Acta Palaeontologica Polonica

On ornithischian phylogeny

Teresa Maryańska and Halszka Osmólska

Acta Palaeontologica Polonica 30 (3-4), 1985: 137-150

The ornithischian dinosaurs are analysed using the cladistic methodology. The preferred hypothesis (see fig. 1) is that: 1. Ornithischia are monophyletic, 2. Ankylosauria are sister group of all other ornithischians, 3. Pachycephalosauria + Ceratopsia are monophyletic unit sharing common characters not found in other ornithischians. Quadrupedality is considered as primitive ornithischian condition.

Key words: dinosaurs, Ornithischia, cladistics.

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