Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

47-Million-year-old Fossil Could Shed Light on Primate Family Tree

27.05.2009
A 47-million-year-old primate fossil, a purported "missing link" between primates and humans, was unveiled this week in New York. The fossil, formally called Darwinius masillae but nicknamed Ida, could, due to it being an essentially whole skeleton, shed light on the construction of the primate family tree, says an expert on primate evolution at Washington University in St. Louis.

Tab Rasmussen, Ph.D., professor of anthropology in Arts & Sciences, studies primate evolution by drawing on two major lines of evidence: the fossil record and the comparative study of living primates.

One goal of this research is to trace the actual course of primate evolution. More importantly, detailed studies of primate evolution can provide insight into the evolutionary process itself. He has been particularly interested in major evolutionary transitions, such as primate origins and anthropoid origins.

Rasmussen explains the significance of the find in the following piece:

The new specimen of Darwinius is truly remarkable. Over the last 150 years of paleontological collecting around the world, thousands of fossil primates have been found representing many hundreds of species, but the new find is the first complete skeleton. Usually we are lucky to find a few fragments of jaws or teeth, or isolated limb bones. Only infrequently do we get partial limbs or multiple bones from a single individual. In Darwinius, we have essentially the whole skeleton, with impressions of body outlines and stomach contents as well.

Some of the bones least likely to be found and properly identified from typical fossil sites are small bones of the feet, hands, fingers, tail, and so forth. In Darwinius, we can judge precisely the proportions and arrangements of these parts. Hands, feet and tail are critical for active arboreal movements, and Darwinius shows us that it had prehensile hands, powerful grasping feet, and a long, counterbalancing tail, all contributing to the efficiency of arboreal running and leaping.

Because Darwinius died at a immature age, the specimen is also very helpful in reconstructing the life history of the animal. The sequence in which deciduous (baby) teeth and adult teeth erupt allows researchers to estimate the rate of development, whether an animal grew up fast like a rabbit, or slow like a human being. It turns out Darwinius had a medium growth rate, slower than most other mammals its size, but faster than modern apes. In this way, it was similar to squirrel monkeys and some lemurs. The individual represented by the new fossil had broken its wrist before dying, possibly from a fall. The stomach contents reveal fruit and leaves.

Darwinius lived at a time (47 million years ago) not too long after the very earliest true primates appear in the fossil record. It provides us with the best look ever at such early primates. The world was much warmer then, and tropical zones extended far north into North America, Europe and Asia. The very widespread Eocene rainforests of the time held a remarkable diversity of primates. The Eocene was truly the golden age of primate evolution, judged by global diversity and abundance.

Darwinius is also of interest regarding the construction of the primate family tree. Among living primates, there are three major groups. (1) Tarsiers are small, nocturnal primates of Southeast Asia, but in the past they were very diverse and widespread. One family of tarsioid primates, the Omomyidae, is well known from the Eocene. (2) Strepsirhini, or lemur-like primates, include nocturnal primates of Africa and Asia, and a considerable diversity of nocturnal and diurnal primates in Madagascar. The earliest members of this group are known from the Eocene of Africa. (3) The third group, Anthropoidea, includes monkeys, apes, and humans. Darwinius is clearly not closely related to the tarsiers or the true lemurs. It lacks any shared specializations with either of these groups that would provide evidence of a close evolutionary kinship. The authors of the report suggest that Darwinius may be a very primitive relative of anthropoids. The tie cannot be established with great confidence at this time. Among the very earliest primates known, Darwinius is a reasonable candidate as our earliest anthropoid kin.

Another possibility regarding the evolutionary tree is that Darwinius is not specially linked to any of the lineages that live today. There is a good possibility that the true anthropoid ancestors lived in Africa during the Eocene. A large number of anthropoid fossils have been found there at younger dates.

One of the main areas of controversy about Darwinius has to do with this hypothetical tie to Anthropoidea. Some researchers feel that early tarsioid primates are better candidates for anthropoid ancestry. Most of them favor an Asian genus called Eosimias as a potential anthropoid. One problem with this idea is that Eosimias is very poorly known, being represented only by teeth and jaws, so that hypothesis is still very insecure. Another problem is that tarsioid primates are very specialized in their limbs and skulls early in the Eocene, probably too much so to have given rise to more generalized anthropoids.

Trying to reconstruct the earliest parts of the primate evolutionary tree is by its nature very difficult. This is because early primates were more primitive than modern ones. Also, fossil primates, even one as complete as Darwinius, cannot provide us with information about all anatomical soft tissues. It will not be possible to retrieve DNA from Darwinius.

Tab Rasmussen
Professor of Anthropology
Washington University in St. Louis
(314) 935-4844
dtrasmus@wustl.edu

Tab Rasmussen | Newswise Science News
Further information:
http://www.wustl.edu

More articles from Earth Sciences:

nachricht Tiny microenvironments in the ocean hold clues to global nitrogen cycle
23.04.2018 | University of Rochester

nachricht Clear as mud: Desiccation cracks help reveal the shape of water on Mars
20.04.2018 | Geological Society of America

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>