The Missing Animals

The Irvington deposits are, indeed, rich in fossils. New species of Irvington fossils recently identified by Firby include the following vertebrates: several birds, a sucker (family Catosomidae), a stickleback (family Gasterosteidae), a perch (family percidae), a minnow (family Cyprinidae), a snake (suborder serpents), a shrew (Sorex), a mole (scapanus), a jaguar (Panthera), and an opossum-like marsupial (the only evidence of this animal in the North American Pleistocene). Numerous as the fossils may be, certain animals that should have been there if ancient ecosystems were like modern ones are still missing.

Toads and frogs were there, but were there salamanders? It doesn’t seem possible that geese and ducks were the only birds. Only three species of mice have been found fossilized at Irvington, and one of these is a species new to science. At least ten species can be found in the San Francisco Bay area today. We have a badger, but no weasels. Why? “stabbing” cats (sabercats) of two kinds were there, but there were no mountain lions or any bobcats, which are animals that live near Irvington today. Peccaries indicate the presence of oak trees (why?), but no tree squirrels have been found in the ancient sediments.

It is important to note that if the remains of large carnivores had not been found at Irvington, other evidence would prove that they were there: Several large limb bones of camels and horses show teeth marks made by strong-jawed carnivores. Specialists believe the marks were made by dire wolves. Since a number of plant-eaters lived in ancient Irvington, what are your speculations about the missing plants? Surely there were more plants at Irvington than the three kinds discovered to date.