Summary

A detailed comparative analysis is presented of the main components of skull and postcranial skeleton of the carnivorous dinosaurs from the Cretaceous of Mongolia. This is the first study of the Mongolian late theropods based on the wide fossil material which allowed to show some important peculiarities in the morphology of the different branches of Theropoda.

Skull structure of theropod type is characterized by a number of features which varied in wide range. There are: a distinctive degree of development of basisphenoid capsule, a bone cavity of the middle ear of a bird type, a palatal complex deviated from the common reptilian type to form supposedly palaeognathic basal features, a structure of parabasal canals more connected with the basisphenoid capsule.

Skull of the theropod type is characterized by the metakinetic form of the intracranial mobility changed in some groups up to its complete exclusion.

In the morphology of postcranial skeleton are described: a sternum quite the same to that in ratites; the modifications of forelimbs characterized by pulley-like and non-pulley like carpal structures; the clavicles of the bird type unusually connected with the pectoral girdle. Theropod pelvis is divided into prepubic and opisthopubic forms both based on the dolichoily; an altiiliac type of pelvis greatly declined from normal theropod example is described. It is suggested that pelvis of Archaeopteryx would be included to opisthopubic dolichoiliac type. The main modifications of theropod pes are considered.

The functional interpretation of postcranial skeletal elements is presented and more dynamic than usually accepted pose of the carnivorous dinosaurs is proposed.

Presently accepted classification is based on the main division of carnivorous bipedal saurischians - Palaeopoda and Theropoda, the latter of which is considered as the large trunk evolved for the most part of Mesozoic. Classification of Theropoda includes 19 families (plus two ones of indefinite position) united into seven infraorders from which four infraorders and nine families are distinguished mainly on the base of Mongolian groups.

The perfection of bipedalism and predatory are believed to be earliest tendencies in the development of Theropoda which were divided into many lines characterized by numerous parallel adaptations. New Mongolian data clearly come out against "two linear" position - carnosaurs and coelurosaurs only - in the ideas of theropod evolution and give proof of conception on the many linear parallel development of the carnivorous dinosaurs.

Probable relationships of theropods with other dinosaurs and archosaurs as a whole and particularity with Archaeopteryx are considered. It is suggested that pelvis of the theropod type characterized by high plasticity structurally reversed many times in the evolution of the group. It argues the probable evolution of ornithischian pelvis from the initial saurischian one and thereby the monophyly of dinosaurs.

In many parallel lines of theropods the bird or basically bird features were widely spread which outlinde in general the ways of "ornithisation" and as a result lead to the "true" birds. Archaeopteryx could not pass the theropod stage in its evolution and probably represented one of the parallel lines developed on the common theropod base and expressed their relationships with birds.

Attempt was made to argue a high degree of authochtonal development of the Central Asiatic groups of the carnivorous dinosaurs on the stage of late theropod evolution.

Functional interpretation of the high adaptations in some groups of the carnivorous dinosaurs may serve as the basis for indicating the main ecological types of theropods.

Dinosaurs and other faunal groups allow to carry out the. regional and the intercontinental correlation of the main Cretaceous stratigrafic horisons of Mongolia and North America.

It is presented the first complete description of the theropod branches of Mongolia showing now the widest variety of the group as a whole. It includes besides a revised definition of suborder also seven infra-orders, 10 families, four subfamilies, 14 genera and 16 species.