...then you learn how to chew.
Scientists studying how early land vertebrates evolved from fishes long thought that the animals developed legs for moving around on land well before their feeding systems and dietary habits changed enough to let them eat a land-based diet, but strong evidence was lacking. Now, for the first time fossil jaw measurements by Philip Anderson at the University of Massachusetts Amherst and others have tested and statistically confirmed this lag.
"This pattern had been hypothesized previously, but not really tested. Now we've done that," Anderson says. He and his team found that the mechanical properties of tetrapod jaws did not show significant adaptations to land-based feeding until some 40 to 80 million years after the four-legged creatures initially came out of the water. Until then, tetrapod jaws were still very fish-like, even though their owners had weight-bearing limbs and the ability to walk on land. Anderson says this finding suggests tetrapods may have shown a limited variety of feeding strategies in the early phases of their evolution on land.
"What it took to really initiate evolutionary changes in the jaw system was for these animals to start eating plants," he says. For the study, published in an early online edition of the journal Integrative and Comparative Biology, Anderson and researchers Matt Friedman of the University of Oxford and Marcello Ruta of the University of Lincoln, U.K., examined images of 89 fossils of early tetrapods and their fish-like forebears. The fossils ranged in age from about 400 to 300 million years old. Anderson and his team were interested in how the jaws of these fossilized animals differed through time.
They used 10 biomechanical metrics to describe jaw differences. One of these, called mechanical advantage, measured how much force an animal can transfer to its bite. Anderson points out that while fossils can't tell you what an animal actually ate, scientists can infer potential feeding behavior from fossilized evidence of biomechanical tools like jaws. The researchers compared jaw features from the fossil record and calculated the rates at which jaws evolved.
"The basic result was that it took a while for these animals to adapt their jaws for a land-based diet," Anderson says. "They stayed essentially fish-like for a long time."
It turns out that just moving into a new environment is not always enough to trigger functional adaptations. In their paper, the authors say the results may be explained by an earlier hypothesis: A shift from gilled to lung breathing in later tetrapod groups was necessary before they could devote their jaw structure to eating plants.
The Moa. Especially the girl moas.
In an environment lacking large mammals, New Zealand's giant moa (Dinornis) evolved to be one of the biggest species of bird ever, with females weighing more than two hundred kilograms -- the same as about 3 average sized men.
Male and female birds often show differences in body size, with males typically being larger. However some birds, like many ratites -- large, flightless species such as emus and cassowaries -- are the opposite, with the females towering over the males.
Moa were huge flightless ratites. Several different species inhabited New Zealand's forests, grasslands and mountains until about 700 years ago. However, the first Polynesian settlers became a moa-hunting culture, and rapidly drove all of these species to extinction.
Dr Samuel Turvey, ZSL Senior Research Fellow and lead author on the paper, says: "We compared patterns of body mass within an evolutionary framework for both extinct and living ratites. Females becoming much larger was an odd side-effect of the scaling up of overall body size in moa.
"A lack of large land mammals -- such as elephants, bison and antelope -- allowed New Zealand's birds to grow in size and fill these empty large herbivore niches. Moa evolved to become truly huge, and this accentuated the existing size differences between males and females as the whole animal scaled up in size over time," Dr Turvey added.
Future research should investigate whether similar scaling relationships can also help to explain the evolution of bizarre structures shown by other now-extinct species, such as the elongated canines of sabretoothed cats.
Televangelist Pat Robertson on Monday explained to his viewers that “sophisticated” Americans received less miracles because they had learned “things that says God isn’t real” like evolution.
On Monday’s episode of CBN’s The 700 Club, Robertson responded to a viewer who wanted to know why “amazing miracles (people raised from the dead, blind eyes open, lame people walking) happen with great frequency in places like Africa, and not here in the USA?”
“People overseas didn’t go to Ivy League schools,” the TV preacher laughed. “We’re so sophisticated, we think we’ve got everything figured out. We know about evolution, we know about Darwin, we know about all these things that says God isn’t real.”
“We have been inundated with skepticism and secularism,” he conintued. “And overseas, they’re simple, humble. You tell ‘em God loves ‘em and they say, ‘Okay, he loves me.’ You say God will do miracles and they say, ‘Okay, we believe him.’”
“And that’s what God’s looking for. That’s why they have miracles.”
I am forever fascinated by human evolution. In the last few years it's got amazingly more complex and interesting with the discovery of Neanderthal and Denisovan DNA in modern human populations.
Popular press articles always seem to either get the facts wrong or misinterpret what they mean. For example, there was a story recently about redating Neanderthal bones in Spain, which indicate that they may have gone extinct there before homo sapiens arrived in the Iberian Peninsula. The conclusion of many articles was that Neanderthals and sapiens could not have interbred, which ignores that Neanderthals and sapiens did actually exchange DNA, as proved by looking at present-day human DNA, and that there have never been any theories that modern human-Neanderthal interbreeding was limited to the Iberian Peninsula. Most theories place interbreeding in the Near East.
When articles came out about a Neanderthal jaw found in Italy, it was announced in the press that this was the first evidence of a sapiens-Neanderthal "lovechild". It wasn't, it isn't and as usual the mainstream press was missing most of what the actual meaning of the discovery is.
Luckily, I recently discovered a blog by John Hawks. He's not as dry as original science papers can be, but sometimes it takes a couple readings to get an understanding around the technical terms. Here is Hawks' article about that Neanderthal jaw. Neanderthals are noted for being pretty chinless, as opposed to modern humans, although you can find plenty of relatively chinless people wandering around the world today.
But the problem with the black-or-white, Neanderthal or sapiens thinking in evolutionary archeology is that it's become quite clear that that dividing line doesn't exist. If modern humans are carrying around Neanderthal DNA it seems pretty likely that Neanderthals were carrying around modern sapiens DNA (modern being the wave of people who came out of Africa around a hundred thousand years ago and settled the world; in other words, us).
Adding to that, some Neanderthal remains discovered in Europe that date back the last 70,000 years have shown signs of "modern" chins.
What does this mean? Is this a sign of sapiens-Neanderthal interbreeding? Maybe. Or maybe Neanderthals were evolving different chins. Or something else. The evidence is not enough to know either. And that's fine. As more evidence comes along, presumptions and theories are shattered or confirmed. That's the way science works.
For around 50 million years, placodonts populated the flat coastal regions of the Tethys Ocean, in modern day Europe and China. The most distinctive feature of these dinosaurs was their teeth: The upper jaw had two rows of flattened teeth -- one on the palate and one on the jawbone -- while the lower jaw only had one set of teeth ideal for crushing shellfish and crustaceans.
The evolutionary origins of these placodonts remained unclear. However, a new find in a 246-million-year-old sediment layer now sheds light on the origin and phylogenetic development of the placodonts. As the Swiss and German team headed by Torsten Scheyer, a paleontologist at the University of Zurich, reveals the skull found in Winterswijk (Netherlands) is the earliest form of all known placodonts. The juvenile animal lived 246 million years ago. At around two centimeters in size, the skull is exceptionally well preserved and its characteristics set it apart from previous placodont discoveries.
The basal-most known placodonts to date have the group's trademark double row of crushing teeth in the upper jaw. The flattened teeth that give these animals their name only appear in more derived placodonts. "Unlike all the other placodonts discovered to date, the Winterswijk specimen has conical, pointed teeth instead of flattened or ball-shaped crushing ones," explains Scheyer, "which means the pointed teeth on the lower jaw slotted precisely into the gap between the palate and upper-jawbone teeth when biting."
The group's trademark double row of teeth in the upper jaw is proof that the new find is actually a placodont. According to the researchers, the teeth of Palatodonta bleekeri, the scientific name given to the Winterswijk specimen, were specialized in gripping and piercing soft prey. "The double row of teeth in the new find combined with its considerable age lead us to conclude that it is a very early placodont, from which the later forms developed," says Scheyer. The formation of crushing teeth and the specialization of a diet of shellfish and crustaceans thus developed later within placodont evolution.
The small Palatodonta bleekeri skull sheds new light on the ongoing debate on where the placodonts originated: Previous finds suggested origins in the shelf sea areas of either present-day China or Europe. Due to the considerable age of the new Dutch find and its basal form, however, the European origin of the placodonts is deemed confirmed. Scheyer and his colleagues are hoping for further exciting finds in Winterswijk to discover more about the evolution of the placodonts.
What constitutes a modern human, a Neanderthal or a Denisovan? Svante Pääbo, the lead DNA detective at the Max Planck Institute for Evolutionary Anthropology, has a new Neanderthal DNA profile from the same cave in Siberia where the Denisovan finger bone was found.
It raises the questions as to whether Denisovans were all that much different from Neanderthals to be separately categorized. Then again, we have lots of people (probably including me) who are carrying around Neanderthal DNA. Are we Neanderthal moderns or moderns? Were Neanderthals homo sapiens?
It's all rather confusing and I think the easy answer is that when you are dealing with a species of billions of individuals that you are going to get a wide variation.
I'm still waiting for my DNA to be decoded, and will dutifully report back when I get some information.
The fossilized remains of a huge prehistoric flying reptile was unveiled Wednesday at the Rio de Janeiro National Museum where an international congress on the extinct species is to be held in May.
“What makes it particularly special is that it is the most complete fossil ever found, with virtually the entire skeleton and even the skull preserved,” said Alexander Kellner, a paleontologist of the Rio Federal University as he presented a life-size mock-up of the pterosaur or “winged lizard.” The creature has a wingspan of 8.2 meters (27 feet).
The fossil, attributed to the “Tropeognathus mesembrinus” species, was found in the Chapada do Araripe plateau of northeastern Brazil.
Kellner described it as “the biggest ever found in the southern hemisphere and the third worldwide.”
“We can prove that these giant reptiles flew in the skies of northeast Brazil much earlier than initially thought because fossils were found in rock formations dating 110 million years,” according to Kellner.
He said it was previously thought that pterosaurs lived at the end of the Cretaceous period, some 72 to 86 million years ago.
Pterosaur species have been found in places like Morocco, Britain, Mongolia, the United States, China and northeastern Brazil.
The latest theory about why the Neanderthals died out is that they had bigger eyes than modern humans.
Although Neanderthals' brains were similar in size to their contemporary modern human counterparts, fresh analysis of fossil data suggests that their brain structure was rather different. Results imply that larger areas of the Neanderthal brain, compared to the modern human brain, were given over to vision and movement and this left less room for the higher level thinking required to form large social groups.
The analysis was conducted by Eiluned Pearce and Professor Robin Dunbar at the University of Oxford and Professor Chris Stringer at the Natural History Museum, London, and is published in the online version of the journal, Proceedings of the Royal Society B. Looking at data from 27,000-75,000-year-old fossils, mostly from Europe and the Near East, they compared the skulls of 32 anatomically modern humans and 13 Neanderthals to examine brain size and organisation. In a subset of these fossils, they found that Neanderthals had significantly larger eye sockets, and therefore eyes, than modern humans.
The researchers calculated the standard size of fossil brains for body mass and visual processing requirements. Once the differences in body and visual system size are taken into account, the researchers were able to compare how much of the brain was left over for other cognitive functions.
Previous research by the Oxford scientists shows that modern humans living at higher latitudes evolved bigger vision areas in the brain to cope with the low light levels. This latest study builds on that research, suggesting that Neanderthals probably had larger eyes than contemporary humans because they evolved in Europe, whereas contemporary humans had only recently emerged from lower latitude Africa.
'Since Neanderthals evolved at higher latitudes and also have bigger bodies than modern humans, more of the Neanderthal brain would have been dedicated to vision and body control, leaving less brain to deal with other functions like social networking,' explains lead author Eiluned Pearce from the Institute of Cognitive and Evolutionary Anthropology at the University of Oxford.
'Smaller social groups might have made Neanderthals less able to cope with the difficulties of their harsh Eurasian environments because they would have had fewer friends to help them out in times of need. Overall, differences in brain organisation and social cognition may go a long way towards explaining why Neanderthals went extinct whereas modern humans survived.'
'The large brains of Neanderthals have been a source of debate from the time of the first fossil discoveries of this group, but getting any real idea of the "quality" of their brains has been very problematic,' says Professor Chris Stringer, Research Leader in Human Origins at the Natural History Museum and co-author on the paper. 'Hence discussion has centred on their material culture and supposed way of life as indirect signs of the level of complexity of their brains in comparison with ours.
'Our study provides a more direct approach by estimating how much of their brain was allocated to cognitive functions, including the regulation of social group size; a smaller size for the latter would have had implications for their level of social complexity and their ability to create, conserve and build on innovations.'
Professor Robin Dunbar observes: 'Having less brain available to manage the social world has profound implications for the Neanderthals' ability to maintain extended trading networks, and are likely also to have resulted in less well developed material culture -- which, between them, may have left them more exposed than modern humans when facing the ecological challenges of the Ice Ages.'
The relationship between absolute brain size and higher cognitive abilities has long been controversial, and this new study could explain why Neanderthal culture appears less developed than that of early modern humans, for example in relation to symbolism, ornamentation and art.