Table 1.

Main histological traits of crocodiles, large mammals, and Myotragus

Histological traits	Crocodiles	Myotragus	Large mammals
Inner and central cortex
Primary bone	Zonal, LNV, LSV, and FLC	Zonal, LNV, LPO, and FLC	Azonal, FLC through LPO
Annuli	Present	Present	Absent
Resting lines (LAGs)	Cyclically throughout cortex	Cyclically throughout cortex	Rare, near periosteum
Outer cortical pattern in adults	Increasingly closer spacing of LAGs	Increasingly closer spacing of LAGs	OCL
Vascularization	Sparse to avascular	Sparse to avascular	Densely vascularized
Orientation of vascular channels	Mostly longitudinal	Longitudinal and concentric	Irregular, variable, increasingly organized with age
Remodeling	Little, in females extensive during egg-shell formation	Extensive	Extensive
Erosion and endosteal bone	Rare	From an early age onward	At subadult age
Haversian systems	Rare	Frequent	Extensive

Bone microstructure of Myotragus is essentially similar to that of crocodiles in tissue pattern, periodicity of bone formation, transition to slower bone formation at skeletal/sexual maturity, and degree and pattern of vascularization. It resembles, however, other large mammals in pattern and rate of remodeling. LNV, lamellar nonvascular bone; LSV, lamellar bone with simple vascular canals; LPO, lamellar bone with primary osteons; FLC, fibrolamellar complex (18, 19). Trait description for crocodiles and large mammals is modified from refs. 21, 23, and 27.