Elaine Meinel Supkis
The discovery and catagorization of many new, ancient species and life forms continues in a great stream. The earliest primates are found in Yellowstone, for example. From gigantic predator birds to a fantastic array of marsupial variations, the past is illuminated: evolution knows no bounds and the very tiny can become giants if the environment is right.
Euroekalert.org: Janet Rettig Emanuel, writer:The origins and earliest branches of primate evolution are clearer and more ancient by 10 million years than previous studies estimated, according to a study featured on the cover of the Jan. 23 print edition of the Proceedings of the National Academy of Sciences.
During the long rule of the dinosaurs who quickly dominated the ecosystems of Pangaea, the mammalians struggled to survive. We still don't wholly understand why, after great extinctions, one group of animals end up dominating most ecological niches. Perhaps this happens mostly when extinctions occur when the various land masses are joined? Certainly, when two landmasses do collide or develop even narrow bridges, species of one usually invade and take over the other continent.
In the case of the greatest extinction, the Permian, the deck was nearly totally swept clean and the struggle to colonize and multiply was won by the saurians who developed the ability to walk on two legs early on. These Thecodonts didn't show signs of walking on hind legs until after the Permian extinction. This event put evolution into racing mode: changes as the survivors coped with a very hostile environment progressed rapidly as nature culled heavily. All large creatures perished. From the unpromising survivors who used little oxygen to keep alive, all the future giants of the Saurian eras descended.
A rough scematic drawing of the evolution of the dinosaurs.
Erickson: Origin of Dinosaurs and Mammals
The question of how and why bipedality evolved has received surprising little ink or attention. Perhaps paleontologists regard the problem as uninteresting or unimportant. But the ubiquity of dinosaur bipeds, contrasted with the rarity of bipeds among other large animals, suggests otherwise. Why did bipedality evolve? What selective advantages did it confer that made it preferable to a four-legged pose? And why was it so common among the dinosaurs?
A very interesting question, well-asked. Indeed, the survivors of the great catastrophe 250 million years ago probably lived very close to each other yet in isolated 'islands' of oxygen-richer environments like deep rift valleys that were below sea level. Namely, even at sea level, the oxygen was too thin to support most higher lifeforms. The world's continents were joined but were now already splitting apart so the joints between South America and Africa were just beginning to split apart and as they did so, as the upwelling magma underneath caused cracks to form and the land to subside, increasingly deep valleys formed and the waters from Africa and South America flowed into this vast, gigantic, the length of most of the planet from north to south, rift valley system. And since the atmosphere is thicker the lower you go in general, this sector was the only place the survivors could live.
And since there was the ability to travel up to 3000 miles from north to south while little reason to go east or west, the competition between developing species was fierce since they were not isolated in small valleys which would have reduced their interactions and we would have seen many more different classes of animals today. Instead, since the continents were still united, the winners of the struggle for survival in the tremendous Africa/South America rift valley, once oxygen levels rose enough to venture above sea level, spread out and took over all the other, smaller ecological niche valleys where the remains of other species that survived the great extinction tried to survive.
The dinosaurs in this great rift valley complex obviously took over the ground as their 'environment' probably right after the Permian disaster. Namely, small therapods that happened to be living in this developing rift, when the big meteorite/comet slammed into Antarctica, triggering the collapse of the entire ecosystem of the earth, they witnessed the sudden death of their tormentors, the various predators who ate them during the Permian. These little, tiny creatures were now Kings of the Earth! On the ground, that is.
They first feasted on the carcasses of all the dying large creatures that collapsed from oxygen starvation. It wasn't cold because no therapod has fur or feathers at this point. They didn't need it, this rift valley was warm! But Therapsids also survived. Or we should say, the therapsids that happened to be very small and living in trees, survived. Perhaps this arboreal life made them evolve scales that turned to fur over the eons because life in the top of trees is very windy, wet and colder than the ground.
Being tree-climbers, the surviving few Therapsids were driven to the ground by the death of many of the forests which were their homes. Indeed, I might suggest that many of the sudden multiplications of new species stemmed from nearly always, scavengers of the dead. This meant, sharp teeth and an ability to fight off other scavengers. I know from my own experience from when a one ton ox died in his stall and we couldn't move his body out except by demolition, we closed off this section and the large predators couldn't get to him but very small scavengers could. And it took them three years to eat everything.
If the Permian fauna died in a great event, the land where the carcasses fell and there was little to no oxygen, they didn't deteriorate rapidly but rather, very slowly. And in the rift valleys, the large creatures probably died not suddenly but slowly, over time. The scavengers who could produce young were also culled: only the swift of foot and small in size, survived.
The swiftest ground dwellers that could rise onto their hind legs to claw at the other scavengers and who could run away from bigger scavengers who were literally gasping for oxygen as they tried to run, meant theropods that could rise on their hind legs and not waste oxygen and energy pumping the front legs too, and I bet, they got better oxygen running on the hind legs just as our lungs work better when we run clutching our arms closer to our bodies. The tree dwellers, our ancestors, came to the ground because the trees died and because that is where the most oxygen was. But their poor hands were made for grasping things, not running fast. Jumping from branch to branch was their business, not kicking and scratching.
The thing people forget when looking at evolution is, when a new base for a species develops due to violent geological events, the survivors are few in number and whatever traits they have kept within their own genetic codes is the only script used in evolving into new species as they flood into new ecological niches. And in the case of mammals, the only ones who survived the great extinction were those who happened to be living in this particular rift valley. All the mammals today evolved from these hardy, small survivors. But the roots of all the major mammalian groups were already established before the Permian extinction. Each radiated into many new species but all were kept underground or arboreal during the dominance of the Theropods for the following 150+ million years. A long time during which they, too, evolved but only in a very limited way, most of the niches being taken over rapidly by the fast-running Theropods who took over the newly-greening landscape as the oxygen levels rose and the highlands became habitable again.
Running animals that can eat low-growing things will colonize new lands faster than tree-dwellers who have to wait for forests to develop, for example. And this is probably why mammals lost this particular race: they were alway coming up in the rear, they literally couldn't run as fast as the hind-leg runners who were the earliest dinosaurs. It got so bad that some dinosaurs evolved the things needed to live in trees, too: feathers that protected from the rain and wind and which also enabled them to compete with the flying Therapsids who could leap from tree to tree.
Now the dinosaurs who ate not just insects but these mammals were in the very tree tops! It is no wonder that all the mammalian species became even smaller as the larger, slower ones were culled. The only safe hours for the fur-animals was at night which they dominated, coming out of various holes in the ground or the tree trunks.
From the Eurekalert article above:
Bloch discovered the new plesiadapiform species, Ignacius clarkforkensis and Dryomomys szalayi, just outside Yellowstone National Park in the Bighorn Basin with co-author Doug Boyer, a graduate student in anatomical sciences at Stony Brook. Previously, based only on skulls and isolated bones, scientists proposed that Ignacius was not an archaic primate, but instead a gliding mammal related to flying lemurs. However, analysis of a more complete and well-preserved skeleton by Bloch and his team altered this idea."These fossil finds from Wyoming show that our earliest primate ancestors were the size of a mouse, ate fruit and lived in the trees," said study leader Jonathan Bloch, a vertebrate paleontology curator at the Florida Museum of Natural History. "It is remarkable to think we are still discovering new fossil species in an area studied by paleontologists for over 100 years."
Researchers previously hypothesized plesiadapiforms as the ancestors of modern primates, but the idea generated strong debate within the primatology community. This study places the origins of Plesiadapiforms in the Paleocene, about 65 (million) to 55 million years ago in the period between the extinction of the dinosaurs and the first appearance of a number of undisputed members of the modern orders of mammals.
Survival isn't pretty. I would assume that the great forests of the Permian--and they were tremendous and covered a lot of the earth--had many, many proto-mammalian animals of a tremendous variety and type. Since we know that they lived in all the continents, nearly uniformly, before the Great Extinction, it is no surprise to see they all were reduced to a very few specimens and of these, many new species evolved. Namely, it wasn't one or two but a long, continuous grouping stretched probably along this rift valley that ran for more than 1,000 miles. So the very first primates were not the same creatures as the first whales or first ungulates, for example. There was a constellation of animals who were already different species even if they were all tree-dwellers, for example. The fact that these earliest primates lived by the hot spot of Yellowstone is most interesting. Did they migrate up there after the oxygen levels rose enough? Was Yellowstone very low so it was an oxygen sink? Did our primates start there and then, as the oxygen levels rose, move down to South America, into the Rift Valley and up into Africa? We are still putting the many puzzle pieces together here!
It would be most interesting if they started off in North America after the destructive collapse of the ecosystems across the whole planet!
BEIJING, Jan. 24 (Xinhuanet) -- A U.S. study on Wednesday suggested a 7-foot-tall prehistoric bird with a monster-size noggin arrived in North America from South America about five million years ago.The flightless, carnivorous terror birds — that's what scientists call them — likely hopped to North America via islands that came to form what is today the Isthmus of Panama, said Bruce MacFadden, a paleontologist at the Florida Museum of Natural History and lead author of the research.
I have raised wild turkeys. They eat anything and indeed, hunt mice, frogs and snakes. They will pull them apart, fighting over them. Seeing a ring of turkeys jumping on a large snake while making quite a racket is something to behold. They will literally trample it to death and then rip it apart, running up and down the mountain side, trying to steal the snake from each other. Quite ferocious. So imagining these guys seven feet tall: very nasty indeed.
The weak spot of all these birds is their eggs: tiny creatures steal them! The dinosaurs solved this problem caused mostly by lizards and mammals by laying lots and lots of eggs. The mammalian solution to bearing young was literally overwhelmed by female Theropods willing to lay a huge abundance of eggs.
today
Palaeontologists digging in northern Australia have found fossil evidence of several new species - including a "killer kangaroo".
The flesh-eating marsupial would have lived between 10 and 20 million years ago, scientists say.The research team has also unearthed evidence of a large carnivorous bird dubbed the "demon duck of doom".
The geological fact that Australia split from Africa and South America in the nick of time meant many non-mammalian, non-dinosaurian animals survived and evolved in isolation which preserved them from the onrush of two-footed saurians chasing down everyone. Climate changes over the last 50 million years plus the fact that Australia is moving northwards at a good clip meant there would be a wild variety of species coming and disappearing without suffering from the competition from the more efficient mammals. The minute the world's nastiest twolegged predator, humans, set foot in Australia, this Garden of Eden came to an abrupt end.
By Steve Connor, Science Editor
Published: 25 January 2007
Zoologists have discovered a new species of squirrel-like mammal, which they have described as a strikingly unusual creature, in the high mountains of Peru.The nocturnal animal looks similar to a squirrel, and is about the same size, but DNA tests have shown that it is more closely related to a family of South American spiny rats, whose fur bristles with spines.
Even as species are being swept away by the tidalwave of human activity, we find ever more species just as they are about to be destroyed, too. This is the tragedy of our times.
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