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262 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
State Museum, Trenton; Richard K. Olsson, Rutgers University;
and Laurel M. Bybell, United States Geological Survey,
provided stratigraphical information about the Hornerstown
Formation. I thank Luis Baptista, California Academy of Sciences,
San Francisco, for providing work space and extended
access to specimens. I also thank Ned K. Johnson, Museum of
Vertebrate Zoology, Berkeley, and George C. Barrowclough,
AMNH, for use of comparative material of recent species. Luis
M. Chiappe, AMNH, and John H. Ostrom, Peabody Museum,
Yale University, New Haven, made it possible for me to study
comparative non-neornithine material in their care. I thank
Olga Titelbaum, San Francisco, for her invaluable translations
from the Russian. Comments by Storrs L. Olson, David C. Parris,
and Per G.P. Ericson have greatly improved the manuscript.
Fossil Localities and Stratigraphy
Graculavus velox was recovered from greensand marl of the
Navesink or overlying Hornerstown Formation of New Jersey
during the last century in the course of commercial mining for
the marl. The greensands were formed along the quiet margin
of what was then the Atlantic coastline during the middle
Maastrichtian through the earliest Paleocene. The phosphatic
sediments provided ideal conditions for preservation. Birds
from the Hornerstown and Navesink were reported earlier by
Marsh (1870, 1872), Shufeldt (1915), and by Olson and Parris
(1987). The new specimen represents a larger species of Graculavus
from the late Maastrichtian Lance Formation, Wyoming.
The first bird discoveries in this area resulted from early
exploration of the dinosaur fields in the North American West.
The University of California began newer expeditions about
1955, and the American Museum of Natural History has been
collecting in the Lance since 1960. Birds from the Lance were
reported by Marsh (1889:83, footnote; 1892) and by Brodkorb
(1963).
The depositional setting and history of exploration in the
New Jersey marls is summarized by Olson and Parris (1987).
The Navesink Formation is entirely Maastrichtian. The age of
the birds from the overlying Hornerstown Formation, whether
Cretaceous or early Tertiary, was long debated because of the
complexity of the sedimentation patterns and the enigmatic
composition of the basal Main Fossiliferous Layer (MFL). This
very narrow, densely fossiliferous zone lies directly over the
Navesink Formation at the Inversand marl pit in Gloucester
County, New Jersey. The MFL in this area includes Maastrichtian
macrofossils, with ammonites, mosasaurs, and Enchodus.
Typically Paleocene foraminifera occur in lower Hornerstown
Formation levels at other localities. Vertebrates have not been
recovered in the Hornerstown immediately above the MFL, but
a Danian (Paleocene) fauna is found approximately 3 m higher
(Gallagher and Parris, 1985). Very recent studies interpret the
MFL as a Cretaceous lag deposit infilled with a Paleocene matrix,
possibly by burrowing arthropods (Gallagher, 1993;
Kennedy and Cobban, 1996; other studies cited in both). There
is iridium elevation within the MFL but not in a sharply defined
high peak. Thus, the Cretaceous/Tertiary boundary probably
is within the MFL but is blurred and attenuated by reworking
of the sediments (Gallagher, 1992).
The Lance Formation in the southeastern comer of the Powder
River basin, Wyoming, consists of massive, loosely consolidated
sandstones with lenses of lignites and lignitic shales
throughout. The Lance lies conformably directly under the entirely
Paleocene Fort Union Formation. The Lance sediments
were deposited near the western margin of the North American
interior seaway during its final retreat in the latest Cretaceous
(Maastrichtian). Plant remains indicate a humid, subtropical
environment. An abundant vertebrate fauna including sharks,
lizards, mammals, and birds is preserved in channel fill of the
ancient, meandering, near-shore streams. Faunal correlation
shows a late Maastrichtian age for the fossiliferous sediments.
The indurated streambeds have survived erosion better than the
surrounding terrain has, and they are exposed now as "blowouts,"
or elevated sandstone outcrops (Dorf, 1942; Estes, 1964;
Clemens, 1960, 1963; Lillegraven and McKenna, 1986).
Systematic Paleontology
NEORNITHES
GRACULAVIDAE
TYPE GENUS.—Graculavus Marsh, 1872:363.
REMARKS.—The name Graculavidae is used herein in the
sense of Olson and Parris (1987), except that Olson (this volume)
has since referred Anatalavis to Anseriformes.
Limosavis Shufeldt, 1915:19.
Graculavus Marsh, 1872
TYPE SPECIES.—Graculavus velox Marsh, 1872.
INCLUDED SPECIES.—Graculavus velox, Graculavus augustus,
new species.
Graculavus augustus, new species
FIGURE 1
HOLOTYPE.—AMNH 25223; proximal end of left humems.
TYPE LOCALITY.—From near Lance Creek, Niobrara County,
Wyoming, University of California Museum of Paleontology
Locality V-5711 (Bushy Tailed Blowout), on the southern
rim of a large valley that empties into Lance Creek, grid coordinates
23,860-23,350 on reconnaissance map of Clemens
(1963). Collected by Malcolm C. McKenna and party, August,
1985.
HORIZON.—Upper part of the Lance Formation (late Maastrichtian).
MEASUREMENTS.—Maximum depth of articular head, cranial
to caudal, 6.8 mm; width of shaft through dorsal tubercle and