TRANSLATION:
HIPPARION-FAUNA FOSSIL LOCALITIES IN PAO-TE-SHIEN, NW-SHANSI
(continued)
The above mentioned deposits are, however, absent from most of the area
studied. The Carboniferous is covered by the Hipparion Clay, sometimes directly.
Most often, however, there is a conglomerate bed of varying thickness (sometimes
up to 4 m thick). The cobbles and the matrix are of calcium carbonate. The
stratification is horizontal. Nonetheless, the conglomerate formed before the
Hipparion Clay. Fossils cannot be found in it. Topographically the conglomerate
can be recognised because it forms a layer between the highest slate-like
members of the Carboniferous unit and the red clay. Being harder than either of
these, it forms a frequently undercut projecting cliff in the ravines. It is
noteworthy that its calcareous matrix is grey, while the carbonate layers in the
Hipparion Clay are cemented by the red clay.
Above this lies the Hipparion Clay, red clay similar to that of Pikermi in
every respect. The maximal observed thickness is about 65 m. A subdivision into
different horizons cannot a priori be carried out because the commonly occurring
shingle beds are not sufficiently continuous. However, they demonstrate that a
horizontal stratification is present. Layers of carbonate concretions occur
sparsely. A fossil-rich horizon appears in this clay about 1150 m (cf. the map).
It is mined by the local population. The fossils of the fauna characterized by
Hipparion Richthofeni Schl. appear in “nests,” in which usually a great
number of bones of the most different forms occur together in a restricted
space, typically from 0.5 to 2.0 cubic meters in volume. Complete skeletons were
not found, but more or less complete limb bones and parts of vertebral columns
are present. Also, carnivore skulls appear with their mandibles attached, and
this is also the case with the rhinocerids. These fossils are quite heavily
mineralised, the marrow cavities are usually filled with crystals of calcite ,
and the surface appears pure white. The clay is infiltrated and hardened by
calcite in the immediate vicinity of the fossil “nests.” At times small sand
lenses are embedded in the clay. They usually contain small fragments of bone.
Often a certain stratification can also be recognised within the fossil “nests.”
In addition to the shingle layer, the clay also contains isolated cobbles of
small size.
As
already mentioned, the fossil “nests” all lay at one level, although there can
be vertical variation of about 5 m, and, indeed, two fossil nests may lay one
directly above the other, separated by a 1 m gap. Of the total thickness of
Hipparion Clay, 25 m thus lie under and 35 m above the fossil level (see
Figure 5). As for the fossil content of
the nests, it is everywhere the same, i.e., no forms are limited to certain
localities only. However, it must be noted that especially locality 30 at
Tai-Chia-Kou [Daijiagou] contains almost exclusively larger ruminants and
carnivores, in addition to rhinocerids, which are common everywhere. In
Yang-Mu-Kou [Yang-Mu-Gou], locality 49, a fossil nest unusually rich in
carnivore fossils was found. On another occasion, the remains of at least four
pigs, which are otherwise quite rare, were found together in the smallest of
spaces. The west-east extent of the region is 5.5 km, and the north-south extent
is 5.0 km. The clay is covered by loess, which can reach a very considerable
thickness. Once it covered the whole region, but in the course of time, the
post-Tertiary streams have carved themselves in, so that the topography has
by-and-large remained unchanged (see profile A-B,
Figure 5). In support of this argument,
it can be stated that in the side valleys, which are naturally younger, the
contact between the Hipparion Clay and loess is always parallel to the modern
surface. Fossils are not known from the loess in this region. Finally, the
hilltops are mostly covered with eolian sand, a circumstance explained by the
proximity of the Ordos Desert.
The question of the formation processes of the fossil nests in the Hipparion
Clay is difficult to answer. It is to be kept in mind that the localities lie in
one horizon, where differences in the level of nests can be up to 5 m. This
indicates that at the time of deposition, the surface in the region was almost
horizontal. That the process of deposition was affected by running water can be
seen from the way the fossil nests are situated, separated by unfossiliferous
spaces in-between, with the occurrence of small sand lenses as well as levels of
bone fragments. The preservation of the fossils indicates they have not been
transported over long distances. And now the author must thank Dr. J.G.
Andersson for making the author aware of his observations of how variable the
flow of (temporary) water channels is today in the Mongolian steppe. It is thus
quite possible, that in the region, which was almost flat at the time of
deposition of the fossil beds, the conditions were similar, so that in the
course of years, maybe even during a single rainy season, the fossils were
transported together from nearby areas by the shifting water channels. Thus, all
the nests cannot be strictly contemporaneous, which also explains the
differences in level already mentioned, likewise the appearance of two nests
above each other. Finally, as for the constrained distribution of the fossil
occurrence to only a fraction of the entire red clay deposit, also here the
author wants to refer to personal communication with Dr. Andersson. According to
Dr. Andersson, some areas in the steppe at certain times could, through a
favourable combination of topographic and climatic conditions, support an
especially lush vegetation, which naturally caused a concentration of animals in
these areas. In the surroundings of Chi-Chia-Kou, we would thus see the remains
of such an oasis. The assumption of a catastrophe, as proposed for example by
Prof. O. Abel for the Pikermi deposits, is not considered likely by the author,
because of the absence of fractures in the remains and the topography at the
time deposition. Neither can the reason for the deposition be a larger
watercourse. Although this could be argued in the case of locality 30, the
irregular distribution of the localities and the fact that in single mines there
are no continuous fossil layers, cannot be brought into harmony with such a
view.
Hereby an attempt will be made to characterise the fauna, as far as possible,
before preparation of the collections. Attention will also be paid to the
material collected earlier by Dr. Andersson’s Chinese collectors. The
perissodactyls
are represented by the already mentioned and quite common Hipparion
Richthofeni, Anchitherium, and rhinocerids, which are
classified to six different species according to a letter from Prof. Wiman. Four
of them belong to the genus Teleoceras, one to the genus Aceratherium,
and finally the most interesting form to Sinotherium Lagrelii, Ringström.
The rhinocerids, because of their size and abundance, are by far the most
notable element of the fauna. The artiodactyls are well represented both
in the number of species and of individuals. There are cervicorns of
various sizes; however, they are not so common. A host of different antelopes
occurs in great quantities; one form of pellicorn was named
Chilinotherium Tingii by Prof. Wiman. The bunodonts are represented
by two species of pigs, one being the same size as Sus erymanthius of
Pikermi, the other being considerably smaller. The number of carnivore species
is quite significant. A gigantic hyena is the most common. Viverrids are not
uncommon. Felids are also found, including the rare Machairodus.
There is also a skull that belongs either to Hyaenarctos or Arctocyon.
Of mustelids, there are at least two species, and finally a skull
resembling that of a badger should be mentioned. Elephants are
represented by Mastodon, Stegodon, and Elephas. Of rodents there are only two
species: a beaver-like mandible and a skull of the size of Sciurus.
Of bird fossils, only the pelvis of a struthionid is known. It is
considerably larger than that of the recent African Ostrich.
Of reptiles there are at least two species of tortoises, one testudinid
and one
emydid.
