Paleontology, the science of the ancient life that inhabited the earth, is the foundation upon which the geological history of the earth in a great part rests. By the aid of fossils, the remains of ancient life, the succession of rocks, their distribution and relations are determined. Kansas is famous as a region for fossils, and within the boundaries of the state varied and remarkable fossil records have been found. According to Zittel, the study of paleontology is carried on by means of fossils which are "all remains or traces of plants and animals which have lived before the beginning of the present geological period, and have been preserved in rocks."

The study of paleontology is closely allied with that of biology and geology. The rocks of the earth's crust are classified according to their periods of origin into four great groups, each of which represents an era of great duration, measured in millions of years. These eras are again divided into periods represented by systems of rock formation, thirteen of which are generally recognized, and the periods are likewise subdivided. Beginning at the top these eras and periods are as follows: Cenozoic era of mammals, divided into Quarternary and Tertiary periods; Mesozoic era of reptiles, divided into Cretaceous, Jurassic and Triassic periods; Palaeozoic era of invertebrates, divided into Permian, Carboniferous, Devonian, Silurian, Ordovician and Cambrian periods; Eozoic, and Azoic eras. With the exception of the last two eras at the bottom of the scale, from which no satisfactory fossil remains have been obtained, each of these divisions has been found to contain fossil organisms, peculiar to that system and era, entirely different from any other. These organisms in any system or geological formation constitute its fossil fauna, which furnishes a somewhat imperfect synopsis of the ancient life that inhabited the vicinity of the ocean, lake or land basin in which the system or formation originated. It has been discovered that formations of different ages contain greatly diverse fauna, but in a single formation the fauna in all portions of its area of distribution are the same in general character and thus serve to identify widely separated districts.

The earliest work with regard to fossils in Kansas was done in the western part of the state. The first person to make any systematic collection was the late Prof. B. F. Mudge, professor of geology at the Kansas State Agricultural College, who headed an expedition up the Republican and Solomon rivers in 1870. In Kansas the upper Cretaceous has been divided into the Fort Pierre, subdivided into Arickaree shales and Lisbon shales; Niobrara, subdivided into Peteranodon beds and Fort Hayes beds; Benton, subdivided into the upper and lower group; Dakota; Comanche; red beds and Permian. The richest fossil fields are found in the chalk beds of Rush county, the Niobrara chalk of Trego county and of Plumb creek, and the Fort Hayes beds of the Smoky Hill river in Gove county.

Birds are the rarest of vertebrate fossils, for although abundant they did not fall into such positions that they would easily fossilize. In the lower Cretaceous no birds are as yet known, and from the upper Cretaceous the only remains in America are from New Jersey and the Niobrara formations of Kansas and Wyoming. Of these, 20 of the best specimens came from Kansas, the first of which was discovered in 1870. One of the most important specimens was discovered by Prof. Mudge near Sugar Bowl mound in northwest Kansas in 1872, and large collections were made in this state in succeeding years.

The group of dinosaurs contains the largest land animals that ever existed, in some cases reaching such enormous proportions as to be almost incredible. The smallest were about the size of a cat, while the largest reached a length of 60 feet or more. These reptiles were not crawling animals, but walked erect, after the manner of a kangaroo. The dinosaurs ranged in time from the Triassic to the close of the Cretaceous. The single known dinosaur specimen from Kansas was discovered in 1872 in the Niobrara chalk of the Smoky Hill river.

The earliest fossil crocodiles are found in rocks of the Triassic age. But two specimens have been discovered in Kansas, one from the lower Cretaceous of Clark county and the other from the upper Cretaceous. More than a century ago the singular group of reptiles known as mosasaurs was discovered and Kansas has been the great collecting ground for them. The first specimen was discovered near Fort Wallace in 1868, since which time several hundred have been collected for the museum of the University of Kansas alone. Their geological range is confined exclusively to the upper Cretaceous. From the upper Cretaceous of Kansas alone, four genera and six species of turtles, all marine, are known, one from the Benton and the others from the Niobrara. The largest and also one of the most remarkable of these fossil turtles reaches a length of 12 or more feet, while the others are smaller, probably not more than 5 or 6 feet in length. Remains of turtles are frequent among the vertebrate fossils of all formations from the Triassic to the present time, and their distribution has been general, but as the specimens have been fragmentary, complete fossil specimens are rare. Turtles are usually divided into three suborders but all of the known fossil turtles from the Kansas Cretaceous belong to the cryptodira, or second suborder.

The remains of microscopic organisms found in the upper Cretaceous of Kansas are some of the most interesting and important fossils. Samples from six of the thirteen beds in the state have shown evidences of organic origin. Particular interest centers in the specimens obtained from the Niobrara group, the Kansas chalk having been investigated and discussed more than any other deposit. It was chalk from Kansas that first established the fact that such a formation existed in the United States. The fact that organic fossil remains existed in it was first proved in 1882. In size these minute organisms vary from 1-100th of an inch to 3 inches in their largest diameter and in their distribution are almost omnipresent, being found in nearly every body of water, salt or fresh, and at all depths. They were so numerous that extensive strata of rock are composed almost entirely of their remains. Their geological range is believed to be from the Silurian to the present time. They are called foraminifera, are nucleated, protoplasmic bodies invested with a shell, and are remarkable for variety and beauty of form.

The animal kingdom has been divided into eight subkingdoms; protozoa, coelenterata, echinodermata, vermes, molluscoidea, mollusca, arthropoda and vertebrata. Seven of these comprise the invertebrate animals and the eighth, or last, the vertebrate. All of the subdivisions except the fifth are represented by fossil remains in the upper Cretaceous of Kansas. Four of the subkingdoms are represented in the Fort Benton, viz., the second, third, fourth, and sixth. The first three are represented by a single form, but the sixth or mollusca is represented by 18 genera and 40 species. The Niobrara fossils are numerous and varied, species belonging to the six of the invertebrate subkingdoms having been found, represented by about 12 genera and more than 30 species. In the lower horizon, that of the Fort Hayes limestone, fossils are not abundant. The Fort Pierre area of Kansas has not produced a great diversity of invertebrate forms. Fossils were collected at an early date from a Fort Pierre outcrop on Butte creek and on the north fork of the Smoky Hill river, in the eastern part of Wallace county, but no extensive Fort Pierre formation occur in Kansas except in Cheyenne county, where it has furnished 15 species.

The Carboniferous invertebrates are again classified under the subkingdoms. The foraminifera are an order of the class known as rhizopods, which means root-footed. They are very minute animals, resembling a glass of jelly full of bubbles. These animals are called formanifera on account of the little holes in the shell. They lived in both fresh and salt water, but were much more numerous in the ocean, where, although so minute, their shells made up masses of deposits which became hardened into limestone extending over vast areas. The only foraminifera found in the rocks of eastern Kansas are what is often called "petrified wheat." Rocks of this formation are numerous and the layers of limestone made up of these shells vary from 2 to 10 feet in thickness and extend across the state from north to south. A second Carboniferous invertebrate is the spongae, a loose collection of single cells, grouped into a mass, which forms a compound organism. The cells of a sponge are held together by horny needles, and the sponge of commerce is not the entire animal but only this skeleton, which is a network of these needles. In nearly almost all of the fossil sponges these fibers of the skeleton are found to be of lime or flint. Two kinds of fossil sponge has been found in Kansas, in the northwest part of Atchison county, western Doniphan county, and in eastern Brown county. They sometimes make up a limestone stratum 6 inches thick.

Corals, or anthozoa, are exclusively marine animals. The reef-building coral is only found in comparatively shallow water, while other forms are found much deeper. The fossil corals of Kansas are of the reef-building class and indicate that rocks in which they were formed were laid down in shallow water. At Fort Scott a stratum of limestone has been found almost entirely made up of coral.

Crinoidea were animals known as sea lillies or stone lillies. They are found at varying depths in the sea. During their geological time they were abundant and reached their highest development in the Carboniferous period. They were well adapted for preservation as fossils and many specimens have been found. Usually the skeleton fell apart when the animal decayed so that an entire specimen is very rare, but masses of stone have been found made up entirely of the pieces of these animals, as they lived in colonies during geological time the same as today. In the Carboniferous and Triassic periods they were more abundant than at present. Specimens have been found in the upper coal measures of Topeka, the horizon of the Osage, and the upper coal measures of Kansas City, Kan., and Argentine.

Sea-urchins, sea-eggs and sea-dollars, or echinoidea, are animals that vary in form from spheres to discs and live in moderately shallow water, generally near oyster beds. Some bury themselves in the sand, others make holes in rocks, but all live in the sea. The only parts of the animal that fossilizes are the spines or plates, and at least four kinds have been found in Kansas rocks—in the upper coal measures of the Topeka limestone and the upper coal maesures of the Deer creek limestone near Topeka.

Brachipods are small animals that in a way resemble clams in external appearance, with a two-valved shell, but internally their structure is very different, resembling worms. They are marine animals and usually live in shallow water. Their distribution has been given as follows: "shore zone, or the beach between high and low tide marks; the shallow water zone, or water to a depth of 90 feet; moderately deep zone, or water from 90 to 300 feet deep; the deep zone, or water from 300 to 1,668 feet deep; and the very deep zone, or water from 1,668 to 17,670 feet or three and a half miles deep." In each zone there are species which are not found in the others, though some are common to two or more zones. One hundred and fifty-eight forms of brachipods are known, and these form but a remnant of what was once one of the most abundant and varied classes of animals of their size, for the fossil species already discovered number 6,000, nearly 2,000 of which are represented in American rocks. They are some of the earliest fossils of which there is a record and reached their height in the earliest part of geological time. About 125 species are known to belong to the Cambrian, or earliest period of which there is any definite knowledge of life. During the Devonian period they reached their highest numbers, with about 1,400 species. At the close of the Paleozoic era they fell to less than 100 species. In Kansas they have been found in the upper and lower coal measures of Kansas City, Topeka, Burlingame, Rosedale, Lansing, Leavenworth county, the Wabaunsee formation, Blue Mound, near Manhattan, Eudora, Grand Summit, Cambridge in Cowley county, Fort Scott, Lawrence, Carbondale, Olathe, Lecompton, Beaumont, Geary county, Osage county, Anderson county, Alma, Marysville and generally throughout the coal measures of the state.

Mussels, clams and oysters, properly called pelecypods, are animals that live both in fresh and salt water. They are covered by a shell made up of two halves; the hard part of the animal or this shell, is all that is preserved in the rocks. Fossil remains of these animals have been found in the upper coal measures at Topeka, Lawrence, Turner, Eudora, Wabaunsee county, Leavenworth county, Wyandotte county, Lecompton, Cowley county, Anderson county, and at Cherryvale, Elmont, Iola and Grant Summit.

Cretaceous fishes have three divisions—selachians, pycnodonts and teleosts—which are also subdivided. Under selachians are included the myliobatidae; or upper Cretaceous selachians; scyllidae from the lower Cretaceous; lamnidae from the lower Cretaceous and Niobrara; and the corax, confined entirely to the Cretaceous. The pycnodontae are subdivided into pycnodonts, found in the Jurassic, Cretaceous and Eocene deposits and lepidosteidae not found in Kansas. The living members of the myliobatidae are the sea devils, many of which attain an enormous size. One species of this fish has been found in the Kansas Cretaceous, occurring only in the Niobrara beds. The scyllidae are a family of small sharks, occurring in the lower Cretaceous, but the only fossil remains consist of teeth, about 80 of which were collected near Castle Rock in Trego county. A single tooth of large size was taken from the Cretaceous of the Smoky Hill river and another series, 110 in number, were found in the Niobrara chalk of that river. Other specimens have been found at Walnut creek, probably of the Benton horizon, in Ellsworth county from the Benton Cretaceous of Salt creek, some in Russell county, and some from the lower Cretaceous in various places.

The lamnidae include the largest sharks, which are represented by a number of living species at the present time. Their teeth are commonly found in the Cretaceous deposits of Kansass,[sic] but as the teeth of one fish vary greatly in size and shape it is difficult to determine the forms. One nearly complete dentition has been found of the most common species of the family in Kansas. The teeth of this fish come from the Kansas Niobrara or the Benton Cretaceous. Specimens have also been collected from the lower Cretaceous (Kiowa shales) in Clark county.

The genus corax is confined to the Cretaceous and is not well known, but isolated teeth have been found in the Niobrara Cretaceous of the Smoky Hill valley and one isolated tooth was found in the Niobrara of Kansas. Specimens have also been collected from the lower Benton of Ellsworth county and near Marquette.

The remains of the peculiar group of glanoid fishes, known as pycnodontae, have been found in the Jurassic, Cretaceous and Eocene deposits. They are small fishes oval in shape. Some specimens have been found in the Kiowa shales near Belvidere, and there is one specimen of the lepidosteidae, from the Kiowa shales, but it was not found in Kansas.

The teleostei is an order that embraces the most generalized type of bony fishes, and are among the most abundant fossils obtained from the chalk of western Kansas, usually in an excellent state of preservation. In size they range from nearly 20 feet to small fish of less than a foot in length. They are found most abundantly in the Niobrara group because the conditions that prevailed at that time were more favorable for fossilization, although they were no more abundant then than during the Fort Pierre and Fox Hill time which followed. Several families are included under this head. The ichthyodectidae family embrace some of the largest physostomous fishes of the Cretaceous period of North America, and from the size of the jaws it is supposed that they rivaled the mosasaurs, at least the smaller ones, in strength and ferocity. Remains of this fish have been found in the Cretaceous deposits of Kansas. The second family is the sauredontidae, which resembles the ichthyodectidae of the known American species. Specimens have been found in the Niobrara Cretaceous of western Kansas. Remains of the stratodontidae, or third family, have been taken from the Niobrara Cretaceous of Graham county, the Fort Pierre and the Lisbon shales of Logan county. The osteoglossidae, the fourth family, is described from remains taken from the Niobrara Cretaceous of western Kansas. The fifth family, called salmonidae, bear a superficial resemblance to some of the mosasaurs and have been found in the Niobrara Cretaceous in the western part of the state. Some of the finest specimens were found isolated in the Butte creek region of Logan county. Remains of the genus pachycormidae, the sixth family, came from the Benton, Niobrara, and Fort Pierre groups. The clupeidae, or seventh family, are closely related to the two families above and resemble them, being found in relatively the same localities. The enchodontidae, or eighth family, includes fishes with laterally compressed bodies. Fossil remains are found in the Niobrara Cretaceous in Kansas. The horizon of the dercetidae is the Niobrara Cretaceous of the Smoky Hill river, where specimens have been collected. Of the tenth family, called mugilidae, only three specimens have been secured in Kansas, of which two came from the Benton Cretaceous.

Kansas has some of the richest fossil fields in the United States; specimens of many species have been preserved in the museums of the state university and the state agricultural college, which are of great value to the students of geology and paleontology. Not only have the state museums been supplied from these fields, but the museums all over the country have Kansas specimens. (See Kansas Geological Survey, vols. viii and ix.