Darwinius

Darwinius masillae ("Darwin's creature from the Messel pit," named to celebrate Charles Darwin's bicentenary ) is a basal or stem group primate from the Eocene, known from a fossil, dubbed Ida, recovered in 1983 from the Messel pit, a disused shale quarry near the village of Messel, about 35 kilometres (22 mi) southeast of Frankfurt am Main. The fossil, divided in two sections after the amateur excavation and sold separately, was not reassembled until 2007.

D. masillae is a specimen of an extinct primate species that lived 47 million years ago. The announcement has included claims that it is significant as a transitional form (a so-called "missing link") between early primitive primates and the later prosimian and simian lineages. The creature appeared superficially similar to a modern lemur, but had opposable thumbs. The fossil is claimed to lie near the separation of two major primate clades, one leading to the prosimians, the other to the anthropoid monkeys and, eventually, to the great apes including Homo sapiens. The animal, which is related to other dry nosed Haplorrhini primates, lived during the Lutetian stage of the Eocene Epoch. Concerns have been raised about the extent of claims made before adequate information was available for scrutiny.

Type specimen
The type specimen, a 95%-complete fossil, has been named "Ida", after the daughter of Jørn Hurum, the Norwegian paleontologist who secured one section of the fossil from an anonymous owner, and led the research.

In addition to the bones, an imprint of Ida's soft tissue and fur outline is present, along with her last meal of fruit and leaves. At the time its discovery was announced, in the scientific and the popular press, the fossil was characterized as the "most complete fossil primate ever discovered"; it is missing only its left rear leg. Remnants of a last meal, of fruit and leaves, can be detected, as can imprints of the creature's fur. Sir David Attenborough has described it as "an extraordinary fossil."

Ida lived in the early Middle Eocene during a period in evolutionary history after the extinction of the dinosaurs, when mammals first began to thrive on the planet. In primate evolution, the anthropoids (monkeys, apes and humans), split from the branch leading to modern prosimians (lemurs, lorises and tarsiers).

Scientists have worked to identify the fossil and place it within the primate family tree along with other fossil primates. Ida was originally thought to be a primitive lemur, but comparative tests revealed her to have anthropoid features. This indicates that she is a transitional fossil between primitive primates and the human lineage. Two of the key anatomical features found in lemurs, a grooming claw on the foot and a fused row of teeth, a toothcomb, in the bottom jaw, are not present on the fossil. Instead she has a short face with forward facing eyes, like humans, as opposed to the long face of a lemur, nails instead of claws, and teeth similar to those of monkeys.

The fossil's hands have five fingers and exhibit human-like opposable thumbs. These would have provided a "precision grip" which, for Ida, was useful for climbing and gathering fruit. Ida also had flexible arms and relatively short limbs.

Digital reconstructions of Ida's teeth reveal that she has unerupted molars in her jaw, indicating that she was about 9 months old, or the equivalent of a 6 years old human. The shape of Ida's teeth provides clues as to her diet; jagged molars would have allowed her to slice food, suggesting that she was a leaf and seed eater. This is confirmed by the remarkable preservation of her gut content. Furthermore the lack of a baculum (penis bone) means that the fossil was definitely female.

X-rays reveal that her left wrist was healing from a bad fracture, which may have contributed to her death. The scientists believe she was overcome by carbon dioxide fumes whilst drinking from the Messel lake. Hampered by her broken wrist, she slipped into unconsciousness, was washed into the lake, and sank to the bottom, where unique fossilisation conditions preserved her for 47 million years.

It is thought that when the organism was alive it was known as Bertie, however, this is yet to be confirmed by palaeontologists.

Discovery and publicity
The significance of the fossil was first recognised by vertebrate palaeontologist Dr. Jørn Hurum from the Natural History Museum, University of Oslo, who uncovered the specimen through a chance encounter at the Hamburg Fossil and Mineral Fair, Germany, in 2006 where a dealer offered the fossil for $1 million. It had been discovered 23 years earlier by an amateur fossil hunter, but remained hidden from the world in a private collection. Hurum acquired the specimen for his museum based on photographs alone, allowing it to be seen and scientifically studied for the first time.

Since its rediscovery it has been studied in secret for two years by a team of scientists; Hurum was joined by primate evolution expert Professor Philip Gingerich of the University of Michigan, and palaeontologists Dr. Jens Franzen and Dr. Jörg Habersetzer of the Senckenberg Museum's Research Institute. They revealed their findings to the world in a paper published on 19 May 2009 in PLoS ONE, the open source journal of the Public Library of Science.

The paper was accompanied by a documentary (Uncovering Our Earliest Ancestor: The Link), made by Atlantic Productions in the UK, to be screened on the History Channel (US) and BBC One (UK) - directed by Tim Walker and produced by Lucie Ridout. A book The Link: Uncovering Our Earliest Ancestors by Colin Tudge and a website, were also launched to explain the significance of the fossil to a broader audience.

Independent experts have raised concern about publicity exaggerating the importance of the find before information was available for scrutiny. News coverage has described the discovery as "the missing link in human evolution" and the "eighth wonder of the world" which "finally confirms Charles Darwin's theory of evolution"	. Science historian John Wilkins has commented that there is no missing link, which is an outdated concept dating back to the great chain of being, instead there are an infinite number of missing branches in Darwin's metaphor of the tree of life. Brian Switek, while describing the fossil as spectacularly complete and "the first time a fossil primate has been found exhibiting such extraordinary preservation", deplores the sensationalist coverage and a lack of adequate research in the published paper to back claims that it is an ancestor of the earliest anthropoids.