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I did not realize at the beginning of the week how exciting it would be. It all started when Will Baird at The Dragon’s Tales linked to me, and then a link from Laelaps, and suddenly I shot from 0-5 page views per day to 100, then 130, then 190! I wanted to strike while the iron was hot so I ramped up my posting frequency this week. It’s not so easy! I feel like Mr. de Worde in Terry Pratchett’s The Truth (which you should all go out and buy):
The press waited. It looked now like a great big beast. Soon he’d throw a lot of words into it. And in a few hours it would be hungry again, as if those words had never happened. You could feed it, but you could never fill it up.
WHENEVER A BABY is born, there are always the inevitable discussions of which parent the baby resembles, whose ears he got, and where that nose came from. However, the father is usually the winner–babies are usually said to look most like the father, and even the mother will usually deny resemblance to herself in preference of the father. Why is this?
SINCE I STARTED this blog I have received an increasing number of hits from search engines. Unsurprisingly, one of the topics funneling people this way is the Nimravidae. My entry on the Dinictis skull replica found at Bone Clones has received the most hits overall since I started this blog. Unfortunately, there is not really much information about nimravids available without some digging, and very little on the open web. So here I will pull together everything I can currently get my hands on!
I MENTIONED in a recent post that 75% of all of the types of mammals that have ever lived are now extinct. We have a tendency to think of extant organisms as all there is. We know dinosaurs once lived and are now extinct, but you’d be hard-pressed to get the average person to name one major extinct non-dinosaurian group. Yet we don’t have to look very far into our own past to find many of them.
I RECENTLY REVIEWED some of the advantages and disadvantages of sexual and asexual reproduction. Sexual reproduction is thought to be chiefly useful in the elimination of negative mutations, while these build up in asexually reproducing lineages. Without some type of genetic recombination it is thought that asexual reproduction will lead eventually to extinction.
YESTERDAY I posted about the evolution of mammals from synapsids, which definitely were not “mammal-like reptiles”! Long before the mammals appeared the therapsids descended from basal synapsids. These animals were highly successful during the Permian, and if they had not been almost eradicated by the Permian-Triassic extinction the dinosaurs might never have had their chance at preeminence. Blogger Will Baird, who dropped by to read that article, has published on his blog an excellent overview of the gorgonopsids, a group of robust carnivorous therapsids.
You can read more about the gorgonopsids and other therapsids in Gorgon: Paleontology, Obsession, and the Greatest Catastrophe in Earth’s History. While Ward unfortunately does spend more time talking about himself than I’d like, he also devotes a lot of time to these carnivores, the alien ecosystem they inhabited, and the catastrophe that brought about their extinction.
I RECENTLY READ a paleontology book that irked me by referring to the basal synapsids as “mammal-like reptiles”. This term pre-dates modern phylogenetics. It violates several rules of phylogenetics, the first being that all clades (groups of related organisms) should contain organisms sharing a single common ancestor in that clade, and the second being that clades should nest within each other, so that each more recent clade fits into its ancestors’ clades as well. In other words, clades should not be polyphyletic, but monophyletic. An example of a polyphyletic group is the pachydermata, an obsolete category containing elephants, hippopotami, rhinoceri, horses, tapirs, and pigs simply on the basis that these organisms have thick skin and hooves. Now these animals are placed into separate clades since they do not share a recent common ancestor. Polyphyletic groups are a great embarrassment to phylogenicists.
ON FEBRUARY 8 my blog had its best day ever, as upwards of a dozen (!!) viewers flocked to my page on sexual and asexual reproduction. Interestingly, most of the traffic was from tag surfers tracking the tag “sex”. I have reached the obvious conclusion that to draw more traffic, I need to sex up my blog. So kick the kids out of the room and continue to the explicit!! photograph below the break.
AMONG EUKARYOTES, sexual reproduction is more common than asexual reproduction, and often organisms that reproduce asexually also have a supplementary means of sexual reproduction. While sexual reproduction does have some drawbacks, it appears that in general the benefits outweigh these.