This would indicate the large and bulky Diadectomorphs laid anamniote eggs (in water). However, no unambiguously Diadectomorph tadpole is known. Whether this is due to an actual lack of tadpole stage or taphonomy (many Diadectomorphs were upland creatures where tadpoles would have a poor probability of being fossilized) is uncertain. Alfred Romer indicated that the anamniote/amniote divide might not have been very sharp, leaving the question of the actual mode of reproduction of these large animals unanswered. Possible reproductive modes include full amphibian spawning with aquatic tadpoles, internal fertilization with or without ovoviviparity, aquatic eggs with direct development or some combination of these. The reproductive mode might also have varied within the group.