Sunday, 28 February 2021
Sunday, 21 February 2021
The dog family has its origins in North America and it seems clear that what happened here is that some wolf-relative that happened to look a bit like a fox headed south at some point, where all of its remaining descendants live today. North and South America joined up relatively recently, geologically speaking, so it's likely that the origins of the South American foxes actually lie in the North, already looking somewhat like their modern form before they made the trip.
Sunday, 14 February 2021
That's common in birds, perhaps in part because they have to physically fetch and deliver food rather than producing milk with the calories from their own diet, not to mention the effort of incubating eggs. But, in mammals, while it certainly occurs in some species (as do the other two options) the most common pattern is polygyny.
Sunday, 7 February 2021
By far the largest are the "murine" or "typical" mice which contains... well, almost everything. According to that particular study, they split from the other members of the mouse family about 18 million years ago, during the Early Miocene. Then, about 16 million years ago, as the Middle Miocene dawned, the remainder split into what are now recognised as two distinct subfamilies: the gerbils and the "deomyine" mice. (The latter look almost exactly like the murine sort, and it took this sort of study to prove that they weren't).