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22
Cor.
Hum.
Uln.
Cpm.
Fern.
Tbt.
Tmt.
-150
I
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
• Falco tinnunculus, standard
• Falco punctatus, min. and max.
O Accipiter nisus
A Falco duboisi
-100 50 50 100
FIGURE 8.—Ratio-diagram of the dimensions of the bones of Falco duboisi compared with the minimum and
maximum dimensions of F. punctatus. For F. duboisi the dimensions of the two known tibiotarsi have been indicated.
The standard is Falco tinnunculus (UCB, Lyon 119-8). Accipiter nisus (male, UCB, Lyon 96-5) is included
for comparison. Coracoid measurement is of internal length; for other bones, measurement is of total length.
When measurements are not known, successive points are united by dashed lines. (Cor.=coracoid,
Cpm.=carpometacarpus, Fem.=femur, Hum.=humerus, Tbt.=tibiotarsus, Tmt.=tarsometatarsus, Uln.=ulna.)
activity and hospitality made it possible for numerous naturalists
to discover the caves of Reunion and, in particular, the
Caverne de la Tortue.
DIAGNOSIS.—Species larger and with stouter tarsometatarsus
than the recent species of the genus.
COMPARISONS WITH LIVING FORMS.—We tentatively place
the extinct rail of Reunion in the genus Dryolimnas, which traditionally
includes only the species D. cuvieri (Pucheran). This
species is represented by two living subspecies, the flying D.
cuvieri cuvieri from Madagascar and the flightless D. cuvieri
aldabranus (Gunther) from Aldabra, and by one extinct subspecies,
D. cuvieri abbotti (Ridgway) from Assumption Island.
The two living forms show great differences in the proportions
of their skeletons and in their morphological characteristics;
the coracoid and wing bones are strongly reduced, and the
sternal carina is lower and more posteriorly situated in the Aldabra
subspecies.
The extinct Reunion Rail shows the following morphological
similarities to D. cuvieri. On the coracoid, the coracoidal fenes­
tra is situated along the middle axis of the shaft and there is a
well-pronounced stemocoracoidal fossa; on the coracoid from
Reunion, only the middle part of the shaft is preserved, but it is
possible to see the top of this stemocoracoidal fossa (Figure
9/'). On the humerus, the shaft is thin and sinuous, and there is
an elongated, narrow depression on the anconal face, distally
below the dorsal pillar of the internal tuberosity (cms dorsale
fossae; Baumel, 1979) (Figure 9c). The ulna is relatively elongate
(Figure 9d,e). The femur is very elongate and incurved. It
has two curvatures in two different planes; the proximal and
distal extremities are incurved both posteriorly and internally
(Figure 9f-h).
The main differences between the Reunion Rail and D. cuvieri
are in size, the former being larger, and in the shape of
the tarsometatarsus (Figure 9a, b), which in the Reunion Rail is
much more robust. The internal trochlea, however, is posteriorly
displaced and is only slightly splayed internally, as in D.
cuvieri. The ossified tendinal loop (retinaculum extensorium
tarsometatarsi; Baumel, 1979) is broken on the two tarsometa-