By Surya Chalil

Gondwanatheria is an extinct group of mammals that has only been known through a few isolated teeth and fragmented jaw pieces. As a result, their clade largely remained a mystery and their placement among the evolutionary tree was uncertain and debatable. However, Stony Brook University paleontologist, David Krause, Ph.D., led the research team that discovered an almost complete cranium of a new fossil animal, which belongs to gondwanatheria. The fossil, named Vintana sertichi, is only the third mammalian skull salvaged from the Cretaceous period in the southern hemisphere. Vintana means luck and Joseph Sertichi is the former graduate student of Dr. Krause that fortunately found a block of sandstone filled with fish fossils. A CT scan of the block revealed the gigantic mammalian skull. Vintana is estimated to be about two to three times heavier than the size of an adult groundhog. This is uncanny since other mammals of its era were usually mouse-sized.

Using micro-computed tomography and scanning electron microscopy, Dr. Krause and his team were able to learn more about the anatomy of early mammals that were previously unknown. Features of the teeth, eye sockets, nasal cavity, braincase, and inner ear illustrates that Vintana was a nimble herbivore with sharp hearing and vision. “We knew next to nothing about early mammalian evolution on the southern continents,” stated Dr. Krause in a news release. “The discovery of Vintana will likely stir up the pot.”

The findings published in the journal Nature in November 2014 entirely altered current views of the evolutionary mammalian tree. In addition, news coverage of the unprecedented discovery went global with customer advertising values coming close to $38 million. The next question that needs to be answered is how such a mammal developed during its time. The current theory is based on the fact that the fossil was discovered in Madagascar, an island that has remained isolated for over 20 million years before the existence of Vintana. The continued isolation of this species in various parts of the southern continents allowed for an extremely odd mix of features to develop over time.

References

1. Newly Discovered Fossil is a Clue to Early Mammalian Evolution. 2014. Stony Brook Newsroom. sb.cc.stonybrook.edu/news/general/141005creature.php

2. Krause, D. W. et al., 2014. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism. Nature 515:512–517.