File:The American journal of science (1908) (17531947333).jpg

Title: The American journal of science
Identifier: americanjourna4251908newh (find matches)
Year: 1880 (1880s)
Authors:
Subjects: Science
Publisher: New Haven : J. D. & E. S. Dana
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
R. S. Lull—Cranial Musculature in Dinosaurs. 395 part of the fenestra if it were present and which probably rep- resents the point of final closure of that aperture.* There is a very precise analogy between the crest of a cha- meleon and that of the Ceratopsia, as it is primarily, in each instance, merely a backward extension of the parietal segment of the skull to obtain a greater area for the origin of the tem- poral muscles. This backward extension of the median region especially gave greater area for the eomplexus major muscles, which could then extend from their old insertion on the supra- occipital backward along the interior surface of the median parietal bar (interparietal), giving greatly increased leverage in wielding the head.
Text Appearing After Image:
Fig. 6. Triceratops serratus. There seems to be an interesting correlation between the development of the squamosal elements of the frill and that of the paired horns. The broadening squamosals evidently increased in size to allow for the extension of the great lateral muscles of the neck from their original insertion on the exoc- cipitals (vide supra, p. 391). This not only provides for larger and more powerful muscles, but also gives greater leverage in wielding the supraorbital horns. Centrosaurus apertus Lambe (1904) (fig. 5) had a straight, powerful nasal horn, evidently its chief weapon, and extremely small squamosals, as shown by the very short parieto-squamosal suture, the major part of the crest being composed of the parietal elements. In the Judith * Triceratops and Torosaurus it must be remembered, while contempo- raneous, are not directly related, but represent parallel races derived independently from Judith river ancestry. In Torosaurus the parietal fenestra? were persistent. (Lull, 1908, p. 101.)

Note About Images