Judithian of eastern U.S.

[bwitzke@gsbth-po.igsb.uiowa.edu]

     A recent request in Dinosaur Digest for "information on Judithian ages 
     faunas of eastern North America" has prompted the following brief 
     overview.  Dinosaur-bearing Judithian-aged strata (mid to late 
     Campanian) along the Atlantic Coast include the Marshalltown Formation 
     of Delaware and New Jersey; the Woodbury Fm of New Jersey; the Black 
     Creek Fm of North Carolina; and the Donoho Creek Fm of South Carolina. 
      Judithian dinosaurs of the Gulf Coast and Mississippi Embayment have 
     come from the Demopolis Chalk of eastern Alabama, the upper Blufftown 
     Fm of Georgia (may be early Campanian), and the unnamed unit from the 
     Chronister site of southeast Missouri (the age of the latter is not 
     well constrained).  If anybody knows of additional units, please let 
     me know.
     
     Basically, all of these units have produced meager and incomplete 
     dinosaur material, and I'm not sure a direct comparison with the 
     unbelievably diverse and well-preserved Judithian faunas of western 
     North America is a completely fair one.  As far as I'm concerned, the 
     absence of hypsilophodonts, ceratopsians, pachycephalosaurs, and 
     ankylosaurs in the east is so much negative evidence, not definitive 
     proof of there actual absence.  Here's what's actually known from the 
     east:
     
     -indet. theropod (Demopolis Chalk, cited in Schwimmer et al., 1993 as 
     a possible tyrannosaurid)
     -indet. theropod material (some of these have been referred to 
     "Dryptosaurus", Carpenter et al. 1997, indicate that these "are based 
     on fragmentary material and only superficially resemble Dryptosaurus; 
     they should be considered nomina dubia)
     -?Albertasaurus sp. (Blufftown, Schwimmer et al., 1993)
     -indet. ornithomimid spp.
     -indet. hadrosaurid spp.
     -Hadrosaurus foulkii (a larger hadrosaurid previously named 
     Ornithotarsus has been provisionally included with H. foulkii, but it 
     could be a separate taxon).
     -Hadrosaurus sp.
     -"Hypsibema crassicaudata" (inclusion in hadrosaurinae is provisional; 
     status doubtful, may be synonym of Hadrosaurus).
     -"Hypsibema missouriensis" (hadrosaurid material from Missouri, 
     possibly of Judithian age; a nomena dubia, possibly synonym of 
     Hadrosaurus)
     
     This relatively meager material provides little basis for comparison 
     I'd say.  However, occurrences of mammal teeth in the Marshalltown Fm 
     of Ellisdale, NJ, strongly indicates that faunal exchange of Campanian 
     vertebrates did indeed occur between eastern and western North 
     America.  These include "cf. Cimolomys clarki" and Protalphadon lulli 
     (see Grandstaff et al.,1992, JVP, v. 12, p. 218), which are common 
     mammals in the Judith River Formation of Montana and Alberta.  
     Possible tyrannosaurids from the east futher underscore the 
     possibility of episodic faunal exchange.
     
     Brian Witzke