@article {6611,
	title = {Direct measurement of age in fossil <i>Gryphaea</i>: the solution to a classic problem in heterochrony},
	journal = {Paleobiology},
	volume = {25},
	number = {2},
	year = {1999},
	note = {PDF},
	month = {Spring},
	pages = {158-187},
	keywords = {bivalvia, evolution, gryphaea, gryphaeidae, heterochrony, mollusca, ostreoida, ostreoidea},
	author = {Jones, Douglas S. and Gould, Stephen Jay}
}
