Fig. 38.—Niobrara Group, Cretaceous chalk with cap rock of Loup Fork Tertiary, known as Castle Rock, Gove Co., Kansas. (Photo, by McClung.)
Fig. 39.—Chalk of Kansas, known as the Coffee Mill. Hell Creek.
Fig. 40.—Bones of Platecarpus coryphæus.
As found by Charles Sternberg. Sent for mounting to Tübingen University.
I am a patriot, and it would have pleased me to see all these splendid examples of ancient life enrich our home museums; but Germany is my fatherland, at least it was the fatherland of my fathers, and I am glad to have been able to build up there the best collection of Kansas and Texas forms in Europe.
One of the greatest prizes of the Munich Collection is a skeleton of Labidosaurus, now mounted there and collected by myself. Labidosaurus is important because it belongs to a very ancient and primitive group of reptiles, which, according to Prof. H. F. Osborn and other authorities, were the ancestors of all the later forms of reptiles.
After Dr. Broili left to return to Munich, I continued my work, camping on east Coffee Creek. Here again our search was rewarded. I found another bone bed of very small lizards, some of them, I think, not over six inches long. The skulls ranged in size from less than half an inch to an inch in length. Cope has given them the name Lysorophus tricarinatus. Drs. Broili and Case in their valuable papers have shown that this Lysorophus is one of the most interesting genera of all this wonderful fauna, since in the structure of the skull it is a veritable “missing link” between the batrachia and reptilia.
The deposit in which I found the Lysorophus was large, containing thousands of bones and many fine skulls. I am convinced that these creatures must have hibernated, as many of them were coiled in a circle in an envelope of hardened mud, and appear to have lain down never to wake again, each tiny reptile and its nest having been preserved through all the ages since. The flesh, of course, decayed soon after death, but by the process of petrification the bones have been replaced by stone.
Now I have always wanted to explain to a popular audience what this process of petrification really is. The word petrification should be dropped from our vocabulary, because it signifies an impossibility. I remember, as a boy, translating from the Latin a sentence like this—“His bones became stone,” that is, turned to stone, and one often hears the expression petrified wood as meaning wood which has turned to stone; as if there were a process in nature by which one substance could be turned into another, as the philosopher’s stone would have changed iron to gold. As a matter of fact, the process denoted by the word petrification is a process of replacement, not of transmutation. After the death of these ancient animals and the decay of their flesh, the water that passed through the bones carried from the cells of which they were made up the organic contents which decay, and left in their place deposits of the silica or lime which it held in solution. The same process continued when the lagoon bed was elevated above the water as solid rock. The rain-water, seeping down through rock and fossil alike, left in the bone cells the mineral matter it was carrying, until they were filled with it. Then, in process of time, the cell walls are broken down and rebuilt with silica or lime, and complete fossilization, or petrifaction as it is called, takes place, as in the case of the fossil bones in the Texas Permian. I found one specimen of the ladder-spined reptile in which the bones had been entirely replaced by iron ore, and others made up of silica.