Table 1.
List of the mosasauroid long bones analyzed in this study.
Table 2.
Non-mosasauroid humeri analyzed.
Table 3.
Non-mosasauroid femora analyzed.
Table 4.
Comparative rib material analyzed.
Figure 1.
Humeral mid-diaphyseal sections.
A, Clidastes sp. UCMP 34536. B, Prognathodon sp. IRScNB 1624. Ant: anterior, Med: medial. Scale bar equals A, 2 mm; B, 5.6 mm.
Figure 2.
Microanatomical and histological features of mosasaurine humeri.
A–C, Prognathodon sp., IRScNB 1624. Spongiosa with different tightness and organization of the trabecular network between the A, posterior, B, antero-lateral and C, inner regions. D–E, Clidastes sp., UCMP 34536. D, broken inner trabeculae displaying secondary lamellar bone (LB). E, cortex illustrating the different primary osseous tissues observable (parallel-fibered bone [PFB], unusual parallel-fibered bone [UPFB] and fibrous bone [FB]) in zones (Z) and annuli (A), and longitudinally oriented primary osteons (PO). F–G, Mosasaurinae indet., SMU 76406. F, as in E but also with clearly distinguishable lamellar bone (LB). G, cortex illustrating the change from PFB to UPFB between annuli and zones, and radially oriented simple vascular canals. H, Mosasaurinae indet., SMU 76407. Detail of osteons with extreme obliteration of the vascular spaces. SMU: Southern Methodist University, Shuler Museum of Paleontology, Dallas, Texas, USA.
Figure 3.
Histological and microanatomical features in mosasaurine long bones.
A–G, Humeri. A, Globidens sp., PA Unnumbered. B-E, Mosasaurinae indet., SMU 76406. A–B, cortex showing the circumferential organization of the longitudinally oriented osteons and the increased resorption centripetally. C–D, external spongiosa in C, natural and D, polarized light (with gypsum filter) showing secondary deposits of parallel-fibered (PFB) and lamellar (LB) bone. E, transition from the external spongiosa (top) with important remains of primary (UPF) bone in the core of the trabeculae (as pointed by arrows), and inner spongiosa with exclusively secondary deposits of PFB and LB (bottom). F–G, Dallasaurus turneri, SMU 76386. F, part of the section illustrating the rather compact micro-organization. G, transition from the avascular external cortex made of PFB and the inner cortex made of UPFB and displaying radially oriented simple vascular canals. H, radius section of Plotosaurus bennisoni, UCMP 152664. Abbreviations as in Figure 2.
Figure 4.
Dallasaurus turneri, SMU unnumbered specimen, microanatomical and histological features.
A–B, femur. A, whole mid-diaphyseal section. B, transition from the avascular external cortex made of PFB to the inner cortex made of UPFB and displaying radially oriented simple vascular canals. C–D, rib. C, transitional area between the cortex and the medullary region showing some secondary LB and PFB as well as some remains of primary UPFB in the core of one of the remodelled trabeculae. D, longitudinally oriented primary osteons (indicated by arrows) in the cortex.
Figure 5.
Results of the Linear Discriminant Analyses (LDA) performed on A, humeri, B, femora and C, ribs.
LD1 and LD2: first and second discriminant axis, respectively. Polygons represent the boundaries of the ecological categories based on the comparative material (see Tables 2–4). Da, Dallasaurus.
Figure 6.
Evolution of microanatomical features in mosasaurine (from top to bottom) vertebrae, humeri and ribs.