HOW WERE THEY PRESERVED?

Camptosaurus—AN ARNITHISCHIAN PLANT-EATER. (DRAWN BY J. G. GERMAN. COURTESY, AMERICAN MUSEUM OF NATURAL HISTORY.)

The concentration and burial of dinosaur bones is only the beginning of the fossil story. The combination of circumstances which operated here was a common one and yet fossil quarries are rare. Why? The bones have to be preserved and this seldom happens. The bones that are buried in one flood are frequently unearthed and scattered by the next. Those that are exposed to the weather usually disintegrate completely in a few years. The bones in the Dinosaur Quarry did not.

Sometime after they were buried, the organic minerals of the bones were more or less completely replaced by minerals of inorganic origin such as silica. No one knows exactly why or how this happened, but it did. Most geologists think this replacement process occurs when subsurface or ground water containing soluble and colloidal minerals dissolves a molecule of the bone and immediately replaces it with a new mineral. Roughly such a process is like removing red bricks from a house and substituting yellow. When the substitution is complete, the house still has the same dimensions but it is composed of different materials. The replacement was a faithful one, too, because microscopic structure of the original bone was faithfully reproduced by the replacing minerals.

ROAD MAPDINOSAURNATIONAL MONUMENTUTAH - COLORADOHigh-resolution Map

Following Morrison time, thousands of feet of younger sediments were deposited on the sandbar that contained the dinosaur bones. The whole sequence of sediments was compacted into rock and some bones were crushed and distorted.

After the sediments became rock and the bones had probably been replaced by stone (fossilized), this part of the world, which lay near or below sea level for millions of years, began to rise. Great forces acted upon the earth’s crust. These forces created faults, or fractures, in the rock crust along which movement occurred. And what had once been sea bottom was moved upward and became lofty mountains. This titanic change has been called the Laramide Revolution; it closed the Mesozoic Era with the formation of the Rocky Mountains.

Stegosaurus.AN ARMORED DINOSAUR OF THE JURASSIC PERIOD. (FROM A DRAWING BY CHARLES R. KNIGHT. COURTESY, AMERICAN MUSEUM OF NATURAL HISTORY.)

Although the effects of the Laramide Revolution were not as profound at Dinosaur as they were east of it, they were quite important. The rocks were lifted to form the southwest flank of Split Mountain—a small arch, or anticline, on the south side of the Uinta Mountains. This mountain building explains the pronounced southward tilt of the Dinosaur Ledge and other rock layers visible in the quarry area. As the land rose, streams flowed more rapidly, cutting deeper into the rocks and carrying away the debris. Gradually thousands of feet of this debris—shale, sandstone, and clay—were stripped away through erosion.

Finally all the material on top of the Morrison sandbar weathered away. Some 140 million years after burial the fossil bones were exposed by the agent that had buried them so long ago—running water! All that remained was for them to be found, and that was the luckiest chance of all. Just suppose they had been uncovered a million years ago—only a second in geologic time. No one would have been present to discover them, and through the years they could well have crumbled into dust and been blown away.

At Dinosaur National Monument only Morrison rocks of the upper Jurassic Period contain the fossil bones of dinosaurs. After Morrison time, the Cretaceous seas invaded this area. More than 5,000 feet of sandstone, shale, and mudstone were formed from sediments deposited in these seas.

Elsewhere in North America and the rest of the world, the diversity and numbers of dinosaurs actually increased. Entirely new groups evolved and achieved success in the battle for survival. The climax of reptile development seems to have come near the end of Cretaceous time in the Mesozoic Era. As the dinosaurs ruled the continents, so did other strange reptiles dominate the seas. Had you been able to see this ancient world, you would surely have been convinced that the dinosaurs and other reptiles would rule forever.

But it was not to be. The dinosaur hordes were wiped out and the reptiles reduced to the position of relative insignificance they occupy today. Such a profound and sudden change in the evolutionary trend of life must have had a cause, and scientists have sought it. Several theories have been proposed to explain extinction of dinosaurs, and they are most interesting.

At the end of Cretaceous time, some of our great mountain ranges were formed. It was a time of earthquakes and of volcanoes that belched forth clouds of ash and rivers of molten rock. Some peoplewould say these catastrophic events killed all the dinosaurs. The scientist shakes his head. If these events killed dinosaurs, why not the other animals that lived with the dinosaurs. And what of those parts of the world that had no volcanoes, what killed dinosaurs there?

Changes in environments, the drainage of lakes and swamps as young mountains rose, changes in vegetation as new plants replaced old, and sudden shifts of climate occurred. These conditions could explain local extinction, but there were places where these changes did not occur and yet all dinosaurs in all places died.

A one-time favorite theory suggested that increasing numbers of small mammals ate dinosaur eggs, but there were many mammals eating dinosaur eggs during all of Cretaceous time and the dinosaur hordes increased. Many more mammals during succeeding ages have not killed off the turtles, snakes, lizards, and crocodiles that lay eggs and exist in great numbers today.

Some disease or combination of plagues may have swept the dinosaurs into extinction. If so, no evidence has been found to date that confirms or denies. However, most paleontologists do not accept this theory.

These are some of the theories that have been advanced to explain the sudden extinction of dinosaurs throughout the world. Each theory will explain the death of some dinosaurs in some places but attempts to apply any of them, or combinations of them, to worldwide extinction have failed.

This dinosaur story is like a mystery thriller with the last pages torn out. A most important part is missing. That is true and the paleontologist knows it. He also knows the riddle will probably never be solved. He might point out, however, that no one has successfully explained the extinction of the passenger pigeon which occurred quite recently, nor do we know why some other species of wildlife are on the brink of extinction today. The paleontologist is not the only one who must say, “I don’t know.”

No one knows how long the old bones had been weathering out of the hills of what is now Dinosaur National Monument before the first man saw them. Curious Indians, wandering between the upturned ridges of Mesozoic rocks, picked up fragments and carried them off to their camps where they are now found among the arrow points, ax heads, and corn-grinding stones. In 1776, the Spaniard, Father Escalante, passed within sight of today’s dinosaur quarry, not dreamingof the antiquity hidden there. Maj. John Wesley Powell, on his second voyage down the Green River in 1871, recorded the presence of “reptilian remains” in the area, but wrote nothing more about them. Sheepherders, cattlemen, and hunters observed them and were impressed in proportion to their understanding. But, through all the years, the nature of the bones remained a mystery.

EARL DOUGLASS, DISCOVERER OF THE DINOSAUR QUARRY.

Then, in 1893, this mystery was solved. O. A. Peterson, a scientist from the American Museum of Natural History, while conducting field work in the Uinta Basin to the south of the present monument boundaries, discovered bones out-cropping from a recognized fossil-bearing stratum. The stratum was the 140,000,000 year-old Morrison formation. The bones? Peterson reported them as the remains of dinosaurs.

That report was to have an important influence, 15 years later, in directing a fellow paleontologist from the Carnegie Museum in Pittsburgh to investigate the area. Earl Douglass was the paleontologist’s name. In 1908, he and W. J. Holland, Director of the Carnegie Museum, found themselves in the region of Peterson’s discovery, searching for dinosaur remains. They extended their search to the north and thence along the Morrison hogback that flanks Split Mountain. Bone was found—not much, but enough to bring Douglass back the following summer and in company with George Goodrich, a local resident, to pursue the hunt.

The hunt came to a triumphant climax on August 17, 1909, when—to quote from Douglass’s diary—“At last in the top of the ledge where the softer overlying beds form a divide ... I saw eight of the tail bones of aBrontosaurus {Apatosaurus}in exact position.”

This was the beginning—the beginning of the celebrated dinosaur quarry which was to yield such a multitude and variety of ancient forms to science, and eventually lead to the establishment of Dinosaur National Monument.

Douglass proceeded to dig into the solid rock along those original eight tail bones and found other parts of the skeleton. In time, the almost complete frame of theApatosauruswas exposed. The skull was missing and parts of the limb bones, but this was to be expected, as fossil vertebrates are rarely preserved in their entirety. What was not expected were the remains of a smaller dinosaur comingled with those of its huge contemporary.

Douglass was elated. This was more than a “one strike”! How much more, only further digging would tell. Sensing a large-scale operation, he informed the Carnegie Museum of his prospects and readied things with the intensity of a man at the gate of destiny. From the neighboring ranches he recruited men, horses, and equipment. He sent for his wife and child. He constructed a road to the discovery site, built a five-room cabin out of logs and lumber, converted a sheepherder’s camp wagon into an office, selected ground for future planting, bought a cow. A forge was set up. Tools were purchased.

Back at the museum, Andrew Carnegie, himself, evinced interest. He had always wanted something “as big as a barn” for his institution. A special annual field fund of $5,000 was added to the regular budget to carry on the work.

Within a year, Douglass and his men had run a cut over a hundred feet long in the hard sandstone, digging down along the almost perpendicular slant of the rock. At the base of this, rails were laid and small mine carts introduced to haul away the cuttings from the rapidly developing quarry.

New specimens appeared: A small plant-eating dinosaur known asDryosaurus; an armored form calledStegosaurus; and another large creature like theApatosaurus. Best of all, theApatosaurusNo. 1 was well on its way out of the rock and would soon be ready to ship to the Carnegie Museum in Pittsburgh.

“... I SAW EIGHT OF THE TAIL BONES OF ABrontosaurusIN EXACT POSITION.” (FROM DOUGLASS’ DIARY, 1909. SHOWN IN PHOTO IS DOUGLASS’ ASSISTANT, ELDER GOODRICH.)

THE FIRST CUT IN THE QUARRY, AS IT LOOKED IN 1910. (COURTESY, A. S. COGGESHALL.)

SAMPLE VIEW OF DINOSAUR REMAINS AS THEY WERE UNCOVERED IN THE QUARRY. THIGH BONE NEAR MAN. (COURTESY, A. S. COGGESHALL.)

QUARRY OPERATIONS. SAURISCHIAN PLASTERED PELVIS UPPER CENTER. (COURTESY, A. S. COGGESHALL.)

In 1913, after 3 years of laboratory work in the Carnegie Museum the bigApatosauruswas on its feet in the Hall of Vertebrate Paleontology—1 of the 4 mounted specimens of this genus in the country and the most perfect of all. Prepared and erected by Arthur S. Coggeshall and his associates, it measures 71½ feet long and stands 15 feet tall at the arch of the back.

As the excavating progressed it was not long before the diggings became what is known to the profession as a “general quarry.” Dinosaurs of “all kinds and sizes” were showing up. Other quarries of this type had been developed in previous years in the Morrison formation at Como Bluff, Wyo., and Canon City, Colo., but they contained nothing like the variety of forms found here. Moreover, these at the monument were better preserved and the skeletons more intact.

The remains most frequently encountered in the diggings were those of sauropods—the huge plant-feeding dinosaurs with long tapering extremities that lumbered about on four pillar-like legs.Camarasaurusand the largerApatosauruswere typical members of this group, and their numerous bones show them as being common animals of their time.

More common were theDiplodoci, of the exaggerated neck and even longer whiplash tail. This genus distinguished itself by producing not only the largest amount of skeletal material from the quarry, but also the largest number of skulls—those rarest of fossils. One skull was found in exact position with the neck bones, which settled all doubts as to the details of this animal’s head piece. The longestDiplodocusto come from the monument extended 75½ feet.

Contrast this with the diminutiveLaosaurus, a 2½-foot biped which ranks as the smallest dinosaur yet taken from the deposit. This tiny creature had hollow limb bones and was one of the agile, quick-running types. Only one was found. When discovered, Douglass thought it a “baby” dinosaur, but study proved it to be a full-grown specimen. The condition of the skeleton reflected considerable agitation before and after burial. It lay on its back, the limbs distended. The tail was gone and the skull crushed.

In many respects, the most interesting dinosaur found was the sauropod,Barosaurus. It was an extremely long-necked form, some of the individual cervical vertebrae measuring 3 feet in length. Two specimens were excavated.

The flesh-eaters, as might be expected from their scarcity in other localities, made but a small showing. Two specimens ofAntrodemuswere unearthed. Thirty feet long, this animal was the ranking predator of its day, although hardly comparable to the toweringTyrannosaurusthat entered upon the earthly scene at a later age.

Stegosaurusremains—so abundant that Douglass grew tired of them—added a bizarre note. An armored form, it was equipped with a frill of bony plates that extended the length of the back and terminatedin a pair of sharp spines. Its chief claim to fame rests in its supposed two sets of “brains,” one a motor-control center situated in the hip region, and the other in the usual place.

Everywhere they dug, the excavators found fresh material—a vast jumble of bones so concentrated and intermingled as to make it difficult to distinguish one specimen from another. Douglass was amazed. Obviously, it was not with animals of a single area that he was dealing, but of an entire region. He was dealing with a dinosaurfauna. He was also perplexed. How did so many different types happen to occur in one small locality?

Slowly, as Douglass’s acquaintance with the deposit grew, the answer came. It was, he reasoned, the work of a river. The sandstones were ancient sediments. In their structure and composition lay the story of swift swirling currents. The coarse granular texture told of fast water; the crossbedding, of shifting channels; the grouping of the bones into clusters, of eddies.

It all added up to an old delta deposit at the mouth of a river, a region of bars where the carcasses of dinosaurs brought down stream accumulated. Settling, the great hulks became buried as they sank into the receptive sand. A number of carcasses multiplied ... and slowly, as flesh and ligament decayed, the bones became mingled, eventually to petrify and remain preserved through the ages.

At the quarry, excavating continued summer and winter. The methods employed were those that paleontologists had used for decades. There was no compressed air, no labor-saving devices. The work was done by hand. The crew, which seldom exceeded four men at any one time, became veterans in the art of fossil extraction. The bone was brittle; the encasing sandstone, hard. It required toil, patient direction, and a knowledge of anatomy.

Judiciously placed charges of giant powder shattered the overburden. Hand drills, wedge-and-feather, and crowbar worked the rock away, until the bone layer was encountered. The slow attrition by hammer and chisel accomplished the final delicate separation of the remains from the enclosing matrix. Team-and-scraper and small handcarts removed the rubble that swiftly accumulated in the cut. As the bones were chiseled from the quarry face in large blocks of rock, they were encased in strips of burlap dipped in flour paste. (Later, plaster of Paris supplanted the flour paste.) Then they were lowered by rope onto a mule-drawn skid and “snaked” down the trail into the gulch to await boxing.

REMOVING A LARGE THIGH BONE FROM THE QUARRY WALL DURING THE CARNEGIE MUSEUM OPERATIONS. (COURTESY, A. S. COGGESHALL.)

PLASTERED SPECIMEN REMOVED FROM THE QUARRY DURING THE CARNEGIE MUSEUM OPERATIONS. (COURTESY, A. S. COGGESHALL.)

Transporting the fossils from quarry to railhead was a major undertaking. It required wagon trains—4-horse teams hauling high-wheeled freight wagons over 60 miles of rutted roads to Dragon, Utah. There the precious goods were loaded onto boxcars of the now abandoned narrow gauge Uintah Railway, later to be transhipped to the standard gauge Denver & Rio Grande line at Mack, Colo.

Specimens continued to show in record abundance, most of them duplicating the earlier finds ofDiplodocusandStegosaurus. But there were new forms, too. One of them was aCamptosaurus, the first to be found at the quarry. It was a modified biped of plant-eating habits, a little more than 10 feet long, with its skull and part of the tail missing.

By 1921 the deposit had been worked to a length of 400 feet east and west, and to a depth of about 60 feet. Rock was being stripped from the quarry face at the rate of approximately 20,000 cubic feet annually, and the chisels of Douglass and his men had penetrated to the richest bone-bearing zone.

In the following year they uncovered one of the most perfect skeletons of a dinosaur ever exhumed. It was a small sauropod named,Camarasaurus lentus. When found, its 17-foot vertebral column was practically intact, except for a few tail segments. The skull was in place, and the limbs in their approximate positions.

It was an important find scientifically. The position of the limbs gave clear evidence of the manner in which these animals carried themselves. The articulation between the thigh bone and the pelvis showed conclusively that sauropods walked with their legs more-or-less vertical to the body and not with the bowed-out crawling posture habitual to lizards, as many scientists had supposed. The skull was the finest known for this genus. It was complete even to the sclerotic ring—a complex of bony plates which surrounded the living eye and protected it.

As exhibit material it was without rival. It was mounted as found, lying on its side, the bones fixed in death in the matrix in which they had been preserved—a fitting climax to the 13 consecutive years that had seen an unknown sandstone ridge in Utah become Dinosaur National Monument.

In those 13 years the Carnegie Museum had taken from the quarry parts of 300 dinosaur specimens, 2 dozen of which were mountable skeletons. Ten different species were represented. It was the best collection of Middle Mesozoic monsters in the world.

In the years that immediately followed, the still-rich “dig” was worked by two other organizations—the Smithsonian Institution and the University of Utah.

CamarasaurusSKELETON—THE MOST PERFECT REMOVED FROM THE QUARRY. (COURTESY, CARNEGIE MUSEUM.)

But finally the museums had reaped their harvest. The fruits of the harvest had gone to enrich many of their finest displays. However, still buried in the untouched part of the wall were the remains of still more dinosaurs. All that was needed was to reveal them. The 67° tilt of the rock made it a perfect exhibit face. Strip off the overlying layers, expose the skeletons, and relief them in place. This had been Douglass’s idea as far back as 1915, when he recorded it in his diary.

But Douglass was not the only one to realize the necessity of preserving this unique fossil record of the dinosaurs for people of today and the future to see on the spot. Officials of the Carnegie Museum realized the extraordinary nature of the deposits and their contribution to our knowledge of the past; and they were not long in takingsteps to protect the dinosaur quarry. To preserve it for science, they sought to lay claim to it as a mineral property. But their claim was disallowed by the U. S. Department of the Interior, because fossil bones could not be classed as a mineral within the meaning of the mining laws.

The museum pressed its case, this time with results—but not what they expected. The outcome was not the establishment of a mere mineral claim, but of a national monument. Under the provisions of the Antiquities Act, to safeguard and preserve objects and areas of significant scientific or historic interest, the dinosaur quarry and 80 acres of surrounding land were declared a national monument on October 4, 1915. Less than a year later it was included in the newly created National Park System.

Several things contributed notably to this action to protect the quarry. They were: the exceptional preservation of the bones; the number, variety and completeness of the skeletons; the relative abundance of skulls, consisting of 8 or more in a complete state, and about an equal number of incomplete ones; and the finding of the first complete tails.

In 1923, knowing that the quarry was protected, and that the scientific collection of the fossil bones for museum exhibit was at an end, Earl Douglass turned again to the idea of making a perfected exhibit of the fossils right where they lie. His letter to Dr. Walcott, secretary of the Smithsonian Institution, reads, in part, “I hope that the Government, for the benefit of science and the people, will uncover a large area, leave the bones and skeletons in relief and house them in. It would make one of the most astounding and instructive sights imaginable.”

ARCHITECT’S DRAWING OF VISITOR CENTER AT QUARRY SITE.

This is precisely what the Government had in mind and, through the agency of the National Park Service, intended to accomplish. Plans for an in-place exhibit were drawn up. But many years were to elapse before the plans passed from blueprint into reality.

In the meantime, the quarry entered the second phase of its existence, a dormant period from a scientific viewpoint, but one in which the forces of the future gathered ground.

During the 1930’s the monument served as a transient camp. A. C. Boyle was installed as resident geologist and custodian for the Park Service. Under his guidance a program for the general development of the area was carried on, financed largely by WPA funds. This entailed, among other things, the deepening and widening of the quarry cut, and the construction of buildings later to accommodate the monument staff and exhibits.

The American Museum of Natural History became interested in the development at this time and, through its curator of fossil reptiles, Barnum Brown, sought to initiate a joint effort with the Park Service for exhibiting the quarry remains.

It was not until September 1953 that the years of Park Service planning bore fruit, and the work of developing an in-place exhibit for the monument was begun. Many factors operated to spring the project into being, not the least of which was the active interest and wholehearted support of Horace M. Albright, a former Director of the Service.

Theodore E. White, formerly with the Smithsonian Institution and with Harvard University, was placed in immediate charge, under the supervision of Jess H. Lombard, the superintendent of the National Monument. His task, and that of his associates, was to expose the remaining specimens in the quarry wall and work them out in bas-relief.

A shelter had been built over the working space and power tools were introduced for the first time. Using compressed air, the rock was scaled off with jackhammers and “paving-breakers,” until most of the overburden had been removed. Subsequent probing into the bone layer was done with smaller chipping hammers, mallet, and chisel. This operation continued through 1954 and 1955 as, slowly and carefully, the extent of the skeletal material was determined. It comprised parts of several large dinosaurs, sufficient in quantity to justify the next step—the construction of a building to enclose the quarry face.

Erection of this unusual structure, the first of its design to be attempted, commenced in 1957 and it was opened to the public in the following year. Now, as one of the many development projects in itsMISSION 66 program, the National Park Service has resumed the delicate work of uncovering this corner of the ancient world and preserving it in-place for all time.

If you stand at the overlook, you will see the Green River, Split Mountain, and a rolling plain to the south that stretches to a hazy line of mountains. To many, it is an unfamiliar land that lies strangely subdued beneath a blazing sun and an intensely blue sky.

That blue sky is the key to the kinds of plants and animals that live in this part of the monument. They live most of their lives under blue sky, and, even when clouds do form over the mountains and drift across the lowlands, the results are disappointing. A high wind, dust and sand, a few drops of rain, and the storm is over.

The climatic conditions under which local plants and animals live are conditions of extremes. On summer days the temperatures may rise above 100°, although the nights are usually cool. During the winter, temperatures may skid to 30° below zero or more. It is not uncommon for the thermometer to remain below zero for weeks on end. But the most influential climatic factor is water—and there is little of it. The total yearly precipitation is a little less than 8 inches! It is interesting then to find such a wide variety of plants and animals that not only survive but flourish under such rigorous conditions.

The methods used by plants in adapting to arid conditions are interesting and varied. The wide-spreading, shallow root system and thick stem of the cactus enhance collection and storage of water. These strange plants are quite plump with stored water in the spring when the snows melt, but they gradually lose this plumpness during the dry summer, and by autumn many seem lifeless.

Other plants conserve their water by minimizing the loss through their leaves. This may be done in a number of ways. The leaves of the spiny greasewood are covered with a waxy substance that inhibits water loss while the leaves of the sagebrush are covered with hairs or fuzz that serve the same function. The leaves of the juniper are scale-like and really don’t look like leaves at all. The most direct method of preventing water loss through leaves is to drop the leaves themselves, and this method is used to a greater or lesser degree by many desert plants. The serviceberry is a good example of this method. In late summer it looks dead, and yet the following spring finds it robed in green and covered with flowers.

In contrast to the frugal habits of the plants just described, the cottonwoods seem lavish indeed. Usually big trees, they spread a canopy of green in whose shade rest birds and animals alike. Have you everrested under a cottonwood? If so, you will remember it as being cool even on the hottest days. Part of the coolness was due to the hundreds of gallons of water which are transpired through the leaves each day. Because cottonwoods require so much water, they usually grow along streams or near springs. Frequently they are seen along dry ravines where their thirsty roots tap the subsurface drainage that lies hidden below. Like the other plants however, when the supply of water becomes inadequate they shed their leaves and wait for the next spring. Fast growing, usually of large size, and wasteful of water where water is dear, the cottonwood seldom lives two hundred years while the twisted juniper on the dry, rocky ledge frequently lives as much as five hundred.

SPLIT MOUNTAIN GORGE.

Inconspicuous through most of the year are the flowering plants. Some of these are annuals—plants that grow from seeds, mature, bloom, produce seeds, and die in the span of a few short weeks. When the snows melt and the sun warms the earth, the seeds that survived the winter germinate. The usually barren hillsides produce spots of green that soon spread to form patches as more and more plants mature. Lupine and locoweed are purple and heliotrope splashescolor along the roads, while the fragrant, white, evening-primrose dots the sandy hillside. Scarlet gilia and Indian paintbrush add a touch of red to the scene, and orange is provided by the mallow.

April, May, and early June provide the best flower show as spring rains supplement the moisture from melted snow. Their races won, their seeds produced, the annuals wither and fade away as the temperatures rise. By the first of July little remains of the splendid show.

Two plants do brighten the desert scene in August and September. Most common is the rabbitbrush, a plant that grows almost everywhere. It is rather inconspicuous except in late summer when its brilliant yellow blossoms turn the whole shrub golden. The other is the bee plant of which there are two species: one has yellow blossoms, and the other has purple. These tall plants grow along washes, stream courses, roads, and irrigation ditches. Their delicate blossoms are always surrounded by insects drawn by the nectar the flowers produce in great quantities.

These, then, are a few of the typical plants. Each has adjusted its needs to those limiting factors—winter cold, summer heat, and aridity. A great number of plants grow on the monument that have not been mentioned here, but they are like the typical plants and have similar ways of meeting the problems of survival.

Many people who profess an interest in nature admit they cannot get very excited about plants. Such disinterest may result in minimizing the importance of plants in the general scheme of nature. That would be a major error. The plants of the world are the foundation upon which other forms of life are dependent. They alone are able to utilize the minerals in the soil and convert carbon dioxide and water to carbohydrates. Because of these abilities, the parade of life has been able to advance only when the plants advance. In the present as in the past, the kinds and abundance of plants set definite limits as to the species and numbers of animals an area may support. Thus, if man changes the plants of an area he will surely change the animals too, whether he realizes it or not.

If you drive to the quarry in the heat of the day you will see only a few of the birds that live here. They don’t like to hunt their food during those hot hours. Frequently a turkey vulture sails majestically above the plains along the Green River. Sometimes so high he appears to be a speck, his telescopic eye searches the ground for the carrion upon which he feeds. Another bird that does not mind the heat is Say’s phoebe. He is usually found perched on a fence post, a wire, or a dead branch waiting for some insect to buzz by. A graceful, short flight, a pop of his beak, and then back to his perch to repeat the cycle again. As he sits motionless, his gray breast and darker gray head and back make him hard to see.

The time to watch birds is in the evening; as the sun sinks and theair cools, they come forth. Small gray-brown rock wrens hop among the boulders near the visitor center. Robins scurry through the leaves in the stream course below the Dinosaur Quarry. Here too, western flycatchers and Audubon’s warblers search among the cottonwoods for insects. A flash of red and white is seen as a red-shafted flicker darts from its nest in the hollow trunk of a tree. The sky is filled with wheeling, twittering rough-winged swallows and white-throated swifts that descend from their nests on the cliffs to feed upon the gnats and other flying insects.

These are the birds that spend the spring and summer here. They raise their families and, young and old alike, depart in autumn when frost kills the insects upon which they feed. As they flee the cold of winter, they are joined by many other birds that make their summer homes at higher elevations or more northern latitudes. Ducks, geese, and swans join the hordes moving southward. So do the various shore birds, bluebirds, and hummingbirds.

But the sagebrush flats and brushy ravines are not left vacant by this wholesale migration, for as the summer residents move out the winter residents move in. The Oregon and gray-headed juncos spend the entire winter here. Great flocks of mountain bluebirds descend from the mountains and piñon jays make the hills resound with their screams. Canada geese and golden-eye ducks live on the Green River and remain until it freezes. The harsh croak of the raven is seldom heard in summer but often in winter.

Few birds live here in winter and summer—the golden and bald eagles, the red-tailed hawk, and the little sparrow hawk. Perhaps the most handsome year-round resident is the magpie with its long, iridescent tail, black and white body, and white patches on its wings. One other resident makes his presence known by his eerie cry on frosty, moonlit nights—the western horned owl. He hunts every night, summer and winter, but is seldom seen. Occasionally he is disturbed upon his daylight roost and as he skillfully dodges through the junipers, he makes a joke of the story that owls don’t see well in daylight.

The mammals that live in the vicinity of the Dinosaur Quarry are almost never seen. There are several reasons for this—almost all of them are nocturnal, are very shy, and most of them are small.

In spite of their retiring habits, they reveal their presence in a number of ways. Patches of bare earth under sagebrush and nearby sandy slopes are crisscrossed with tiny paths beaten into the dust by deer mice. Along the river bank, gnawed tree stumps, a few fresh chips, and perhaps a webbed footprint tell us beaver have been active during the night. The paired hind footprints of the kangaroo rat are common on the hillside. Freshly fallen snow records the preceding night’s activities in perfect detail.

GOLDEN-MANTLED GROUND SQUIRREL

Were it not for the golden-mantled ground squirrels, our evidence of mammals would be mostly indirect. But these little fellows are very much in evidence all day long as they play around the visitor center and in the picnic areas. They are handsome too, with their alert black eyes, cinnamon neck and shoulders, and dark side patches with white stripes. Most people call these ground squirrels chipmunks because both are striped. Actually the two are easy to tell apart; the chipmunk’s stripes run to the tip of its nose, but those of the golden-mantled ground squirrel extend forward only to the shoulder region. Any small, striped mammal seen near the quarry is probably a ground squirrel, as chipmunks are rare here.

The water problem is an ever-present one for the mammals as well as the plants. At first this may seem strange with the Green River so close and several springs in the hills, but most of the smaller animals have very restricted ranges. A deer mouse, for example, seldom travels more than 100 feet from his home burrow in his entire lifetime. The kangaroo rat and the desert woodrat also have limited ranges although theirs are somewhat larger than those of deer mice. The majority of such animals must meet their water needs without springs and seeps. How do they do it?

COYOTE. (COURTESY, U. S. FISH AND WILDLIFE SERVICE.)

BADGER. (COURTESY, U. S. FISH AND WILDLIFE SERVICE.)

The food they eat contains some water. The green vegetation of springtime contains large amounts. Even air-dried foods such as seeds contain some. And these animals don’t need much. Through the thousands of years these little creatures have lived in arid lands, evolutionary processes have altered their bodies and life patterns to fit the conditions under which they must live. Surely one of the most useful and interesting of their abilities is that of utilizing metabolic water. Such water is obtained through oxidation of hydrogen contained in food and is a by-product of metabolism. Putting it another way, during the digestive process these animals are able to manufacture water from the chemical constituents of their food and the oxygen in their blood. The amount of water thus obtained is between 70 and 100 percent of the dry weight of the food eaten. Thus some desert animals are able to live a normal life span without ever taking a drink, and probably many of them do.

Carnivores such as the badger and the coyote get some of theirwater from the animals they eat and may go for days without visiting a spring. But eventually they return to the river or a spring for a drink. This is no special effort as carnivores generally range for miles in search of prey.

Winter is a time of difficulty for most animals. Some of them like the ground squirrels hibernate and sleep the winter away, but the majority must rustle their “daily bread.” Winter storms drive the mule deer down from the high country. Mice tunnel through the snow in search of food. The white-tailed jackrabbit and the snowshoe hare change their coats from brown to white. In particularly hard winters the animals die in great numbers, first the weak and old, then the young, and sometimes even animals in prime condition fail to survive.

The reptiles that make their homes in the Quarry Area of Dinosaur National Monument are few in number. The rattlesnake is rare and seldom seen. The only common snake is the bull or gopher snake. This snake can appear very threatening as it swells its body and hisses loudly, but it is not poisonous. Gopher snakes climb well and are often seen in trees where they hunt for eggs and young birds.

Two lizards are commonly seen here during the summer. The side-blotched lizard is about 1¾ to 2⅛ inches long with a somewhat longer tail. These small brown lizards are frequently seen among the rocks near the parking and picnic areas. The name, side-blotched lizard, is taken from the black or bluish-black area behind the foreleg of the males. These lizards are also called brown utas.

The western whiptail is also a very common lizard. As its name suggests, it has a very long slender tail which it lashes from side to side as it runs. This lizard is easily distinguished from the side-blotched lizard by its larger size, longer more slender tail, and the presence of bars and spots of black upon its back. In late summer, junior-sized young whiptails appear, but their 3-inch total length is unimpressive compared to 8-inch adults. The young are quite handsome with pleasing body colors and bright-blue tails.

Often lizards are seen whose tails are missing. When the tail is pulled or injured it can be shed by its owner. The shed tail may wriggle for several minutes and attract the predator’s attention while the lizard escapes. The tailless lizard soon grows another one that is usually recognizable by its subdued or otherwise different color pattern. Sometimes the broken tail does not fall off so it and the new tail form a fork.

In summary then, we see that this apparently lifeless desert does support a wide variety of living things and a great number of individuals. Some of them, the plants and small animals, live here all year round while others, such as most birds, live here only part of the time. But whatever the length of stay, all living things must adapt themselves to existing conditions at the time of their stay. If they cannot adapt to static or changing conditions they must move or become extinct.

Some 60 million years have passed since the dinosaurs ruled the world. In that time mountains have risen, wasted away, and risen again. Glaciers have come and gone. Many species of plants and animals evolved and passed on to extinction. Every life form meets the test—adapt or die. That test is as real to the dusty lizard basking on the quarry face as it was to the dinosaurs whose bones you came to see.

Back to Index Next