During excavation, bones and skeletons were found from extinct mastodons, mammoth, camel, sloth, dire wolf and long-horned bison.

Paleontologists from the San Bernardino County Museum in Redlands, California uncovered thousands of fossils in the Diamond and Domenigoni valleys that will add immensely to the store of public knowledge about the region.
 Collectively, these animal fossils are named the Diamond Valley Lake Local Fauna.

The paleontological finds of mammoth, mastodon, bison, and other Pleistocene Epoch species from Diamond Valley Lake provide a unique snapshot on inland southern California during the Ice Ages, and bridge a massive information gap between fossil deposits at La Brea Tar Pits in Los Angeles, California and Ice Age sites in the Mojave Desert.
Unofficially, the Diamond Valley Lake area is often referred to as the "Valley of the Mastodons".
Fossils from the Diamond Valley Lake site comprise a classic late Pleistocene assemblage, which includes the following extinct animals:
Jefferson's ground sloth, Megalonyx jeffersonii
Harlan's ground sloth, Paramylodon harlani
Dire wolf, Canis dirus
Giant short-faced bear, Arctodus simus
Sabre-toothed cat, Smilodon fatalis
American lion, Panthera leo atrox
American mastodon, Mammut americanum
Columbian mammoth, Mammuthus columbi
Western horse, Equus occidentalis
Small horse, Equus conversidens
Flat-headed peccary, Platygonus compressus
“Yesterday’s” camel, Camelops hesternus
Ancient bison, Bison antiquus
Long-horned bison, Bison latifrons
Diminutive Pronghorn, Capromeryx minor
Many fossils of rabbits, rodents and pond turtles, as well as coyotes, deer and the Black bear, have been recovered as well.
One of the most common animals identified from the Diamond Valley Lake site by San Bernardino County Museum scientists was the extinct American mastodon, Mammut americanum.
 In North American paleontology, mastodons are thought to have been solitary forest-dwelling browsers.
 The abundance of mastodons in the fossil record from the site suggests that, during the last Ice Age, the Diamond Valley Lake site was more wooded or forested than today.
 Fossil remains of ponderosa pine and manzanita recovered from the site lend credence to this interpretation.
Radiometric dating of fossil plants from the Diamond Valley Lake site confirms an age range of less than 13,000 years ago to more than 60,000 years ago for these fossils.
During excavation, bones and skeletons were found from extinct mastodons, mammoth, camel, sloth, dire wolf and long-horned bison. 
Paleontologists from the San Bernardino County Museum in Redlands, California uncovered thousands of fossils in the Diamond and Domenigoni valleys that will add immensely to the store of public knowledge about the region.  Collectively, these animal fossils are named the Diamond Valley Lake Local Fauna.
The paleontological finds of mammoth, mastodon, bison, and other Pleistocene Epoch species from Diamond Valley Lake provide a unique snapshot on inland southern California during the Ice Ages, and bridge a massive information gap between fossil deposits at La Brea Tar Pits in Los Angeles, California and Ice Age sites in the Mojave Desert. Unofficially, the Diamond Valley Lake area is often referred to as the "Valley of the Mastodons". Fossils from the Diamond Valley Lake site comprise a classic late Pleistocene assemblage, which includes the following extinct animals:
Jefferson's ground sloth, Megalonyx jeffersonii
Harlan's ground sloth, Paramylodon harlani
Dire wolf, Canis dirus
Giant short-faced bear, Arctodus simus
Sabre-toothed cat, Smilodon fatalis
American lion, Panthera leo atrox
American mastodon, Mammut americanum
Columbian mammoth, Mammuthus columbi
Western horse, Equus occidentalis
Small horse, Equus conversidens
Flat-headed peccary, Platygonus compressus
“Yesterday’s” camel, Camelops hesternus
Ancient bison, Bison antiquus
Long-horned bison, Bison latifrons
Diminutive Pronghorn, Capromeryx minor
Many fossils of rabbits, rodents and pond turtles, as well as coyotes, deer and the Black bear, have been recovered as well. One of the most common animals identified from the Diamond Valley Lake site by San Bernardino County Museum scientists was the extinct American mastodon, Mammut americanum.  In North American paleontology, mastodons are thought to have been solitary forest-dwelling browsers.  The abundance of mastodons in the fossil record from the site suggests that, during the last Ice Age, the Diamond Valley Lake site was more wooded or forested than today.  Fossil remains of ponderosa pine and manzanita recovered from the site lend credence to this interpretation. Radiometric dating of fossil plants from the Diamond Valley Lake site confirms an age range of less than 13,000 years ago to more than 60,000 years ago for these fossils.
Diamond Valley Lake