Dinosaurs, with Special Reference to the American Museum Collections

E OF R

ion and Significance

y-his "forty centuries of civilization"[1] but a passing episode. It is by no means easy for us to adjust our perspective to the immensely long spaces of time involved in geological evolution.

we must first get some idea of the length of geologic periods and

t is included along with the much shorter time during which civilization has existed, in the latest and shortest of the geological periods, the Quaternary. It was the age of the mammoth and the mastodon, the megatherium and Irish deer and of other quadrupeds large and small which are now exti

successive stages through which the ancestors of horses, camels, elephants, rhinoceroses, etc., were gradually converted into their present form in adaptation to their various habits and environment. And with them were slowly evolved various kinds of quadrupeds whose descendants do not now exist, the Titanotheres, Elotheres, O

ater Ages of

dominance of Reptiles, and are grouped together as the Age of Reptiles or Mesozoic Era. This was the reign of the Dinosaurs, and i

r any related to nor resembling them. But in their place were reptiles larg

izards (Mosasaurs) with flippers instead of feet; and another group of great marine reptiles (Plesiosaurs) somewhat like sea-turtles but with long neck and toothed jaws and without any carapace.

size. Strange bat-winged creatures, the wing membrane stretched on the enormously elongated fourth finger, they are

larger quadrupeds do today. They have been called the Giant Reptiles, for those we know most about were gigantic in size, but there were also numerous smaller kinds, the smallest no larger than a cat. All of them had short, compact bodies, long tails, and long legs for a reptile, and instead of crawling, they walked or ran, sometimes upon all fou

THE AGE O

REP

to the larger quadrupeds

RDS AND TURTLES

REPT

SIO

HYOS

whales, dolphins, seals, et

TILES OR P

TH (scarce and

f minute size (scar

them of extinct races, all more o

Age of Reptiles but all of them were more or less different from mo

a race very numerous and varied during all the periods of the Reptilian Era, but disappearing at its close, leaving only a few collateral descendants in the squids, cuttlefish and nautili of the modern seas. The Brachiopods wer

ly those adapted to feed on flowers. There were no butterflies or moths, no bees or wasps or ants although there were plenty of dragonflies,

and huge equisetae or horsetail rushes, still surviving in South American swamps and with dwarfed relatives throughout the world, were the dominant plant types of that era. The flowering plants and deciduous trees had not appeared. But in the latter half of the era these appeared in ever increasing multitudes, displa

ower and fruit afforded a more concentrated and nourishing food, depended largely the evo

TNO

and Chaldaea extend back