Mosasaur
Mosasaurs (from Latin "Mosa" meaning the 'Meuse river', and Greek σαύρος "sauros" meaning 'lizard') are an extinct group of large marine reptiles containing 38 genera in total. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. Mosasaurs probably evolved from an extinct group of aquatic lizards known as aigialosaurs in the Early Cretaceous. During the last 20 million years of the Cretaceous period (Turonian-Maastrichtian ages), with the extinction of the ichthyosaurs and pliosaurs, mosasaurs became the dominant marine predators. They became extinct as a result of the K-Pg event at the end of the Cretaceous period, about 66 million years ago.
Mustelidae
The oldest fossil of the mustelids were dated at the end of the Oligocene to the beginning of the Miocene. “There is debate regarding which fossils from these epochs represent possible ancestral forms that led to Mustelidae and which fossils represent the first modern mustelids.”(Wund, M. 2005. "Mustelidae" (On-line), Animal Diversity Web.) From the fossil record we can see that Mustelids appeared in the late Oligocene period (33 mya) in Eurasia and migrated throughout the continents. The Mustelids inhabit every continent except Antarctica and Australia. The mustelids migrated all throughout the continents that were connected during the early Miocene. The Mustelids made their way to North and South America via the Bering land bridge.