Abstract
Fossil spermatozoa are extremely rare. Among the eight cases reported here, including two cases of spermatophores without visible sperm cells, six are fossils preserved in amber. All six concern animals with indirect sperm transfer by means of spermatophores or spermatodesmids. Preservation of subcellular organelles shows once again that amber is an extraordinary preservation medium.
Highlights
Vegetal reproductive structures are common in the fossil record: spores, cysts, pollen grains, seeds and fruits are frequently encountered in many kinds of sediments
It is presumed that the small packet with developing spermatozoa adjacent to the female fossil was deposited by a male shortly before C. lobiferus was entombed in resin
In all species with internal fertilization by free sperm or spermatophores, the spermatozoa are never exposed to conditions of fossilization
Summary
Vegetal reproductive structures are common in the fossil record: spores, cysts, pollen grains, seeds and fruits are frequently encountered in many kinds of sediments. Kojeta (1998) described “in action inclusions” in amber, i.e. fossilized events of biological importance. Due to their microscopic size and lack of hard parts, are among the rarest preserved structures as fossils. He illustrated this notion, among other examples, by scale insects that ejected sperm when entombed in resin, with several cases of spermatophores, but very few cases of (questionable) sperm cells. Margarodids from Baltic amber were shown to exhibit spermatophores and one questionable case of spermatozoa. Monophlebids from Baltic amber and New Jersey amber show spermatophores and possible spermatozoa. Sperm ejection was thought to have been a response to entombment in resin
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