Data from: More than one way to be a giant: convergence and disparity in the hip joints of saurischian dinosaurs
Data files
May 20, 2020 version files 72.65 KB
-
ArchieAltTreeMS.phy
-
ArchoMS.phy
-
continuous_characters.txt
-
Discrete_characters.txt
-
EoraptorAltTreeMS.phy
-
HerreraAltTreeMS.phy
-
OrnithoscelidaAltTreeMS.phy
-
SilesaurAltTreeMS.phy
Abstract
Saurischian dinosaurs evolved seven orders of magnitude in body mass, as well as a wide diversity of hip joint morphology and locomotor postures. The very largest saurischians possess incongruent bony hip joints, suggesting that large volumes of soft tissues mediated hip articulation. To understand the evolutionary trends and functional relationships between body size and hip anatomy of saurischians, we tested the relationships among discrete and continuous morphological characters using phylogenetically corrected regression. Giant theropods and sauropods convergently evolved highly cartilaginous hip joints by reducing supraacetabular ossifications, a condition unlike that in early dinosauromorphs. However, transitions in femoral and acetabular soft tissues indicate that large sauropods and theropods built their hip joints in fundamentally different ways. In sauropods, the femoral head possesses irregularly rugose subchondral surfaces for thick hyaline cartilage. Hip articulation was achieved primarily using the highly cartilaginous femoral head and the supraacetabular labrum on the acetabular ceiling. In contrast, theropods covered their femoral head and neck with thinner hyaline cartilage and maintained extensive articulation between the fibrocartilaginous femoral neck and the antitrochanter. These findings suggest that the hip joints of giant sauropods were built to sustain large compressive loads whereas those of giant theropods experienced compression and shear forces.
Methods
Discrete characters: The bony hip joints of saurischian-line archosaurs were examined for discrete characters, including osteological correlates of hip joint articular soft tissues. We identified 14 osteological characters based on osteological correlates of homologous articular soft tissues among extant diapsids (Tsai and Holliday, 2015)
Continuous characters: Linear dimensions of fossils were measured using a SPI 31-518-4 dial caliper and a tape measure on physical specimens, as well as from reconstructed 3D surface models of hip joints using the measure distance function of Geomagic (V11 see Appendix S1 of manuscript). Surface area dimensions were measured from reconstructed 3D surface models of hip joints by highlighting relevant osteological correlates and using the select area function of Geomagic (V11 see Appendix S1 of manuscript).
Phylogenetic trees: Composite phylogenetic trees (Fig. 4) were constructed using Mesquite (V2.73) based on published studies (See citations in manuscript), with branch lengths based on hypothesized divergence date between sister clades and sister taxa.
Usage notes
The dataset includes five tree files (.phy) and two text documents for continuous characters and discrete characters respectively.
Among the tree files, ArchoMS.phy contains the "consensus" tree used in this study. The other trees are of alternative topologies in light of contentiously placed taxa, as explained in Figure 4.
The contents of the text documents is best viewed when opened using Excel, as their columns correspond to the continuous and discrete characters. Continuous characters are presented as logged values.
In continous characters, the column's correspondence to characters used in this study are as follows
Column 1: Femur length | |
Column 6: Femoral head circumference | |
Column 7: Femoral head height | |
Column 8: FAA length | |
Column 9: Femoral head width | |
Column 10: Acetabular length | |
Column 13: Acetabular depth | |
Column 14: Acetabular height | |
Column 15: Acetabular circumference | |
Column 16: Femoral subchondral surface area | |
Column 17: Femoral growth plate surface area | |
Column 18: Femoral metaphyseal collar surface area | |
Column 19: Acetabular labrum attachment surface area | |
Column 20: Ilial bony antitrochanter area | |
Column 21: Bony antitrochanter surface area | |
Column 22: Bony acetabulum | |
Column 23: Acetabular fossa For discrete characters, the columns' correspondence to characters used in this study are as follows: |
|
Column 21: | Perforated acetabulum |
Column 30 | Lateral expansion of the supraacetabular rim |
Column 31 | Orientation of the supraacetabular rim |
Column 26 | Expansion of the bony antitrochanter |
Column 34 | Shape of the ischial peduncle of the ilium |
Column 23 | Co-ossification of the bony antitrochanter |
Column 5 | Femoral head deflection |
Column 9 | Surface texture of the proximal femoral growth plate |
Column 10 | Concentration of irregular rugosities on the femoral head |
Column 18 | Transphyseal striations |
Column 19 | Fovea capitis |
Column 20 | Ischiofemoral ligament sulcus |
Column 11 | Cartilage cone trough |
Column 14 | Expanded metaphyseal Collar |