A team of scientists have completed the first in-depth look at the evolutionary tree for placental mammals, and the results show that the group's genetic diversity took off after the dinosaurs died out 65 million years ago.
Placental mammals are mammals that give birth to live young - such as humans, dogs, and any other number of household creatures. Other mammals that lay eggs, such as the duck-billed platypus, weren't included in the study.
Through the study, the scientists concluded that placental mammals really gained their diversity after the dinosaurs, not before, and that humans had a tiny, insect-eating ancestor that looks somewhat like a mole with an incredibly long tail (pictured above).
"With regards to evolution, it's critical to understand the relationships of living and fossil mammals before asking questions about 'how' and 'why,' " said co-author of the study Jonathan Bloch, associate curator of vertebrate paleontology at the Florida Museum of Natural History.
"This gives us a new perspective of how major change can influence the history of life, like the extinction of the dinosaurs -- this was a major event in Earth's history that potentially then results in setting the framework for the entire ordinal diversification of mammals, including our own very distant ancestors."
The study was made possible by a computing system that allows for more DNA and genetic to be processed, and the scientists expect it to be widely used for research in the coming years. The researchers ended up pouring through 12,000 images of 4,500 traits in order to hone in on the common ancestors and create their placental evolutionary tree.
You can read the published study in the journal Science.
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