. Bulletin - United States National Museum. Science. 40 BULLETIN 110, UNITED STATES NATIONAL MUSEUM. The centra are deeply excavated on the sides and inforiorly, this feature becom- ing more pronounced as the posterior part of the series is approached, where the en- A B. Fig. 23.—Fourih dorsal vertebra of Antrodemus valens Leidy. No. 8367, \ NAT. size. A, Side view. B, Front view, d, diapophysis; p, parapophysis; z, anterior zygapophysis; z', posterior zygapophysis. larged ends are flangehke. The median sides above the middle are pinched in, forming a shallow lon- gitudinal depression
. Bulletin - United States National Museum. Science. 40 BULLETIN 110, UNITED STATES NATIONAL MUSEUM. The centra are deeply excavated on the sides and inforiorly, this feature becom- ing more pronounced as the posterior part of the series is approached, where the en- A B. Fig. 23.—Fourih dorsal vertebra of Antrodemus valens Leidy. No. 8367, \ NAT. size. A, Side view. B, Front view, d, diapophysis; p, parapophysis; z, anterior zygapophysis; z', posterior zygapophysis. larged ends are flangehke. The median sides above the middle are pinched in, forming a shallow lon- gitudinal depression as shown in figures 26 and 27. In passing backward in the series these depressions become sUghtly deeper, though on none except perhaps the last dorsal could they be classed as pits. In both Gorgosaurus and Tyrannosaurus lateral pits are present in most of the dorsal centra. The anterior face of the sixth dorsal is nearly ])lane, but in the seventh it is slightly concave, this concavity continuing back through the series. The posterior articular surfaces are partly am- phiplatyan, with a characteristic slight anterior concavity in the upper portion of the face below the neural canal. This feature is especially pro- nounced on the last dorsal, where it articulates with the sacrum. The centrum of the twelfth dorsal viewed from the side is slightly wedge- shaped, being narrower below than above—a condition observed in the seventh dorsal of Tyrannosaurus as depicted by Osborn.' To a less degree some of the other dorsals are also shorter longitudinally at the bottom than at the top, thus forming a slight upward bow of the articulated vertebral column. The height of the centra exceeds their Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States National Museum; Smithsonian Institution; United
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