Jan. 27, 2009 -- A sperm-looking creature called monosiga is the closest living surrogate to the ancestor of all animals, according to new research that also determined animal evolution may not always follow a trajectory from simple to complex.
Yet another find of the study, published in the latest PLoS Biology, is that Earth may have given rise to two distinct groups of animals: bilaterians -- animals with bilateral symmetry, like humans -- and non-bilaterians, which include corals, jelly fish, hydra, unusual, often poisonous, creatures known as cubozoans, and other organisms.
Free-living, unicellular organisms called choanoflagellates, however, could be on every person's family tree, so long as it was a gigantic one.
http://dsc.discovery...l-ancestor.html
