A wide gap separates _Archaeopteryx_ from the next order of fossil birds of the Cretaceous epoch, and, since freshwater deposits of that age are rare, bird remains are uncommon. Many bones formerly referred to birds have since proved to belong to Pterodactyls, e.g. _Cimoliornis_ from the English Chalk. But in 1858 were discerned in the Upper Greensand of Cambridgeshire remains which are now known as _Enaliornis_. W. Dames has described bones from the Chalk of southern Sweden under the name of _Scaniornis_, probably allied to _Palaelodus_. From the Cretaceous rocks of North America a large number of birds have been described by O.C. Marsh. Of these the most interesting are _Ichthyornis_ (= _Graculavus_) and _Hesperornis_, from the Cretaceous shales of Kansas. They were placed by Marsh in a distinct subclass of birds, _Odontornithes_ (q.v.). Probably all birds of Cretaceous age were still possessed of teeth. _Baptornis_, another of Marsh's genera, seems to be allied to _Enaliornis_, _Palaeotringa_ and _Talmatornis_, were by him referred to Limicoline and Passerine birds. _Laornis_ from the Cretaceous marls of New Jersey was as large as a swan. Entry: A
So important a place was occupied by reptiles during this period that it has been well described as the "age of reptiles." In the seas the fish-shaped Ichthyosaurs and long-necked Plesiosaurs dwelt in great numbers and reached their maximum development; the latter ranged in size from 6 to 40 ft. in length. The Pterosaurs, with bat-like wings and pneumatic bones and keeled breast-bone, flew over the land; _Pterodactyl_ with short tail and _Rhamphorhyncus_ with long tail are the best known. Curiously modified crocodilians appeared late in the period (_Mystriosaurus_, _Geosaurus_, _Steneosaurus_, _Teleosaurus_). But even more striking than any of the above were the Dinosaurs; these ranged in size from a creature no larger than a rabbit up to the gigantic _Atlantosaurus_, 100 ft. long, in the Jurassic of Wyoming. Both herbivorous and carnivorous forms were present; _Brontosaurus_, _Megalosaurus_, _Stegosaurus_, _Cetiosaurus_, _Diplodocus_, _Ceratosaurus_ and _Campsognathus_ are a few of the genera. By comparison with the Dinosaurs the mammals took a very subordinate position in Jurassic times; only a few jaws have been found, belonging to quite small creatures; they appear to have been marsupials and were probably insectivorous (_Plagiaulax Bolodon_, _Triconodon_, _Phascolotherium_, _Stylacodon_). Of great interest are the remains of the earliest known bird (_Archaeopteryx_) from the Solenhofen slates of Bavaria. Although this was a great advance beyond the Pterodactyls in avian characters, yet many reptilian features were retained. Entry: A