The skull of Megacephalosaurus
(formerly Brachauchenius lucasi Williston 1903)
A photographic atlas of FHSM VP-321
Copyright © 2002-2013 by Mike Everhart
Page created 11/30/2002; revised 05/07/2013
LEFT: The skull of Megacephalosaurus eulerti (FHSM VP-321 reconstructed by Triebold Paleontology Inc and displayed at the 2012 meeting of the Society of Vertebrate Paleontology.
Until recently the only pliosaur recognized from Kansas was Brachauchenius lucasi Williston 1903. A few fragmentary specimens suggest other species may be present. In Kansas, these short-necked pliosaurs are relatively rare in the Greenhorn Limestone and Carlile Shale, but are represented by two excellent specimens, the largest of which is on exhibit at the Sternberg Museum of Natural History. The FHSM VP-321 specimen was found on June 5, 1950 by Robert and Frank Jennrich while hunting sharks teeth in the Fairport Chalk of Russell County. It was collected by G. F. Sternberg in October, 1950,, with the help of the Jennrich brothers. The lower jaw is 68 inches (170 cm) long.
See these other webpages: Pliosaurs and Polycotylids and Kronosaurus for more information.
In April, 2011, a full size reconstruction of Megacephalosaurus eulerti was mounted in the entry of the Sternberg Museum.
|LEFT: The Sternberg Museum of Natural History has
recently added the exhibit of a life-size sculpture of the Late Cretaceous
pliosaur, Megacephalosaurus eulerti, created by master paleo-artist
Gary Staab (Staab Studios). The full size reconstruction was based on the 5 ft long skull
(FHSM VP-321) collected by G.F Sternberg in 1950 from the Fairport Chalk
of Russell County, Kansas. Photos are copyright by Gary Staab and used
here with his generous permission.
RIGHT: Megacephalosaurus eulerti in right lateral view in the entry area of the Sternberg Museum. The reconstruction is 23 ft (7 m) long and about 16 ft (4.8 m) wide across the paddles.
|LEFT: Megacephalosaurus eulerti reconstruction in left
RIGHT: A young visitor thinks he's about to become a snack for a giant pliosaur. Here's looking at you!
|LEFT: A head-on view of Megacephalosaurus eulerti;
possibly the last thing that many of his prey items would have seen.
RIGHT: The scale of this beast is hard to gauge in the previous pictures, but this photo with its creator, Gary Staab, pretty much tells the story. (Staab Studios)
Bruce Schumacher, Ken Carpenter and Mike Everhart provided technical assistance on the reconstruction.
|LEFT: Somewhere in the Western Interior Sea, a giant
pliosaur (Megacephalosaurus eulerti) is about to make lunch out of a small turtle
similar to Desmatochelys. Megacephalosaurus
was one of the last of the pliosaurs and made it's final appearance in Kansas during the
deposition of the Blue Hill Shale Member (Middle Turonian) of the Carlile Shale. Varner
painting courtesy of the Museum of Northern Arizona.
RIGHT: "Brachauchenius and Squid" from a painting done for Pete Von Sholly. This picture recreates a specimen found in the Turner Sandy Member of the Carlile Shale Formation (Turonian / Late Cretaceous) near Edgemont, South Dakota. This was the latest age that these giant pliosaurs were found in North America.... coincidentally the same time that mosasaurs first appeared.
painting by Daniel W. Varner, 1989, titled “Shootout in
|LEFT: Brachauchenius lucasi Williston was the
only genus of pliosaurs known from Kansas. The holotype (USNM 4989) was collected from the
"Benton Formation" in Ottawa County, Kansas, by Charles H. Sternberg in the
spring of 1884 while working for O.C. Marsh (Everhart, 2007), and described by S.W.
Williston in 1903. The skull was originally mounted as discovered, upside-down, with
37 vertebrae. Skull length is 90 cm (Williston, 1907). Click here for Williston's drawing of the reconstruction
skull of the holotype specimen.
From the notes C. H. Sternberg sent to O.C. Marsh, "It is well preserved as far as it goes but only 12+ feet are preserved. The under jaws are 49 in. long. The spread of them at the distal end [is] 14 inches. Most of the cervical vertebrae are present." and "Under jaw fifty inches, nineteen inches between branches, nearly perfect cervicals present, good, [limbs] gone, few dorsals." The specimen and the slab that contained it weighted 1370 pounds when shipped to Marsh.
|LEFT: A second specimen (USNM 2361, LEFT) was collected from the
Eagle Ford Formation, on Bouldin Creek near Austin, Texas, and described by Williston in
1907. Skull length is 80 cm (Williston, 1907).
Order Plesiosauria, de Blainville 1835
Superfamily Plesiosauroidea, Welles 1943
Family Brachaucheniidae Williston 1925
Genus Brachauchenius lucasi Williston 1903
|LEFT: The skull of a second genus and
specie (Megacephalosaurus eulerti - FHSM VP
321) shown in left dorso-lateral view, is much larger, more
complete, and somewhat better preserved than either of the two earlier specimens. It was
collected by George Sternberg in October, 1950, from the Fairport Chalk Member of the
Carlile Shale (Middle Turonian) near the town of Fairport in northwest Russell County,
A a larger, but fragmentary specimen preserving just the front of the skull ahead of the eye sockets is in the collections of the University of Nebraska State Museum (below)
The skull of VP-321 is on exhibit in the Sternberg Museum of Natural History at Fort Hays State University. A cast of the skull is also on display at the University of Kansas Museum of Natural History, Lawrence, Kansas. This skull is about five feet (152 cm) in length along the mid-line, and must have come from a large bodied animal that is estimated to have been at least 7 m (22 ft) long. Williston (1907) and Carpenter (1996) agree that Brachauchenius is closely related to the Jurassic pliosaur, Liopleurodon ferox.
|Additional Megacephalosaurus eulerti remains, including a partial skull, have been collected in Russell County (see "FHSM (unnumbered)" in Schwimmer, et al., 1997, Table 1; J. D. Stewart, pers. comm., 1999) but have not yet been officially described.|
Click on the pictures below to see details of skull of FHSM VP-321:
|The figure at LEFT is from a 1994 draft of Carpenter (1996) and is
copyright © by Kenneth Carpenter; used with permission of Kenneth Carpenter. CLICK TO
Key to bones of the skull and lower jaw of Megacephalosaurus eulerti: d - dentary; ep - epipterygoid; fr - frontal; ju - jugal; mx maxilla; o - orbit; p - pineal foramen; pa - parietal; pal - palatine; pf - prefrontal; pm - premaxilla; pt - pterygoid; en - external nares; q - quadrate; qpt - quadrate ramus of pterygoid; sa - surangular; sq -squamosal; tf - temporal fenestra
|LEFT: The right lower jaw in medial view, anterior to the left. The right dentary was lying across and on top of the skull when discovered and is not included in the exhibit mounting.|
|LEFT: Fragments of teeth collected in association with VP-321. Many of the teeth were found loose, scattered around the skull and lower jaws.|
|LEFT: A partial skull of a Megacephalosaurus eulerti
specimen from an unknown locality in the collection of the University of Nebraska. The
specimen is somewhat larger then FHSM VP-321, but similar in preservation to FHSM VP-321.
RIGHT: A portion of the skull and a jaw with teeth of another possible Megacephalosaurus eulerti specimen (UNSM 112437) that was discovered in the Graneros Shale during the construction of the Glen Elder Dam in Mitchell County. Possibly the oldest known specimen of this genus/species. Specimen is in the collection of the University of Nebraska State Museum.
Carpenter, K. 1996. A review of the short-necked plesiosaurs from the Cretaceous of the Western Interior, North America. Nues Jahrbuch für Geologie und Paläontologie, Abhandlungen, (Stuttgart), 201(2):259-287.
Everhart, M. J. 2007. Historical note on the 1884 discovery of Brachauchenius lucasi (Plesiosauria; Pliosauridae) in Ottawa County, Kansas. Kansas Academy of Science, Transactions 110(3-4):255-258.
Lucas, F. A. 1903. A new plesiosaur. Smithsonian Miscellaneous Collections 45:96, pl. XXVIII (Quarterly Issue Vol. 1), 1457.
Schumacher, B. A. 2008. On a pliosaur skull (Plesiosauria) from the Upper Cretaceous of the North American Western Interior. Kansas Academy of Science, Abstracts of the 140th Annual Meeting, Transactions 111(1/2):186.
Schumacher, B.A., Carpenter, K. and Everhart, M.J. 2012. A new pliosaur
(Plesiosauria, Pliosauridae) from the Carlile Shale (Cretaceous, Middle
Turonian) of Russell County, Kansas. Supplement to the online Journal of
Vertebrate Paleontology ISSN 1937-2809, pp.
Schumacher, B.A., Carpenter, K. and Everhart, M.J. 2013. A new Cretaceous Pliosaurid (Reptilia, Plesiosauria) from the Carlile Shale (middle Turonian) of Russell County, Kansas, Journal of Vertebrate Paleontology 33(3):613-628
Schumacher, B.A. and M. J. Everhart. 2005. A stratigraphic and taxonomic review of plesiosaurs from the old Fort Benton Group of central Kansas: A new assessment of old records. Paludicola 5(2): 33-54.
Schwimmer, D. R., J.D. Stewart, and G. D. Williams. 1997. Scavenging by sharks of the genus Squalicorax in the late Cretaceous of North America. PALAIOS, 12:71-83.
Williston, S. W. 1903. North American plesiosaurs, Field Columbian Museum, Pub. 73, Geological Series, 2(1):1-79, 29 plates.
Williston, S. W. 1907. The skull of Brachauchenius, with special observations on the relationships of the plesiosaurs. United States National Museum Proceedings 32:477-489. pls. 34-37.