Deinotherium thraceiensis sp. nov. from the Miocene near Ezerovo ...

Scaphoideum (radiale) (Fig. 10 A, B No.1). Long,
narrow and almost flat with rough lateral surface.
Two large facets on the medial surface. Proximal
contacts lunare, distal – centrale. A facet on the
very proximal end, articulating with the distal end of
the radius. The lower end of the scaphoid articulates
with the fifth metacarpal.
Lunare (Fig. 10 A, B No. 2). Triangular. Anterior
surace rounded. Two concave facets in the proximal
part, articulating with the distal parts of the ulna
and radius. Lateral larger. Two slightly concave facets
in the distal part articulate with magnum and
centrale. The lateral facet of the scaphoid and the
medial of the cuneiform are divided in the middle
by a crest for the attachment of sinews.
Cuneiforme (ulnare) (Fig. 10 A, B No. 3). The bone
has a peculiar form. It is flat. Medially, a large processus
turns down to the proximal part of McI. On
the inner side of this processus is os unciforme, which
is part of the distal row. In the proximal posterior
part there is a small facet for the pisiform. The anterior
and the medial surfaces of the bone are rough.
Pisiforme (Fig. 10 A, B No. 4). Smallest bone of the
wrist. Its anterior part contacts the ulna and the cuneiform
by two pronounced facets. Rounded in the
other parts. Slightly curving downward at the very end.
Magnum (Fig. 10 A, B No. 7). Almost square, elongated
anteriorly. Situated in the middle of the distal
row, between os unciforme and os centrale. Two facets
on the distal part. Medial larger, touching the
proximal part of McIII, the other touches a small
part of McIV. Surface rough in the anterior part,
and the facets for articulation with os unciforme and
os centrale are concave in the middle – this is the
place where sinews are attached.
Unciforme (Fig. 10 A, B No. 8). Largest of the distal
row. Tetragonal. Slightly rounded anteriorly, elongated
posteriorly. The proximal acet for the cuneiform
is large and medially inclined. Two facets in
distal end, medial larger and contacting McII, lateral
– McIII.
Centrale (Fig. 10 A, B No. 9). Although slightly elongated
in the ends, it also has a square shape. Situated
between the magnum and the scaphoid. Distal
surface slightly concave, entirely lying on the proximal
articular surface of McIV. Facet for articulation
with the magnum concave in the middle with a place
for the attachment of sinews.
Metacarpus (Pl. XVII; Fig. 10 A, B; No. I, II, III, IV
and V). Here, as with the wrist, more bones are preserved
from the left forelimb.
First metacarpal McI. Long, wide and flat. Facet for
articulation with the cuneiform and the unciform
narrow and long. Slightly convex in the proximal end,
slightly concave in the middle. Large rounded articular
surface on distal end. Strong sinew processes in
posterior and anterior parts.
Second metacarpal McII. Also long, but narrow.
Rounded in the anteriror part, strongly elongated posteriorly,
gradually becoming narrower. Facet for unciform
in the proximal end long and wide. Laterally to it
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a facet for McIII, smaller than the first. Slightly concave
diaphysis, distal end widening with a large articular
surface for the first phalanx of the second digit.
Sinew processes strong and on both sides of the bone.
McIII and Mc IV resemble McII. Facets in proximal
parts for magnum, unciform and central.
McV is a mirror image of McI. Facet for the scaphoid
in anterior part.
Phalanxes (Pl. XVII and XVIII; Fig. 10 A and B No.
1, 2 and 3).
First phalanx of the first digit PH-I,1 is medium-sized,
with arounded, elongated flat shaft. Deep articular
surface on proximal end for the distal surface of McI.
Phalanx rounded in posterior part. Narrowing diaphysis,
distal end thicker and wider. Articular facet
for the next phalanx rounded and convex. Above and
parallel to it the sinew concavity, weakly pronounced.
First phalanx of second digit PH-II,1 resembles McII.
PH-III,1 and PH-IV,1 do not differ from PH-II,1, but
PH-V,1 is a mirror image of PH-I,1.
Second phalanx of the first digit PH-I,2 is smaller
than the other phalanxes. In its posterior part, by the
sinew crests, it is more convex, and concave in the
middle. Proximal articular surface concave, distal
rounded and also concave in the middle.
PH-II,2 is also smaller than the other phalanxes.
It looks like a second phalanx of a horse, i.e. short
and wide. Very thick proximal end, thinner in the
middle, thick again distally at the articular surface.
PH-III,2 and PH-IV,2 look like PH-II,2. PH-V,2 is
a mirror image of PH-I,2.
PH-I,3, PH-II,3, PH-III,3, PH-IV,3 and PH-V,3,
third phalanxes of all digits have almost the same
structure. Only their size is different, so we’ll describe
just one phalanx.
D. thraceiensis sp. n. has a long and large hoof.
In its proximal part it is slightly convex, in the middle
and in the distal part – concave. Large articular
surface for the second phalanx on the posterior part.
Slightly rounded in front. Measurements of the digits
are given in Table 17.
Height of the entire manus (wrist and digits) is
460.0 mm; diameter with spread digits – 902.0 mm.
Comparison
All carpal and metacarpal bones, as well as the phalanxes
are similar in D. giganteum Kaup, D. gigantissimum
Stefanescu and D. bavaricum H. v. Meyer.
No taxonomically significant differences were found.
Maybe only the hoofs show some. It was already said
that in D. thraceiensis sp. nov. they are long. Their
walking surface is flat and concave in the middle
which means they were touching the ground with all
their surface. In the other species the hoofs seem to
touch the ground in most cases only with their anterior
part.
Pelvis (Pl. XIX, Fig. 1; Pl. XX, Fig. 1). Both hipbones
are entirely preserved.
The wing of the hipbone is a wide S-shaped curved
plate, anteriorly rounded, with a pronounced pubic