Utah State University Eastern provides life-changing experiences for students in all stages of life. Let USU Eastern transform your life for good.
Maintained by pioweb@ucsc.edu. The common ancestor of placental mammals probably looked like Eomaia scansoria, the earliest known placental mammal, shown here in an artist's reconstruction based on a 125-million-year-old fossil skeleton found in China in 2002.aintained by pioweb@ucsc.edu. The common ancestor of placental mammals probably looked like Eomaia scansoria, the earliest known placental mammal, shown here in an artist's reconstruction based on a 125-million-year-old fossil skeleton found in China in 2002.
Comments. A six year study analyzed genomic information and fossil evidence to construct a mammalian family tree, and discovered our earliest common mammal ancestor lived soon after the extinction of the dinosaurs 66 million years ago.he oldest fossil they identified as being a modern placental lived 200,000 to 400,000 years after the impact. Their analysis showed that rapid evolution followed, producing the first members of the major placental mammal lineages, such as primates and rodents, 2 to 3 million years later.