sign in sign up
<<
Home , History of Nebraska

University of - Lincoln DigitalCommons@University of Nebraska - Lincoln

Papers in Ornithology Papers in the Biological Sciences

December 2001

The History of Life in Nebraska: A Time-Travel Adventure

Paul A. Johnsgard University of Nebraska-Lincoln, [email protected]

Follow this and additional works at: https://digitalcommons.unl.edu/biosciornithology

Part of the Ornithology Commons

Johnsgard, Paul A., "The History of Life in Nebraska: A Time-Travel Adventure" (2001). Papers in Ornithology. 33. https://digitalcommons.unl.edu/biosciornithology/33

This Article is brought to you for free and open access by the Papers in the Biological Sciences at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Papers in Ornithology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. I Wispy blue skies are timeless but, in their present form, Nebraska's are only 10,000 years old.

t is difficult for humans, whose times older than the time scale Evidence of animal life comparable to lives are measured in years and described here, and the earliest known these early types can be found in Idecades, to fathom the age of the algal are 3.8 billion years old. limestone outcrops such as those near Earth, whose history is patiently but To start at the approximate age of the Weeping Water, not far south of Omaha inexorably written on thin pages of planet Earth, we would have to travel in southeastern Nebraska. landscape, each lasting millions of years about 4,500 miles, rather than 450 miles, In traveling the 50 miles to Lincoln, or more. As an exercise in Earth-time, to get a sense ofthe time involved (see we cover 50 million years of late let a single mile represent a million years. drawing on page 26). The age of the Ordovician and Silurian times, to Thus .5 mile would represent 500,000 universe is perhaps three or four times 400 million years ago, and are entering years, .10 mile equals 100,000 years, greater, or more than half the distance the Devonian period, and the warm .0 1 mile (52 feet) equals 10,000 years; around the globe at Nebraska's latitude, waters of the Paleozoic sea still surround .001 mile (5.2 feet) equals 1,000 years, at the rate of I mile per 1 million years. us. We must drive (or boat) all the way and about 6 inches equal 100 years. A to Kearney, some 270 million years decade would equal about half an inch. Once a Gmt Seabed ago, before the last remnants of this It is 450 miles from the 60th Street great sea have retreated and left us on on-ramp on Interstate 80 in downtown As we join 1-80 in Omaha, same dry land. To reach the start of the age Omaha to the westernmost 1-80 exit at 450 million years ago, we are in the of dinosaurs, the Mesozoic era (the era the border, which may be middle of the Paleozoic era, the "era of "middle animal life"), which began thought of as equal to 450 million of ancient life." Then we would need some 220 million years ago, we must years. This period of nearly half a a boat, as Nebraska was actually get to Cozad, traversing both the billion years encompasses most of the submerged under a great inland sea, Carboniferous and Permian periods in time that evidence of animal life has and the animals present would be mostly the process. From there to Ogallala, a been found on Earth, but Earth itself is corals, sponges, and mollusks, plus a distance that includes the Triassic and more than 4 billion years old, or ten few primitive fishes, such as . Jurassic periods and encompasses the

24 hlBR4SliAland December 2001 peak of the dinosaurian reign, there is advanced wing structures than the ecology of Mesozoic life. no clear geologic record in Nebraska. pterosaurs, which were doomed to All of this life came to a crashing However, abundant dinosaur fossils extinction at the end of the Mesozoic. halt about 65 million years ago. The occur in the Mesozoic deposits of The third and last segment of the scenario is still being debated, but eastern Wyoming and South Mesozoic, the Cretaceous period, is many scientists believe that the curtain Dakota and tell us much of what is now approximately represented by the was brought down on the Mesozoic era known of these beasts. 65-mile distance from Ogallala to with the arrival of a huge asteroid that Sidney. It was a time when Nebraska entered the Earth's atmosphere and Flying Reptiles was again covered by shallow seas, struck the Caribbean Sea, immediately with long-necked plesiosaurs swim- or eventually killing much of the Earth's These regions were probably then ming swiftly through the waters in terrestrial and aquatic life and altering mostly warm, moist bottomlands and search of fish and sometimes rivaling the climate permanently. evergreen forests of primitive trees and the largest dinosaurs in size. There Even such giant marine animals as ferns, with an abundance of plant life were also carnivorous , the plesiosaurs, mosasaurs, . and other animals. Crouching among sea-going lizards with large crushing and the largest marine lurtles met their all these large beasts were the first jaws, killing and eating large sharks end, as did many marine invertebrates mammals, smaIl and timid creatures and bony fishes. A few large but such as mollusks and mollusklike that perhaps lived on insects and such flightless loonlike birds swam along brachiopods. Warmwater marine small reptiles as they could easily the ocean's shorelines, also in search phytoplankton that depended on capture or on the eggs and young of of fish, and some smaller ternlike ones calcium supplies for forming their larger species. Also, early birds were hovered about its surface. Even then shells also disappeared, as did many starting to share the skies with flying the mammals and birds were still other calcium-dependent marine groups. reptiles. Even these rather primitive relatively inconspicuous and of little It was not only the end of an era but birds had larger brains and more ecological significance in the overall also the end of the entire Mesozoic

NEBRASKAIand December 2001 25 The geological history of Nebraska, with the time scale represented as a million years for each mile along 1-80. Representative extinct animals of the three malor geologic eras are depicted in east-to-west (older to newer) sequence. Animals of a single geologic era are generally arranged vertically upward from older to newer forms, with a few exceptions. Not all of these North American types are known from Nebraska. lifestyle, both on land and at sea. greater seasonal temperature variations. common, and by 17 million years ago Thus, near Sidney, about 65 miles Great elephant-sized titanotheres the earliest true cats had appeared. from the Wyoming border, we have just lumbered across the uplands of Nebraska The first elephants arrived from Asia entered the Cenozoic era, the age of nearly 40 million years ago, or near 14 million years ago; these were largely "modem animal life,'' also called the Potter on our 1-80 time scale. Many browsing mastodons and four-tuskers. Age of Mammals. Over this 65-million- other browsing and grazing mammals These species would be replaced later year period what is now Nebraska was were present, with grassland-adapted by more modern varieties of elephants covered sequentially (over millions of forms progressively replacing the forest- that were better adapted for grazing. years) by tropical forests, then savanna- adapted browsers as the woods and like mixtures of trees and grasses, and forests slowly gave way to . Ash ('afcheS Animals finally true grasslands, an interval called These grazing mammals include camels, the Tertiary period. This progressive rhino, horses, and many others. About 10 million years ago, or near drying of Nebraska's climate was It isn't until we reach Kimball, about Bushnell on our 1-80 time scale, vast largely the result of the rising of the 20 million years ago, that Nebraska volcanic clouds of dust settled on Rocky Mountains to the west, which began to resemble the grassy plains we Nebraska, gradually choking herds of shut down the supply of moisture-rich know today. At that time grazing animals horses, camels, and rhino and providing air masses from the Pacific Ocean and such as horses, rhino, camels, grass- the skeletal framework for what is now produced a much drier climate with eating rodents, and wolflike dogs were the State Historical

26 NEBRASKAland December 2001 Park in nortkastern %btaska Birds in the Minnesota- border such as cranes shikOQ Africa's pl%sent- region, and in other locations farther The day crowned craecs wa& also caught north in Canada. Probably caribou, in this catac1ysm.k cwmt. Yet elsewhere musk oxen, and other arctic-adapted mammals followed the slowly retreating Nature of ice sheets northward, feeding on the tundralike grassy vegetation at their edges. By then there were Mytwo kinds of bison on the plains of Nebraska. One was a very large species with A little morethm2miWa yaws massive horns that became extinct ago, orjust 2 &frcaaatbdof about 11,000 years ago, when the last mammoths also disappeared from America. The other bison was smaller and the direct ancestor of the modem bison, which would become the keystone species for survival of Native Americans which were sepamtd by interglacial on the High Plains for nearly a periods of similar lengths. Only two of millennium. We have now reached the these glaciers wtudy brought ice as last major milepost of time, the start of far south as eastern Nebraska, but one the Holocene epoch, during which glacial lobe even reached northeastern humankind would come to control the . These glaciers deposited great destiny of the planet. beds of potential soils in the form of glacial till, scraped off from lands much Brief Euroamerican Era farther north. They also occasionally and randomly left enormous boulders, America wasn't discovered by called glacial "erratics," that they had Europeans until about five centuries carried south from Minnesota or the ago, or about 3 feet from the end of our Dakotas. road. Nebraska was mostly settled by During the rather dry interglacial Europeans little more than a century periods, strong winds stimd up the vast ago, or about 6 inches from the last beds of sand, silt, and clay that had turnoff. Also, by about then the eroded off the highlands of Coldo passenger pigeon became extinct, as and Wyoming and that lmd previously did the Carolina parakeet, both of been carried to western Nebraska by which were well known to the Native meltwater rivers from the High Plains Americans who had lived in eastern and Rocky Mountains. Thus were Nebraska. The last Eskimo curlew to formed the Nebraska Sandhills. The be shot in America, and one of the last finer, silty materials were similarly ever to be seen alive anywhere, was worked by the winds and were carried killed in Nebraska about 90 years ago. varying distances to the south and east, The gray wolf, elk, pronghorn, bighorn mostly accumul~gsouth of the Platte sheep, and free-ranging herds of bison and reaching eastward to Iowa and were also gone from Nebraska by then, perhaps even beyond. as were the last free-living Native The first humans, the antecedents of Americans. Native Americans, probably reached The people who are alive today, and North America about 12,000 years ago, the interstate highway on which we or about 75 feet from the end of our have mentally traveled, represent only a trip. This was near the end of the last few inches of the Earth's total history, nahld- ,@MIpreserves. I glaciation, when there was still a based on our 450-million-year scale relatively dry Bering Sea causeway between Omaha and the Wyoming connecting Alaska with the great Asian border. A single year, which sometimes landmass. However, remnants of the seems endless to us humans, corresponds glaciers in the central were with about the thickness of the steel on then melting and fonning enormous but the last Nebraska 1-80 exit sign as we temporary lakes, such as Lake Agassiz end our imaginary trip. rn

NEBRtISKAland December 2001 27