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170
cional Autonoma de Mexico, for permission to include the partial
carpometacarpus from Mexico in this study; B. MacFadden,
Florida Museum of Natural History, for the loan of the
Leisey Shell Pit specimens; and S. Emslie, S.J. Parry, and an
anonymous reviewer for comments on an earlier version of this
paper. Photographs are by R. Meier and D. Watson, Natural
History Museum of Los Angeles County (LACM) staff photographers;
the map in Figure 2 was produced by G.T. Braden,
San Bernadino County Museum (SBCM).
Systematics
Order CICONIIFORMES
Family TERATORNITHIDAE
Aiolornis, new genus
TYPE SPECIES.—Teratornis incredibilis Howard, 1952; type
by original description.
REFERRED SPECIES.—None.
ETYMOLOGY.—Aiolos, Greek, masculine, god of the winds;
ornis, Greek, masculine, bird.
EMENDED DIAGNOSIS.—Placed in the family Teratornithidae
and differing from genera of the Vulturidae by having the os
carpi ulnare with the following characters (from Howard,
1952:51): (1) attachment for Lig. ulno-ulnocarpale long, diagonal,
and ridge-like (short, almost papilla-like in the Vulturidae);
and (2) external prominence and attachment for Lig.
ulno-ulnocarpale in close proximity (broad space separating
the two in the Vulturidae).
Differs from Teratornis by having the os carpi ulnare with
(1) external prominence a long, prominent ridge forming one
end of and extending from the facies articularis ulnaris to very
near the attachment for Lig. ulno-ulnocarpale (short, rounded,
not contacting facies articularis ulnaris in Teratornis); (2) attachment
for Lig. ulno-ulnocarpale proportionately longer,
more prominently protruding from body of bone; (3) facies articularis
ulnaris narrowing slightly distad, more concave, with
dorsal rim notably lower than ventral rim (narrows abruptly,
less concave, with dorsal rim only slightly lower than ventral
rim in Teratornis); (4) facies articularis metacarpals a slightly
elongated oval, with long axis nearly aligned with long axis of
facies articularis ulnaris, with external end very near facies articularis
ulnaris, and lying at greater angle to facies articularis
ulnaris (markedly elongated oval with long axis at low angle to
that of facies articularis ulnaris and external end at some distance
from facies articularis ulnaris in Teratornis); and (5) with
ventral surface of bone bordering and surrounding incisura
metacarpalis nearly flat (markedly concave in Teratornis).
Aiolornis incredibilis (Howard, 1952), new combination
HOLOTYPE.—Complete right os carpi ulnare, LACM(CIT)
5067.
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
TYPE LOCALITY.—Section 7-F-310 of LACM(CIT) locality
251, Smith Creek Cave, Snake Range, 54.4 km north of Baker,
White Pine County, Nevada.
AGE.—Rancholabrean NALMA (North American Land
Mammal Age).
DIAGNOSIS.—As for genus.
REFERRED MATERIAL.—Left humerus: Proximal end and
portion of shaft, missing caput and much of crista deltopectoralis
(Figure 1); SBCM A2239-2829, Section of Earth Sciences.
The specimen was collected by Quintin Lake (PRAP), April
1993, from locality SBCM 05.006.399, which is located approximately
1 km northeast of Murrieta, Riverside County,
California, at an approximate elevation of 368 m. The locality
lies within the unsurveyed Temecula Land Grant (Figure 2),
within the SWV4, NEtt, SWA section 9, T. 7S, R. 3W, San Bernardino
Base and Meridian. The specimen was exposed in situ
in an erosional gully approximately 0.15 m below grade.
The partial humerus came from sediments of an unnamed
sandstone and conglomerate formation that unconformably underlies
the middle Pleistocene Pauba Formation and may unconformably
overlie the lower Pliocene Temecula Arkose in
the Elsinore Fault Zone (Kennedy, 1977). Two faunal components
have been recognized from the unnamed sandstone formation,
one dating to the late Blancan NALMA (late Pliocene,
as interpreted by Lundelius et al., 1987) and the other to the
Irvingtonian NALMA (early Pleistocene) (Scott and Cox,
1993). The partial humerus is derived from sediments that are
late Blancan in age (pre-Olduvai subchron, 2.6-1.9 Ma), based
on sites producing Blancan faunas in the area immediately adjacent
to SBCM 05.006.399. These localities (SBCM
05.006.156, 05.006.157, 05.006.158, 05.006.159, 05.006.397)
are all located within 15 m of SBCM 05.006.399 and have
yielded Hypolagus sp., Prodipodomys sp., Mimomys {Ophiomys)
parvus R. Wilson, and Sigmodon minor Gidley, but they
lack any Pleistocene or later indicator taxa, such as Microtus
sp. or Mammuthus sp. (Scott and Cox, 1993).
The partial humerus is placed in the family Teratornithidae
based on the following characters: (1) crista bicipitalis elongated
and prominently bulbous for entire length; (2) planus interruberculare
smooth, broad, and symmetrically and deeply convex
in transverse section from caput to middle of crista
deltopectoralis; (3) crista deltopectoralis low, very stout, curving
ventrad on facies anterioris of corpus humeri just distal to
end of crista bicipitalis, and tapering off gradually as it crosses
to near midline of corpus humeri; and (4) distal insertion for M.
pectoralis long, broad, and near midline of facies anterioris of
corpus humeri.
Other avian taxa, such as some of the orders Procellariformes,
Pelecaniformes, and Ciconiiformes, resemble teratorns
somewhat in having a bulbous crista bicipitalis. In these taxa,
however, the bulbous portion is more limited, being present
only at the distal end of the crista bicipitalis. In Teratornis the
bulbous portion occupies the entire length of the crista bicipitalis
and is more pronounced; it is missing from the only
known humerus of Argentavis. Although most of the bulbous