New specimen of shark scavenged dinosaur (hadrosaur) remains from the Smoky Hill Chalk (Upper Coniacian) of western Kansas
Copyright © 2005-2009 by Mike Everhart
Page created 06/19/2005
LEFT: Ginsu sharks (Cretoxyrhina mantelli) on the prowl - Adapted from a portion of a mural in the University of Nebraska State Museum, Lincoln, NE
On June 2, 2005, I was with Keith Ewell when he discovered what is only the sixth set of dinosaur remains to be documented from the Smoky Hill Chalk of western Kansas. The first remains of a dinosaur found in the chalk, a hadrosaur, were collected by O.C. Marsh in 1871 along the Smoky Hill River in Logan County (see Carpenter, et al., 1995). The second set of remains, a nodosaur (possibly two individuals, see Liggett, 2005) was discovered by Charles Sternberg in 1905 and described by G. R. Wieland in 1909 and 1911. Virgil Cole recovered the remains of another nodosaur in 1930 (Mehl, 1936; Cole, 2007) from southeastern Gove County. This specimen (Niobrarasaurus coleii) was transferred to the Sternberg Museum of Natural History in 2002 (Everhart, 2004) and additional remains were recovered in 2003. J.D. Stewart found the fragmentary remains of still another nodosaur (KUVP 25150) in Rooks County in 1973. The previous most recent discovery of dinosaur remains was made by Shawn Hamm in 2000 when he collected the right radius and ulna of a sub-adult nodosaur from the middle Santonian chalk of Lane County (Everhart and Hamm, 2005). That specimen also preserved evidence of being scavenged by a large shark.
The newest dinosaur specimen (FHSM VP-15824) comes from the lower Smoky Hill Chalk in southeastern Gove County and consists of nine articulated caudal (tail) vertebrae from an adult hadrosaur (credit for the ID goes to Ken Carpenter). The vertebrae were laying on their right side. The most anterior vertebrae (#1 and #2) of the series had partially eroded out and were exposed on the surface of the chalk. The other seven vertebrae were still completely enclosed in the matrix. The specimen is 22 in (55 cm) in length, is from the distal part of the tail and represents an adult animal that was about 10 m in length. There are non-serrated bite marks on both sides of the last vertebrae (#9, see pictures below). The bone surface at both ends of the articulated series are severely eroded and appear to have been partially digested. Consistent with many other specimens of large vertebrates (mosasaurs, plesiosaurs, turtles, etc) from this time period during the deposition of the Smoky Hill Chalk, these remains appear to have been consumed by a large shark, partially digested and then regurgitated. See Everhart and Ewell (2006) for additional information.
Gudger (1949, p. 41) reported finding a cow's skull in the stomach of a modern Tiger shark caught off the coast of Florida, and that " the outer hard smooth layer of the skull bones everywhere had been dissolved leaving only the inner cellular or cancellous material. This in turn was so soft that one could dent it with a finger. The digestive juices of a shark's stomach (presumably chiefly hydrochloric acid) are very concentrated." In another instance, he (ibid., p. 42) reported finding a horse's skull in the stomach of another Tiger shark and that the "outer hard smooth surface of the horse's skull had all been corroded away leaving the cancellous material about the consistency of sponge-rubber."
|LEFT: (LARGE FILE): The red vertebrae indicate the approximate location of the specimen in a drawing of the tail of the Late Cretaceous hadrosaur, Corythosaurus casuarius (adapted from Brown, 1916).|
The new specimen represents the first (and the earliest) remains of a hadrosaur to be collected from the Smoky Hill Chalk in more than 130 years. The type specimen of Claosaurus agilis was found by O.C. Marsh about 50 miles further west, on the north side of the Smoky Hill River, in Logan County, and much higher (a couple million years later) in the chalk. It was also a much smaller individual, estimated by Marsh (1890) to be about 15 feet long. Questions remain in regard to how the remains of these dinosaurs managed to drift hundreds of miles from land before final burial on the bottom of the Western Interior Sea.
|LEFT: My view of a large Cretoxyrhina mantelli shark scavenging on the tail of a dead hadrosaur floating in the Western Interior Sea. Drawing adapted from the original illustration by William J. Frazier in a Dinofest International paper by David Schwimmer (1997). Used with permission.|
|LEFT: An articulated series of nine caudal vertebrae (FHSM VP-15824) in left (upper) and right lateral view from a dinosaur discovered in the Smoky Hill Chalk of western Kansas by Keith Ewell, June, 2005. According to Ken Carpenter, the long, slender neural spines are distinctive to hadrosaurs. (Scale = cm)|
|LEFT: Posterior (upper) and dorsal views of the caudal vertebrae
(FHSM VP-15824) - most anterior to the left. (Scale = cm)
RIGHT: Vertebrae #7, 8 and 9 in left lateral view, showing the articulation between the elongated neural spines and the following vertebra. (Scale = cm)
|LEFT: Vertebra #2 (left) and #1 (right) in anterior (cranial) view
showing the amount of damage done to the exposed end of the most anterior vertebra (#1) in
the series by the acids in the shark's stomach.
RIGHT: Vertebra #8 (left) and #9 (right) in posterior (caudal) view showing the damage done to the most posterior vertebra (#9) by exposure to the acids in the shark's stomach. (Scale = cm)
|LEFT: The most distal of the vertebrae in the series (#9) in right lateral, proximal end and left lateral view. It preserves deep, non-serrated (e.g., NOT Squalicorax falcatus) bite marks on both sides of the vertebrae. This is probably an indication of an earlier bite that severed the tip of the tail. There is also evidence of severe erosion of the bone surface, probably due to exposure to digestive fluids in the shark's stomach. Little or no damage due to digestion is visible on the interior vertebrae of this series, most likely because they were covered with enough skin, muscle and connective tissue to provide some degree of protection. (Scale = cm)|
|LEFT: Left lateral and dorsal views of the most
complete vertebrae (#5). (Scale = cm)
RIGHT: A close-up of vertebrae #5 and #6 with re-attached neural spines.
|LEFT: (Click to enlarge) An unusual Squalicorax sp. tooth (FHSM VP-16355) in labial (left) and lingual views that was found in situ under the dinosaur vertebrae. Note the very weak serrations on the main cusp and the lack of serrations on the posterior accessory cusp. These teeth are fairly common in the lower chalk (below MU 9) and may represent an undescribed species.|
|LEFT AND RIGHT: The site where the specimen was collected in the lower chalk (Upper Coniacian) of Gove County, Kansas. The rock pick is about 16 inches (40 cm) long. Marker Unit 4 (Hattin, 1982) appears as a series of reddish-brown iron concretions about a half meter under the specimen. This site is about a mile north of the type locality of Niobrarasaurus coleii (FHSM VP-14855) and slightly higher in the rock column (both Upper Coniacian).|
LEFT: For comparison, a series of distal caudal vertebrae (left lateral view) from the type specimen of Niobrarasaurus coleii (FHSM VP-14855) in the collection of the Sternberg Museum of Natural History.
RIGHT: Three caudal vertebrae from FHSM VP-14855 in left lateral and dorsal view. (Scale = cm)
|LEFT: A juvenile nodosaur caudal vertebra (FHSM VP-16385) found by Keith Ewell in 2004 in southwestern Trego County (Smoky Hill Chalk - Upper Coniacian). The vertebra appears to be partially digested, most likely by a large shark. Approximately life-sized. Keith is now the only person in 134 years to ever find the remains of two dinosaurs in the Smoky Hill Chalk.|
|EIGHTH DINOSAUR SPECIMEN FOUND IN THE SMOKY HILL CHALK (FHSM
LEFT: Over the Memorial Day weekend in 2007, Laura and Scott Garrett were prospecting for fossils in the lower Smoky Hill Chalk (below Hattin's Marker Unit 3 - Late Coniacian) of southwestern Trego County. Laura found an isolated anterior caudal vertebra (near the base of the tail) from what appears to be a large ankylosaur, most likely Niobrarasaurus coleii. Note that this vertebra is very similar to, but much larger than, the one collected by Keith Ewell in 2004 (above). Laura becomes the first woman (and only the 7th person) to ever collect dinosaur remains from the Smoky Hill Chalk. The Garretts generously donated the specimen to the Sternberg Museum of Natural History (VP-17229). The specimen comes from about 6 miles south of the site where VP-16385 was collected in 2004, and from about 5 miles east of where the type specimen of Niobrarasaurus coleii (VP- 14855) was collected in 1930. All are Late Coniacian in age.
|LEFT: A remains of an isolated and partially digested dorsal mosasaur vertebrae (FHSM VP-16356) in ventral, right lateral and dorsal views, that is comparable in size to the hadrosaur caudal vertebrae above. In this case, however, the vertebra was severely damaged by the digestive fluids and a tip of a shark tooth (circles) remains embedded in the bone. Note the damage to the surface of the bone. The flattened appearance is due mostly to post-mortem crushing. Click here for a close-up of the embedded Cretoxyrhina mantelli tooth (FHSM VP-16357).|
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