. Bulletin. Natural history; Natuurlijke historie. --â ^ FIG. 18. Left splenial of Deinonychus antirrhopus, YPM 5237, in lateral (A) and medial (B) views. The rostral extremity of the prearticular apparently lay external to the upper (internal) flange. Abbreviations: angâangular; deâdentary contact; parâareas of contact with the pre- articular. surface of the dentary. This lamina increases in height posteriorly to about mid- length, where it ends in a dorsoposteriorly directed flange which is separated by a long V-shaped notch (infra-Meckelian fossa) from the ventroposterior or angular process
. Bulletin. Natural history; Natuurlijke historie. --â ^ FIG. 18. Left splenial of Deinonychus antirrhopus, YPM 5237, in lateral (A) and medial (B) views. The rostral extremity of the prearticular apparently lay external to the upper (internal) flange. Abbreviations: angâangular; deâdentary contact; parâareas of contact with the pre- articular. surface of the dentary. This lamina increases in height posteriorly to about mid- length, where it ends in a dorsoposteriorly directed flange which is separated by a long V-shaped notch (infra-Meckelian fossa) from the ventroposterior or angular process. The latter is a stout, slightly curved, tapering process that extends back beneath the anterior extremity of the angular. The upper surface is a shallow groove which narrows and deepens anteriorly, passing between the lateral and medial lamina. The medial lamina of the splenial is less than half the height of the lateral lamina, its upper margin slopes forward to form a thin anterior proc- ess separated from the lateral lamina by a narrow, elongate notch. No sutural scars are recognizable and contacts with the dentary, angular and prearticular probably were rather loose. ANGULAR Two angulars are known, one from each of the skulls from the Yale site. Nei- ther is complete and little can be said about precise relationships to adjacent jaw elements. Anteriorly, the angular consists of a stout, slightly curved process, tri- angular in section, which presumably met the dentary anteriorly and the splenial and prearticular dorsomedially. Caudally, it expands into a strongly curved and very thin sheet of bone which overlapped the ventrolateral portion of the surangu- lar. The dorsal margin is well preserved in both specimens and clearly shows the inferior limits of a very large external mandibular fossa (Fig. 19). Although the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of
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