''Zambiasaurus'' is an extinct genus of dicynodonts that was discovered in the Middle Triassic ( Anisian) Ntawere Formation of Zambia, southern Africa. It was a large dicynodont, reconstructed using several fossil fragments, in majority belonging to probably a juvenile ''Zambiasaurus submersus''. ''Zambiasaurus submersus'' is the type species of the genus ''Zambiasaurus''. It is a

stahleckeriid Stahleckeriidae is a family of dicynodont therapsids whose fossils are known from the Triassic of North America, South America, Asia and Africa. Classification Phylogeny Below is a cladogram A cladogram (from Greek ''clados'' "branch" and ...

, the first

known outside South America, and it is also the oldest known

Description

Skull

The skull of ''Zambiasaurus submersus'' was reconstructed by using eighteen different juvenile fossil fragments and fragments of an adult Zambiasaurus. The immature skull had the dimensions of long and wide while the adults had a skull long and wide. There are no teeth in both upper and lower jaws making it a herbivorous species. Skull tapers

anteriorly Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

, widest across occiput. Wide inter-orbital region and narrow inter-temporal region. A blunt

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, rostrum, or proboscis. The wet furless surface around the nostrils of the nose of many mammals is c ...

and a short median suture between nasals. Pineal foramen surrounded by parietals. Preparietal bone absent. Parietals slightly concave

antero-posteriorly Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

and from bulk of intertemporal bar.

Interparietal bone An interparietal bone (os interparietale or Inca bone or ''os inca var.'') is a dermal bone situated between the parietal and supraoccipital. It is homologous to the postparietal bones of other animals. In humans, it corresponds to the upper p ...

doesn't extend far forward. No sharp median intertemporal ridge. Sharp transition between dorsal and occipital surface. Occipital wings of squamosal extend laterally and somewhat posteriorly. Palatal surface of premaxilla bears pair of anterior ridges.

Post-cranial elements

Fragmented vertebrae showed the

prezygapophyses The articular processes or zygapophyses (Greek language, Greek ζυγον = "yoke" (because it links two vertebrae) + απο = "away" + φυσις = "-physis, process") of a vertebra are projections of the vertebra that serve the purpose of fitting ...

is concave and the postzygapophyses is convex. Fragments of ribs did not provide any useful information. Reconstructed from a lower and upper fragment, the scapula showed a long and narrow blade, low

scapular spine The spine of the scapula or scapular spine is a prominent plate of bone, which crosses obliquely the medial four-fifths of the scapula at its upper part, and separates the supra- from the infraspinatous fossa. Structure It begins at the vertical ...

running along the antero-lateral edge. Acromion process is not very large. Origin of scapular ligament of triceps muscle on postero-dorsal edge above the glenoid. There is no notch on the lower edge of the scapula so the foramen laid entirely inside the precoracoid. Fragments of clavicle provided no useful information. Sternum is hexagonal and ventral side is slightly concave. Dorsal side has postero-lateral bosses that have cartilage-ornaments on the ends. Reconstructed from two complementary fragments, the

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

is strongly twisted expressing very poorly muscular insertion and articulation areas. The radius is also incomplete and reconstructed from two

distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

fragments. It is slender and configured to be longer than the ulna. A complete ulna shows a slender bone and convex distal ends.

Classification

''Zambiasaurus'' is characterized as a stahleckeriid, because of many shared characteristics such as; * Blunt

* Wide but low occiput * Short temporal opening * Lack of a high intertemporal crest * absence of Preparietal area 5, preparietal * Nasal septum deviation, Nasals meet for a short distance in the midline or separated by a junction * Narrow neural spine similar to Anterior vertebral muscle, anterior vertebrae of juvenile ''Stahleckeria'' * Coracoid, Sternum, and Pelvis generally similar * Absence of tusks signify a close relation to ''Stahleckeria'' rather than ''Dinodontosaurus'' or ''Chanaria'', the other two Stahleckeriidae, Stakleckeriid Genus, genera

History

''Zambiasaurus'' was named after the country of origin Zambia and ''Zambiasaurus submersus'' means the likelihood that the species drowned. Fossil reptiles were first found in upper Luangwa River valley by Dixey in 1928 and 1935. The area was later re-examined in 1960 and 1960 by Dr. A. R. Drysdall and James Kitching. They examined an area north-west of Sittwe, Sitwe for four months and collected almost 500 Zoological specimen, specimens. Later an expedition to Sittwe, Sitwe was done by a joint effort of the Natural History Museum, London, British Museum (Natural History) and University of London. They spent six weeks collecting 220 specimens. Even though there was a large collection of specimens the specimens themselves were imperfect or poorly documented.

Paleobiology

Thought to be Herbivore, herbivorous because of the lack of teeth and movement of lower jaws that appeared to be efficient in mastication. ''Zambiasaurus'' had a barrel shaped body that was strongly built but very slow. The body was held off the ground but it either had a sprawling stance or a more upright stance.

References

External links

The main groups of non-mammalian synapsids at Mikko's Phylogeny Archive
{{Portal bar, Paleontology Kannemeyeriiformes Anisian life Middle Triassic synapsids of Africa Fossils of Zambia, Fossil taxa described in 1969 Anomodont genera