. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Skull of American Tritylodontidae • Sues 223. Figure 3. Skull of Kayentathehum wellesi, MCZ 8812. Right lateral view, with zygomatic arch and lower jaw removed. Unfin- ished distal surfaces on paroccipital process indicated by stippling. are only delimited posterodorsally by bony knobs on the frontals. The posterior por- tion of the skull bears a distinct sagittal crest and posterolaterally diverging lamb- doidal crests. A pineal foramen is absent. The broad and short snout of Kaijenta- theriiim tapers anteriorly and
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Skull of American Tritylodontidae • Sues 223. Figure 3. Skull of Kayentathehum wellesi, MCZ 8812. Right lateral view, with zygomatic arch and lower jaw removed. Unfin- ished distal surfaces on paroccipital process indicated by stippling. are only delimited posterodorsally by bony knobs on the frontals. The posterior por- tion of the skull bears a distinct sagittal crest and posterolaterally diverging lamb- doidal crests. A pineal foramen is absent. The broad and short snout of Kaijenta- theriiim tapers anteriorly and its sides di- verge only little posteriorly. A well-devel- oped secondary bony palate, formed by the maxillae and palatines, extends almost to the posterior end of the upper tooth row in Kayentatherium (Fig. 6). The pos- terior region of the palate shows a rather complex arrangement of longitudinal ridges and channels, reminiscent of that found in many non-therian mammals. The basicranium is broad posteriorly and tri- angular in ventral view, with the apex of this triangle directed anteriorly. The par- occipital process is robust and divided at its distal (lateral) end. Prominent occipital condyles, formed by the exoccipitals, are situated ventrolateral to the foramen magnum and are separated by a shallow notch for the robust dens. The broadly tri- angular occipital region is separated from the zygomatic arches laterally by a V-shaped notch on either side. The lower jaw is characterized by a very large dentary with a tall and distinctly re- curved coronoid process (Fig. 12). The postdentary bones are much reduced and form slender bony rods. They are lodged in a median sulcus on the dentary and articulate with a diminutive quadrate. The reflected lamina on the angular and the retroarticular process are well-developed. Kayentatherium has one greatly en- larged lower incisor in each upper and lower jaw (Figs. 1, 4). In Dinnebitodon three (except two in MCZ 8836) upper incisors a
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Keywords: ., bookauthorharvarduniversity, bookcentury1900, booksubjectzoology
