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Claosaurus agilis Marsh

An excerpt from:

Marsh, O.C. 1890.  Additional characters of the Ceratopsidae, with notice of new Cretaceous dinosaurs.  American Journal of Science, Series 3, 39: 418-426, with pls. v-vii.  

Copyright © 2005-2009 by Mike Everhart

Created 06/27/2005 - Updated 02/14/2009

LEFT: The mounted specimen of Claosaurus agilis Marsh in the Yale Peabody Museum, adapted from an old photograph.  The skull is added.

Wherein, O.C. Marsh renames Hadrosaurus agilis Marsh (1872) to a new genus, Claosaurus agilis, in recognition of certain distinct characters. See Marsh, 1872 for the original description.

             O.C Marsh -- New Cretaceous Dinosaurs                                                     423

Claosaurus agilis, gen. nov.

     The small dinosaur described by the writer, in 1872, as Hadrosaurus agilis* proves on investigation to represent a distinct genus which may be called Claosaurus. The remains of this reptile were found by the writer, in the Pteranodon beds of the Cretaceous, near the Smoky Hill River in western Kansas.  After the species was described, the writer again visited the locality and secured other portions of the skeleton, so that now the more important parts are available for comparison.

     The teeth are of the Hadrosaurus type, but, apparently only a single row was in use at one time. The cervical vertebrae are very short, and strongly opisthocoelian. The fore limbs were very small. There are seven vertebrae in the sacrum, firmly coössified. The caudals are longer than wide and the tail was quite elongate.

              * This journal, vol. iii, p. 301, April 1872.



424             O. C. Marsh -- New Cretaceous Dinosaurs

     The astragalus was closely applied to the end of the tibia, but not coössified with it. The fibula is strong and complete, with both ends nearly equal in size. There were three functional digits in the pes, with their metatarsals moderately elongate. The terminal phalanges are broad, and ungulate in form.

     The ilium is intermediate in form between that of Hadrosaurus and Stegosaurus, and its general characters are shown in the cut below. The portion in front of the acetabulum is very slender and elongate. The face for the pubis is much smaller than that for the ischium.

     The present genus is very distinct from Nodosaurus which was described by the writer from a higher horizon of the Cretaceous. The present animal had apparently no dermal armor and was of much more slender proportions. When alive, it was probably not more than 15 feet in length.

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Above: Ilium of Claosaurus agilis, Marsh; right lateral  view; a, acetabulum; is surface for ischium; p, surface for pubis (Marsh, 1890)

Credits: Dr. Jane Davidson provided a copy of the Marsh 1890 paper used to prepare this ePage.

Suggested references:

Brown, Barnum. 1916.  Corythosaurus casuarius: Skeleton, musculature and epidermis.  Bulletin of the American Museum of Natural History 35: 709-716, pls. xiii-xxii.

Carpenter, K., D. Dilkes, and D. B. Weishampel. 1995. The dinosaurs of the Niobrara Chalk Formation (upper Cretaceous, Kansas). Journal of Vertebrate Paleontology 15(2): 275-297.

Everhart, M. J. 2003. First records of plesiosaur remains in the lower Smoky Hill Chalk Member (Upper Coniacian) of the Niobrara Formation in western Kansas. Kansas Academy of Science, Transactions 106(3-4): 139-148.

Everhart, M. J. 2004. Late Cretaceous interaction between predators and prey. Evidence of feeding by two species of shark on a mosasaur. PalArch, vertebrate palaeontology series 1(1): 1-7.

Everhart, M. J. 2004. Notice of the transfer of the holotype specimen of Niobrarasaurus coleii (Ankylosauria; Nodosauridae) to the Sternberg Museum of Natural History. Kansas Academy of Science, Transactions 107(3-4): 173-174.

Everhart, M. J. 2005. Bite marks on an elasmosaur (Sauropterygia; Plesiosauria) paddle from the Niobrara Chalk (Upper Cretaceous) as probable evidence of feeding by the lamniform shark, Cretoxyrhina mantelli. PalArch, Vertebrate paleontology 2(2): 14-24.

Everhart, Michael J. 2005. Oceans of Kansas - A Natural History of the Western Interior Sea. Indiana University Press, 320 pp.

Everhart, M. J. and S. A. Hamm. 2005. A new nodosaur specimen (Dinosauria: Nodosauridae) from the Smoky Hill Chalk (Upper Cretaceous) of western Kansas. Kansas Academy of Science, Transactions 108(1/2): 15-21.

Liggett, G. A. 2001. Dinosaurs to Dung Beetles: Expeditions through time - A guide to the Sternberg Museum of Natural History. Sternberg Museum of Natural History, Hays, KS. 127 p.

Liggett, G. A. 2005. A review of the dinosaurs from Kansas. Kansas Academy of Science. Transactions 108(1/2): 1-14.

Hamm, S. A. and M. J. Everhart. 2001. Notes on the occurrence of nodosaurs (Ankylosauridae) in the Smoky Hill Chalk (Upper Cretaceous) of western Kansas. Journal of Vertebrate Paleontology 21(suppl. to 3): 58A.

Hattin, D. E. 1982. Stratigraphy and depositional environment of the Smoky Hill Chalk Member, Niobrara Chalk (Upper Cretaceous) of the type area, western Kansas. Kansas Geological Survey Bulletin 225, 108 pp.

Marsh, O. C. 1872. Notice of a new species of Hadrosaurus. American Journal of Science, Series 3, 16: 301.

Marsh, O.C. 1890.  Additional characters of the Ceratopsidae, with notice of new Cretaceous dinosaurs.  American Journal of Science, Series 3, 39(233): 418-426, with pls. v-vii.   (The renaming of Hadrosaurus agilis to Claosaurus agilis.

Mehl, M. G. 1931. Aquatic dinosaur from the Niobrara of western Kansas. Bulletin of the Geological Society of America 42: 326-327.

Mehl, M. G. 1936. Hierosaurus coleii: a new aquatic dinosaur from the Niobrara Cretaceous of Kansas. Denison University Bulletin, Journal of the Scientific Laboratory 31: 1-20, 3 pls.

Shimada, K. 1997. Paleoecological relationships of the late Cretaceous lamniform shark, Cretoxyrhina mantelli (Agassiz). Journal of Paleontology. 71(5): 926-933.

Shimada, K., and G. E. Hooks, III. 2004. Shark-bitten protostegid turtles from the Upper Cretaceous Mooreville Chalk, Alabama. Journal of Paleontology 78(1):205-210.

Parmenter, C. S. 1899. Fossil turtle cast from the Dakota epoch. Kansas Academy of Science, Transactions 16: 67.

Sternberg, C. H. 1909. An armored dinosaur from the Kansas chalk. Kansas Academy of Science, Transactions 22: 257-258.

Stewart, J. D. 1990. Niobrara Formation vertebrate stratigraphy. Pages 19-30, In Bennett, S. C. (ed.), Niobrara Chalk Excursion Guidebook, The University of Kansas Museum of Natural History and the Kansas Geological Survey.

Varricchio, D. J. 2001. Gut contents from a cretaceous tyrannosaurid; Implications for theropod dinosaur digestive tracts. Journal of Paleontology 75(2):401-406.

Walters, R. F. 1986. Memorial: Virgil Bedford Cole (1897-1984). AAPG Bulletin 70(2):208-209.

Wieland, G. R. 1909. An armored saurian. American Journal of Science 27: 250-252. (March)

Wieland, G. R. 1909. A new armored saurian from the Niobrara. Contributions to the Peabody Museum, XIX: 250-252

Wieland, G. R. 1911. Notes on the armored Dinosauria. American Journal of Science 31: 112-124.