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New Material of Juncitarsus (Phoenicopteriformes), with
a Guide for Differentiating that Genus
from the Presbyornithidae (Anseriformes)
ABSTRACT
In many aspects the postcranial skeleton of the early Tertiary
Juncitarsus (Phoenicopteridae) is very similar to that of Presbyornis
and Telmabates (Presbyornithidae). The phylogenetic positions
of the two families indicates that these similarities are due to the
retention of morphologies possessed by their most recent ancestor.
This paper shows how finds of isolated skeletal elements of either
genus can be correctly identified.
Introduction
Despite repeated claims to the contrary, remains of birds are
not rare in the fossil record (cf. Olson, 1985); for example, numerous
bird bones have been collected from early Tertiary deposits
in the United States, Europe, Russia, and China. One of
the most abundant taxa in certain Paleocene and Eocene deposits
is the Presbyornithidae, a family of long-legged filter feeders
that is the sister group to the Anatidae within the order
Anseriformes (Ericson, 1997). The Presbyornithidae are normally
found in inland freshwater, or possibly saline, environments.
This habitat also was occupied by several other longlegged
wading birds. Most of these species are represented in
the fossil record by isolated bone elements; however, one of
these, Juncitarsus, is known from several associated elements
from at least four individuals, which were described and allocated
to the Phoenicopteridae (flamingos) (Olson and Feduccia,
1980).
In the course of a revision of the New World material of the
early Tertiary Presbyornithidae (Ericson, in prep.), great similarities
in many aspects of the osteology of the Presbyorni-
Per G.P. Ericson, Department of Vertebrate Zoology, Swedish Museum
of Natural History, P.O. Box 50007, S-104 05 Stockholm, Sweden.
Per G.P. Erics on
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thidae and Juncitarsus were noticed. Nevertheless, many of
these elements also exhibit consistent differences that serve to
differentiate the two taxa. These differences are pointed out
herein with the intention of facilitating the future identification
of isolated skeletal elements of the Presbyornithidae and Juncitarsus.
Unfortunately, apart from a partial skeleton ofAnatalavis
from the London Clay, now assigned to the Anseranatidae (Olson,
this volume), no articulated or otherwise associated specimens
exist of the taxa assigned to the form-family Graculavidae
(Olson and Parris, 1987), or to any other Late
Cretaceous or early Tertiary group of wading birds supposed to
be closely related to the Presbyornithidae. It has thus not been
possible to extend the comparisons to include these groups.
ACKNOWLEDGMENTS.—Storrs L. Olson kindly put the undescribed
material of Juncitarsus at my disposal and strongly encouraged
the study. Thanks also are directed toward the curators
of the following museums, who willingly loaned their
material to me: American Museum of Natural History
(AMNH), New York; the Buffalo Museum of Science, Buffalo;
the Carnegie Museum of Natural History (CM), Pittsburgh;
the Geological Museum, University of Wyoming (UW),
Laramie; the Museum of Paleontology, University of California
(UCMP), Berkeley; and the National Museum of Natural
History (USNM; collections of the former United States National
Museum), Smithsonian Institution, Washington, D.C.
Charlotte Holton provided information on the AMNH specimens,
and Storrs L. Olson and David C. Parris reviewed the
manuscript; their assistance is greatly acknowledged.
MATERIAL
The Presbyornithidae consists of two genera, Presbyornis
and Telmabates, known from numerous specimens collected
from Paleocene and Eocene deposits in Wyoming, Utah, Colorado,
Argentina, and Mongolia (Ericson, in prep.). In this