Spines on the tibiae and the femora are usually more sharp and nonarticulated. The ant's antennae, tibiae, tarsi, and mandibles are also yellow or orange. The tibiae lack a dorsal preapical bristle. The tibiae of the hind legs are swollen in egg-laying females. The front tibiae bear large strong spurs or a circlet of spines. The pakicetid tibiae are long with a short tibial crest. The legs are gracile and the tibiae usually bear long bristles. The tibiae of the rear legs usually have a conspicuous spine at their distal end. Males and females can be differentiated by the fore tibiae. Albertosaurines are characterized by more slender builds, lower skulls, and proportionately longer tibiae than tyrannosaurines. It also has unfused tibiae, unlike the fused tibiae of the robust form. The legs have spurs on their fourth segments, the tibiae. Females have two sharp spikes on the outside of the tibiae. In some species the tibiae of the males have modifications. Tibiae and tarsi with broad black rings.