Taxonomy, Morphology, Masticatory Function and Phylogeny of Heterodontosaurid Dinosaurs
PenSoft Publishers LTD, 3 ott 2012 - 225 pagine
This major study on heterodontosaurid dinosaurs is the first to review the taxonomy, morphology, functional anatomy, and phylogeny of this important early radiation of small-bodied herbivores. Heterodontosaurids persisted for approximately 100 My, from Late Triassic to Early Cretaceous time, during which they evolved some of the most sophisticated dentitions for processing plant materials. Some species required reevaluation to establish unequivocally their status as heterodontosaurids, such as Echinodon from rocks in southern England, one of the first and smallest dinosaurs ever described. Tianyulong from northern China is described in more detail in the study and is shown to have unusual skeletal proportions, including a relatively large skull and very short forelimb. A new taxon, Pegomastax africanus gen. n. sp. n., is described from southern Africa with a short parrot-shaped bill. Tooth replacement and tooth-to-tooth wear is more common than previously thought among heterodontosaurids, which the author argues are herbivores despite their prominent caniniform teeth. Heterodontosaurds appear to have split early in their history into a northern group with primitive, subtriangular crowns and a southern group with deeper crown proportions.
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Abbreviations Ahrictosaurus alveolar margin angustidens antorbital fenestra antorbital fossa apical arched diastema articular surface articulation autapomorphies buccal emargination Butler Butler et al centrum length cheek teeth Clarens formations dashed lines indicate dentary caniniform tooth dentary crowns dentary tooth row denticles dentition diastema dorsal Echinodon Elliot and Clarens ﬁg ﬁgured ﬁrst ﬂange foramen formations of South Fruitadens Galton Hatching indicates broken heterodontosaurids Heterodontosaurus Fig Heterodontosaurus tuc/ei holotype identiﬁed indicate estimated edges indicates broken bone jugal Jurassic Upper Elliot labial LACM lateral view left dentary Lesothosaurus lines indicate estimated lower jaw Lower Jurassic Upper Lycor/ainus Lycorhinus Manidens maxilla maxillary maxillary and dentary maxillary crowns maxillary tooth metacarpal metatarsal NHMUK RU A100 occlusion ornithischians Pegomastax Phalanx Pisanosaurus portion postcaniniform posterior predentary premaxillary teeth preserved ramus reconstruction Santa Luca Scale bar equals Sereno skeleton South Africa specimen surangular synapomorphies Thulborn Tianyulong tone indicates matrix transverse ungual Upper Elliot Formation vertebrae wear facets