Tropidostoma

Botha-Brink, Jennifer & Angielczyk, Kenneth D., 2010, Do extraordinarily high growth rates in Permo-Triassic dicynodonts (Therapsida, Anomodontia) explain their success before and after the end-Permian extinction?, Zoological Journal of the Linnean Society 160 (2), pp. 341-365 : 351

TROPIDOSTOMA

The bone histology of this genus has already been described in detail by Botha & Angielczyk (2007). Therefore, only a summary will be given here. Several elements, including a humerus, femur, tibia, and fibula from a single subadult individual (SAM-PK- K9960) were used to analyse the bone histology. The cortex of Tropidostoma is relatively thick, with a humeral cortical thickness of 42% and femoral cortical thickness of 31% ( Table 2). The bone tissue consists of rapidly deposited fibrolamellar bone, interrupted by annuli or LAGs ( Fig. 3D ). The bone tissue becomes slowly deposited parallel-fibred bone towards the periphery and Sharpey’s fibres are present in the tibia ( Botha & Angielczyk, 2007). Enlarged channels were not observed.

Figures

Figure 3. Permo-Triassic dicynodont bone histology. A, subadult Cistecephalus ulna NMQR1465b; B, early subadult Dicynodontoides tibia NMQR479a; C, adult Rhachiocephalus ulna SAM-PK-3714a; D, subadult Tropidostoma tibia SAM-PK-K9960c; E, adult Oudenodon femur SAM-PK-K4807a; F, adult Aulacephalodon femur NMQR3016. Arrows indicate enlarged midcortical channels in Rhachiocephalus and Aulacephalodon. Scale bars: A, D, E = 500 mm; B, C, F = 413 mm.