Fossil daddy longlegs sports a 99-million-year erection
Normally this male organ is hidden within the body when not in use. By chance, in this extraordinary amber fossil the penis is preserved fully extended outside the body. It shows that Cretaceous harvestmen also used a penis to transfer sperm directly into the female's body. In the taxonomy of modern harvestmen penis anatomy is extremely important: each species has its own unique structure. Also the major groups (or families) of the harvestmen have different penis forms. So far only a few fossil harvestmen have revealed their penis, which makes it difficult to compare them effectively with living species.
In Halitherses grimaldii the penis is spatula-shaped at the tip and is heart-shaped in outline, with a small tube extending from the very end. No living harvestman has a penis with exactly this shape. Also unusual are the large eyes of the fossil, although new results suggest that such large eyes are probably a primitive character in these harvestmen. In other words some early harvestmen should have had large eyes. This combination of features enabled the scientists to propose a new (extinct) family, Halithersidae, within the suborder Dyspnoi. This is the first time that a fossil family has been defined using a mixture of features relating to both the body and the genitalia, and allowed the researchers to study the relationships of these ancient fossils using the same approaches that they would use for living species.
Source: Museum fur Naturkunde [February 03, 2016]