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Data from: More than one way to be a giant: convergence and disparity in the hip joints of saurischian dinosaurs

Citation

Tsai, Henry P.; Middleton, Kevin M.; Hutchinson, John; Holliday, Casey M. (2020), Data from: More than one way to be a giant: convergence and disparity in the hip joints of saurischian dinosaurs, Dryad, Dataset, https://doi.org/10.5061/dryad.hmgqnk9dc

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

Funding

Jurassic Foundation, Award: N. A.

Doris O. and Samuel P. Welles Research Fund, Award: N. A.

University of Missouri, Award: Life Science Travel Grant

Brown University, Award: Bushnell Research and Education Fund

Natural Environment Research Council, Award: NE/G005877/1

Natural Environment Research Council, Award: NE/K004751/1

Missouri Research Board, Award: N. A.

University of Missouri, Award: Department of Pathology and Anatomical Sciences Internal Funding

University of Missouri, Award: Research Council Grant

Doris O. and Samuel P. Welles Research Fund, Award: N. A.

Missouri Research Board, Award: N. A.