Page:The American Cyclopædia (1879) Volume VII.djvu/349

 FOSSIL is the seat of a bishop, and has an academy of science and art, a veterinary school, a phil- harmonic academy, and a theatre. It was a walled place in the 13th century, was frequently attacked by the counts of Asti and Saluzzo, and early in the 14th century put under the protec- tion of Philip of Savoy. It figured in the wars between Charles V. and Francis I. It was taken by the French in 1Y96, and in 1V99 the French under Championnet were defeated here by the Austrians under Melas. FOSSIL (Lat. fossilis, dug up), a term formerly applied to all mineral substances, but now used to designate only the remains of organic bodies found in geological formations. The general subject will be treated under the title PALE- ONTOLOGY, and the more important fossil ani- mals under their respective names. FOSSIL FOOTPRINTS, or Ichnolites (Gr. Z^vof, a track, and M0o?, a stone), in geology, impres- sions originally made by animals in clay or in sand, and preserved in the shale or sandstone rock resulting from the solidification of those materials. Under these names have been in- cluded markings of various forms in rocks of very different geological ages. Some of these markings, though doubtless made by animals, are not the impressions of their feet, but have been produced wholly or in part by their tails or their carapaces; and to these, although truly ichnolites or track-stones, the name of fossil footprints does not therefore apply. It will, however, be convenient to include under this head all the markings of animals found in rocks. Recent impressions of the feet of quad- rupeds, birds, and reptiles, and the markings made by crustaceans, mollusks, and worms, may be studied on the shores of tidal waters, where successive layers of mud and sand pre- serve them in the accumulating sediments ; and the careful study of these by Dawson has thrown much light on some of the markings found in earlier rocks. To begin with the ich- nolites found in rocks of cenozoic or tertiary age, we may notice those in the eocene of the basin of Paris, where, in the marls which are in- terstratified with the gypsum beds which there abound, are found a great variety of markings. Prominent among these are the trilobed foot- prints of several species of palceotherium, a large pachyderm allied to the modern tapir, besides those of cmoplotheriim, an animal more nearly allied to the ruminants, and of certain carnivo- rous mammals. In addition to these are tracks of various land and fresh-water tortoises, of a gigantic bird, and of crocodiles, iguanas, and great' batrachians or frog-like animals. The bones of many of the mammals whose tracks are here met with occur in the gypsum beds which are inter stratified with the marls ; but there were evidently numerous species of which the bones have not been discovered, and which are consequently known to us only by their foot marks. The whole condition of things here shows that there then existed nu- merous small lakes of fresh water, the shores FOSSIL FOOTPRINTS 341 of which were frequented by great numbers of pachyderms of numerous species, and by beasts of prey which occasionally devoured them, the tooth marks of the carnivora being found on the bones of the former. It will thus be seen that it is only in rare local- ities that the conditions necessary for the for- mation and preservation of these foot marks occur, and it is a fortunate chance which ex- poses them for our inspection. It was not till 1859 that these were discovered in the neigh- borhood of Paris. In the mesozoic period the footprints of the trias or new red sandstone are remarkable for their number and variety, and also for the interest which attaches to the his- tory of their discovery in the valley of the Con- necticut river, where they are very abundant. Attention was first called to these so-called bird tracks by Mr. Dexter Marsh, and they were subsequently studied by Dr. James Deane and by Prof. Edward Hitchcock, who after a careful examination of them concluded that they were truly the footprints of birds; and they were therefore called by him ornithich- nites or bird tracks. He ascertained their ex- istence in numerous localities, and showed that they occur at intervals through a thickness of 1,000 ft. of sandstones and shales. He further remarked that although the beds bearing the tracks are now inclined at angles of from 5 to 30, they must have been horizontal at the time the impressions were made ; and showed that their occurrence throughout so great a thickness of strata could only be accounted for by. supposing that the surface was subsiding during the deposition of these rocks. Some of these tracks were of gigantic size, one of them measuring 10 by 16 in., and recurring at in- tervals of from 4 to 6 ft. along the surface of the rocky bed ; these distances indicating the length of the strides made by the animal. A careful study of these markings during many years convinced Prof. Hitchcock that many of them were made not by birds, but by batra- chians or huge frog-like animals; and in an elaborate report by him, published by the state of Massachusetts in 1856, he showed that the ichnolites of the red sandstone had been foun4 in not fewer than 38 localities, extend- ing over a length of 90 m., with a breadth of 2 or 3 m., in the Connecticut valley. The markings known to him were referred to as many as 119 species of animals, including quadrupeds, birds, lizards, batrachians, tor- toises, fishes, crustaceans, insects, and worms. While most of these markings were made on land, others were apparently produced by ani- mals like fishes, swimming near the bottom. The surfaces of many of the beds bear the marks of waves or ripples, and others are dis- tinctly marked by rain drops. The collection of these ichnolites made by Prof. Hitchcock, and now in the museum of Amherst college, is very great, and shows more than 8,000 indi- vidual tracks. A few remains of bones and coprolites have been found in the sandstones