Mesozoic mammals were fascinating little beasts. They burrowed, climbed, glided, and swam through the Age of Dinosaurs, not as underdogs waiting for their moment to be free of the great reptiles, but as varied, successful creatures. And they keep getting stranger. Mammals previously known only from their dentition are starting to come into view thanks to the discovery of skulls and skeletons. The latest to debut is Vintana sertichi – what looks like a Mesozoic muskrat with some evolutionary tales to tell.
Vintana was a lucky find. The mammal’s skull was hidden inside a 150 pound chunk of sandstone collected from the 72 to 66-million-year-old rock of Madagascar by then-graduate-student, now Denver Museum of Nature and Science paleontologist, Joseph Sertich. A CT scan of the block is what gaveVintana away and allowed paleontologists a rare look at a lineage of prehistoric beasts previously known from teeth and bits of jaw.
What makes Vintana so remarkable isn’t what we know about it. It’s what we don’t know just yet. While Vintana shows some specialized traits not seen among Mesozoic mammals before, Krause and coauthors point out, aspects of the mammal’s ear and braincase more closely resemble those of protomammals that lived over 130 million years earlier. That makes Vintanaof “mosaic” of archaic and derived traits that point to an unusual evolutionary history. Isolation on islands may explain why.
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