San Diego Natural History Museum--Your Nature Connection[BRCC San Diego Natural History Museum: Paleontology]
New excavating site in Oceanside reveals fossils of mammoth, mastodont, and tapir

The set of this scene is a large river meandering through the landscape, just east of Oceanside in north San Diego County. The time is late Pleistocene, approximately 200,000 to maybe 50,000 years ago, during one of the interglacials when the sea-level was higher. Nearby the river is an oxbow lake with freshwater, created as the river took on new turns when the sea-level rose, rich with fish, turtles, and clams. Around it grows large sycamore trees, creating refuges for birds. Among the animals coming here to drink are mammoths, mastodonts, and tapirs.

Our paleontologists have been busy this summer uncovering a fossil-rich excavation site in Oceanside, including one tapir being among the many fossils discovered. One of the first fossils found on this project was track ways left in the mud by either mammoths or mastodonts as they plodded along the margin of the river or pond. Later, fossil bones of a mammoth and a mastodont were also collected from the same river deposits as the tapir.

Tapir bones from excavation

Left to right: Palate with three upper cheek teeth; one vertebrae; and a rib fragment of a fossil tapir. This specimen was collected from late Pleistocene (approximately 200,000 to maybe 50,000 years ago) pond deposits east of the city of Oceanside in northern San Diego County.

Mammoth and mastodonts are long gone, but tapirs still live in tropical areas of the world. They have a disjunct distribution, one population living in the Amazon basin of South America and the other in Southeast Asia. They are large herbivorous mammals that eat vegetation such as leaves and shoots and are distantly related to horses and rhinos. Apparently during the late Pleistocene, the weather in the area was significantly different than present day, since tapirs live in tropical rain forests today. There must have been considerably more moisture and denser vegetation along the coastline at the time when the tapirs were living here.

The museum's paleo crew spent two weeks recovering several hundred fossils at this site, and will stay busy for a long time cleaning and categorizing each individual fossil.

Text and photo by Bradford O. Riney