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The cretaceous birds of New Jersey

Chapter 25: Genus Tytthostonyx, new genus
By Storrs L. Olson
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Archaeology & AnthropologyScience - Biology

About This Book

This revision presents fossil avian material from Late Cretaceous (Maastrichtian) marine deposits of New Jersey, incorporating newly collected specimens from the Inversand marl pits and reexamining century-old types. About eight genera and nine species are recognized, most assigned to a primitive charadriiform-like assemblage provisionally referred to the form family Graculavidae (including genera such as Graculavus, Telmatornis, Anatalavis, Laornis, and Palaeotringa). A new family, Tytthostonychidae, and the genus and species Tytthostonyx glauconiticus are proposed for a distinctive humerus possibly allied to procellariiform or pelecaniform birds. The fauna appears neognathous but cannot be placed in modern families.

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.