Historical geology

Natural History of Sakhalin

Ammonite. This fossilized shell is about 70 mln. years old.

Desmostylus hesperus.

Fossilized skeleton (copy) of an extinct mammal inhabiting Northern Pacific shores in the mid Miocene (12–15,8 mln. years ago). The animal was described for the first time by O. Ch. Marsh — famous discoverer of dinosaurs — who was able to describe it having only one tooth at his disposal. Teeth in Desmostylus hesperus resemble a bunch of columns. The animalТs name is based on its teeth structure. Desmos means bunch or stack, and stylus means pillar or column in Greek.
Desmostylus hesperus skeleton, the copy of which is displayed in the museum, was found by chance. In July of 1933 Nagao Takumi, Hokkaido University professor, was visited by a man who was engaged in shipping timber from Sakhalin island. He brought in a strange looking fossil — a skull of an unknown animal — which had been found by chance to the north-west of contemporary town of Smirnykh. Professor Nagao identified the skull as belonging to the Desmostylus species based on the teeth shape. Without delay he got together a group of scientists and left for Sakhalin. Unfortunately, that year the bones from the fore part of the body only were collected, but in 1934, in the second expedition, the remaining bones were found. The fossilized bones were shipped to Japan and processed in the University of Hokkaido. It was for the first time in the world that the whole skeleton of the animal was found. Paleontological community as a whole was taken by big surprise. It became clear that Desmostylus hesperus had well developed fore and hind limbs and also hands and feet well suited for rowing. (before then the Desmostylus hesperus were thought to have flippers). The animals apparently used long shovel-like tusks for ploughing bottom sediments in search of benthic organisms, such as: shell-bearing mollusks, crabs and echinoderms.
Desmostylus hesperus reached 3 m in length and were as heavy as 1200 kg. The animals led coastal life and were good swimmers and divers, taking rest on coastal cliffs. During their reproductory period they stayed on the coast, however moving on land in a rather clumsy way.
Warm shallow water areas of the Sea of Japan and those of the Western Sakhalin islands with their shallow water shelf and numerous inland and coastal water bodies of the other parts of the Paleo-Sakhalin were favorable habitat for Desmostylus hesperus in the Neogene Period.
Reconstruction of the skeleton was performed by the professor Nagao Takumi together with taxidermist Sinoda Syudziro. It was the first reconstruction of the Desmostylus skeleton ever. Based on the teeth size, Nagao described the animal above-mentioned as a new species — Desmostylus mirabilis. Today it is accepted that the attribution to a different species was caused only by the individual features and now the skeleton in question is attributed to the Desmostylus hesperus species.
During the World War II in the Pacific the skeleton was taken to pieces and buried in the ground to be preserved. The skeleton was reassembled after the war by the professor Kamei Setsuo.
The copy of the Desmostylus hesperus skeleton was presented to the Sakhalin Regional Museum as a gift by the Association for Bilateral Relationships of Museums of the Northern Regions and Hokkaido on July 26, 2006.


Exposition of the museum

Ground floor
Historical geology
The fauna of the Far Eastern seas
First floor
Plant and animal life
Ancient cultures and indigenous peoples
In the depths of the ocean
Second floor
Postwar period. Modernity
The discovery and development of the islands
Before the war. World War II
Penal servitude

Kommunisticheskiy prospekt - 29
Yuzhno-Sakhalinsk, Russia, 693010
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