Spinosaurinae

Aureliano, Tito, Ghilardi, Aline M., Fernandes, Marcelo A. & Ricardi-Branco, Fresia S., 2024, Air sac attachments or tendon scars: the distinction between soft tissue traces in archosaur bone, Zoological Journal of the Linnean Society 202 (1), pp. 1-8 : 3

Spinosaurinae indet.

LPP-PV-0042, tibia ( Aureliano et al., 2018).

The fragmentary tibia of a large Spinosaurinae presents a pachyosteosclerotic condition. The cross-section at the distal-most slice of the metaphysis indicates a growing subadult. This is supported by the absence of an EFS, prevalence of plexiform vascularization and limited presence of secondary osteons in the outer cortex. Lamellar bone populates the cortex and secondary osteons are present in the periosteum ( Fig. 1 G-L). There are long Sharpey’s fibres medially and ‘cross pattern’ ones posteriorly ( Fig. 2 G-I).

Figures

Figure 1. Lamellar bone fibres in an anhanguerid pterosaur ulna (DGEO-CTG-UFPE 7516; A-F) and in a spinosaurine theropod tibia (LPP-PV-0042; G-L). Note that these fibres are only visible at high magnifications (100×; arrowheads). Silhouettes in A and G indicate sampled elements (not to scale; art by Felipe A. Elias). All polarized light. Crossed nicols in A-E and G-L. Parallel nicols in F. Compensator in A-D, G-I and L. The relative angle to the cortical surface is approximately 80° in A, B; 340° in C; 290° in D-F; 120° in G-L.Scale bar in A, H = 250 µm; in B, I = 50 µm; G = 500 µm; in C-F, J-L = 10 µm.

Figure 2. Sharpey’s fibres in a dorsal vertebra of Arrudatitan (MPMA 12-0001-97-1024; A-F) and in a spinosaurine theropod tibia (LPP-PV-0042; G-I). Note that these fibres are visible at low magnifications (5×; arrowheads).G, H show a cross pattern of Sharpey’s fibres. Silhouettes in A and G indicate sampled elements (not to scale; art by Felipe A.Elias). All polarized light. Crossed nicols in A-F. Parallel nicols in. Compensator in G, H. The relative angle to the bone surface is approximately 150° in A-C; 90° in D; 70° in E; 120° in F; 90° in G-I. Scale bar in A = 300 µm; in D, I = 250 µm; in B, C, E, F = 100 µm; in G, H = 500 µm.