PDF (Lo-Res) - Smithsonian Institution Libraries

NUMBER 89 227
B
C
D
FIGURE 6.—The distal end of left ulna, in distal view (left) and in anconal view (right), of Chaunoides antiquus,
n. gen. n. sp., compared with other Anhimidae: A, Anhima cornuta (HA 902); B, Chauna torquata (HA 702); C,
Chauna chavaria (USNM 347738); D, Chaunoides antiquus, n. gen. n. sp., (paratype, MNRJ 4632-V); E,
Chaunoides antiquus, n. gen. n. sp. (paratype, MNRJ 4622-V). (Scale bar=l cm.)
has a similar morphology to that in other anhimids, but, in
contrast, there is no pneumatic foramen (Figure 7).
The femur (Figure 8) is less robust than in Anhima and
Chauna, with its neck longer and more similar to that in
Anseranas and other anatids. Its distal end is similar to that of
Anhima and Chauna, with a shallow patellar groove and a flat
articular surface of the internal condyle. The prominent crista
supracondylaris medialis, being in a posteromedial position,
gives a square shape to the distal end of the femur in medial
view. The tibiotarsus of Chaunoides has the distal end of the
shaft slightly bowed toward the midline, and the internal
condyle extends far mediad, as is generally the case in Anseriformes
(Figure 9). The tendinal groove is not pneumatized, in
contrast to that of extant anhimids, and its medial border is
very pronounced and extends proximad to the middle of the
FIGURE 7 (right).—The distal end of (A) right radius (paratype, MNRJ
4623-V), and (B) left radius (paratype, MNRJ 4624-V), of Chaunoides
antiquus, n. gen. n. sp., in palmar view, compared with the left radius, also
in palmar view, of other Anhimidae and Anatidae: C, Chauna chavaria
(USNM 347738); D, Anhima cornuta (HA 902); E, Chauna torquata (HA
41); F, Anseranas semipalmata (HA 1201). (Scale bar=l cm.)