328 R. S. LULL SAUROPODA AND STEGOSAURIA OF THE MORRISON 



me, no apparent direct connection l)etween the allied English, French, 

 and rortuguese Saurojjoda. on the one hand, and the (ici'inan Eas^t 

 African forms on the otlier. 



TENDAOVRU DIS'IHICI or (IHUM.W I:AST M'IUVA 



(icncinl (Icscrijil Ion. — 'Flic dark ((Hit iiiciit srciii- drstiiKMl to fui'iiisli 

 the data which will ult iiiiatcly decide llie age of llie Saiii'o|i(i(|d)cariiig 

 beds of Norlh Ainei'ica and |t(issii>ly of lMir()|te. fni- here the dinosaur- 

 hearing strata aie inlerlxMlded willi marine zones rich in invcrtel)rates. 

 which will enable stratigraphers to li\ their age with a gi'eat degree of 

 aecui'acv. Professor Schuehert. in a review of Hennig's work. "Am 

 Tendaguru," - thus describes the region : 



"The hill Tendaguru, less than 100 feet high, lies isolated on a high, thickly 

 wooded plateau averaging about 650 feet above the sea, and is the central 

 point from wiiieh all of the diggings have been (»])erated. It is in the midst of 

 an extensive dinosaur cemetery, for at oni' time there were twenty exhuma- 

 tions in operation scattere<l over ."10 sipiare kilometers, or across one degree of 

 latitude (between i)° and 10° south and 39° and 39° 30' east). 



"In a thickness of about 500 feet exiioscd along the stream Mbenkuru are 

 found three distinct horizons of soft sliale with <linosanr remains, separated 

 from one another l)y hard eoarsc-gr.iiiied sandstones to conglomerates that 

 have an abundant marine invertebrate fauna. Each marine division has its 

 own assemblage of forms, and makes terraces along the river valley. . . 

 All of the beds are of one continuous series of deposits, as the different hori- 

 zons grade into one another. The conditions of deposition tlierefore appear to 

 have been an alternation of exceedingly shallow marginal seas that came to 

 be filled with detritus and changed into great mud flats flooded by rivers and 

 possildy in part by high tides. Three such cycles are recorded. Dinosaur 

 Ixaies do not occur in the marine deposits l)ut begin in the transition zones; 

 where they occur with Belemnite guai'ds, and may be so abundant as to make 

 bone conglomerates. Where the bones occur in greater abundance there ap- 

 pear to be no marine invertebrates. 



•'In the lowest dinosaur zone there is but little good material, while the 

 highest one is not at all so rich in remains as is the middle division, out of 

 which most of the bones . . . have been taken." 



Sauropoda. — The dinosaurian material, in so far as it has l)een made 

 known to ns, contains representatives of all three snhoi'ders of dinosaurs. 

 Of these the Sauropoda are re])resented hv three genera, each of which 

 includes two species, and there are in addition at least two other forms 

 as yet iindescribed (191-J). The Sauropoda thus far recorded are, first. 

 Gigantomurus Fi'aas. including the species afruaniis and rohnstw^. 

 These Fraas considers most nearly like the Morrison genus Diplodociis 



^Amer. Jour. Sci. (4), vol. xxxv, 1913, p. 36. 



