Article: Fossil blood droplets in Miocene Dominican amber yield clues to speed and direction of resin secretion
Two spiders (Filistatidae) in Miocene Dominican Republic amber, one newly identified and only the second known fossil of this family, have autospasized legs (detached at a predetermined locus of weakness when restrained by a non-self-induced source) at the patella-tibia joint. In both specimens, droplets of haemolymph (blood) are preserved exiting the patellae. The autospasized legs and the presence of haemolymph suggests that both spiders were engulfed in rapid-flowing resin seeps of relatively low viscosity, rather than having wandered onto a sticky exudate, becoming stuck and then covered by a subsequent resin flow. These are the first reported incidences of such fossilized blood droplets, the shape, size and position of which provide clues to preservational taphonomy, an understanding of which is necessary for reliable conclusions concerning fossil communities and ecosystems. In addition, haemolymph droplets may serve as reservoirs for fossil DNA.