ECO S Eugene

Economic S Eugene

Dinosaurs Evolution – Buffalo New York

Dinosaurs Evolution article imageDinosaurs Evolution – The two most important problems involved in the Theory of Evolution are the origin and characteristics of new species and the struggle for existence. We know that there are thousands of distinct forms of life existing in the world today, and the record of the rocks, corroborated by countless observations over the entire surface of the earth, shows that there have existed, flourished, and passed out of the picture many thousands more.

While the word extinct is ordinarily applied to all such vanished species, it must be remembered that in many cases present-day animals bear such a close resemblance to fossil forms that we can only assume them to be direct descendants, while other vanished groups are not represented by any existing animals. Of this latter class are the dinosaurs, which appeared in the early Triassic, flourished through the Jurassic, and apparently passed at the close of the Cretaceous, about a hundred million years ago.

These grotesque animals, in spite of their mammal-like appearance, were true reptiles. They breathed air through lungs and produced a large egg which may or may not have been laid before hatching, in this latter respect resembling the modern snakes. Their bodies were covered with scales or armored with bony plates. While it is natural to suppose that they were cold-blooded, this point has not been definitely settled. We do know that they possessed neither feathers nor hair, devices found essential among the warm, blooded animals of today. We may be sure, from the teeth and the other preserved structures, that there were flesh and plant-eating types.

Scientists have reported their remains over practically the whole world, and it is reasonable to assume that in areas of the proper outcrop where dinosaur fossils have not been found this absence of evidence is due to lack of sufficient investigation.

While most of them were purely terrestrial, certain groups give conspicuous evidence of amphibious habits. In size they varied from that of a domestic cat to a length of over eighty feet and a weight of probably forty tons, greater than any living inhabitant of the earth except possibly a few of the larger whales.

Dinosaurs Evolution

The new exhibit, in its proper location in the Hall of Evolution, was designed primarily to illustrate the theme that certain animals appeared during geologic times, achieved a maximum in bulk and specialization, and were unable to survive in the final struggle. Immediately preceding it we represent the graphic story of the rocks and directly following are a number of forms whose extinction has occurred within the memory of man. This exhibit must not be considered as presenting anything approaching a complete story of the dinosaurs. It shows but a few species and those of a definite period, the upper Cretaceous. While we cannot assume that the forms in the group were contemporaneous or were represented in one locality, this may easily have been the case, as they undoubtedly overlapped considerably.

In the left background we see the trachodon or duckbill and the corythosaurus. The trachodon is one of the best known of the dinosaurs, many of the great museums of the country having complete mounted fossil skeletons. Its length did not exceed thirty feet, and we believe the animal had considerable ability as a swimmer. Science has discovered several specimens of this animal in which not only the skeleton but also the skin has been preserved. The forefeet were webbed but it is not known whether the hind members were similarly constructed.

The corythosaur was closely related to trachodon but is easily distinguished by the unusual helmet-like structure on the top of the head. Both of these animals were strict vegetarians. No animal, past or present, has ever been provided with a greater number of teeth than the trachodon.

In the foreground we see the tyrannosaur, apparently about to engage in battle with the triceratops. The first species represents the most terrific flesh-eating creature this earth has ever known. Nearly fifty feet 1ong, its bulk must have equaled that of the largest living elephant. A conspicuous character of this animal is the insignificant proportions of the front limbs. Its very size would indicate a lack of quickness and agility, and its prey was undoubtedly confined to its ponderous and slow, moving contemporaries of the vegetarian type. We must remember that the brain capacity of these reptiles was very small and their movements largely automatic and instinctive.

Dinosaurs Evolution

The triceratops, a purely herbivorous creature, in its general aspect suggests more than anything else a huge rhinoceros, an impression which the three hornlike prominences of the head do little to dispel. In this animal the head, instead of being small, represents from one fourth to one third the size of the body. Of particular interest is the backward extension of the skull into a widely expanded frill for the protection of the neck. There are evidences, in the form of areas for muscle attachment, indicating an enormous strength in the fore part of the body. In addition to the frill and the three horns, from which the name is derived, this animal possessed a sharp cutting bill, like that of the turtle. Undoubtedly these structures in this herbivorous animal were largely for defense, as there are many instances in the fossil remains of broken and healed bones.

In the background to the right we note the struthiomimus and the monoclonius. The monoclonius was a sort of a first cousin to the triceratops but possessed a body of a somewhat more ornamental character. Struthiomimus was a more slender-lined and agile form, herbivorous in habit and taking its name from its resemblance to the modern ostrich.

The vegetation shown in our exhibit suggests a semitropical and rather damp environment. There is no evidence of anything resembling our modern deciduous trees.

There has been much speculation among scientists as to the reasons for the gradual passing out and extinction of these very interesting animals. We are told that in the rocks of the Tertiary period not a single trace of the dinosaurs can be found. They may have completely destroyed each other through continual warfare, or smaller animals may have wrought havoc by consuming the eggs. It is an accepted law, that over-specialization, whether it be in size or structure, is a factor in limiting survival.

It may be that these animals reached a size which required more food than their enormous bulks could secure within the limits of their range. If, for example, a swallow in its flight to capture a gnat consumed more energy than was furnished by the gnat, the swallow would have to change its diet or fail to survive.

Possibly the most satisfactory explanation is the theory that “with the extensive changes of land which mark the close of the Mesozoic came the great draining of the inland Cretaceous seas, along the low-lying shores of which the dinosaurs had their homes and with the consequent restriction of old haunts came the blotting out of a heroic race.” Thus ends this Museum of Science dinosaurs evolution article.