Scientists are in a debate as to when mammals first appeared on Earth, and new research is making researchers question whether mammals diversified 30 million years before science originally thought, according to the Guardian. There are two classes that researchers use to classify animals that are perceived to be part of the mammal ancestry: mammaliformes and crown mammals.

Crown mammals are considered early mammals and ancestors to the warm-blooded milk makers of today, but mammaliformes are considered a side branch of evolutionary ancestry that are simply "mammal-like."

Scientists at the University of Chicago have joined with other universities to conduct a study on the Haramiyavia clemmenseni, a rodent-like creature and one of the "earliest known proto-mammals."

Through their research, they discovered other qualities that were previously missed, which take the animal out of the crown classification and into the mammaliformes. This suggests that mammals had roots in the Triassic period, then continued to evolve and diversify in the Jurassic. The significance of these details influences where humans were on the time scale as well.

The presence of these animals could suggest that humans survived not only the event that killed dinosaurs, but also the event that paved the way for dinosaurs to rule, making the evidence that much more important to decipher.