A Feline Predator in Arms Lab

Credit: Lance Hayashida

By Julia Ehlert

In an unassuming corner of the Charles Arms Laboratory of the Geological Sciences, a fanged feline snarls behind a glass cage. But this predator can no longer hurt you. The skeleton of a Smilodon fatalis, or saber-toothed cat, has been on display since 1997, when it was loaned to the Division of Geological and Planetary Sciences (GPS) by the Natural History Museum of Los Angeles County (NHM). 

The blackened Smilodon bones excavated from LA’s La Brea Tar Pits between 1913–15 come from multiple saber-toothed cats between 12,000 and 33,000 years old; the composite skeleton was assembled in the mid-20th century. Caltech paleontologist Chester Stock measured the skull for his 1932 publication, The Felidae of Rancho La Brea, and, in many ways, the Smilodon on display in Arms tells his story. 

Stock, who went on to shape GPS, NHM, and public engagement with paleontology for generations to come, became enamored with the La Brea asphalt pools after excavating there as a geology student at UC Berkeley, and he continued to study the site’s large vertebrate fossils for the rest of his career. 

Stock joined the Caltech faculty in 1926, helping to found the GPS division and establish its paleontology program. In the classroom, Stock wove vivid lectures about the Pleistocene-era creatures that once roamed the region. He also took students into the field on fossil-digging expeditions across the American West and Mexico. When the Arms building opened in 1938, most of its ground floor served as a museum to display Stock’s specimens, including a towering dinosaur skeleton. 

Meanwhile, Stock also served as a curator at NHM, where he ignited imaginations with fossils and laid the groundwork for the development of the La Brea site into a museum that invited guests to descend into an excavation area. Stock did not live to see the results, passing away in 1950. But the Observation Pit, now part of NHM’s La Brea Tar Pits Museum, opened in 1952 and was dedicated in his honor. 

After his death, NHM acquired Stock’s fossil collection at Caltech for $100,000, and the museum in Arms was converted to office space. GPS used the funds to invest in a new research frontier: geochemistry (see story on page 14). “I find it interesting that the money from the collections helped to start the geochemistry program,” says Julia Tejada, an assistant professor of geobiology at Caltech and a William H. Hurt Scholar. “It’s very full circle, because my research combines both paleontology and geochemistry.” 

Tejada also has an academic connection to her paleontological predecessor at the Institute. Her master’s advisor at the University of Florida and her PhD advisor at Columbia University both were advised by Stock’s student Malcolm McKenna. 

Now working just a few doors down from the Smilodon, Tejada finds that the skeleton connects Caltech’s history with that of the region. “Having such a magnificent specimen here is incredible. It shows you how LA was only 15,000 years ago: populated by mammoths, giant ground sloths, saber-toothed cats, and camels. It just humbles you and evokes your imagination.”