Introduction
Fossils of Cretaceous birds are scarce and usually difficult to interpret. The better known forms such asHesperornisandIchthyornisbelong to strange and archaic groups having little or nothing to do with the modern avian radiation. The only areas that have yielded Cretaceous birds of essentially modern aspect in sufficient quantities to be regarded as avifaunal assemblages are the inland deposits of the Lance Formation and strata of similar age in Wyoming (Brodkorb, 1963a) and the marine deposits of New Jersey. Of these, the assemblage from New Jersey is the more diverse.
Fossil birds were described from the Cretaceous greensands of southern New Jersey over a century ago by Marsh (1870, 1872). These have been carried, largely uncritically, in lists and compilations ever since (e.g. Hay, 1902; Lambrecht, 1933; Rapp, 1943; Miller, 1955; Brodkorb, 1963b, 1967). Although some of these specimens were subsequently re-examined and their status altered (Shufeldt, 1915; Cracraft, 1972, 1973), there has been no modern comprehensive revision of all of the avian taxa that have been named from the Cretaceous of New Jersey. In recent years, additional fossil birds have been recovered from these deposits that add further to our knowledge of late Mesozoic avifaunas, making a review of this material all the more desirable.
In spite of the relative diversity of the New Jersey Cretaceous avifauna, the total number of specimens is still small. The decline of the glauconite greensand industry and the difficulty of recovering small fossils have contributed to this paucity of specimens. The glauconite industry is now confined to a single operation, the Inversand Company in Sewell, Mantua Township, Gloucester County, New Jersey. Fortunately, the late owner of the company, Mr. Churchill Hungerford, Jr., generously allowed fossils to be recovered on his property by the New Jersey State Museum, which houses most of the newly discovered specimens, the Academy of Natural Sciences of Philadelphia being the repository of the rest. Another specimen came from a locality in Upper Freehold Township, Monmouth County, New Jersey and was donated to the New Jersey State Museum by Gerard R. Case.
Acknowledgments.—We gratefully acknowledge the late Churchill Hungerford, Jr., for permitting fossil material to be recovered from his property by the New Jersey State Museum (NJSM). We are much indebted to John H. Ostrom, Peabody Museum of Natural History, Yale University (YPM), and Gay Vostreys and Charles Smart of the Academy of Natural Sciences of Philadelphia (ANSP) for their patience in lending types and other material from their collections for a very extended period. Pat V. Rich, Monash University, assisted Parris in the early stages of this study. Comparative material ofPresbyorniswas obtained from the collection of the University of California Museum of Paleontology (UCMP), the University of Wyoming (UW), and the National Museum of Natural History, Smithsonian Institution (USNM). The photographs are by Victor E. Krantz, Smithsonian Institution. For valuable comments on the manuscript we are grateful to Donald Baird, Princeton University, and Jonathan Becker, Smithsonian Institution.
The extensive deposits of Cretaceous age in eastern North America have been widely studied for over 150 years. These generally poorly consolidated sediments have provided valuable resources, notably glauconite, fire clay, and chalk. As the publications by Morton (1829), Vanuxem (1829), Conrad (1869), and other early authors showed, the sediments are also quite fossiliferous.
In the eastern United States, significant Cretaceous deposits occur from New Jersey to Texas (Figure 1), with extensive outcrop and subsurface records in both Atlantic and Gulf coastal plains. The surface distribution and correlations were first summarized by Stephenson et al. (1942). Subsequent works by various authorities have refined, but not substantially altered his views of outcrop stratigraphy. Petroleum explorationhas encouraged more recent restudy of the subsurface stratigraphy, notably along the east coast (Minard et al., 1974; Perry et al., 1975; Petters, 1976).
Figure 1.—Distribution of Cretaceous rocks in the eastern United States. Arrow indicates New Jersey. (Modified after Moore, 1958, fig. 15.2).
Figure 1.—Distribution of Cretaceous rocks in the eastern United States. Arrow indicates New Jersey. (Modified after Moore, 1958, fig. 15.2).
In New Jersey, the latest Cretaceous deposits are remarkably rich in glauconite, especially the Navesink and Hornerstown formations. Besides providing a local industry in agricultural fertilizers, the glauconite greensands, locally called "marl," yielded many specimens to the fiercely competitive vertebrate paleontologists of the nineteenth century. Preservation of vertebrate fossils in a glauconite deposit may be excellent, apparently due to autochthonous formation of the mineral and the probable quiescence of the depositional environment. The Hornerstown Formation, for example, contains few grains of terrigenous origin and little evidence of disturbance by water currents. Such depositional environments were apparently favorable for the preservation of small and delicate bones. The accumulation of sediment occurred during a period of marine transgression with the shoreline not far to the northwest but at sufficient distance to prevent deposition of terrigenous material.
During their great rivalry, E.D. Cope and O.C. Marsh sought greensand fossils vigorously. Marsh, however, obtained all of the Cretaceous birds (Marsh, 1870, 1872), largely due to efforts of marl pit owner J.G. Meirs. Although in the years subsequent to Marsh's original descriptions of the New Jersey birds from the Navesink and Hornerstown formations there was some confusion regarding their probable age (Wetmore, 1930), this was later definitely established as Cretaceous by Baird (1967), who attributed the specimens to the Navesink and Hornerstown formations.
The summary of Petters (1976) represents current ideas of the Cretaceous stratigraphy of New Jersey. Baird's (1967) discussion is consistent with Petters's view that the Hornerstown Formation is regarded as partly Cretaceous and partly Tertiary. Some authors have used the term New Egypt Formation instead of Navesink in more southerly outcrops.
Cretaceous birds have been recovered from three geographically distinct localities in New Jersey (Figure 2). With the exception ofLaornis, all of the specimens described by Marsh (1870, 1872) came from Upper Freehold Township, MonmouthCounty, in the area including the settlements of Hornerstown, Arneytown, and Cream Ridge. The Meirs family operated a number of pits in this area and it is no longer possible to ascertain the exact provenance of specimens labelled only as being from Hornerstown. These could have come either from the basal Hornerstown Formation or the underlying Navesink Formation, both of which are Maastrichtian in age. Baird (1967:261) ascertained that the holotype ofPalaeotringa vetus, from "friable green marl near Arneytown" was from the lower (i.e., Cretaceous) part of the Hornerstown Formation. The holotypes ofTelmatornis priscusandT. affinis, from the Cream Ridge Marl Company pits, on the other hand, are from the Navesink Formation. A more recently collected specimen from this area is the proximal end of an ulna (NJSM 11900) collected by Gerard R. Case from "marl piles near junction of Rtes. 537 and 539 in Upper Freehold Twp., Monmouth County, near Hornerstown." This definitely came from the Hornerstown Formation but it cannot be said whether from the Cretaceous or Paleocene sediments included therein.
Figure 2.—Localities in southern New Jersey of the main fossiliferous deposits that have yielded Cretaceous birds. (The bold line demarcates the inner and outer coastal plain physiographic provinces; B = Birmingham; H = Hornerstown; S = Sewell.)
Figure 2.—Localities in southern New Jersey of the main fossiliferous deposits that have yielded Cretaceous birds. (The bold line demarcates the inner and outer coastal plain physiographic provinces; B = Birmingham; H = Hornerstown; S = Sewell.)
The second general locality is near Birmingham, Burlington County, where the type ofLaornis edvardsianuswas obtained from "greensand of the upper, Cretaceous marl bed ... in the pits of the Pemberton Marl Company" (Marsh, 1870:208). There is nothing to be added to Baird's (1967) conclusion that this specimen is latest Cretaceous in age.
The third locality, and that yielding most of the recently obtained specimens, is the Inversand Company marl pit, located near Sewell, Gloucester County. In accordance with the wishes of the Inversand Company, the precise locality of this pit will not be disclosed, although this information is preserved in records sufficient in number and distribution to assure that it will not be lost. The Inversand specimens came from the main fossiliferous layer within the basal portion of the Hornerstown Formation (Figure 3). This layer is of late Maastrichtian age (latest Cretaceous), on the basis of invertebrate fossils, including three genera of ammonites, and a substantial vertebrate fauna, including mosasaurs (see Appendix). It is probable that the upper part of the Hornerstown Formation within the pit is of Paleocene age, as it is known to be elsewhere, but most paleontologists believe the basal portion to be Cretaceous in age (Gaffney, 1975; Koch and Olsson, 1977). One avian specimen is from an unknown level in the pit.
Figure 3.—Stratigraphic diagram of the Inversand Company marl pit at Sewell, Gloucester County, New Jersey.
Figure 3.—Stratigraphic diagram of the Inversand Company marl pit at Sewell, Gloucester County, New Jersey.
Type Genus.—Graculavus Marsh, 1872.
Included Genera.—GraculavusMarsh, 1872;TelmatornisMarsh, 1870;Anatalavis, new genus;LaornisMarsh, 1870;PalaeotringaMarsh, 1870; and an additional unnamed genus.
Remarks.—Most of the birds from the New Jersey deposits belong with what Olson (1985) has termed the "transitional Charadriiformes," a group that seemingly tends to connect the Gruiformes and the more typical Charadriiformes. The only living family in this group that has traditionally been considered charadriiform is the Burhinidae, the thick-knees or stone curlews. Other apparent descendants include ibises (Plataleidae) and the ducks and geese of the order Anseriformes. The latter are linked with the "transitional Charadriiformes" through the Paleocene and Eocene genusPresbyornis, which is known from abundant material from widely scattered areas of the world (Olson and Feduccia, 1980b; Olson, 1985).Presbyorniscombines a long-legged shorebird-like body with the head of a duck. The fragmentary Cretaceous fossils from New Jersey, all of which are postcranial, usually show more similarity toPresbyornisthan to any modern group of birds except the Burhinidae. Therefore, our comparisons have been made chiefly with these two groups.
With the fragmentary material at hand it is difficult, well nigh impossible, to make hard and fast taxonomic judgments concerning the number of species, genera, or families represented. Birds with very similar wing or leg elements could have had completely different feeding adaptations and could represent ancestral forms leading to different modern groups not considered to be closely related. For example, without the skull,Presbyorniscould not be determined as having anything to do with the Anseriformes (Olson and Feduccia, 1980b: 12-13).
Late Cretaceous fossil birds of modern aspect have been described in a variety of genera, most of which have been used as the basis for family-group names. Taxa from New Jersey that appear to belong with the "transitional Charadriiformes" for which family-group names are available include: Graculavinae Fürbringer, 1888; Palaeotringinae Wetmore, 1940; Telmatornithidae Cracraft, 1972; and Laornithidae Cracraft, 1973.
Taxa from Upper Cretaceous deposits in western North America that appear to fall in the same category (Olson and Feduccia, 1980a) include: Apatornithidae Fürbringer, 1888; Cimolopterygidae Brodkorb, 1963a; Torotigidae Brodkorb, 1963a; and Lonchodytidae Brodkorb, 1963a.
Tertiary taxa that may possibly be related to the "transitional Charadriiformes" and that have been used as the basis of family-group names are: Presbyornithidae Wetmore, 1926 (Nautilornithinae Wetmore, 1926, and Telmabatidae Howard, 1955, are definitely synonyms); Scaniornithidae Lambrecht, 1933; and Dakotornithidae Erickson, 1975.
Doubtless there are others that we have overlooked. How many families are actually represented here and what their interrelationships may be is purely a matter of conjecture in the absence of better fossil material. Because the entire skeleton ofPresbyornisis known, the familial name Presbyornithidae may justifiably be retained and used for that genus.
In the case of the Cretaceous birds under consideration here, we have decided for the time being to adopt a version of paleobotanical convention in recognizing a "form family" Graculavidae, which implies a general similarity in morphology of the constituent taxa, although the material available is simply not sufficient for determining phylogeny or key adaptations.