Tritylodonts
| Tritylodonts Temporal range: 221–113 Ma Late Triassic - Early Cretaceous |
|
|---|---|
 |
|
| Life restoration of Oligokyphus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | Therapsida |
| Suborder: | Cynodontia |
| Clade: | Mammaliamorpha |
| Family: |
†Tritylodontidae Cope, 1884 |
| Genera | |
|
See below |
|
See below
Tritylodontids ("three knob teeth", named after the shape of animal's teeth) were small to medium-sized, highly specialized and extremely mammal-like cynodonts, bearing several mammalian hallmarks like erect limbs, and endothermy. They were the last known family of the non-mammalian synapsids. Tritylodontidae probably descended from a Cynognathus-like cynodont. Most tritylodontids are thought to have beenherbivorous, feeding on vegetation, such as stems, leaves, and roots. A recent studiy indicate some may have had more omnivorous diets. Tritylodontid fossils are found in the Americas, South Africa, and Eurasia - they appear to have had an almost global distribution, including Antarctica.
The tritylodont's skull has a high sagittal crest. They retained the reptilian joint between the quadrate bone of the skull and the articular bone of the lower jaw - the retention of the vestigial reptilian jawbones is one of the reasons they are technically regarded to not be mammals, but are instead mammaliaformes. The back of the skull had huge zygomatic arches for the attachment of its large jaw muscles. They also had a very well-developed secondary palate. The tritylodont dentition was very different from that of other cynodonts: they did not have canines, and the front pair of incisors were enlarged and were very similar to rodents of today. Tritylodontids had a large gap, called a diastema, that separated the incisors from their square-shaped cheek teeth. The cheek teeth in the upper jaw had three rows of cusps running along its length, with grooves in between. The lower teeth had two rows of cusps which fitted into the grooves in the upper teeth. The matching of the cusps allowed the teeth to occlude more precisely than in earlier cynodonts. It would grind its food between the teeth in somewhat the same way as a modern rodent, though unlike rodents tritylodontids had a palinal jaw stroke (front-to-back), instead of a propalinal one (back-to-front). The teeth were well suited for shredding plants matter; however, there is evidence that some tritilodontids had more omnivorous diets, much in the same vein as modern mammals with "herbivore dentitions" like modern rats.
...
Wikipedia