Theriodont

Three members of the Theriodontia: Arctognathus ( Gorgonopsia ) Lycosuchus ( Therocephalia ) Progalesaurus ( Cynodontia )

• Worldwide

The Theriodontia ( " Tierzähner " ) are terrestrial vertebrates from the group of therapsids ( " mammal -like reptiles "). Among them are three more developed, especially carnivore groups. From one of them, the Cynodontia, finally emerged the mammals.

Features

Theriodonten were rather small to medium in size and resembled removed the later mammalian predators. Primitive forms were more meat and insectivores, some more advanced also lived herbivores. The dentition is predatory and already differentiated front incisors, one or more canines, molars behind, pointed in primitive forms in the higher provided with nodular occlusal surfaces. Palate teeth were rarely present. The skull was flat, the mouth wide, the base of the skull straight, without bending like the Anomodontia. The muzzle top edge was horizontal with the nostrils. The dorsal extension of the premaxilla was shortened. The skullcap narrowed between the skull windows and there is narrower than the width between the orbit. Quadrate and Quadratojugale are shortened and were in a recess in the squamosal ( squamosal ). The lower jaw had a Coronoidfortsatz and presented, with newer forms so that a longer lever arm and more space for the temporalis muscle are available. The mandibular joint was perpendicular to the axis of the skull base and was at the height of the occipital joint and the teeth. The following dental mandibular bone were reduced, the canines of the lower jaw longer in relation to those of the upper jaw than in previous taxa. The legs were placed vertically under the body and allowed the animals a quick run.

In this group, mammal -like body proportions developed with a strong back- formed tail and a higher metabolic rate with endothermy.

System

• Theriodontia Gorgonopsia
• Eutheriodontia Therocephalia
• Cynodontia Mammals ( Mammalia)