I have been reading a lot of Darren Naish's Tetrapod zoology blog. Its fascinating and I have learnt loads from reading it. Especially because it bought to my attention a series of rather unusual ideas on evolution proposed by scientists in the past that clearly are not very well known and are not supported by the fossil record.
Firstly I will cover the theory of initial bipedalism. This idea proposes that the human form is the most basal for all vertebrates and that all modern vertebrates are descended from a foetus like creature called a marine homonculus. This little creature floated around with its gas filled head and possessed gills and the ability to breath air. Eventually this critter came on to land and colonized it in all sorts of ways. Some returned to the water to become fish. Others evolved into quadrupedal reptiles, mammals and amphibians on land. Whales are a highly evolved form of marine homonculus and are allegedly; like humans, among the least derived vertebrates. Apes are apparently humanoids that have recently evolved a quadrupedal stance. This is of course a lot to take in. But there is no evidence supporting these ideas and the fossil record blatantly contradicts this. For a start there is not fossil evidence to suggest that the marine homonculus ever existed. Whale fossils show a clear sequence of evolution from a terrestrial artiodactyl. Humans appeared after the first apes, not before. The list goes on. And the theory would require a ghost lineage of humanoids extending back about 500 million years. Clearly the theory is not very likely to be true. Its a shame because it is a pretty cool idea.
I believe that the idea stemmed from the fact that humans have a lot of aquatic characteristics including hairlessness, the ability to voluntarily hold our breath, vestigial webs in between digits and other features. A slightly less radical theory used to explain these features is the aquatic ape hypothesis which suggests that our early hominid ancestors may have become adapted to living in the water during the Miocene epoch and that they became bipedal when wading in shallow water. These apes than came back on to land and retained their bipedality, eventually evolving in to humans. When modern chimpanzee apes take to the water they take a bipedal stance. The buoyancy from the water allows them to do this and this may also be the way that our ape ancestors learnt to walk on 2 legs. I remember reading somewhere about a hypothetical creature called a sea ape. This allegedly lived on shorelines foraging for food in the shallows and walking on 2 legs.
Now on to the haematotherm hypothesis. This states that birds and mammals are sister taxa. In other words birds and mammals are each others closest relatives. This is based mainly on the fact that both have skin covered in filamentous integumentary structures and warm bloodedness, as well as a few other characteristics. So you can forget about all of those feathered gliding non avian dinosaurs and Jurassic Cynodonts and instead think about something like an arboreal wingless bat out of hell. Yes ladies and gents. I present the Haematotherm. A hypothetical missing link between birds and mammals. I could go in to loads of detail about the historical background on this thing, but I really don't have the time. For more type it in to google and find Tetrapod Zoology's take on the idea.
Finally my favorite idea; that dinosaurs evolved intelligence; a civilization which then destroyed itself due to nuclear war or environmental destruction causing the KT extinction 65 million years ago. First to propose the idea was John McLoughlin in his article "Evolutionary bio paranoia" published in Animal kingdom magazine in 1984. This proposes that civilizations are very short lived due to the ecological and weapon destruction that they cause and that they would therefore appear very briefly in the geological timescale (Human civilization is almost certainly on the verge of self destruction. With the discovery and invention of nuclear weapons, an unsustainable population and ecological destruction we don't have much more time, and we have only been a global civilization for about 300 years or so.). McLoughlin proposed a hypothetical intelligent Dromaeosaur. McLoughlin's beast has a tail and a horizontal back and is generally what I would expect an intelligent dinosaur to look like.
A book published in 1993 called "Who lies sleeping?" by Mike Magee suggests a similar idea. He thinks that the intelligent dinosaurs (Anthroposaurus sapiens) caused severe pollution in the industrial period that occurred in the late Maastrichtian period. This is suggested by the rise in iridium, global temperature, acid rain and so on. He suggests that the Lambeosaurine crests and Ankylosaur nose tribunals were adaptations to cope with a toxic atmosphere created by the industrial waste of the Anthraposaurs. Finally the Anthraposaurus finished itself off with a nuclear war. Evidence interpreted by some as suggesting a meteor impact may, in Mikes view, suggest nuclear explosions instead. These explosions evidently wiped out the dinosaurs 65 million years ago.
To expand on the intelligent dino hypothesis the title of the book suggests something about the Anthraposaurs sleeping or lying in wait. Perhaps he believes that these animals are hibernating until conditions improve. This idea reminds me of some old Doctor Who episodes where creatures called Silurians and Sea Devils (former civilized reptilian rulers of the earth) awaken from a slumber lasting millions of years only to find their world dominated by "stinking apes" aka Homo sapiens. It is possible that these episodes, broadcasted in the 1970's and 80's, were the inspiration for Mike's ideas.
At the end of the day the idea is not supported by fossil evidence. If there was a former civilization on earth I think we would know, or do we already? Could the whole thing be covered up to prevent world panick as to the indication of our own fate. Who knows?
Tertapod zoology : How intelligent dinosaurs conquered the world
Posted on: March 24, 2008 8:05 AM, by Darren Naish
Goodbye from the stem-haematotherm, goodbye from me
Posted on: March 6, 2008 6:07 AM, by Darren Naish
Aquatic proto-people and the theory hypothesis of initial bipedalism
Posted on: March 17, 2008 4:34 AM, by Darren Naish