The Phytosauria; With Especial Reference to Mystriosuchus and Rhytidodon

The Phytosauria; With Especial Reference to Mystriosuchus and Rhytidodon

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...spine comparable to the so-called "proatlas" of crocodiles has been found. Axis (Pl. VIII, Figs. 8, 8a, 8b, and text-'fig. 13).--In neither M ystriosuchus nor Rhytidodon has the axis been discovered, and it was my expectation to send the present memoir to press without any description of this very important element, when I discovered in the National Museum in Washington, an axis of the large Heterodontosuchus ganei Lucas (see page 94), which Mr. F. A. Lucas kindly placed at my disposal. Though this species is much larger and more powerful than Rhytidodon, an examination of various parts of the skele ' ton leaves no doubt of its phytosaurian character. Since there is no reason to believe that the axis differs essentially from that of Rhytidodon, it may be described here. In the specimen the neural arches are broken off at the level of the middle of the neural canal, and the posterior third of the centrum is missing, but the important portion, the anterior two-thirds, with odontoid, intercentrum, and rib articulations, is well preserved. Both the odontoid process (= atlas centrum) and the second intercentrum are firmly coossified with the axis centrum, though the lines of fusion are still discernible with some distinctness. The middle of the axis centrum is greatly constricted from side to side, its transverse diameter being only 21 mm., while that of the intercentrum is 65 mm. The ventral surface of the centrum presents a mesial keel-like ridge. The odontoid is a blunt process, the face of which is greatly elongated transversely, its measurements being, transverse, 48 mm., vertical, 19 mm. It is well-nigh certain that no portion of this process could have been in contact with the occipital condyle; immediately below the face of...show more

Product details

  • Paperback | 36 pages
  • 189 x 246 x 2mm | 82g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236968123
  • 9781236968128