This month’s instillation of the BWOM is inspired by the recent unveiling of a phenomenal fossil from the Eocene epoch (approximately 55 to 35 million years ago). This period in geological history is notable for the emergence of many modern forms of mammals. The fossil, dubbed Ida by its discoverers, is from the Messel Pit in Germany which has yielded many exceptional fossils. Her scientific name, Darwinius masillae, honors Charles Darwin (one of the founders of modern evolutionary biology) and the area of Messel in Germany where she was unearthed. All paleontologists agree that the specimen is amazingly well preserved. Only the left leg is missing and many details like the texture of the fur and the contents of the stomach are easily observed.
The scientists that completed the biological description of Ida placed her in a group know as the Adapiforms. This group contains many extinct species that resemble modern lemurs but has no living members. Paleontologists disagree on exactly where the group fits in the evolutionary history of the two main groups of primates. The authors of the study describing Ida believe she represents an important transitional fossil or “link” between the prosimian (lemurs and relatives) and simian (monkeys and apes) lineages of primates.
The authors have assembled an unprecedented publicity apparatus for their discovery. You can learn more about their interpretations at their website, on their History Channel documentary, or by reading the associated book.
As with most major discoveries, scientists are still debating the details of the significance of the fossil. Several paleontologists take issue with some of the specifics of the study of Ida’s fossilized remains.
The story of Ida’s discovery and the subsequent debate about her role in primate evolution are a great way to learn more about the process of science. Disagreements about Darwinius masillae will not be settled quickly. Some observers mistakenly believe that this debate reflects some weakness of the scientific method. On the contrary, the process of community examination of the claims of the original authors is the way that scientists will finally reach a conclusion. Only when the idea has survived extensive examination can it be considered a viable theory.