Dinosaurs seem to have been in trouble

lovethee History

Actually,Walking dinosaur costume dinosaurs seem to have been in trouble well before the end of the Cretaceous.22 About seven to ten million years before the final event, predatory and herbivorous diversity was high on the western coastline of the interior seaway of North America-not only in numbers of species, but in relative proportions of the population. A large number of horned dinosaurs and duckbills formed a diverse herbivore fauna, and two or more species of big tyrannosaurs were fairly common. Whether the number of species then declined is argued about.23 It is clear that just before the end, one or two species of Tricerafops made up 50 to perhaps 90 percent of the coastline’s total herbivore populations, andlJnannosounr rex was the only common predator.2a This was an unstable sifuation, for the reduced populations of the other species were in grave danger of extinction.Realistic dinosaur costume If the few abundant species suffered setbacks, then all the species were in the same dire straits. A big question is whether all areas in the world were experiencing similar situations; we do not have enough data to be sure. We know that diversity increased in Mongolia sometime before the extinction, but it was never very high there any\rvay, and the modest increase may have been due to the shift away from very arid conditions. We cannot tell what happened in Mongolia as the Cretaceous closed, because the sediments for that time are missing there.