Tim wrote...
>_Seismosaurus_ looks like it will be sunk into _Diplodocus_. (This
>has been
I was not aware that Diplodocus had that distinctive down turn in the first third of the tail vertebrae the way Seismosaurus has. And then there is the considerable size differential between Seismosaurus hallorum and Diplodocus carnegii. I will grant the dinosaurs probably grew throughout their lives, but this is a bit much. I would have to say that Seismosaurus is most likely a valid genus.