. Bulletin - United States National Museum. Science. OSTEOLOGY OF CAENIVOEOUS DINOSAUKS. During the half century that has elapsed since Antrodemus was established, it will be observed from the abore review, but little attention has been given this genus, due, no doubt, to the scanty materials on which it was founded. Recently I have made a very careful comparison of the type specimen of Antro- demus vaJens with the anterior caudal vertebrae of No. 8367 , a specimen previously identified as AUosaurus fragiUs Marsh, and such close resemblances were |_found as to indicate their generic id
. Bulletin - United States National Museum. Science. OSTEOLOGY OF CAENIVOEOUS DINOSAUKS. During the half century that has elapsed since Antrodemus was established, it will be observed from the abore review, but little attention has been given this genus, due, no doubt, to the scanty materials on which it was founded. Recently I have made a very careful comparison of the type specimen of Antro- demus vaJens with the anterior caudal vertebrae of No. 8367 , a specimen previously identified as AUosaurus fragiUs Marsh, and such close resemblances were |_found as to indicate their generic identity. In plate 1, figures 1 to 6, is shown, in tlii-ee aspects, comparative views of the genotype of Antrodemus with a caudal of corresponding size of the above specimen. Their close resemblance down to the minutest details is clearly indicated. Their comparative measurements are as follows: No. S3fi7, , sixth Greatest vertical diameter of posterior end of centrum Greatest transverse diameter of same Length of centrum Least transverse diameter of centrum at center « Estimated. The medullary cavities within the body of the centrum are larger in the genotype than in No. 8367, but this may be due to a slight difference in the position of the point where the cross section was taken. At most it is only a difference of degree and certainly does not indicate any important structm-al modification. Unfortunately direct comparison can not be made with the genotype of AUosaurus, inasmuch as no anterior caudals are preserved with that specimen. The so-called caudal mentioned in Marsh's original description, below, turns out to be the damaged centrum of a dorsal vertebra. See plate 2, fig. 2. The original description ^ of AUosaurus fragilis Marsh consists of the following: This genus may be distinguished from any known Dinosaurs by the vertebrae which are peculiarly modified to insure lightness. Although apparently not pneumatic, they have the weight of the centra greatl
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