I always find it odd that generalizations can be made such as "[this] was the most abundant animal to be found 145 million years ago" when it is based on so inf

I always find it odd that generalizations can be made such as "[this] was the most abundant animal to be found 145 million years ago" when it is based on so infinitesimal a fraction of the evidence. Perhaps this article is simply missing the bulk of the data, but it strikes me as odd that a corner of the Andes could be accurately representative of the world so very, very long ago.