"Form Family" Graculavidae Fürbringer, 1888
Type Genus.—Graculavus Marsh, 1872.
Included Genera.—Graculavus Marsh, 1872; Telmatornis Marsh, 1870; Anatalavis, new genus; Laornis Marsh, 1870; Palaeotringa Marsh, 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 genus Presbyornis, which is known from abundant material from widely scattered areas of the world (Olson and Feduccia, 1980b; Olson, 1985). Presbyornis combines 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 to Presbyornis than 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, Presbyornis could 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 of Presbyornis is 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.
Genus Graculavus Marsh, 1872
Limosavis Shufeldt, 1915:19.
Type-Species.—Graculavus velox Marsh 1872, by subsequent designation (Hay, 1902).
Included Species.—Type species only.
Remarks.—Limosavis Shufeldt, 1915, substitute name for Graculavus, considered inappropriate; not used in direct combination with any specific name when originally proposed.
Graculavus velox Marsh, 1872
[Figure 4] b,d,f,h
Graculavus velox Marsh, 1872:363.
Limosavis velox (Marsh).—Lambrecht, 1933:546.
Holotype.—Proximal end of left humerus, YPM 855.
Locality and Horizon.—From Hornerstown, Upper Freehold Township, Monmouth County, New Jersey; collected by J.G. Meirs; Late Cretaceous (Maastrichtian), either basal Hornerstown Formation or Navesink Formation.
Measurements (in mm).—Proximal end of humerus, YPM 855: proximal width through dorsal and ventral tubercles 21.1, depth through bicipital surface and tuberculum ventrale 11.6, depth of head 5.7.
Figure 4.—Proximal ends of left humeri of Graculavus velox and related birds: a, Esacus magnirostris (Burhinidae), USNM 19649; b,d,f,h, Graculavus velox, holotype, YPM 855; c,e,g, i, Presbyornis sp., UCMP 126205. a-c, anconal view; d,e, anconal view with distal portion tilted upwards; f,g, palmar view; h,i, proximal view. All figures × 2; specimens coated with ammonium chloride to enhance detail.
Comparisons.—Marsh (1872) originally described this as a species of cormorant (Phalacrocoracidae, Pelecaniformes) and included the species G. pumilis Marsh, 1872, also from New Jersey, and G. anceps Marsh, 1872, from the Late Cretaceous of Kansas, in the same genus. Marsh (1880) later referred G. anceps to the genus Ichthyornis, where it has remained. Shufeldt (1915:17-19) went into considerable detail to show that the species of Graculavus, particularly G. velox, were not cormorants, instead being limicoline shorebirds with similarities to the Burhinidae, Haematopodidae, and Charadriidae. Accordingly, Lambrecht (1933:540, 546) placed these taxa among the charadriiform birds, but rather inexplicably listed velox under Shufeldt's substitute name Limosavis in the suborder Laro-Limicolae, while retaining pumilis in the genus Graculavus in the suborder Limicolae. Brodkorb (1963b:249) ignored Shufeldt's assessment of relationships and placed G. velox and G. pumilis in the Phalacrocoracidae, subfamily Graculavinae. Cracraft (1972) did not examine the specimens attributed to Graculavus in his consideration of the relationships of Telmatornis.
We have synonymized Graculavus pumilis Marsh, 1872, with Telmatornis priscus Marsh, 1870, and discuss below the characters by which Graculavus (restricted to G. velox) may be separated from Telmatornis. Shufeldt (1915) has already presented adequate evidence that Graculavus is not a cormorant and is instead a charadriiform. The following combination of characters of the proximal end of the humerus is shared by Graculavus and Presbyornis and distinguishes these genera from other Charadriiformes: (1) lack of a distinct lanceolate scar for M. coracobrachialis cranialis; (2) lack of a distinctly excavated second (dorsal) tricipital fossa; (3) presence of a distinct tumescence in the proximoventral portion of the tricipital fossa; scars for (4) M. scapulohumeralis caudalis and (5) M. scapulohumeralis cranialis very large and distinct; (6) attachment of M. latissimus dorsi cranialis a well-defined, raised protuberance situated dorsal to the median ridge of the shaft; (7) tuberculum dorsale well defined, distinctly pointed. In most of the preceding characters that it preserves, the single proximal end of humerus referred to Telmatornis (the holotype of G. pumilis) agrees with Graculavus and Presbyornis.
Among living families, the Burhinidae are the most similar to Graculavus; both agree in characters 1, 2, 4, and 7, with certain species of Burhinus also having characters 3 and 6 present but less developed. Graculavus differs from Burhinus mainly in having (8) the head not as deep and bulbous; (9) distance from head to tuberculum dorsale greater; (10) tuberculum dorsale smaller, much less projecting; (11) tuberculum ventrale in ventral view more elongate; and (12) scar on tuberculum ventrale for M. coracobrachialis caudalis much larger and more distinct.
Graculavus is very similar to Presbyornis, agreeing with that genus in characters 8 and 10 but differing in characters 11 and 12 and in (13) having the head more deeply undercut. Presbyornis is intermediate between Graculavus and the Burhinidae in character 9.
Graculavus velox was a fairly large bird, being approximately the size of Presbyornis cf. pervetus and somewhat larger than the large living burhinid Esacus magnirostris.