But the corollary to this is that many of these species look extremely similar. It's often the case that, once a new species has been described on the basis of genetics, we can point to physical differences between it and whichever species we split it off from. But these are necessarily minor differences, perhaps previously thought sufficient to justify a designation as a subspecies, but more likely not noticed at all. Given the physical similarities, we'd expect that their diet, behaviour, and so on would also be similar - they are, after all, very close relatives.
Sunday, 5 December 2021
Saturday, 27 November 2021
Further along in this blog I have posted a summary of the family tree of the living species of deer. This is derived from molecular and genetic studies, but it turns out to map reasonably well to what we would have guessed purely from looking at the animals and their skeletons, which is good news if we want to try and place fossil deer into it. The first thing that's apparent from the tree is that, as predicted back in the 19th century, there is a deep split within it, representing the two subfamilies: the cervines (at the top in the diagram) and the capreolines.
Sunday, 21 November 2021
|Dissopsalis, another member |
of the "monster-tooth" family
Sunday, 14 November 2021
Much of this variation seems to date from the Middle to Late Miocene when both dolphins and porpoises underwent a rapid increase in the number of known species. This may be related to the loss of the connection between the Mediterranean and the Indian Ocean, creating a change in the worldwide circulation of water and corresponding changes in the habitats available to these animals, allowing them to exploit new opportunities.
Sunday, 7 November 2021
At any rate, moose are undeniably large, considerably larger than the American elk. They typically stand around 200 cm (6' 6") at the shoulder, with females not much shorter than males. The males are, however, significantly bulkier and more muscular, with a full-grown bull typically weighing between 300 and 600 kg (660 to 1300 lbs) and females around 25% less. The occasional exceptional individual can, of course, be much larger than this but, even ignoring those, that's pretty big for a deer.
Sunday, 31 October 2021
|Greater noctule bat|
At least in the parts of the world with a temperate climate, the great majority of bat species are insectivorous. Of course, there are a number of vegetarian bats, especially in the tropics, including the large fruit bats of the Old World as well as smaller, often fig-eating, species in the Americas. But insect-eating does seem the default, even though there is general agreement these days that bats are more closely related to the larger carnivores and to the hoofed mammals than they are to the other small insectivores, such as shrews and hedgehogs.
From an ecological, trophic web, perspective, insectivores are a type of carnivore - after all, they eat other animals, even if they're small ones. But, when talking about mammals (and similarly sized vertebrates) most researchers tend to draw a distinction between those that hunt invertebrate prey and those that eat comparatively large vertebrates. So there's a distinction between leopards and killer whales on the one hand, and shrews and anteaters on the other.
Sunday, 24 October 2021
Two of these South American groups would outlast the Miocene, only dying out relatively recently. These were the litopterns and the notoungulates, both of which bore most of their weight on the third toe of each foot, and which may, indeed, be related to the group containing the tapirs, horses, and rhinos, which does the same today.