part of part of Ornithorhynchus pes lower limb segment platypus calcaneus spur hind-leg spur The female platypus, in common with echidnas, has rudimentary spur buds which do not develop (dropping off before the end of their first year) and lack functional crural glands. Not to be confused with 'calcaneal spur', a small osteophyte (bone spur) located on the calcaneus (heel bone) ankle spur poisonous ankle spur UBERON:0011581 calcaneus spur