Mesosuchus
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Mesosuchus Temporal range: Middle Triassic, 246 Ma |
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| Life restoration of Mesosuchus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | †Rhynchosauria |
| Genus: |
†Mesosuchus Watson, 1912 |
| Species | |
Mesosuchus is an extinct genus of basal Rhynchosaur from early Middle Triassic (early Anisian stage) deposits of Eastern Cape, South Africa. It is known from the holotype SAM 5882, a partial skeleton, and from the paratypes SAM 6046, SAM 6536, SAM 7416 and SAM 7701 from the Aliwal North Euparkeria site. Mesosuchus is quite small, spanning around 30 cm in length. Mesosuchus was discovered and named by David Meredith Seares Watson in 1912.
SAM 5882, the holotype for Mesosuchus, consists of a partial rostrum, palate, braincase, lower jaws, sections of articulated presacral vertebral column, nine articulated caudal vertebrae, portions of scapula and pelvic girdle, and partial forelimb and hindlimbs.
SAM 6046, one of the paratypes of Mesosuchus, consists of an incomplete right maxilla, an articulated series of the last ten presacrals, both sacrals, and first six caudals, partial forelimbs, left and right pelvic girdles, right hind limb, as well as element of left tarsus.
SAM 6536, another paratype, consists of a virtually complete skull with lower jaws, articulated cervical vertebrae and ribs, dorsal vertebrae and ribs, complete left scapulocoracoid and partial right scapula, interclavicle, clavicles, distal end of left humerus, and gastralia.
SAM 7416, another paratype, consists of an articulated vertebral column composed of the last dozen presacrals, both sacrals and at least the first 15 caudal vertebrae, fragments of right forelimb, pevic girdle, complete right femur, right crus and partial left crus, and right and left tarsi and pedes.
All diagnostic traits of Mesosuchus come from diagnosis of the Mesosuchus browni as it is the only known species. Most of the autapomorphies used to identify Mesosuchus browni pertain mostly to the skull as that is the most researched since there are more parts for it to compare with others. The Mesosuchus is a small Rhynchosaurian diapsid with multiple rows of maxillary and dentary teeth with each row consisting of only a small number of teeth. The two premaxillary teeth are approximately twice the size of the maxillary teeth and the maxillary teeth inset medially while projected below the internal naris. There is also an occlusion between the vomerine teeth and dentary teeth with saddle-shaped vomers that overhang dorsally the premaxillary symphysis. Looking at the spine, the length of the axis neural spine is greater than the length of axis centrum. It also has a craniocaudally narrow neural spine of the third cervical and a prominent midventral groove on the first two caudal centra.
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