carissa Raymond of the University of Nebraska-Lincoln, who went on a fossil hunt in the San Juan Basin of New Mexico in 2014. In the process of the field activity, Raymond uncovered fossilized remains consisting of teeth and jaw fragments, which were later determined to be the fossils of a previously unidentified mammal species.

The animal was identified as a new species of the multituberculate mammal family, namely Kimbetopsalis simmonsae. What makes this discovery unique is the place it was made. Despite having been excavated for decades, the San Juan Basin yielded a species that was yet to be scientifically defined by researchers.

Unidentified mammal species found after the first fossil hunt


As stated by the University of Nebraska-Lincoln, Raymond made the discovery during her first fossil field trip and research at the university in New Mexico. This made the entire event quite unique for undergraduate students. They help with digs, cataloging, and surveys, but big finds aren't common on their first visit. This fossil wasn't just casually collected and documented. It was carefully dug out, and the information about its geological background was preserved, which is essential for paleontology.

Paleontologists explain this kind of organized fieldwork is so important as fossils become valuable when scientists know their location, stratigraphy, and additional details. Researchers working with the specimen in university publications revealed that it became obvious early on that the fossil was unusual.

Teeth and jaw fragments showed something new

This fossil didn't contain an entire skeleton. However, some significant features were preserved by it. According to the university's description, the specimen included teeth, jaws, incisors, molars, premolars, and a portion of the braincase. Fossils of teeth are particularly important for paleontologists since their structure helps identify species.

It became clear that the tooth structure didn't match any known specimens of multituberculates in the area. The specimen was examined against fossils held in museums around the world before declaring its identification as a new species. Multituberculates were a group of mammals that lived in the dinosaur age and even persisted for many years after the end of the dinosaurs.

The multituberculates have since gone extinct, but are still studied by scientists to understand the evolutionary history of mammals. The precise anatomical information provided in Raymond's specimen was enough to officially classify Kimbetopsalis simmonsae as a new species.

Why New Mexico turned important for fossil hunting

The discovery was made at Kimbeto Wash in the San Juan Basin, which is one of the most famous fossil locations in North America. Fossil deposits of plants and animals spanning different geological periods have been extensively studied for decades in the basin. Nevertheless, scientists found Raymond's specimen noteworthy in that it originated from older rock formations compared to other multituberculate fossils.

Even a simple-looking fossil might become scientifically interesting if it turned out that its age and sediments were not common. According to paleontologists, location is sometimes as critical for analysis as the fossil itself, as it helps establish the time period the creature had lived in and its evolution process.

Museum collections confirmed the species

This case also demonstrated how valuable museum collections are in the sphere of paleontology. It appears that Thomas Williamson, curator at the New Mexico Museum of Natural History and Science, suspected that the fossil was a unique species from the very beginning. Nevertheless, the specialists needed to do some more comparisons to be sure that the fossil was really something special.

Collections like the one kept at the University of New Mexico’s Museum of Southwestern Biology allow the specialists to analyze thousands of samples from various time periods.

If there were no such collections, the specialists would not be able to determine the unique nature of Raymond's find. According to specialists, findings such as these usually do not belong to one person only. The role is played by students, field crews, curators, and researchers at museums.

Why the discovery was considered significant by scientists

One of the reasons that led to the importance of the discovery, according to the researchers, was the fact that it represented the first time after more than a century that a new multituberculate mammal species was discovered in the San Juan Basin. As seen from the fact above, sometimes the findings are scientifically significant because they show that even highly researched fossil sites can bring surprising discoveries.

New evidence presented in Scientific Reports shows that the region of New Mexico still brings fossils that can be linked to the history of mammals' evolution. This finding has shown that a fossil fragment that preserved enough features can change the way science sees things. It should also be mentioned that the finding was important for another reason – it showed that important discoveries can be made even when students still start their careers.