I think he (Mikelson) buys the raw materials from the locals who know where to find it. Somewhere on his site is an extensive article on an island where there are stacks and stacks of mammoth and other creatures bones...time out, I'll go hunt it up....Here's an excerpt from the text on that page:
Hedenstrom explored Liakoff's island in 1809 and discovered that". .. the quantity of fossil ivory . . . was so enormous, that, although the ivory diggers had been engaged in collecting ivory from it for forty years, the supply seemed to be quite undiminished. On an expanse of sand little more than half a mile in extent, Hedenstrom saw ten tusks of mammoths sticking up, and as the ivory hunters had left these tusks because there were still other places where the remains of mammoths were still more abundant, the enormous quantities of elephants' tusks and bones in the island may be imagined?' Indeed, a number of explorers reported that after each ocean storm the beaches were littered with bones and tusks which had been lying on the sea bottom and brought to shore by wave action.
The elephant or mammoth bones and tusks were the most spectacular finds primarily because they were so plentiful and consequently they attracted public attention the most. The islands contained an incredible mixture of bones of many extinct and some living species of mammals. Mixed with the animal bones were trees in all kinds of conditions. Whitley quoted some of the Russian explorers as reporting "it is only in the lower strata of the New Siberian wood-hills that the trunks have that position which they would assume in swimming or sinking undisturbed. On the summit of the hills they lie flung upon another in the wildest disorder, forced upright in spite of gravitation, and with their tops broken off or crushed, as if they had been thrown with great violence from the south on a bank, and there heaped up?
And here's a link to read the rest of it if you like. It brings some pretty wild visions of what might have caused such a thing to happen so long ago in my own pore cashew sized brain.