Paleontologists have called the preserved burrows “devil’s corkscrews”—_Daemonelix_—since the time they were first found. At first, scientists thought they might be holes left by the giant tap roots of some unknown plant. But when _Palaeocastor_ skeletons were found in the bottoms of the spirals, almost everyone had to concede that they were truly beaver burrows. Admittedly, the skeleton of a _Nothocyon_ was found in one burrow; but this predator probably followed a beaver home for supper and just stayed. Three other kinds of beavers lived around Agate in the Early Miocene, but their bones have never been found in the burrows. No one knows what they did for homes: perhaps their burrows were much shallower or were in the river banks where running water soon destroyed them.
Near the river bank in some soft sand is a nest of tortoise eggs. The hot sun has brought the babies out of their shells and they’re stumbling off in all directions. Right now the biggest is only about twice the size of a silver dollar; but when they’re grown they’ll be about 60 centimeters (24 inches) across the shell, or perhaps even larger. They’re strict vegetarians, grazing and browsing on soft plants and leaves. There are probably some pond turtles around too, but we’ve never seen any.
A little farther up the bank, under the roots of that big walnut tree, is a rabbit’s burrow. Several _Palaeolagus_ (“ancient rabbit”) live there with their many offspring. Although they look very much like cottontails, their ears are smaller and they haven’t the same leaping and running ability. They’d much rather hide than flee their enemies.
These dwellers of the savanna, common during the Miocene Epoch, comprise the major species found at the Agate Fossil Beds. Their discovery in the late 1800’s and early 1900’s was highly important to the young science of paleontology. In those decades of major discoveries, large gaps remained in the story of evolution. Quarries like those at Agate helped provide the missing pieces of the puzzle. In their time, the discoveries at Agate were an important contribution toward understanding the world far beyond the dawn of mankind.
Today, advances in paleontology still depend primarily upon major field discoveries, but paleontologists also make use of highly refined analytical and measurement techniques. Closely connected with paleontology are several other sciences, among them geology, zoology, and botany. The paleontologist, for example, must depend on geology to provide important answers about the age of fossil specimens. Fossil botanical specimens, in turn, can provide answers about animal diets and climate. Though paleontology may center on the study of fossil remains, it is an interdisciplinary science. This fact will become increasingly apparent in the following chapters, which reveal the strands of evidence used in constructing the picture of Miocene Agate.