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NUMBER 89 15
Measurement
total length
proximal width
proximal depth
distal width
distal depth
midshaft width
midshaft depth
Tibiotarsus
total length
proximal width
proximal depth
distal width
distal depth
midshaft width
midshaft depth
Tarsometatarsus
total length
proximal width
proximal depth
distal width
distal depth
midshaft width
midshaft depth
mean (n)
69.0(1)
18.8(1)
11.8(1)
16.9(1)
12.6(1)
6.9(1)
7.8(1)
-
-
-
-
-
6.0(1)
5.8(1)
80.5(1)
14.8(1)
13.4(1)
-16(1)
-11(1)
5.95 (2)
5.30(2)
A. (M.) kervazoi
range
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
5.2-6.7
4.8-5.8
Humerus UCB FSL-330517 (Figure li) also shows a slight
difference compared with A. aegyptiacus. On the anconal face,
below the head, and on the medial side of the pneumatic fossa,
there is a proximodistally elongated depression that does not
exist in A. aegyptiacus. Moreover, on this humerus, the pneumatic
foramen, which opens at the bottom of the pneumatic
fossa, has a small surface compared with that of the fossa,
whereas in A. aegyptiacus the pneumatic foramen occupies all
the surface of the pneumatic fossa.
On the whole, because of the great similarities between the
Reunion sheldgoose and the living Egyptian goose, we think
that Mascarenachen must be considered a subgenus, and that
the Reunion form can be designated as Alopochen {Mascarenachen)
kervazoi (Cowles), new combination. This subgenus includes
only the type species, kervazoi.
Although the size of A. aegyptiacus is highly variable (Table
6), the mean dimensions of A. (M) kervazoi are smaller than
those of A. aegyptiacus. The size of the Reunion sheldgoose either
is at the lower limit of variation in A. aegyptiacus or is
slightly smaller.
COMPARISON WITH FOSSIL FORMS.—An extinct sheldgoose,
Chenalopex sirabensis, was described by Andrews (1897) from
Holocene deposits in Madagascar. Because Chenalopex is a
synonym of Alopochen, it is now known as Alopochen sirabensis
(Brodkorb, 1964). It varies widely in size, so Andrews divided
the material into two sets that he attributed to males and
females. In a large amount of material at MNHN, the size of
the bones also varies according to the locality, the material
TABLE 6.—Continued.
mean (n)
71.04(11)
17.31(10)
12.01 (10)
17.60(10)
13.38(10)
7.24(10)
7.70 (9)
133.30(11)
14.52 (9)
17.42(9)
14.01 (10)
15.33(10)
7.44(10)
6.14(9)
86.42(11)
15.25(10)
13.23(10)
16.17(10)
11.96(9)
6.13(10)
5.90(10)
A. aegyptiacus
range
65.0-78.0
14.9-20.6
11.0-13.7
15.5-20.1
12.1-15.0
6.4-7.9
6.1-9.0
124.2-146.2
12.8-17.0
16.0-18.7
12.6-15.6
13.7-17.6
6.5-8.3
5.3-6.9
77.0-96.6
14.3-16.1
12.1-14.6
14.6-18.7
10.9-13.4
5.3-7.0
5.2-6.6
mean (n)
72.64(12)
-
-
-
-
8.03(12)
-
136.97(19)
-
-
-
-
7.55 (19)
-
86.03(17)
-
-
-
-
6.01 (17)
-
A. sirabensis
range
66.8-78.4
-
-
-
-
7.3-9.0
-
123.7-144.8
-
-
-
-
6.2-8.7
-
76.5-94.3
-
-
-
-
5.3-7.3
-
from Antsirabe being larger than that from Ankazoabo. We
present measurements of specimens from both sites (Table 6)
without trying to separate males and females. Bones of A. sirabensis
on average are larger than those of living A. aegyptiacus
and are thus distinctly larger than A. (M) kervazoi.
Another extinct species, Sarkidiornis mauritianus, was described
by Newton and Gadow (1893). The holotype is a left
carpometacarpus with a very projecting alular metacarpal ending
in a callosity. Andrews (1897) showed that this bone corresponded
to the genus Chenalopex and did not differ from the
species Chenalopex sirabensis that he was describing from
Madagascar (although the former name has priority). The
length of this carpometacarpus (77 mm) is within the variation
of A. sirabensis (Table 6) and is slightly larger than the largest
individuals of A. {M.) kervazoi. The Reunion form shows some
characteristics that are probably related to insularity (see below).
The Mauritian form also may be an endemic insular
form. With more fossil material from Mauritius, it might be
possible to discern distinctive characteristics compared with
the Madagascar and Reunion forms.
The ratio-diagram (Figure 5) drawn for the species Alopochen
aegyptiacus, A. sirabensis, and A. (M) kervazoi shows
a slight lessening of flying ability in A. sirabensis compared
with A. aegyptiacus, as indicated by shortening of the ulna and
carpometacarpus and by the slight lengthening of the femur.
The curve of A. (M) kervazoi closely parallels that of A. sirabensis,
but it also shows a slight reduction of the ulna and carpometacarpus
and a slightly longer femur. For comparison, an-