text: A structure possessed by these animals consists of an os calcaris and a cornu calcaris.
full_question: A structure possessed by these animals consists of an os calcaris and a cornu calcaris. In some of these animals, defensin-like proteins are produced in the crural glands, which are largest during the mating period and produce a potent venom. In the epididymises of some of these non-insect animals, their sperm agglomerate into cooperative bundles containing around a hundred sperm to increase swimming speed. The evolutionary divergence of these animals is the subject of the "Theria hypothesis." These animals possess extratarsal spurs, and they are the only land mammals that exhibit electroreception. For 10 points, name this order of egg-laying mammals that includes echidnas and duck-billed platypuses.
first_sentence: A structure possessed by these animals consists of an os calcaris and a cornu calcaris.
raw_answer: monotremes [or Monotremata; accept platypuses until "order" is read; accept echidnas until "order" is read; accept spiny anteaters until "order" is read]