Recent molecular evidence suggests that pinnipeds evolved from a bearlike ancestor about 23 million years ago during the late Oligocene or early Miocene epochs, a transitional period between the warmer Paleogene and cooler Neogene period.
Neogene |
By studying the Rocky Mountains in Colorado, Idaho, and Wyoming, Leopold helped recreate the paleoenvironment of the Paleogene and Neogene periods.
His research involves the evolution of Eurasian land mammals and terrestrial environments during the Neogene, ecomorphology of ungulates, developmental biology, the function and evolution of mammalian teeth, and scaling problems (changes in size with growth or as species evolve).
The genus Plesiocetus was originally coined for three mysticete species from Neogene marine deposits in the vicinity of Antwerp, Belgium: P. garopii, P. hupschii, and P. burtinii.