Chelychelynechen, new genus
Type species: Chelychelynechen quassus, new species.
Included species:T ype-specieso nly.
Distribution: Kauai, Makawehi dunes.
Etymology: "Turtle-jawed goose," from Greek, chelys, turtle, chelyne lip, jaw,
and chen, goose; so named for the decidedly chelonian aspect of the rostrum
and mandible. The gender is masculine.
Diagnosis: Postcranially a typical moa-nalo. Differs from Thambetochen and
Ptaiochen in the unique shape of the rostrum, which is almost as high as it is
long, with the palatal surface being much broader, especially so in the spaces
between the two median ridges and the edge of the bill. The occlusal surface of
the dentary is correspondinglyb road and flat, and both jaws lack the bony toothlike
projectionso f Thambetochena nd Ptaiochen.I n Chelychelynechenth e nostril
is reduced and oriented almost vertically instead of horizontally. In lateral view
of the mandible, the symphysis curves upward anteriorly, rather than being straight,
the coronoid area is much higher and more expanded, with the coronoid process
much better developed and more dorsally situated, and the retroarticular process
markedly shorter and deeper.
Remarks: From what we know of the postcranial skeleton of Chelychelynechen,
this genus has developed its flightless characters in a manner extraordinarily
similar to that of Thambetochen. The structure of its feeding apparatus is so
different, however, that we can only assume that Chelychelynechend eveloped
from an ancestor similar to that of Thambetochen, rather than from some other
kind of anatid. Material of the genus is still scant and we know nothing of the
structure of the syringeal bulla, nor whether salt-gland impressions were present
or absent, an important character distinguishing the other two genera of moanalos
from each other.
Chelychelynechenq uassus,n ew species
(Fig. 9) .
"Large Kauai goose" Olson and James, 1982b:34, 44; 1984:771.
Holotype: Associated rostrum, mandible, and os entoglossum, USNM 389743
(Fig. 9A-C). Collected 11 August 1976 by Storrs L. Olson. The rostrum lacks
much of the surface of the right side and tip, and the mandible lacks most of the
right ramus, although fragments of it may be included among the considerable
amount of uncleaned scrap found at this site.
Type locality: Site K-1, Makawehi dunes, Kauai, Hawaiian Islands.
Distribution: Kauai: Makawehi dunes.
Etymology.' Latin, quassus, broken, shattered, in reference to the regrettably
fragmented condition of the type material, which was probably deposited as a
complete skeleton but was unfortunately exposed in a jeep wail.
Measurements(r am) ofholotype:R ostrum:l engthf rom verticalp osteriorb order
to tip as preserved, 45; posterior height as preserved, 42.8; posterior width of
palatal surface, 37.7; greatest diameter of nostril, 9.4. Mandible: total length
without retroarticular process, 91.2; symphysis length, ca. 27; greatest width of
dentary, 10.2; height at coronoid process,2 5. Os entoglossum:le ngth and width,
20.3 x 7.9.
Paratypes: From Site K-1, all doubtless from the same individual as the holotype:
left pterygoid, USNM 389750; 16 vertebrae or large fragments thereof,
USNM 389767-79; right (Fig. 9E) and left coracoids, USNM 389762-3; left
scapula, USNM 389764 (Fig. 9D); distal and proximal ends of right humerus
USNM 389758-59; left humerus lacking head, USNM 389757 (Fig. 9G); proximal
end of radius, USNM 389761; left carpometacarpus3, 89760 (Fig. 9F); proximal
end of left femur, USNM 389755; proximal end of left fibula, USNM 389756;
two fragmentso f pedalp halangesU, SNM 389765-6; plusm any other fragments.
Site 303: anterior portion of a pelvis including about two-thirds of the sacrum
and the right innominate extending far enough posteriorly to include the anterior
third or more of the ilioischiatic fenestra, BBM-X 150095.
Measurements (ram) ofparatypes: Coracoid (right): greatest length 34.2; depth
through scapular end, 13.2; width and depth of shaft just below glenoid facet, 7.0
x 7.1; width at sternal end, 28.5. Scapula: length 82. Humerus: estimated length
56; shaft width and depth at midpoint, 6.9 x 6.8; distal width, 13.0. Carpometacarpus:
length, 23.4. Pelvis: estimated width across antitrochanters, 76; greatest
internal diameter of acetabulum, 13.8. Femur: greatest diameter of head, 16.8.
Fibula: proximal width and depth, 5.8 x 20.0.
Diagnosis: As for the genus. Compared to Thambetochen, the shafts of the
coracoid and humerus are more robust, the latter being very straight. The os
entoglossumis shortera nd wider than that in the holotype of T. chauliodousb, ut
like it has a distinct fenestra in the proximal end.
Remarks:T he rostruma nd mandibleo f this speciesa re remarkablyc onvergent
with tortoises. This might be due to the greater geological age of Kauai, which
would allow for a longer period of evolution, in which case, given enough time
the other moa-nalos might have evolved similar adaptations. On the other hand,
the unique morphology of Chelychelynechenm ay have been a responset o ecological
conditions unique to Kauai, such as the predominance of some vegetation
type that was rare or absent on the other islands.
Storrs L. Olson & Helen F. James,
Descriptions of thirty-two new species of birds from the Hawaiian Islands: Part I. Non-Passeriformes
Ornithological Monographs 45 (1991)
The American Ornithologists' Union, Washington D.C.
elibrary.unm.edu/sora/om/om045.pdf
