From Yale University in the USA:
Paleontologists discover most primitive primate skeleton
Wed, 2007-01-24 07:36 — BJS
The origins and earliest branches of primate evolution are clearer and more ancient by 10 million years than previous studies estimated, according to a study featured on the cover of the Jan. 23 print edition of the Proceedings of the National Academy of Sciences.
The paper by researchers at Yale, the University of Winnipeg, Stony Brook University, and led by University of Florida paleontologist Jonathan Bloch reconstructs the base of the primate family tree by comparing skeletal and fossil specimens representing more than 85 modern and extinct species.
The team also discovered two 56-million-year-old fossils, including the most primitive primate skeleton ever described.
In the two-part study, an extensive evaluation of skeletal structures provides evidence that plesiadapiforms, a group of archaic mammals once thought to be more closely related to flying lemurs, are the most primitive primates.
The team analyzed 173 characteristics of modern primates, tree shrews, flying lemurs with plesiadapiform skeletons to determine their evolutionary relationships.
High-resolution CT scanning made fine resolution of inaccessible structures inside the skulls possible. …
Bloch discovered the new plesiadapiform species, Ignacius clarkforkensis and Dryomomys szalayi, just outside Yellowstone National Park in the Bighorn Basin with co-author Doug Boyer, a graduate student in anatomical sciences at Stony Brook.
Previously, based only on skulls and isolated bones, scientists proposed that Ignacius was not an archaic primate, but instead a gliding mammal related to flying lemurs.
However, analysis of a more complete and well-preserved skeleton by Bloch and his team altered this idea.
“These fossil finds from Wyoming show that our earliest primate ancestors were the size of a mouse, ate fruit and lived in the trees,” said study leader Jonathan Bloch, a vertebrate paleontology curator at the Florida Museum of Natural History.
“It is remarkable to think we are still discovering new fossil species in an area studied by paleontologists for over 100 years.”