Because sterols are found throughout the eukaryotic family tree, they are thought to have been present in the last common ancestor of all modern eukaryotes.
The importance of embryological characters and of rudimentary organs in classification is intelligible, on the view that a natural arrangement must be genealogical.
His doctoral thesis was on the genealogy of Gall wasps, a subject he tackled with intensity; meticulously collecting over five million samples, measuring hundreds of thousands of specimens.
Still, I'll grant you that sponges are pretty weird as animals go – probably because they branched off very early from the rest of the animal family tree.
Now, on the other side of the decapod family tree, there's Platykotta, just a little older than Eoprosopon at about 200 million years old, from the late Triassic Period.
We're very interested to have the opportunity to CAT scan the skull of Allosaurus because in terms of its position in the family tree of predatory dinosaurs, it was kind of right in the middle.
But instead, genealogists were using location to say, if you want more information, go here in my family tree and here's a link, or here's a folder where I've stored hundreds of photos related to the same thing.