Mystery Solved

Manawatu Times, Volume 60, Issue 196, 21 August 1935, Page 13

Mystery Solved

STRANGE creatures GOBI SHOVE L-TUSKERS DESERTS THAT WERE SWAMPS WASHINGTON, July 15. About 20,000,000 years ago, some of the strangest creatures the earth has known inhabited the Gobi desert of Central Asia. They were Hie shoveltusked mastodons—elephants whose lower jaws were elongated in the form of shovel's, about the size of the ordinary eoal scoop. These curious loolh formations obviously were in some way associated with the food habits of the animals, but the association has puzzled palaeontologists, because, even when the creatures were in their heyday, Ihc land was desert like, and food must have been scarce. Where could au elephant have found enough to cat in this desolate land to have survived at all—to say nothing of shovelling food into its stomach in scoopfuls? The mystery was increased by the fact that no fossil plants of any kind were found associated with tire elephant bones. The problem has been solved by Dr. Ralph W. Chaney, palaeontologist of the Carnegie Institute of Washington, through the identification of plant remains found in rock formations of 'about the same period in the same general region. The animals lived on water-lilies and other succulent swamp plants, which they scooped up by the roots and swallowed, mud and all. The fossils found in the Gobi rocks by the Swedish explorer, Sven Hedin, and sent to Dr. Chaney's laboratory for identification, were all close relatives to the vegetation which would be found in a swamp to-day.

When the shovel-tusked bones were first brought to America, Dr. Henry Fairchild Osborne, of the American Museum of National History, suggested that the elephants must have been swamp-dwellers. Their strange dental

apparatus was not adapted to any other form of feeding. Tho anatomical adaption had become necessary with Ihc disappearance of tho abundant herbage upon which elephants arc accustomed to feed. Causes of Disappearance.

‘•The probable causes of tho dispcarance of the shovlc-tuskers at the close of tho Tertiary period," Dr. Chaney writes in a report of his work, “was the drying up of the lakes of Central Asia and western North America, resulting in the temporary elimination of the plants on which tho animals fed. Any animal as highly specialised as these elephants, with jaws and teeth only suited to a special sort of foodgctling, faces tho certainty, of extinction if living conditions change so as to destroy its food supply. “In arid regions of these continents, in modern times, lakes even many square miles in extent have been known to become dry during a series of rainless years. Goose Lake, extending across the border of north-western California into Oregon, is shown on most maps as a body of water JO miles in length and 10 miles wide. As a result of several arid years following 1920, this lake was so nearly dry in 19J0 that there was exposed oil its bottom the wagon tracks of tho "forty-nin-ers," who crossed this region during an earlier period of drought. “Tho accounts of these hardy migrants, telling of a climate- having less rainfall than during tho years following, have been considered as the exaggerations of old-timers. The uncovering of their wagon tracks on the bottom of Goose Lake proves decisively that a series of arid years proceeding IS-19 resulted in its almost complete disappearance. Then followed nearly SO years during which rainfall filled the lake basin. Within the past decade the arid conditions of 1549 have returned, and the size of the lake again has been greatly reduced.

■‘Similar reduction in rainfall has been responsible for the drying up of several lakes which 1 visited in the Gobi Desert in 1925. Tsagan Nor— White Lake in the language of 111? Mongol—had an area of six square miles when it was first visited by the Central Asiatic Expedition in 1922. Three years later it had sunk to a third of that size, and a month after that the water had gone, leaving a flat of mud, white with salt. An old Mongol who had lived near the lake all his life reported that GO years before it uad been dry. This was about the time of the earlier drying up of Goose Lake in California. “It is clear that recurrent climatic changes have reduced the size of lakes in the more arid portions of Asia and North America during the past century and it may be supposed that similar changes occurred iu the past. With the consequent, destruction of the aquatic plants it came about, many millions of years ago, that the gradual extinction of the race of strangely built elephants took place. The only evidence of their having lived at all is the finding of their petrified bones

buried in the muds and sands of the ancient lakes of Asia and North America. This record of fossil plants of aquatic types, which appear to have served as their food, completes tho picture."

Plants as Rain Gauges Much more than fossil animals, Dr. Chaney says, fossil plants serve as “thermometers and rain gauges” of the remote past. They are more immediately responsive to climatic changes. Animals, if they are not too highly specialised, can change their lood habits and can linger on for many generations in an. inhospitable environment. But the plant is directly dependent on the immediate conditions of. temperature and water supply. The fossil vegetation collected by tne Swedish expedition shows tbat there has been little change in the climatic conditions of the Gobi desert since the days of the shovel-tuskers. The predominant vegetation to-day consists ot low, bushy poplar and elms around the rare watering places. Travellers, ever since the days of Marco Polo, have described much the same sort of scenery.

Fossil' imprints of leaves and stems of the very same poplars and elms were fouud in rocks laid down 20,000,000 years ago. They arc typically plants of a cool desert. The size of both trunks and leaves is limited by tho drywinds which sweecp almost constantly across the plateau. The shovel-tuskers probably did not exist in great numbers. Each auinial required au cuonnous food supply aud, at the best, the supply of aquatic plants in the shallow lakes must have been small. On the other hand, the animals must quite frequently have become mired in the mud of the lake bottoms —an ideal sort of death for the formation of fossils. Iu one place bones of more, than 20 animals were found together. Through the centuries the mud was compressed into rock, thus preserving the skeletons. —N.A. N.A.