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Sunday, 27 December 2009

Dinosaurs and evolution, 2009

Today:

  1. Are humans still evolving? Absolutely, says new analysis of long-term survey of human health
  2. Ancient Flying Pterosaur Also Sailed Seas (Update)
  3. African Origin Of Anthropoid Primates Called Into Question With New Fossil Discovery
  4. Reptiles stood upright after mass extinction
  5. Tiny T. rex fossil discovery startles scientists
Plesiosaur a victim of shark attack
Bizarre new horned tyrannosaur from Asia described.
Dinosaurs had 'earliest feathers'
A Third of Dinosaur Species Never Existed? - Very interesting article suggesting that dinosaurs went trough morphology changes during their lives which caused part of the fossils to be misinterpreted as new species. It makes sense...Again, it only proves how little we know about dinosaurs.

Are humans still evolving? Absolutely, says new analysis of long-term survey of human health

October 19th, 2009

As part of a working group sponsored by the National Evolutionary Synthesis Center in Durham, NC, the team of researchers decided to find out if natural selection — a major driving force of evolution — is still at work in humans today. The result? hasn't ground to a halt. In fact, we're likely to evolve at roughly the same rates as other living things, findings suggest.

Taking advantage of data collected as part of a 60-year study of more than 2000 North American women in the Framingham Heart Study, the researchers analyzed a handful of traits important to human health. By measuring the effects of these traits on the number of children the women had over their lifetime, the researchers were able to estimate the strength of selection and make short-term predictions about how each trait might evolve in the future.

After adjusting for factors such as education and smoking, their models predict that the descendents of these women will be slightly shorter and heavier, will have lower blood pressure and cholesterol, will have their first child at a younger age, and will reach menopause later in life.

"Humans are currently evolving," said Stearns. "Natural selection is still operating."

The changes may be slow and gradual, but the predicted rates of change are no different from those observed elsewhere in nature, the researchers say. source

My comment: I like how some people are absolutely convinced that there is no evolution to be seen around us and that is the proof that it never existed at all. This is I think the second study I paste here that proved that there is still evolution in humans even if it's harder to notice it, since it's so slow and we're not looking in the right direction. Take that, creationists :)

Ancient Flying Pterosaur Also Sailed Seas (Update)

October 19th, 2009 by John Davis
(PhysOrg.com) -- Tapejara was an excellent flyer that also had an innate nautical knowledge of sailing.

At first glance, the 115-million-year-old pterosaur looks like a Cretaceous design disaster. With a tail rudder on its head and a spindly, bat-like body, Tapejara wellnhoferi may appear fit for nothing but extinction.

However, researchers at Texas Tech University, the University of Kansas and University of Florida have found that the animal’s strange body actually made it a masterpiece of nature’s drawing boards. Not only could it walk and fly, but also it could sail across the sea.

Much like a Transformer, it could manipulate its body to match the same configuration as the world’s fastest modern windsurfers and sail across the surface of the ocean in search of prey. Then, it could take off quickly if the toothy underwater predators of its time got too close for comfort.

Chatterjee and his research team determined Tapejara’s sailing ability by studying the aero-hydrodynamics of pterosaur wings through physics and computer simulation. He will present his findings Oct. 21 at the Geological Society of America’s annual meeting in Portland, Ore.

“Most likely, Tapejara would orient the wings in a fore-and-aft position like that of a sailing boat to exploit upwind sailing. The tilted cranial sail would create a slot effect like a sailboat, which produces a greater lift by improving airflow over the main sails. With the wind coming from ahead and to the side at about a 45-degree angle to the body, Tapejara could achieve speeds exceeding the wind speed. The fastest way to sail is with the wind coming from the side.”

were highly successful flying reptiles that lived 228 to 65 million years ago from the late Triassic Period to the end of the Cretaceous Period. They dominated the sky, swooping over the heads of other dinosaurs. Their sizes ranged from a sparrow to a Cessna plane with a wingspan of 35 feet, he said.

source

My comment: Awesome, huh? I think people are barely starting to understand what life was like when dinosaurs reined on the Earth!

African Origin Of Anthropoid Primates Called Into Question With New Fossil Discovery

ScienceDaily (Sep. 17, 2009)Well-preserved craniodental fossil remains from two primate species have been discovered during excavations at an Algerian site. They reveal that the small primate Algeripithecus, which is 50 million years old and until now was considered as the most ancient African anthropoid, in fact belonged to another group, that of the crown strepsirhines.

This research was carried out by a team of French researchers from the Institut des Sciences de l'Evolution (Université de Montpellier/CNRS), working with Algerian paleontologists from the universities of Tlemcen, Oran and Jijel. The resulting publication reopens the debate on the African origin of anthropoids, the group to which humans and apes belong.

In Egypt, the presence of more than a dozen fossilized anthropoid primates dating from 30 to 38 million years ago had long been known. This recent Franco-Algerian discovery thus advances the first true appearance of anthropoid primates on the African continent by more than 15 million years. With its major consequences on the evolutionary history of African anthropoid primates, this observation further strengthens the alternative hypothesis of an Asiatic origin for anthropoids. Furthermore, this paleontologic research reveals a hitherto unsuspected diversity and great antiquity of the first crown strepsirhines in Africa. source

Reptiles stood upright after mass extinction

September 15th, 2009 (PhysOrg.com) -- Reptiles changed their walking posture from sprawling to upright immediately after the end-Permian mass extinction, the biggest crisis in the history of life that occurred some 250 million years ago and wiped out 90% of all species.

In a detailed study of 460 fossil tracks of reptiles from below and above the boundary, Tai Kubo and Professor Mike Benton from the University of Bristol have found that before the Permian extinction all the reptiles moved with their arms and legs held sideways in a sprawling posture, just like and do today.

After the mass extinction, the medium-sized and large reptiles of the subsequent Triassic period, walked with their legs tucked underneath their bodies, just like modern mammals.

Professor Benton said “Dinosaurs - and later the mammals - owe their success to being upright. An upright animal, like an elephant or a Diplodocus, can also be very large because its weight passes directly through the pillar-like legs to the ground. In addition, other upright animals, such as monkeys, could use their arms for climbing or gathering food.”

Walking upright can have great advantages - it means the stride can be longer and the animal can move with much less stress on the knee and elbow joints. Upright walking was the key to the success of the dinosaurs, which originated 25 million years after the great end-Permian crisis. The first dinosaurs were all bipeds and they also became very large. Sprawlers cannot become too big or their legs collapse.

Up to now, the transition from a sprawling to an upright was seen as long-term, possibly lasting some 20-30 million years, but the new evidence suggests that the event was much more rapid, and was perhaps initiated by the crisis. This new understanding shifts the evolutionary assumptions as well. source
My comment: I don't really understand why this transition was so quick, it doesn't really make sense, but precisely because of that, it is so interesting. And it is the obvious truth that bad things can ultimately lead to good things.

Tiny T. rex fossil discovery startles scientists

September 17, 2009

(CNN) -- A pint-sized version of the Tyrannosaurus rex, with similarly powerful legs, razor-sharp teeth and tiny arms, roamed China some 125 million years ago, said scientists who remain startled by the discovery.

An adult Raptorex was about 9 feet tall and weighed about 150 pounds, scientists say.

The predator, nicknamed Raptorex, lived about 60 million years before the T. rex and was slightly larger than the human male, scientists said.

The findings, to be released Friday in the journal Science, are based on fossilized remains discovered in lake beds in northeastern China. They show a dinosaur with many of the specialized physical features of Tyrannosaurus rex at a fraction of its size.

"The most interesting and important thing about this new fossil is that It is completely unexpected," said Stephen Brusatte, co-author of the article, in a conference call with reporters.

Scientists who have studied the fossilized animal, which was 5 to 6 years old when it died, believe it was an ancestor of the fearsome T. Rex.

Based on estimates of other similar-sized theropods, or "beast-footed" dinosaurs, Sereno and his colleagues estimate an adult Raptorex was about 9 feet tall and weighed about 143 pounds.

By contrast, the Tyrannosaurus rex, which topped the prehistoric food chain until dinosaurs went extinct about 65 million years ago, was believed to weigh at least five tons.

Scientists hypothesize that Raptorex ran its prey down, using its enlarged skull, powerful jaws and sharp teeth to dispatch animals much larger than itself. Like the T. rex, the Raptorex also had tiny forelimbs, they said. source

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