Texas State University’s Shelly Wernette, Ph.D., a senior lecturer in the Department of Geography and Environmental Studies, joins the Big Ideas TXST podcast to discuss her discovery of 10 new species of extinct trilobites in Thailand and what those discoveries reveal about ancient world geography.

Trilobites are extinct sea creatures that rolled up like some types of armadillos or rolly pollies and breathed through their legs. Fossils of the creatures were trapped in sandstone between layers of petrified ash, created by volcanic eruptions that settled on the sea floor and formed a green layer called a tuff. Unlike some other kinds of rocks or sediment, tuffs contain crystals of zircon — a mineral that formed during eruptions and are, as the name of the rock layer containing them suggests, tough. Zircon is chemically stable as well as heat and weather resistant. It is hard as steel and persists when minerals in other kinds of rocks erode. Inside these resilient zircon crystals, individual atoms of uranium gradually decay and transform into atoms of lead. Radio isotope techniques enable researchers like Wernette to determine when the zircon crystals formed and thus put a date range to the volcanic eruption that laid down the tuff formation.

Wernette studies stratigraphy and invertebrate paleontology with special attention to the lower Paleozoic of Gondwana and trilobites. She is interested in how the physical earth affects biodiversity, relying heavily on paleogeography and geochronology to frame this investigation. She earned her doctorate in geological sciences from the University of California Riverside, and her bachelor’s and master’s, both in geology, from the University of Oklahoma.

FURTHER READING:

Trilobites of Thailand's Cambrian–Ordovician Tarutao Group and their geological setting

Trilobites rise from the ashes to reveal ancient map