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An extinct genus of toothed birds found in the American Cretaceous formation. It is remarkable for having biconcave vertebræ, and sharp, conical teeth set in sockets. Its wings were well developed. It is the type of the order Odontotormæ.

and allied forms; -- called also Ichthyopterygia. They have not been found later than the Cretaceous period.

cies, varying in length from ten to thirty feet, are known from the Liassic, Oölitic, and Cretaceous formations.

f large, fossil, bivalve shells,allied to the mussels. The genus is characteristic of the Cretaceous period.

A genus of huge, carnivorous, dinosaurian reptiles from the Cretaceous formation of the United States. They had very large hind legs and tail, and are supposed to have been bipedal. Some of the species were about eighteen feet high.

Mountains, and formerly supposed to be of the Tertiary age, but now generally regarded as Cretaceous, or of intermediate and transitional character. It contains beds of lignite, often valuable for coal, and is hence also called the lignitic group. See Chart of Geology.

Liriodendron tulipifera is the only extant species, but there were several others in the Cretaceous epoch.

Any species of ammonites of the genus Lituites. They are found in the Cretaceous formation.

An order of large, extinct, marine reptiles, found in the Cretaceous rocks, especially in America. They were serpentlike in form and in having loosely articulated and dilatable jaws, with large recurved tteth, but they had paddlelike feet. Some of them were over fifty feet long. They are, essentially, fossil sea serpen…

form of paddles. The first known species, nearly fifty feet in length, was discovered in Cretaceous beds near Maestricht, in the Netherlands. [Written also Mososaurus.]

A term applied to the lowest deposits of the Cretaceous or chalk formation of Europe, being the lower greensand.

A genus of large arenaceous fossil Foraminifera found in the Cretaceous rocks. The species are globular, or nearly so, and are of all sizes up to that of a tennis ball.

A genus of American Cretaceous pterodactyls destitute of teeth. Several species are known, some of which had an expanse of wings of twenty feet or more.

eptilian age (Geol.), that part of geological time comprising the Triassic, Jurassic, and Cretaceous periods, and distinguished as that era in which the class of reptiles attained its highest expansion; -- called also the Secondary or Mezozoic age.

An extinct order or suborder of bivalve mollusks characteristic of the Cretaceous period; -- called also Rudista. See Illust. under Hippurite.

the Ammonite family and having a chambered boat-shaped shell. Scaphites are found in the Cretaceous formation.

In european geology, a name given to the middle division of the Upper Cretaceous formation.

One of the subdivisions into which the Upper Cretaceous formation of Europe is divided.

iceous fossil sponges belonging to Ventriculites and allied genera, characteristic of the Cretaceous period.

Of or pertaining to the lowest division of the Cretaceous formation in England and on the Continent, which overlies the Oölitic series.