The Deseado Formation of PatagoniaLoomis, Frederic Brewster
Science
The Deseado Formation of Patagonia
Loomis, Frederic Brewster
Paleontology -- Patagonia (Argentina and Chile)
The sternum had a moderate keel but both this and body of the bone are
very thin, so much so, that in my specimen, much is broken away, giving
the figure the appearance of the bone being fenestrated, which was not
the case. In general the sternum is similar to _Pelecyornis_.
The coracoid is a decidedly stout bone, with a wide distal end for
articulation of the sternum. The proximal end has a long articular
facet for the scapula. This bone is heavier than the corresponding one
in _Pelecyornis_.
The femur has a small rounded head on a short neck, the articular
surface spreading over the entire proximal end of the bone. Thus the
trochanter is abbreviated and does not rise above the top of the head.
The shaft is of considerable length and fairly heavy.
The tibio-tarsus has a wide flaring end to receive the articulation of
the femur. The bone is very long as in _Pelecyornis_. On the external
side is a long ridge along which the fibula was attached by cartilage
or by ligaments, but was not fused to the tibio-tarsus. The shaft is
approximately cylindrical in section and fairly heavy. The distal end
is missing, but if I have associated correctly the specimen figured by
Ameghino, the condyles are flattened, the inner being the flatter, and
the outer rising in a narrow margin.
Figure 157 shows a fibula which would have occupied the position
indicated along the side of the tibio-tarsus and corresponds entirely
with the same bone in _Pelecyornis_.
The tarso-metatarsus is long and slender, almost exactly the
counterpart of the same bone in _Pelecyornis_. The bone has a
triangular upper end, with two shallow articular concavities, separated
by a median spine. The shaft is rectangular in cross section, has a
shallow depression on the anterior face extending from the upper end
to below the middle of the shaft; while on the posterior surface is
a similar furrow, which is however bounded by a higher ridge on the
external margin. The distal articular condyles are almost bilaterally
symmetrical, the middle one being about half again as large as the two
lateral ones. Just above the cleft between the condyles for digits III
and IV there is a moderate sized perforation.
[Illustration: Fig. 155. Femur—½ natural size.]
[Illustration: Fig. 156. Tibio-tarsus—½ natural size; fibula indicated
in outline.]
[Illustration: Fig. 157. Fibula—½ natural size; outline from impression
in matrix.]
[Illustration: Fig. 158. Tarso-metatarsus, front view—½ natural size.]
Of the phalanges, I have two unguals which are narrow curved claws.
These were not found in association with any of the foregoing bones,
but correspond in size and general character to those of _Pelecyornis_,
and so I consider them as belonging to this genus and species.
[Illustration: Fig. 159. Ungual phalanx—½ natural size.]
[Illustration: Fig. 160. Femur of unknown bird—natural size; special
No. 3217.]
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