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Edmontosaurus, NOT Claosaurus "gastroliths"

From: Ben Creisler bh480@scn.org
Edmontosaurus, NOT Claosaurus "gastroliths"

While researching hadrosaur nomenclature for a paper I was 
invited to write, I turned up an error that keeps getting 
repeated in print and on various websites.  Since it may 
be some time before my paper appears (with luck), I 
thought I would do a posting on an old mix-up before it 
spreads further.
In 1900, Barnum Brown found hadrosaur remains near the 
Cheyenne River in Weston County, Wyoming. A short note 
about the find appeared in a 1901 issue of  the American 
Museum Journal (forerunner of Natural History), in which 
Brown stated: "I found specimen No. 8..., a nearly 
complete skeleton of Diclonius (Claosaurus?)."  Note that 
this specimen is now listed as Edmontosaurus sp. AMNH No. 
5863 in the American Museum collection. In Science 
magazine in 1907 (Science N.S. 25 (636):392)  Brown 
mentioned finding "gastroliths"  with the bones: "In 1900, 
while collecting fossil is Weston County, Wyoming...I 
found a Claosaurus skeleton imbedded in a hard 
concretionary sandstone....three rounded well-worn pebbles 
were found near the fore legs, embedded in the same 
For reasons that now seem inexplicable, O.C. Marsh had 
assigned Lance age specimens from Wyoming of what is now 
called Edmontosaurus to his own earlier genus Claosaurus, 
established on a partial skeleton from the Niobrara beds 
of Kansas (Claosaurus agilis). Apparently the limb bones 
were hollow in both the Kansas and Wyoming fossils,  while 
the limb bones in Hadrosaurus were solid, and Marsh 
thought this detail was diagnostic. Marsh described his 
species Claosaurus annectens (now Edmontosaurus annectens) 
in detail and published reconstructions of the skull and 
skeleton. Well into the early 20th century, usage of the 
generic names Hadrosaurus, Trachodon, Thespesius, 
Diclonius and Claosaurus remained a muddle--all were used 
for either Edmontosaurus or Anatotitan at various times.  
Brown's Claosaurus from Wyoming is Edmontosaurus, not true 
Claosaurus (a primitive hadrosaur).
Nonetheless, Per Christiansen in his article  "Hindlimbs 
and Feet" in the 1997 Encyclopedia of Dinosaurs , page 327 
states: "Most iguanodontids have only a vestigial first 
metatarsal, and in all hadrosaurids except Claosaurus it 
was absent. Claosaurus is also unusual in being the only  
ornithopod in which gastroliths have been reported (Brown 
1907)."  Phil Currie, in his article "Gastroliths" in same 
book, page 270, states: "Gravel within the body cavities 
of the hadrosaur Claosaurus (Brown, 1907)...was probably 
acquired postmortem during burial." The idea that the real 
Claosaurus was reported to have gastroliths is obviously 
wrong. Moreover, Edmontosaurus is known from dozens of 
excellent skeletons and a few mummies, and to my knowledge 
there is no evidence from any other specimen that it had 
gastroliths. The stones found with Brown's 1900 specimen 
were undoubtedly acquired during burial as Currie suggests.
The ZoomDinosaurs.com website lists Claosaurus as a 
dinosaur with gastroliths, and the error has even been 
posted here: 
If anybody knows of other references in which Claosaurus 
is said to have gastroliths, please let me know. For some 
reason, the Bibliography of Fossil Vertebrates rarely 
indexed mentions of gastroliths.