Comparisons.—The very large size of this specimen has undoubtedly been a factor in misleading those who have attempted to identify it, as it came from a bird the size of a swan or a large crane. The affinities of this fossil have long been questioned and the species has for most of its history been in limbo. Marsh (1870:207) concluded only that Laornis "shows a strong resemblance in several respects to the Lamellirostres [Anseriformes], and also to the Longipennes [Charadriiformes (Lari) and Procellariiformes], but differs essentially from the typical forms of both of these groups." In its own nebulous way, this assessment is concordant with our placement of Laornis in a charadriiform group that was near the ancestry of the Anseriformes. Doubtless only on the strength of Marsh's comments. Cope (1869-1870:237) placed Laornis in the "Lamellirostres." Hay (1902:531) included Laornis in the Anatidae. Shufeldt (1915:23) hardly clarified matters when he characterized Laornis as "at least one of the generalized types of waders," being a "remarkable type, which seems to have, judging from this piece of the tibiotarsus, Turkey, Swan, Crane, and even other groups all combined in it." Lambrecht (1933:526) included Laornis as a genus incertae sedis in his "Telmatoformes," between the Aramidae and Otididae.
The type was restudied by Cracraft (1973:46) who put Laornis in the Gruiformes and created a new family (Laornithidae) and superfamily (Laornithoidea) for it. He included it in his suborder Ralli, the only other member of which was the Rallidae. After preliminary comparisons, Olson (1974) ventured that Laornis belonged in the suborder Lari of the Charadriiformes. Brodkorb (1978:214) listed Laornis under Aves incertae sedis and guessed that it might be related to the Pelecaniformes.
Except for the extreme difference in size, the tibiotarsus of Laornis is in many respects similar to that of Presbyornis ([Figure 8]), especially in (1) the shape and position of the tubercle proximal to the external condyle; (2) the transverse pit in the intercondylar sulcus; and (3) the broad, shallow intercondylar sulcus as seen in distal view. It differs in a seemingly minor but quite characteristic feature, the large nutrient foramen situated in the groove for M. peroneus brevis ([Figure 8c]). This is absent in Presbyornis but is present in both of the tibiotarsi from the Cretaceous of New Jersey in which that portion of the bone is preserved (the holotypes of Palaeotringa littoralis and P. vagans), as well as in a tibiotarsus (Science Museum of Minnesota P75.22.25) from the type-locality of Dakotornis cooperi Erickson, 1975, that may be referable to that graculavid-like species. The foramen in the peroneus brevis groove may also be found in at least some specimens of Stercorariidae, which is partly what led Olson (1974) to suggest a relationship between Laornis and the Lari. Laornis appears to have been an extremely large member of the "transitional Charadriiformes," though where its relationships may lie within that group cannot be determined.
Genus Palaeotringa Marsh, 1870
Type-Species.—Palaeotringa littoralis Marsh, 1870; by subsequent designation (Hay, 1902:527).
Included Species.—Palaeotringa littoralis Marsh, 1870, and Palaeotringa vagans Marsh, 1872.
Palaeotringa littoralis Marsh, 1870
Figure 7l
Palaeotringa littoralis Marsh, 1870:208.
Holotype.—Distal portion of left tibiotarsus lacking most of the inner condyle, YPM 830.