Fossil of Country’s Oldest Land Mammal Unearthed

Costa Rican geologists this year unearthed the tooth of a Desmostylus hesperus, an extinct, large, amphibious animal related to elephants and manatees.

The fossilized tooth, found during an excavation in January in the country’s southwest coastal region, set a new record for the oldest land mammal found in Costa Rica. It is estimated to be between five and seven million years old.

The find became the first evidence that these animals lived in tropical regions, because all other fossils have been found in Japan, Siberia, Mexico’s Baja California and the U.S. states of Oregon and California.

The tooth found in Costa Rica is believed to belong to an infant D. hesperus. The colossal herbivores measured 1.8 meters long and 1.5 meters tall when full grown.