806 



SCIENCE. 



[N. S. Vol. IV. No. 101. 



Jurassic vertebrates have been taken dur- 

 ing my long explorations there. 



The base of this section is a red sand- 

 stone, apparently of Triassic age. Next 

 above are Jurassic marine beds, with many 

 invertebrate fossils and a few remains of 

 reptiles. Over these beds is a series of 

 peculiar, highly colored clays of fresh- 

 water origin and considerable thickness, 

 rich in vertebrate fossils. Crowning all is 

 the characteristic Dakota sandstone, gen- 

 erally considered of Cretaceous age. The 

 position of this series of strata in the geo- 

 logical scale is shown in the section below, 

 which represents especially the succession 

 of vertebrate life in the West during Meso- 

 zoic and Cenozoic time. 



in 1870, near the Green River in Utah, and 

 since then at various other points. These 

 strata I have named the Baptanodon beds, 

 from a genus of large swimming reptiles 

 entombed in them. 



THE ATLANTOSAURUS BEDS. 



The extensive fresh- water deposits 



of 



Jurassic age that lie over the marine strata 

 at Como, I have called the Atlantosaurus 

 beds, from a gigantic Dinosaur especially 

 characteristic of the horizon. Other Dino- 

 saurs, large and small, and a great number 

 and variety of vertebrate fossils — mammals, 

 birds, reptiles and fishes — I have likewise 

 secured from this locality and at several 

 other points in the same horizon, chiefly in 



a 



-L-J-, ' , ' i' I 'r': 



1. I, I 



t~r 



I t 





Recent. 

 Quaternarr, 



Pliocene. 



Miocene. 



Eocene. 



Cretaceous. 



Triassic. 



Equus Beds. 

 Pliohippus Beds, 



Mioiiippus Beds. 

 Oreodon Beds. 

 BrontotheriumBeds 



Diplacodon Beds. 

 Dinoceras Beds. 

 HeliolDatis Beds. 

 Coryphodon Beds. 



Ceratops Beds of 

 Laramie Series. 



Fox Hills Group. 



Colorado Series, or 

 PteranodoQ Beds. 



Dakota Group. 



Atlantosaurus Beds 

 Baptanodon Beds, 

 Hallopus Beds. 



Otozoum, or 

 CoDo. Iliver, Beds. 



apir, Peccary, Bison. 

 Bos,Equiis,Tapirus,Dicott/Ui>,MAaatherium,Mylodon. 



Equus, Tapirus, EUphas. 



5 PlioMppus, Tapiravvs, Mattodon, ProcameVus, 



X AceratAerium, £os, Morotherium, Flatygonus. 



Miohippus, DiceratheriUTn, Thinohyus, Protoceras. 

 5 Oreodon, Eporeodon, Sycenodon, Moropus, Ictops, 

 I Hyracodon, Agriochoerus, Colodon, Leptochoe,rus. 

 ^Brontotherium, Brontops, ATlops, Titanops, Titano- 

 I therium, Meso/iippus, Ancodus, Entelodon. 



Diplacodon, Epihippus, Amynodon, Eomeryx. 



5 Dinoceras, Tinoceras, Zfintatherium, Palmosyops, 



\ Orohippus, Eyrachyus, Colonoceras, Eomacodon 



Beliobatis, Amia, Lepidosteus, Asineops, Clupea. 



5 Coryp'hodon.Eo'hippus.Eohyu8,Eyracops,Parahyus 



\ Lemurs, Ungulates, Xilloaonts, Kodenis, Serpents 



Ceratops, Triceratopn, Claosaurus, Ornithomimus. 

 Mammals, Cimolomys, Pipriodon, Selenacodon, 

 Nanomyopa, Stagodon. Birds, Cimolopteryx. 



Birds with TeettiMesperornis, Ichthyornis, Apatornis. 

 Mosasaurs, Edestosaurus, Lestosaurus, Tylosaurits. 

 Pterodactyls, Pteranodon, f lesiosaurs, Turiles. 



■j Dinosaurs, Brontosaurus, Morosaurus, Piplodoeus, 

 I Stegosauru8,Camptosaurus, Ceratosaurus. Mam- 

 (. mals, Pryolestes, IStylacodon, Tinodon, Ctenacodoti. 



First Mammals. Promatherium. First Dinosaurs, 

 Anchisaurus, Ammosaurus, Bathygnathus, Clepsy- 

 saurua. Many footprints. Crocodiles, Belodon. 

 Fishes, Catopterits, Jschypterus, Ptycholepis. 



Figure 1. — Geological Horizons of Vertebrate Fossils. 



THE BAPTANODON BEDS. 



The same marine beds that constitute 

 the base of the Como Jurassic series, Meek 

 had previously identified near the Black 

 Hills, by means of invertebrate fossils 

 (Proc. Acad. Nat. Sci., Phila., Vol. X., pp. 

 41-59, 1859), I found these deposits again 



Wyoming and Colorado. Among these ex- 

 tinct forms, the gigantic Sauropoda, the 

 largest of all land animals, are the most 

 wonderful, and are known only from the 

 Jurassic. They are therefore of special 

 value as evidence of geological age. 



The main physical features of the Juras- 



