The cretaceous birds of New Jersey

by Storrs L. Olson; David C. Parris

Graculavidae, Genus and Species Indeterminate

Figure 9b,c

Referred Material.—Abraded distal end of left humerus and associated proximal portion of humeral shaft, proximal end of radius, and fragment of shaft of ulna, NJSM 11302.

Locality and Horizon.—Collected from the main fossiliferous layer of the Inversand Company marl pit, Sewell, Gloucester County, New Jersey; Hornerstown Formation, latest Cretaceous (Maastrichtian); collected 15 August 1972 by David C. Parris.

Measurements (in mm).—Humerus: distal width 19 mm, depth through dorsal condyle 9.7, width of shaft at proximal extent of brachial fossa 11.0; greatest proximal diameter of radius 7.0.

Comparisons.—The distal end of the humerus is the only reasonably diagnostic element in this assortment and indicates a large, robust species that would have exceeded in size any of the others known in this Cretaceous avifauna except Laornis edvardsianus, which was much larger still. In size this bird would have approximated the modern flamingo Phoeniconaias minor, which it somewhat resembles in morphology as well. The humerus is not greatly different from that of other Graculavidae in general aspect but is distinct in having a larger, much deeper, and more proximally situated brachial depression. It represents a species distinct from any of the others yet known in the fauna and is certainly generically distinct from all except possibly Graculavus, for which comparable elements are unknown.

Order Procellariiformes?

Among the newly collected material from the Inversand pit is a singular avian humerus that cannot be assigned to the Graculavidae or to any other known family, fossil or modern. Although it is generally inadvisable to name even Paleogene birds on single elements, to say nothing of Cretaceous ones, the specimen under consideration here is superior to any of the other avian fossils yet collected from the Cretaceous of New Jersey, both in preservation and in diagnostic qualities, and it would seem incongruous to leave it innominate when practically all the other fragments from the same deposits have received names.

Figure 9.—Miscellaneous elements, a, Palaeotringa littoralis? (NJSM 11303), distal end of left humerus, palmar view; b, Graculavidae, genus and species indeterminate (NJSM 11302), distal end of left humerus, palmar view; c, proximal end of radius associated with b; d, Graculavus velox? (NJSM 11854), right carpometacarpus; e,f, Procellariiformes?, genus and species indeterminate (ANSP 15713), distal end of left ulna (e, external view;/dorsal view); g, Aves, incertae sedis (NJSM 12119), distal end of left femur, posterior view. (a,b,c,d, × 2; e,f,g, × 5; specimens coated with ammonium chloride to enhance detail.)

The most distinctive features of this specimen are the deep brachial depression and the incipient ectepicondylar spur, thus calling to mind both the Lari (Charadriiformes) and the Procellariiformes among modern birds. Among the Pelecaniformes it also bears a resemblance to the Phaethontidae and especially to the Eocene frigatebird Limnofregata (Fregatidae) (Olson, 1977).

Family Tytthostonychidae, new family

Type Genus.—Tytthostonyx, new genus.

Included Genera.—Type genus only.

Diagnosis.—Differs from the Lari and other Charadriiformes in (1) the low, narrow head; (2) the very large, long pectoral crest; (3) the virtual absence of the incisura capitis or any excavation for M. coracobrachialis cranialis; and (4) the shallow, indistinct tricipital grooves. It agrees with the Procellariiformes and differs from Phaethon and Limnofregata in characters 2 and 4, and in the large, deeply excavated brachial depression. The ectepicondylar spur is better developed than in any of the Pelecaniformes but not as well developed as in the Procellariiformes. The apparently very broad pectoral crest extends much farther distally than in any of the Procellariiformes or even in Limnofregata, to which the fossil is somewhat more similar in this respect. Tytthostonyx differs from any of the taxa compared in having the ventral condyle very rounded, extending distally well past the dorsal condyle.

Genus Tytthostonyx, new genus

Type-Species.—Tytthostonyx glauconiticus, new species.

Included Species.—Type species only.

Diagnosis.—As for the family.

Etymology.—Greek, tytthos, little, plus stonyx, any sharp point. The name is masculine in gender and refers to the small, presumably rudimentary, ectepicondylar spur. It should not be confused with the coleopteran genus Tytthonyx, based on onyx, claw.

Tytthostonyx glauconiticus, new species

Figures 10, 11

Holotype.—Right humerus lacking the ventral tubercle, portions of the pectoral crest, and other parts of the proximal end, where partially reconstructed, NJSM 11341.

Locality and Horizon.—Main fossiliferous layer of the Inversand Company marl pit, Sewell, Gloucester County, New Jersey; basal portion of the Hornerstown Formation, latest Cretaceous (Maastrichtian); collected 11 October 1973 by David C. Parris.

Measurements of Holotype (in mm).—Length as reconstructed, 110; width and depth of shaft at midpoint 7.0 × 5.6; distal width 14.8; depth through dorsal condyle 8.7.

Etymology.—From Latin, glaucus (Greek, glaukos), bluish green or gray, sea-colored, applied to greensands because of their color, although appropriate because of their marine origins as well; in reference to the holotype having been recovered from beds of glauconite.

Remarks.—A possible relationship between the Procellariiformes and Pelecaniformes has been previously suggested (Sibley and Ahlquist, 1972:70; Olson, 1985:142), and among the pelecaniform taxa most often mentioned as being procellariiform-like are the Fregatidae. It is tempting to regard the humerus of Tytthostonyx as being similar to that possessed by the ancestral stock that gave rise to the Procellariiformes. Its similarities also to the Eocene frigatebird Limnofregata would thus be seen as corroborating the primitiveness of the Fregatidae within the Pelecaniformes. Whereas Tytthostonyx definitely has not achieved the highly distinctive and presumably derived morphology of the humerus of modern Procellariiformes, the incipient development of the ectepicondylar spur and deep brachial depression could be interpreted as tending in that direction.

On the other hand, we must admit that we are dealing with only a single bone and one of very great age at that, so that the risk of overinterpreting the fossil is correspondingly great. We can only discern the overall similarities of the specimen and phylogenetic inferences can therefore be only tentative at best.

Family and Genus Indeterminate

Figure 9e,f

Referred Material.—Distal portion of left ulna ANSP 15713.

Locality and Horizon.—Inversand Company marl pit, near Sewell, Gloucester County, New Jersey; Hornerstown Formation, Late Cretaceous (Maastrichtian); not found in situ, collected on shelf formed by "blue bed"; collected 31 August 1977 by Richard S. White.

Measurements (in mm).—Distal width 2.6, distal depth 3.1, width and depth of shaft near point of break 1.8 × 1.9.

Comparisons.—This specimen comes from a very small bird. The only modern pelagic birds in this size range are the storm-petrels of the family Oceanitidae and the fossil resembles this family in the extremely straight shaft of the ulna, the shape and depth of the tendinal grooves, and the relatively well-developed scars for the attachment of the secondaries. It differs from the Oceanitidae in having the ventral lip of the external condyle much more rounded and protrudent past the plane of the shaft, whereas the carpal tubercle in dorsal view is markedly smaller. On this basis, the fossil certainly could not be referred to the Oceanitidae and that it should be associated with the Procellariiformes may be doubted as well.

Figure 10.—Tytthostonyx glauconiticus, new genus and species (holotype, NJSM 11341), right humerus: a,b, anconal and palmar views of uncoated specimen to show reconstructed areas, × 0.8; c,d, stereophotographs of coated specimen in anconal and palmar views, × 1.3.

Figure 11.—Tytthostonyx glauconiticus, new genus and species (holotype, NJSM 11341), stereophotographs of distal end of right humerus: a, anconal view; b, palmar view; c, ventral view; d, dorsal view; e, distal view. (All figures × 2; specimens coated with ammonium chloride to enhance detail.)

Aves, incertae sedis

Figure 9g

Referred Material.—Distal end of left femur, NJSM 12119.

Locality and Horizon.—Inversand Company marl pit, Sewell, Gloucester County, New Jersey; from processed spoil piles, precise stratum unknown; collected 12 December 1981 by Cynthia Miller. Presumably from the Hornerstown Formation but could be either Late Cretaceous or Paleocene.

Measurements (in mm).—Distal width 4.3, distal depth 3.8.

Comparisons.—This is also from a very small bird, possibly the same size as the species represented by the preceding ulna (ANSP 15713; [Figure 9e,f]) but probably somewhat larger. It is characterized by an extremely well-developed tubercle for the attachment of M. gastrocnemius lateralis. A perfunctory perusal of modern taxa revealed nothing similar.

Discussion

Because the specimens treated here are avian and of Mesozoic age, it is almost certain that too much importance will be made of them by some future authors. Indeed, it will probably be years before the literature can be expunged of the records of presumed occurrences that arose from previous misidentifications of these fossils. Therefore, in an effort to forestall overenthusiasm for these fragments we shall present our own brief assessment of their significance.

Unlike most other Cretaceous birds, such as the Hesperornithiformes, Ichthyornithiformes, and Enantiornithiformes, which represent totally extinct lineages (Olson, 1985), the Cretaceous birds of New Jersey are of essentially modern aspect. However, there are no modern families of birds represented in the fauna. The differences among the fossils suggest that at least two orders are represented, but whether any or all of the species can be placed in modern orders is more difficult to say. This stems as much from the unsatisfactory state of the ordinal classification of modern birds (Olson, 1981, 1985), as from the incompleteness of the fossils. There are certain modern birds, for example the Burhinidae, with sufficient similarities to some of the Cretaceous fossils that there would be no problem with associating them in the same ordinal-level taxon, though it would be more difficult to say which other modern families should also be included.

The material is too poor to state how many families are represented in the fauna, although if the various members of the "form-family" Graculavidae were better known there can scarcely be any doubt that more than one family would be recognized in this group. Within the Graculavidae from New Jersey there appear to be six genera (Graculavus, Telmatornis, Palaeotringa, Laornis, Anatalavis, and an unnamed genus). These are diverse, ranging in size from the smallest of the modern Burhinidae to that of a large crane. The very short, robust, curved humeri of Anatalavis indicate some diversity in mode of flight as well. The greatest similarity of most of these forms is to the early Paleogene bird Presbyornis, and then to the modern family Burhinidae. Because these two groups are very different in their habits and feeding adaptations we may expect that the various members of the Graculavidae were probably as divergent from one another as are Presbyornis and Burhinus, their similarities being almost certainly due to the retention of primitive characters.

Including the two genera and species that show some similarities to the Procellariiformes, along with the small indeterminate femur, the total avifauna from the New Jersey greensands comprises 8 or 9 genera and 9 or 10 species. As far as can be determined, all of the birds in this assemblage were probably marine or littoral in habits. We certainly would not interpret this as indicating that waterbirds are primitive and that they gave rise to land birds, as suggested by Thulborn and Hamley (1985) in their fantastic and highly improbable conjectures as to the mode of life of Archaeopteryx. Indeed, just the opposite is probably the case (Olson, 1985), the lack of Late Cretaceous fossils of truly terrestrial or arboreal birds most likely being due to sampling bias.