Boffins find RAT-SIZED bug-muncher links man to beast
But don't you see what that means, you dull-witted animal?
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The missing link between man and beast is a ancient rat-like creature that preceded all placental mammals - a group that encompasses both whales and humans.
Boffins have figured out that primates and dinosaurs did not co-exist, as the mammal ancestors didn't start diversifying into placental mammals (which includes primates) until after the dino extinction event. The finding was made with a cloud-based publicly accessible database called MorphoBank.
"Analysis of this massive dataset shows that placental mammals did not originate during the Mesozoic," said lead author Maureen O’Leary, associate professor at Stony Brook University and a research associate at the American Museum of Natural History.
"Species like rodents and primates did not share the Earth with non-avian dinosaurs but arose from a common ancestor - a small, insect-eating, scampering animal - shortly after the dinosaurs’ demise."
Scientists use two major types of data to figure out evolution: phenomic data - observational traits like anatomy and behaviour - and genomic data in DNA. The new study combines this data in simultaneous analysis.
"Discovering the tree of life is like piecing together a crime scene - it is a story that happened in the past that you can’t repeat,” O’Leary said. “Just like with a crime scene, the new tools of DNA add important information, but so do other physical clues like a body or, in the scientific realm, fossils, and anatomy. Combining all the evidence produces the most informed reconstruction of a past event.”
Some studies have suggested that placental mammals were around in the Late Cretaceous period and then survived the Cretaceous-Paleogene (KPg) extinction. But this analysis puts mammal life 36 million years later and so contradicts the idea that these animals evolved due to the fragmentation of supercontinent Gondwana during the Jurassic and Cretaceous periods.
"Determining how these animals first made it to Africa is now an important research question along with many others that can be addressed using MorphoBank and the phylophenomic tree produced in this study,” said author Fernando Perini, professor at the Minas Gerais Federal University in Brazil.
The full study, "The Placental Mammal Ancestor and the Post-KPg Radiation of Placentals", published in Science, can be read here. ®
COMMENTS
The thing I find most fascinating about evolution
is this: I look at my Dad and see a man similar to myself. Then there's his father - my grandfather, who was a sergeant-major and tank commander in North Africa in WWII. Then his father, who was a coal miner who lived in Wales.
And so on, and so on, following father to father, back through the centuries. Ask yourself this: Who was your direct line ancestor at the time of Shakespeare? Or the time of William the Conqueror? Charlemagne? Julius Caesar? Hammurabi? During the times of each of these historical figures, there existed a man who had a son who had a son which eventually led directly to me. Who was he? What was he like? What did he do with his life? These are questions we've all asked at some point in our lives.
Now keep going back - into the time of the Cro-Magnons, Homo habilis, Homo erectus, and Australopithecus. 3 million years ago, there existed a hominid ape who had a son who had a son which eventually led directly to me.
Finally, as we go back through the millions of years, this patrilineal trail leads to completely non-human creatures - cynodonts like the "ratlike" creature described in the article, reptiles, amphibians, fish, and finally stromatolites and pond slime. Somewhere in Earth's distant past, billions of years ago in the warm salty waters of the Proterozoic, there existed a stromatolite who had an offspring who had an offspring which eventually led directly to me.
I'd love to travel back in time and meet one of these creatures and say to it, "Hi great-something-granddad, how's the nesting these days?" The idea that the vast majority of my lineage, from the first organisms on Earth, is non-human, is something I find absolutely fascinating.
It makes me wonder: At what point did my ancestors "become" human - human enough for, say, a modern woman, to mate with them and conceive a child? Obviously this wouldn't be possible with an australopithecine man-ape, most likely not even with H. erectus or habilis, so at what point would it become possible?
It leads to an interesting paradox; evolution occurs so slowly that, if you can mate with the offspring, you can mate with the parent - yet at some time in the past, there existed an ancestor with whom mating would no longer produce offspring. Where does this "break" occur?
Re: hmmm
Actually, that's the alien symbiote controlling him.
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