The Origin of the Ornithischia – to scale
Sometimes size is important. In the case of basal Ornithischia, most taxa are similar in size. Hexinlusaurus and Lesothosaurus appear to be smaller. Scelidosaurus is much larger.
Figure 1. The origin of the Ornithischia according to the large reptile tree, to scale. Scelidosaurus is the oversized outlier here. Most of the other taxa are similar in size. Panphagia and Pampadromaeus link theropods to phytodinosaurs, which include sauropods. Pisanosaurus nests at the base of the Poposauridae, not the Ornithischia with present data.
The origin of the retroverted pubis is still unknown, but Panphagia may provide clues. A study of its pubis in this regard is warranted. Lesothosaurus is traditionally considered THE most basal ornithischian, but the large reptile tree found otherwise. Daemonosaurus and Scelidosaurus nest there. Outgroups include Massospondylus, Pisanosaurus and Panphagia + Pampadromaeus.
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
2012-12-11 01:06:27
Source: http://pterosaurheresies.wordpress.com/2012/12/11/the-origin-of-the-ornithischia-to-scale/
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