Pegomastax
Holotype of Pegomastax africana: partially preserved skull with jaw bones and teeth. The scale bar corresponds to 2 cm.
- Elliot Formation ( South Africa)
- Pegomastax africana Sereno, 2012
Pegomastax is a genus of bird Beck dinosaur from the Early Jurassic of Africa. The only species of the genus, Pegomastax africana, was a small, herbivorous Representatives of Heterodontosauridae and lived around 200-190 million years ago in what is now South Africa.
The fossil remains of the genus were found in the Elliot Formation, which is about 200 to 190 million years old. Have been described genus and species, 2012 by Paul Sereno. Is Pegomastax phylogenetic studies have shown that a relatively derived member of the Heterodontosauridae, it probably is the sister taxon to the genus Manidens.
Features
The traditional fossil material can only be drawn on the head morphology of Pegomastax to. It had a for Heterodontosauridae typical, rounded Keratinschnabel, who served as an extension of the maxilla and mandible, as can be ascertained from the appropriate lugs at the tip of the snout. Its morphology resembled those of modern parrots well and was movable suspended from the jaw. The muzzle itself was short and narrow, the lower jaw was wedge-shaped. As with all Heterodontiden and in contrast to most other dinosaurs, the teeth indicated different tooth types ( Heterodontie ). The front teeth of P. africana were vampire -like and slightly jagged at the leading edge, but unlike other Heterodontosauriden not bent backwards. Connected to the front teeth on both sides of the mandible ten diamond-shaped teeth on whose cutting surfaces were corrugated.
About other morphological characteristics of P. africana can be partly due to the proportions of the skull, conjecture and partly by comparison with closely related genera. The position in the pedigree of Heterodontosauridae suggests that the jaw muscles relatively far back ansetzte the lower jaw. The row of teeth of Pegomastax is significantly shorter than that of the related Heterodontosaurus 42 mm, which was about 1.2 m long by 27 mm. Since the Heterodontosaurier Tianyulong fossil is delivered together with elongated bristle feathers, it is possible that Pegomastax wore similar bristles.
Locality, fossil material and stratigraphy
From Pegomastax only a highly fractured skull is preserved in a sandstone block from which mainly the teeth and part of the lower jaw could dissect out. The fossil comes from the Elliot Formation near the South African Voyizane (Eastern Cape ). The formation of a life time on the steps of the chronostratigrafischen Hettangiums and Sinemuriums ( 201.3 to 190.8 million years ago) and thus comes from the Lower Jurassic. At that time the region was still connected with the east coast of present-day South America, where the closest known relatives of the genus lived.
Paleoecology
The wear of the teeth in the jaw of Pegomastax and other Heterodontosaurier suggests that it is all representatives acted to overwhelming or obligatory herbivores, a thesis that is supported by the shape of the Keratinschnäbel. Similar mouth forms occur in frugivorous parrots or even in herbivorous tortoises. The extended, fang -like front teeth are likely to have served more than the defense or show fights where they were sitting too deep in the mouth to serve as effective weapons, and hardly show wear.
Systematics and Taxonomy
Tianyulong
Lycorhinus
Pegomastax
Manidens
Heterodontosaurus
The later holotype of Pegomastax (inventory number SAM -PK - K10488 ) was already found 1966/67, in joint excavations of Yale University, the British Museum of Natural History and the University of London. The fossil was prepared at the University of Harvard, where Paul Sereno came to the conclusion that there must be an independent taxon. However, the fossil remained undescribed several decades before Sereno it turned into its own genus and species, 2012.
The genus name Pegomastax he chose based ( "strong" dt ) to the Greek combination pegos and mastax (German " pine "). The specific epithet refers to the locality of the holotype African. Originally it was on africanus, but had to be corrected on africana to comply with the rules of nomenclature subsequently by Sereno. Comparisons with well-preserved representatives of Heterodontosauridae reported Pegomastax as a member of this group; phylogenetic analysis of morphological characters showed that the genus is within the Heterodontosaurinae. This group includes Heterodontosaurier with a deep suspension of the jaw and is geographically limited to the then West Gondwana. It occurs for the first time at the Triassic - Jurassic boundary and can be with Manidens, the South African sister genus of Pegomastax, follow into middle Jurassic.