The land mass available to the Dinosaurs may have been less than what is available to us today so how could the land available to the Dinosaurs have possibly supported them in such apparently gigantic numbers?
"Asian elephants are grazers (Africans are browsers). A full-grown Asian elephant eats approximately 150-200 pounds of food and drinks 30-50 gallons of water every day. Both Asian and African elephants will walk 30 to 50 miles daily in search of food, water, and preferred climate. "
We are talking here of an animal that reaches a maximum weight of around 13 tons but averages 6-8 tons fully grown. Asian Elephants are smaller.
But if we start making a comparison with the larger non- meat eating Dinosaurs which apparently achieved weights of up to 100 tons and,again, apparently herded in large groups (they must have done in order to protect themselves from other Dinosaurs and they were egg laying dont forget which means they would have been vulnerable to attack from a large variety of scavengers) then the quantity of food they would have required to sustain them in one day must have been quite staggering.
For instance - a herd of say 50, 70 ton vegetarian Dinosaurs would have required at least 82,500 LBS of vegetable matter per day in order to sustain them and would have cleared an estimated 5 square miles of food bearing land every day!!!!!!!!!!
Now, I would accept these figures if perhaps only a few herds of the larger Dinosaurs existed, but they must have in reality existed in very large numbers as they had 150 million years to evolve so we may be looking at herds numbering tens of thousands!!!!!!
And another factor has to be worked into this - the largest Dinosaurs must have been very restricted as to the type of land they could cross. A creature weighing 70-100 tons would have been denied access to mountainous or very soft ground which again. restricts the amount of food available to them.Swampy regions would have been entirely denied to them as would lake shores and river beds.
Actually not only are the carnivores huge, but you must also consider that we have dug up quite a number of them. Fossilization is normally a rare event, were it not for the Le Bria Tar Pits we would not have nearly as much data on early mammalian carnivores.
Clearly, to support such carnivores, the herds and the plants to support the herbivores had to exist on a whole different scale. And this seems to be what we are finding. The sad truth is, today's world is almost a desert compared to the age of dinosaurs.