Sloth tracks in the Carson prison

In much the same manner that a print of man's hand or foot leads to individual identification, so fossil footprints reveal the kinds of creatures who unwittingly have left their mark on the sands of time. Some four-footed animals, whose tracks have been uncovered in ancient rock formations, furnish for posterity only this evidence of a former existence. On the other hand, tracks like those of a dinosaur convey something more tangible. Scientific fact and popular fancy have done much these days to make the layman dinosaur-conscious. But realization that particular tracks were left by reptiles now long extinct comes largely from demonstration that the skeletal parts and bodily form of these animals correspond exactly to those surmised from the imprints

Ice Age Elephants of the Channel Islands

Of the small company of land mammals native to the Channel Islands of Southern California none reaches large size, and, if we exclude aboriginal man and his dog, the largest is the fox. This interesting creature, once more numerous than it now is, exists under a variety of conditions on the several islands and may be seen occasionally searching for food along the seashore or living in cactus patches, brushy ravines, and on the open slopes of hills to an elevation of more than 2,000 feet. It seems to lead at present a solitary life. The island species was long ago recognized by biologists as a distinctive type, related to the mainland gray fox rather than to the kit fox and red fox. Six races have now been identified, one for each of the principal islands comprising the Channel Island group

Reality: Each Day I Escape It

I was dreaming. But the realness of my dream with frighteningly vivid and at the same time morbid, and as it progressed it took on nightmarish proportions..

A further study of the Quaternary antelopes of Shelter Cave, New Mexico

Since the preliminary description of Tetrameryx? conklingi from Quaternary deposits in Shelter Cave, New Mexico, additional materials of this interesting antilocaprid species have been obtained in the course of further excavations in the cavern by Mr. R. P. Conkling and by members of an expedition from the Los Angeles Museum. The collections include, moreover, the cranial portion of the skull to which the horn-cores of the holotype belong. Definite association of these specimens permits therefore a fuller description of the type

Titanothere remains from the Sespe of California

Until very recently, all occurrences of American titanotheres have been known from either Eocene or lower Oligocene horizons of the Rocky Mountains and western Great Plains. Absence of any trace of these mammals in Tertiary deposits located in the region to the west of the Cordilleran Province lends considerable interest to the presence of titanotheres in one of the Sespe horizons of southern California

Hyaenodontidae of the upper Eocene of California

Since the announcement(1) of the discovery of upper Eocene mammals in the Sespe deposits north of the Simi Valley, California, excavations have been continued in these beds, particularly at Locality 150 C. I. T. Vert. Pale., by field parties of the California Institute. Recently an opportunity has been afforded the writer to compare a number of the mammalian types found here with related forms known from the late Eocene and Oligocene. This has permitted a more precise determination of the genera and species than was attempted in the original statement. It is planned therefore to present in this and in subsequent papers brief descriptions of individual types, reserving a fuller discussion for a monographic treatment of the Sespe faunas

A Law of Nature?

Is there an overriding principle of nature, hitherto overlooked, that governs all population behavior? A single principle that drives all the regimes observed in nature - exponential-like growth, saturated growth, population decline, population extinction, oscillatory behavior? In current orthodox population theory, this diverse range of population behaviors is described by many different equations - each with its own specific justification. The signature of an overriding principle would be a differential equation which, in a single statement, embraces all the panoply of regimes. A candidate such governing equation is proposed. The principle from which the equation is derived is this: The effect on the environment of a population's success is to alter that environment in a way that opposes the success.Comment: Revised equation-numbering to correspond to published versio

Eocene Amynodonts from Southern California

Introduction.-Since the description [1] of a skull of Amynodontopsis bodei and of a lower jaw referred to this species from the uppermost Eocene, further dental parts have become available for study from localities in the Sespe. These furnish additional characters of value in recognizing the species represented in western Eocene deposits. Now also available is a fragment of skull with cheek-teeth from the Poway Eocene of San Diego County, California. This specimen possesses special significance because it permits a comparison with related forms in America and China. It is likewise of interest because it differs from the amynodonts of the Sespe and is clearly an earlier type