Earliest known marsupials.

The infraclass Metatheria has not been reported from deposits predating the mid-Cretaceous. Fossil material just recovered from Albian deposits in northcentral Texas has definite characteristics of the family Didelphidae and is submitted as being from the oldest known marsupials. The same locality has also produced remains referable to Eutheria, demonstrating a somewhat earlier divergence of these two important groups than was known before.