272 c. schuChert — moRrison and i^eNdAguRu formations 



Doctor Jauensch regards the shale dinosaur zones as the mud deposits 

 of very shallow-water lagoons formed behind bars of sand, and at ebb-tide 

 exposed to the air. Proof of this he sees in the presence of many armored 

 dinosaurs and ornithopods that were mired in the upper dinosaur zone 

 and especially in the middle one. These were animals of the dry land 

 that had wandered out over the tidal flats, where they were drowned, and 

 later on their carcasses floated about for a time before they sank to the 

 bottom. In addition there are local accumulations of ganoid remains 

 and driftwood bored by Teredo, all, he thinks, the materials of the strand. 

 In the deeper waters farthest away from the land, there will accordingly 

 occur the more complete skeletons and only rarely the disjointed distal 

 parts, while nearer the shore will be found commonly the limbs, scattered 

 bones, and connected sections of the necks and tails. 



"The occurrence of such larger skeletal parts, the usual condition in the 

 Tendaguru, speaks unmistakably for deposition in very shallow waters that 

 were moved about by the action of the waves." ^* 



In quarry X of the upper dinosaur zone almost all of the bones of 

 sauropods are of the feet, with rarely other single bones present. In 

 quarries IX and XVI of the same horizon nearly all the sauropod remains 

 consist of legs, shoulder blades and pelvis, and almost nothing of the body 

 or neck. In these places eighteen to twenty femora were secured. Such 

 occurrences Janensch holds are due to continued assorting by the waves 

 and currents. In further support of this conclusion he states that the 

 ends of the leg bones show considerable wear due to rubbing by the em- 

 bedding sands, and this is not the case when they occur in the clay. In 

 three cases they got bodies with the ribs still attached, but in none were 

 the tails present. 



"As a rule, the sauropods occur in single bones and small skeletal parts, but 

 often several individuals of the same species are found together over a limited 

 space. Even though other species may be associated, yet one gets the impres- 

 sion that the sauropods also were destroyed in a catastrophe and embedded in 

 troops." 



Janensch holds it is probable that they were mired and drowned by the 

 returning tidal flood and then washed apart by the Avaves. As evidence 

 of miring he cites the occurrence of complete feet of Sauropoda standing 

 vertically and articulated in the mud and the more distal but completely 

 articulated parts of the legs lying prostrate. In other cases where there 

 was an abundance of material the bones of the feet were rare or absent. 



3* Op. cit., part li, pp. 239-240. 



