A Fossil of the Jurassic Mother, known to be the earliest ancestor of today's placental mammals has been discovered by a paleontologist in China.
Zhe-XI-Luo, a paleontologist at the Carnegie Museum of Natural History in Pittsburgh, has discovered a 160-million-year- old fossil of Juramaia Sinensis-the Jurassic Mother from China, extending the mammalian family tree back by 35 million years. Previously the earliest finding of an ancestor to today's mammals dates back to 125 -million- years ago.
Because it lived 160 million years ago, and nobody was there to sign the birth certificate of its descendants,Juramaia could be our great grandmother 160 million years removed or it could also be our great grand aunt that represents a relative on the side lines, lead author Zhe-Xi Luo told Discovery News.
The new found fossil is well preserved with all its teeth intact. The Skull is incomplete, but there are impressions of residual soft tissues such as hair. This mammal has scansorial forelimb features, and provides the ancestral condition for dental and other anatomical features of eutherians, researchers wrote in a report published in the Nature Science Journal.
The teeth found on the fossil lead researchers to believe that the mammal was closest to living placental mammals instead of pouched marsupials, like kangeroos.Luo suspects the animal ate insects and was was small and skinny and generally more active at night.
Marsupials, by contrast, make up for the short development of fetuses in the mother by having a longer pouch life before the fetuses become independent, Luo said Marsupials just optioned for a different reproductive strategy, he said.
This hard rock evidence coincides and matches with the molecular evidence and gives us independent corroboration between fossils and DNA, Luo added.
This new specimen is a real jewel among the spectacular treasure chest of the Chinese fossil record, said Gregory Wilson, an assistant professor at the Universityof Washington's Biology Department. The exquisitely preserved anatomical details leave little doubt that we're looking at the earliest eutherian yet known, he continued, explaining that it was not quite a placental yet but on the line to placentals, he told Discovery News.