Context: The oldest known fossil among the Eutheria ("true beasts") is the small shrewlike Juramaia sinensis, or "Jurassic mother from China", dated to 160 million years ago in the Late Jurassic. A later eutherian, Eomaia, dated to 125 million years ago in the Early Cretaceous, possessed some features in common with the marsupials but not with the placentals, evidence that these features were present in the last common ancestor of the two groups but were later lost in the placental lineage. In particular:

Question: What is the oldest know fossil among the Eutheria group? 
Answer: shrewlike Juramaia sinensis

Question: How long ago does oldest know fossil date back to?
Answer: 160 million years ago

Question: In what time period did early animals share some features with marsupials?
Answer: 125 million years ago

Question: Which lineage were some of these early marsupial features were lost?
Answer: placental

Question: What is the oldest known feature among the marsupials?
Answer: Unanswerable

Question: What time period is a marsupial dated to in the Early Cretaceous?
Answer: Unanswerable

Question: What do Juramaia have in common with placentals?
Answer: Unanswerable

Question: What lineage shows some early eutherian features were lost?
Answer: Unanswerable

Question: When was the marsupial mother from the Cretaceous dated to?
Answer: Unanswerable