Page:Popular Science Monthly Volume 12.djvu/542

524, since, although reptilian in all their main characters, they show clear affinities with the birds, and have some features which may point to mammals. The Cretaceous Dinosaurs were all of large size, and most of them walked on the hind-feet alone, like modern struthious birds. Two well-marked types may be distinguished among the remains discovered in deposits of this age: the herbivorous forms, represented mainly by Hadrosaurus, a near ally of the Iguanodon of Europe; and their carnivorous enemies, of which Dryptosaurus (Lœlaps) may be considered typical in this country, and Megalosaurus in Europe. Near the base of our Cretaceous formation, in beds which I regard as the equivalent of the European Wealden, the most gigantic forms of this order yet discovered have recently been brought to light. One of these monsters (Titanosaurus montanus), from Colorado, is by far the largest land-animal yet discovered; its dimensions being greater than was supposed possible in an animal that lived and moved upon the land. It was some fifty or sixty feet in length, and, when erect, at least thirty feet in height! It doubtless fed upon the foliage of the mountain forests, portions of which are preserved with its remains. With Titanosaurus, the bones of smaller Dinosaurs, one (Nanosaurus), not larger than a cat, as well as those of crocodiles and turtles, are not uncommon. The recent discovery of these interesting remains, many and various, in strata that had long been pronounced by professional explorers barren of vertebrate fossils, should teach caution to those who decline to accept the imperfection of our knowledge to-day as a fair plea for the supposed absence of intermediate forms.

In the marine Cretaceous beds of the West, only a single Dinosaur (Hadrosaurus agilis) has been found, but in the higher fresh-water beds, which mark the close of this formation, their remains are numerous, and indicate several well-marked species if not genera. In the marine beds on the Atlantic coast, the bones of Dinosaurs are frequently met with, and in the Upper Cretaceous Greensand of New Jersey, the type specimens of Hadrosaurus and Dryptosaurus were found. In Cretaceous fresh-water deposits on the coast of Brazil, remains of this order occur, but the specimens hitherto discovered are not sufficiently characteristic for accurate determination. This is unfortunately true of many Dinosaurian fossils from North America, but the great number of these reptiles which lived here during the Cretaceous Period promises many future discoveries, and substantial additions to our present knowledge of the group.