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duboisi are larger than the largest individuals of N. nycticorax
or N. caledonicus in the USNM collection.
The supratendinal bridge is incompletely ossified in the
three tibiotarsi of N. duboisi. The condition is unknown in N.
mauritianus, whereas in N. megacephalus the supratendinal
bridge is completely ossified (Milne-Edwards, 1874, pl. 14:
fig. 7). The dimensions of Mascarene Nycticorax are given in
Table 2. Most of the remains ofN. duboisi are larger than those
of either N. megacephalus or N. mauritianus (Figure Ai-j), except
for the tarsometatarsus, which is almost the same size as in
N. megacephalus, and the femur, which is smaller in most dimensions
than that in N. megacephalus.
The ratio-diagram (Figure 2) shows the differences in the relative
proportions of the bones in the three Mascarene species,
compared with the modern species N. nycticorax and N cale­
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donicus. In N. mauritianus and N. megacephalus the wings
(humeri, ulnae, carpometacarpi) are considerably reduced, and
the legs (particularly the femora) are longer than in modern
species. In contrast, N. duboisi is larger than living species, but
the proportions are almost the same. The tarsometatarsus is
slightly longer than in N. nycticorax or N. caledonicus, but
only two are available, and for one of them the length is estimated.
The ratio-diagram clearly demonstrates that the Rodrigues
and Mauritius species had a reduced flying ability,
whereas the Reunion form had a flying ability quite similar to
that of living species.
By the proportions of the tarsometatarsus, which is short and
thick, the Mascarene night herons are more similar to Nycticorax
nycticorax than to other congeners, particularly N. cale-
TABLE 2.—Dimensions (mm) of the long bones of Nycticorax duboisi, from Reunion, N. megacephalus, from
Rodrigues, and TV. mauritianus, from Maritius. (a=data from Milne-Edwards (1874), Giinther and Newton
(1879), and material at MNHN; b=data from Newton and Gadow (1893) and from material at MNHN; c=from
base of glenoid facet to top of acromion; d=from the most internal part to the most external part; est.=estimated;
/j=number of specimens.)
Measurement
Scapula
length art. part (c)
width art. part (d)
width shaft
depth shaft
Coracoid
internal length
width midshaft
depth midshaft
Humerus
total length
distal width
width midshaft
depth midshaft
Una
total length
proximal width
proximal depth
distal width
depth ext. cond.
width midshaft
depth midshaft
Femur
total length
distal width
distal depth
width midshaft
depth midshaft
Tibiotarsus
total length
distal width
distal depth
width midshaft
depth midshaft
Tarsometatarsus
total length
proximal width
proximal depth
distal width
distal depth
width midshaft
depth midshaft
Mean (n)
11.10 (2)
12.65 (2)
4.90 (2)
2.90 (2)
-
-4.8 (1)
-5.4 (1)
est. 137 (1)
18.4 (1)
8.1 (1)
7.2 (1)
est. 155 (1)
13.5 (1)
11.5 (1)
-10.3 (1)
-9.0 (1)
6.20 (2)
5.65 (2)
est. 85 (1)
14.8 (1)
14.2 (1)
6.6 (1)
6.2 (1)
-144.5 (2)
12.87 (3)
13.2 (1)
6.80 (3)
6.03 (3)
est. 97.55 (2)
-13.5 (1)
-13.5 (1)
14.2 (1)
7.35 (2)
6.53 (3)
4.73 (3)
N. dubo isi
Range
10.2-12.0
12.4-12.9
4.7-5.1
2.8-3.0
-
-
-
-
-
-
-
-
-
-
6.2-6.2
5.6-5.7
-
-
-
-
-
-139—150
12.4-13.2
-
6.8-6.8
5.9-6.1
95.1-est. 100
-
- -
7.2-7.5
6.4-6.8
4.4-5.0
N. megacephalus
Range (a)
-
- -
est. 53.0-57.0
-
-
114-119
16.5-16.8
6.9-7.0
5.9
121
- ---
-
-
86-90
15.0
-
6.2
-
136-140
13.0
-
6.0
_
93-95.5
13.7-14.0
13.5
13.5-13.8
7.4
6.0-6.5
5.0
N. mauritianus
Range (b)
-
-
-
est. 45.5
4.3
4.2
-
- --
111-112
-
-
_
_
-
_
79.3
13.8
11.7
6.4
5.8
_
_
_
_
_
79.5-87
12.7-12.8
12.4-12.6
11.7-12.1
7.1-7.3
5.8-5.9
4.7-4.8