This is another of the illustrations I did for Don Prothero's book,"Evolution, What the Fossils Say and Why It Matters". The caption in the book reads... "The transformation from primitive synapsids like Ophiacodon and the fin-backed Dimetrodon to the predatory gorgonopsians to the weasel-like Thrinaxodon and finally to true mammals is one of the best transitional series in the entire fossil record."
The fossils of these animals were found and this transition took place from the early Permian period through the Paleozoic/Mesozoic extinctions to the Triassic.
Thylacine Dingo Comparison
Although we talk all the time of the incredible diversity of life on our planet, that diversity is really an amazing amount of variation on a relatively very few themes.
Here we have a recently extinct, marsupial Thylacine (3.) and its ecological equivalent (and replacement in Australia), the Dingo, a placental canine carnivore. These mammals have had separate evolutionary histories since at least the early Cretaceous. Both are the descendants of little insectivorous creatures that lived in the shadow of the dinosaurs. So are aardvarks and elephants, but in this case both these creatures evolved to do the same ecological task. And apparently the best functional form for a cursorial mammalian predator is “doggish”.
Seems that Carl doesn't have a change to update much, but he keeps a fabulous blog called "Dealing with the Beasts" under the pen name Olduvai George. Don't miss his flickr photostream.
- Found Carl via Visualizing Evolution.