s, 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 fours, more generally upon the hind limbs, like
ostriches, the long tail balancing the weight of the body. Some modern
lizards run this way on occasion, especially if they are in a hurry.
But the bodies of lizards are too long and their limbs too small and
slender for this to be the usual mode of progress, as it seems to have
been among the Dinosaurs.

ANIMALS OF THE AGE OF REPTILES.
LAND REPTILES.
DINOSAURS corresponding to the larger quadrupeds or land
mammals of today.
CROCODILES, LIZARDS AND TURTLES still surviving.
SEA REPTILES.
PLESIOSAURS } corresponding to whales, dolphins, seals,
ICHTHYOSAURS } etc., or sea-mammals of today.
MOSASAURS }
FLYING REPTILES OR PTEROSAURS.
BIRDS WITH TEETH (scarce and little known).
PRIMITIVE MAMMALS of minute size (scarce and little known).
FISHES and INVERTEBRATES many of them of extinct races, all
more or less different from modern kinds.

Fishes, large and small, were common in the seas and rivers of the Age
of Reptiles but all of them were more or less different from modern
kinds, and many belonged to ancient races now rare or extinct.

The lower animals or Invertebrates were also different from those of
today, although some would not be very noticeably so at first glance.
Among molluscs, the Ammonites, related to the modern Pearly Nautilus,
are an example of 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 were another group of molluscs, or
rather molluscoids for they were not true molluscs, less abundant even
then than in previous ages and now surviving only in a few rare and
little known types such as the lamp-shell (_Terebratulina_).

_Insects._ The Insect life of the earlier part of the Age of Reptiles
was notable for the absence of all the higher groups and orders,
especially those adapted to feed on flowers. There were no butterflies
or moths, no bees or wasps or ants although there were plenty of
dragonflies, cockroaches, bugs and beetles. But in the latter part of
this era, all these higher orders appeared along with the flowering
plants