University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Conservation and Survey Division Natural Resources, School of 1915 NEBRASKA OSF SILS WHICH EXCITE COMMON INQUIRY Erwin H. Barbour Nebraska Geological Survey Follow this and additional works at: http://digitalcommons.unl.edu/conservationsurvey Part of the Geology Commons, Geomorphology Commons, Hydrology Commons, Paleontology Commons, Sedimentology Commons, Soil Science Commons, and the Stratigraphy Commons Barbour, Erwin H., "NEBRASKA OF SSILS WHICH EXCITE COMMON INQUIRY" (1915). Conservation and Survey Division. 644. http://digitalcommons.unl.edu/conservationsurvey/644 This Article is brought to you for free and open access by the Natural Resources, School of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Conservation and Survey Division by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 37b NEBRASKA GEOLOGICAL SURVEY ERWIN HINCKLEY BARBOUR, State Geologist VOLUME 4 PART 22 NEBRASKA FOSSILS WHICH EXCITE COMMON INQUIRY BY ERWIN H. BARBOUR 176 B NEBRASKA FOSSILS vVHICH EXCITE COMMON fNQUIRY llY ERWIN H. BARBOUR Tbi3 paper must not be mistaken for a report on the fossils of N e­ lJ:·aska. It is merely a circular letter to correspondents describing and figuring those fossils only which occasion frequent comment. In two recent papers of the Survey consideration was given to the comm011 minerals and rocks of Nebraska, and it seems opportune to br.iefly discuss our fossils in a like manner. Probably no other State can boast of such a well-preserved and varied fauna. The Tertiary, the most recent of the great geologic ages, includes six subdivisions, and extends over a period of several million years, according to geologic reckoning. By reference to the list below one can readily associate the fossils mentioned m this report with the geologic age in which they occurred: 6. Present 5. Pleistocene Recent 4. Pliocene One-half million years ago 3. 2\fiocenc One-half to one million years ago Tertiary 2. Oligocene One to two million years ago Bad land formation 1. Eocene Two to three million years ago Vv' anting in Nebraska CHALK SHELLS, FORA'-"fi!\fiFERA. Chalk is abundant at Superior, Niobrara, and at certain intennedi­ ate points. It is composed of minute shells, some of them wl1ole, Fig. 1.-Chalk and chalk shells. a, section of chalk rock as seen under the microscope; b, chalk shells, greatly magnified. some of them broken. They are seldom visible to the eye, although a few attain considerable size. Our chalk beds are of marine origin. 304 NEBRASKA GEOLOGICAL SURVEY "FOSSTL RICE," FORAMINIFERA. The most abundant fossil in Nebraska is unquestionably the "rice shell," Fusulina sccalica, which resembles a grain of rice in shape anlf. size. Portions of the Nebraska Coal Measures are solid masses of these shells. Such rock is called "rice stone." The foundations of th~ old University buildings, the old Lincoln Post Office, and the Capitol are all built of rice stone. a b c FrG. 2-Fusulina secalica. a, "rice stone," characteristic of the Carbonifer-< ous formation, natural size; b, Fusulina, enlarged; c, cross section of the same; enlarged. SPONGES, AMBLYSIPIIONELLA. One kind of fossil sponge is abundant in the Carboniferous rocks and shales of the \;\T eeping \Vater valley. It resembles coarsely jointed crinoid stems. In 1R91, the State Museum secured several hundred specimens near \Veeping vVater. They are also found at Nehawka in considerable numbers. Fig. 3.-Amblysiphonella, a Carboniferous sponge from the Weeping Water valley. Reduced. COMMON NEBRASKA FOSSILS 305 CORALS. Corals in Nebraska are confined to the Carboniferous rocks. The most abundant forms are those called horn corals, or "petrified horns." One of the determining characters of a coral is the cup with its radiat­ ing lines. The large horn corals, so abundant in the Weeping Water yalley, are known by the name Campophyllum. The small horn corals arc called Lophophyllum. Occasional pieces of "organ pipe" coral arc found. At Nehawka, certain limestone ledges are composed wholly of horn corals, and some of the stone fences are literally coral fences. Corals have always been important rock-building animals. e a b c d FIG. 4.-Carbonifcrous corals and corallines. a, Campophyllum torquium, horn coral, reduced; b, Lophophyllum profundum, a small horn coral; c, Syrin­ gopora multattenuata, organ-pipe coral; d, Rhombopora lepidodendroides, a branched coralline (bryozoan) ; e, Septopora, windowed coralline. b, c, d, and e are natural size. CORALLINES. Many m1mature corals, really Bryozoa, occur in our Carbonifer­ ous shales and limes. There are many species, but for the purpose of this paper, they may be divided into the branched or ramose, and the windowed or fenestrated corallines. In Nebraska, these corallines always ~ignify the Carboniferous formation. They added materially to our great beds of limestone. NEBRASKA GEOLOGICAL SURVEY CRINOIDS. Crinoids are close relatives of the starfish and sea urchins. They grow on stems, much like a lily, and are spoken of as "sea lilies," "stone lilies," and the like. Crinoid stems are mostly round and com­ posed of a number of stony drums set one above the other. Rock layers composed of crinoid stems and heads are called "crinoidal lime,. stone." In some cases, it is fine enough for ornamental purposes, and is polished and sold as crinoidal marble. Some of our great masses of limestone are composed essentially of disjointed crinoids, b .' i' -~~ a c d Fig. 5.-Crinoids and sea urchins. a, crinoid stump, stem, and head, Eriso• crinus; b, base of crinoid head, Barycrinus; c, crinoidal limestone; d, spine and plate of sea urchin, Echinocrinus. All reduced. SEA URCHINS. Sea urchins, like crinoids, are closely related to the starfishes, Fossil sea urchins, like their survivors, have rounded bodies composed of bony plates carrying spines of various sizes and shapes. So far no Nebraska sea urchin has been found intact, although the scattered plates and spines are numerous. FOSSIL WORM TUBES. Our Carboniferous worm tubes are small and rather inconspicuous,, yet they have attracted considerable notice because they look like. small spiral shells, generally attached to some larger shell. They belong t!ill the genus Spirorbis. A much larger worm tube, Serpula tenuicarinatal is found in the Cretaceous of northeastern Nebraska, commonly af:~ tached to some large shell like the Ammonite. COMMON NEBRASKA FOSSILS 307 a. b Fig. 6.-Worm tubes. a, Spirorbis growing on a lamp shell, Carboniferous; b, Serpula tenuicarinata, Cretaceous. Both natural size. MOLLUSCOID SHELLS. As the name implies, molluscoids are similar to mollusks, but are generally smaller, and have one valve differing more or less from the other, and ordinarily have a hole or opening in the beak. These shells are called Brachiopods, or popularly "lamp shells." They are so abundant in certain strata that they constitute the entire rock mass from 'vhich it is evident they were important rock-builders. a d b e c Fig. 7.-Carboniferous brachiopod shells. a, Chonetes granulifer, natural size, abundant; b, Composita subtilita, natural size, very abundant; c, Productus semireticulatus, abundant at Roca, reduced; d, Spirifer cameratus, butterfly shell, reduced; e, Meekella striatocostata, natural size. MOLLUSK SHELLS. The best known mollusk shells are bivalves such as clams and oysters, and univalves such as snails. Bivalve shells are abundant in the Carboniferous of southeastern Nebraska. The largest of these is called the Pinna, or wing shell, which closely resembles living forms in shape and size. The clam shell in the Carboniferous which at- 308 NEBRASKA GEOLOGICAL SURVEY a b c Fig. B.-Carboniferous bivalves. a, Allorisma subcuneatum; b, Myalina re­ curvirostris; c, Aviculopecten occidentalis; d, Pinna peracuta. All reduced. tracts most attention is called Allorisma. There are deposits of "oyster shells" in our Cretaceous limestones which are so exten.sive and continuous that they are called "oyster beds." These shells occur in great numbers at Hebron, Milford, Wynot, and intermediate points, wherever the thick overlying ·soil is removed and the Greenhorn lime-' stone exposed. They belong to the genus Inoceramus. The miniature oyster, called Ostrea congesta, grows closely together in large clusters, Their resemblance to oysters is such that their identification is easy. a b Fig. 9.-Cretaceous bivalves. a, Inoceramus labiatus, x;.i, Greenhorn lime., stone; b, Ostrea congest a, a small oyster, natural size. UNIVALVE SHELLS, GASTROPODS. In addition to the common bivalve shells, there are certain univalve shells of attractive outline, and of varying sizes and shapes. Many of these may be likened in general appearance to the shells of snails and periwinkles. Euomphalus is abundant at Roca, while Belerophon is frequently found in southeastern Nebraska. COMMON NEBRASKA FOSSILS 309 a b c FIG. 10.-Carboniferous univalves. a, Euomphalus; b, Bellerophon, view of aperture; c, W orthenia. All about natural size. NAUTILOID SHELLS. The commonest nautiloid shell in Nebraska is Orthoceros, the "straight-horn" shell. The name suggests the form, and its identifica­ tion is easy. A closely related shell is coiled, and is known as Nautilus. Nautiloids, though similar to ammonoids, have much simpler suture lines. b Fig. H.-Carboniferous Nautiloid shells. a, Orthoceros, the "straight horn'' shell, x Y, ; b, Nautilus, greatly reduced. AMMONOID SHELLS. Shells belonging