FamilyTytthostonychidae, 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 fromPhaethonandLimnofregatain 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 inLimnofregata, to which the fossil is somewhat more similar in this respect.Tytthostonyxdiffers from any of the taxa compared in having the ventral condyle very rounded, extending distally well past the dorsal condyle.