Fig. 1: Reconstructing body proportions and centre-of-mass in bird-line archosaurs.
From: Decoupling body shape and mass distribution in birds and their dinosaurian ancestors
a Supertree of all taxa in the study, with branch lengths scaled to unit time. The larger yellow circles represent the major reconstructed nodes through avian evolution, and are numbered as followed, 1. Sauropsida, 2. Archosauria, 3. Dinosauria, 4. Saurischia, 5. Theropoda, 6. Neotheropoda, 7. Dilophosaurus + Neotetanurae, 8. Neotetanurae, 9. Coelurosauria, 10. Maniraptoriformes, 11. Pennaraptora, 12. Eumaniraptora, 13. Avialae, 14. Ornithuromorpha, 15. Neornithes, 16. Palaeognathae, 17. Neognathae, 18. Galloanserae. Three dimensional skeletal, minimum skeletal convex hull and skin volume models were generated from CT scans of 17 extant non-avian sauropsids (green branches), 13 hindlimb-dominated (HLD; red branches) and 20 forelimb-dominated (FLD; blue branches) extant birds. These data were used to statistically assess associations between body proportions and locomotion in extant birds, and (b) to develop predictive relationships between minimum skeletal convex hulls and skin volume that could be applied to estimate segment and whole-body mass properties in archosaurian fossils, including those along the dinosaurian lineage leading to extant birds (black branches). In (b) the minimum skeletal convex hulls of Archaeopteryx (left image) have been expanded by the average expansion factors measured for individual body segments (right image) in the two extant phylogenetic bracket groups (non-avian sauropsids and birds), allowing calculation of the whole-body centre-of-mass position (blue spheres).
