Fossils The Messel Pit provides the best preserved evidence of Geiseltalian flora and fauna so far discovered, with over 1000 species identified. Most other sites are lucky to contain partial skeletons, but Messel boasts extensive preservation of structural integrity, even going so far as to preserve the fur, feathers and "skin shadows" of some species. Unusual preservation has sparked some closely reasoned interpretations. The symptomatic "dumb-bell"-shaped bite marks on either side of the leaf vein on a fossilised leaf have been identified as the death-grip of a carpenter ant terminally parasitized by the fungus Ophiocordyceps unilateralis, that, apparently then as today, commandeered its behavior, in order to release its spores from a favourable location; it is the earliest concrete sample of fungal behavioural manipulation. The diversity of species is remarkable partly as a result of the hypothesized periodic gas releases. A brief summary of some of the fossils found at the site follows: Nine mating pairs of fossil turtles have been found. The turtles, Allaeochelys crassesculpta, were in coitus (in the act of having sex). They are male-female pairs, with the male's tail tucked under the female, which is how they copulate. Their death must have been rapid. It is supposed that the turtles had started mating in the aerated surface waters of the ancient lake. As they sank into deeper water, they were overcome by the release of toxic volcanic gas. They were then buried in the lakebed sediment. Turtles belonging to this clade are still living. They have lost their reptilian scales, and their skin absorbs oxygen from the water. Normally, this is an advantage: it helps them stay submerged for long periods. However, under anoxic conditions it is a disadvantage, because carbon dioxide and dissolved poisons are absorbed as well. Over 10,000 fossilized fish of numerous species Thousands of aquatic and terrestrial insects, some with distinct coloration still preserved Innumerable small mammals including pygmy horses, large mice, primates, ground dwellers (hedgehogs, marsupials, pangolins), aardvark relatives and bats. The fossilized bat specimens have provided insights into the evolution of echolocation. Large numbers of birds, particularly predatory species. Crocodiles, frogs, turtles, salamanders and other reptiles or amphibians Remains of over 30 distinct plant species, including palm leaves, fruits, pollen, wood, walnuts and grapevines The following is only a partial list: Mammals Darwinius masillae, identified in 2009 as an adapiform primate Kopidodon, an extinct arboreal cimolestan Leptictidium, an extinct omnivorous