Author Topic: Halbred's Paleo-News Thread  (Read 118326 times)

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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #200 on: April 30, 2010, 06:10:09 PM »
Well, that's certainly true. Current theory for the avian bottleneck is that ornithurine birds diverged from their enantiornithine contemporaries by filling freshwater niches. This is the same environment that crocs and turtles survived in, so they may have made it through because they were occupying a more favorable environment. I'm unaware--of the top of my head--of any wading/waterbird enantiornithines, although that group WAS ridiculously diverse.

But yeah. All of the currently-known Cretaceous ornithurine birds are fairly similar to waterbirds today and probably resembled ducks and geese to some extent.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #201 on: May 06, 2010, 01:54:53 PM »
New episode of Dinorama is up. It flows better than the first episode, but there are still some technical issues holding us back. Enjoy!
 
http://www.dinorama.net/podcasts/Dinorama_podcast_0002-Shark_bites.mp3
 
Also, this is very important: turns out we DO share some genes with neanderthals through interbreeding. Read the easy-to-digest story here:
 
http://johnhawks.net/weblog/reviews/neandertals/neandertal_dna/neandertals-live-genome-sequencing-2010.html
« Last Edit: May 06, 2010, 04:09:46 PM by Halbred »
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #202 on: May 12, 2010, 03:44:29 PM »
More news: Through gene insertion, scientists have discovered another mechanism for how mammoths stayed warm in the cold: their blood contained an antifreeze agent, allowing oxygen to be pumped efficiently through the body even at very low temperatures. Hooray for splicing genes into E. coli!
 
Also, an abelisaurid theropod was described based on a very partial skeleton (Austrocheirus) that has an unreduced forelimb--a first for the group. Not only does this make Austrocheirus very basal within Abelisauroidea, it also means that Limusaurus' hand probably isn't relevant to the frame-shift discussion that I talked about several pages ago...I think.
 
Finally, this isn't new (it's from 2006) but I just learned about it. Three authors reconstructed the soft tissue of the muzzles of five ground sloths, among them Megatherium, Glossotherium, and Scelidotherium. They found that ground sloths have very large, mobile lips and (probably) long muscular tongues. Furthermore, the five sloths differ in terms of how wide the lips are, implying some degree of niche partitioning among ground sloths. Some were very selective feeders, while others ate anything they could get their giant lips around.
 
The sloth paper is very interesting and applies well to paleo-art. If anyone wants a copy of any of these papers (I recommend the sloth one!), just give me a holler.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #203 on: May 26, 2010, 11:05:07 PM »
An animal from early Cambrian may represent the earliest known cephalopod (squid, octoupus, etc) by 30 million years.  The animal, Nectocaris pteryx, had previously been problematic because the one fossil found was small, poorly-preserved, and had a strange combination of features (which is not uncommon for pre-cambrian and cambrian fossils, unfortunately). This made it impossible to reconstruct, not to mention definitively place relative to modern creatures.  However a huge group of samples, 91, have been recently found in the Burgess Shale, painting a much clearer picture of the creature and, the authors conclude, making it most likely an early cephalod. 

It had a pair of tentacles, a pair of fins, a siphon, and camera eyes (like the eyes found in modern cephalodos and chordates like us, but not like the compound eyes typically found in arthropods).  It also, interestingly, had no hard shell, which (according to the article) people assumed the earliest cephalopods possessed (due to the earliest cephalopods up to this point being similar to the modern shelled nautilus, and the fact that most other molluscs have shells).  It also had other internal similarities to modern cephalopods.  In short it looked very much like a two-tentacled squid or, strangely, superficially like an Anomalocaridid (although it differs significantly in many details).  However, it is fairly small, only 4cm long.  It is unclear whether the two-tentacle or shell-less nature of creature is the ancestral state of all cephalopods are are specializations in this early sub-group, but other traits of the creature are found in other cephalopods.  Unfortunately the mouthparts were not preserved, which are critical because there are mouth features found in all molluscs but only in molluscs that would definitively identify it as one.

 

http://www.nature.com/nature/journal/v465/n7297/full/nature09068.html
http://blogs.discovermagazine.com/notrocketscience/2010/05/26/nectocaris-mystery-fossil-was-actually-a-500-million-year-old-squid-relative/

You can find a description of it prior to this discovery, and an earlier reconstruction based on the one poor sample, here:
http://www.burgess-shale.bc.ca/discover/ancient-creatures/nectocaris
The armored headpiece is actually the funnel, which was crushed and flattened against the head in the original fossil.
« Last Edit: May 26, 2010, 11:22:05 PM by TheBlackCat »
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #204 on: May 31, 2010, 03:02:46 PM »
Wow, that's awesome. I just got back from a week-long trip, so I'm behind on my paleo-news. I didn't have access to my email, either. I just checked it, and I found a ton of papers that friends sent me. I'll be catching up for the next few days!
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Offline Kytim89

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Re: Halbred's Paleo-News Thread
« Reply #205 on: May 31, 2010, 05:00:03 PM »
Wow, that's awesome. I just got back from a week-long trip, so I'm behind on my paleo-news. I didn't have access to my email, either. I just checked it, and I found a ton of papers that friends sent me. I'll be catching up for the next few days!

What can you tell me abouut the Solutrean solution?
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #206 on: June 04, 2010, 03:07:45 PM »
I don't know what that is, Kytim.
 
Stories digested! On May 28th, Indiana University Press finally published New Perspectives on Horned Dinosaurs, the lengthest treatment on the group since Hatcher's monograph from the early 1900's: http://books.google.com/books?id=HbsQAAAAIAAJ&printsec=frontcover&dq=Ceratopsia&cd=1#v=onepage&q&f=false
 
I'm eagerly awaiting my copy to arrive on my doorstep. In the meantime, I can tell you the stories that the interwebs have been abuzz about. These are some very interesting critters. First up: Diabloceratops, a basal centrosaurine from Utah. It's a big animal, and wierd, too. It has good-sized brow horns, a very small nasal horn atop a big snout, and a surprisingly narrow frill with large parietal fenestrae and two recurved spikes growing out of the dorsal margins. Click this link for a good picture of the skull: http://archosaurmusings.files.wordpress.com/2010/05/lc-ceratopsian-side-vw-email.jpg.
 
Next up is Coahuilaceratops, from Mexico. It looks to be related to Chasmosaurus and Ajugaceratops, but it has extremely thick, four-foot-long brow horns. It is the first horned dinosaur known from Mexico. Here's a great life restoration (by my favorite paleo-artist, Lukas Panzarin) and a map of the skull bones: http://palaeoblog.blogspot.com/2010/05/coahuilaceratops-first-horned-dinosaur.html.
 
Finally, there's Rubeosaurus, who looks like a leveled-up Styracosaurus. I'm not sure where it was found or how much the skull is known, but here's another Lukas Panzarin mock-up:
http://1.bp.blogspot.com/_6fVePgcYTJc/TACx52ObjkI/AAAAAAAAC2w/6-7LdEWffG0/s1600/coahuilaceratops+%26+rubeosaurus.jpg
 
But it hasn't all been from books. Two new journal articles have named ceratopsian dinosaurs, too. First, a fragmentary skull (not worth posting) turned up in Hungary: Ajkaceratops is a bagaceratopsid, which is more or less related to Protoceratops (but without a big frill). It is the first ceratopsid from Europe, which was an island archipelago during the Cretaceous. It must have gotten there by island-hopping from Asia.
 
Finally, there's Sinoceratops from China, the first membe of the Ceratopsidae to turn up there. It's a basal centrosaurine. The authors suggest that Sinoceratops provides evidence that the big-bodied horned dinosaurs originated in Asia and migrated to North America, but it could be just as likely that they originated in North America and this one genus migrated back to Asia. At any rate, it's a spectacular discovery. I can't wait to see if more ceratopsians turn up there. Here's a picture of the holotype skull (there is referred material, too). The skull is pointing right, and the hole is the orbit (eye socket). The bottom two images are the dorsal margin of the frill.
http://2.bp.blogspot.com/_m6sVhskT_Fs/S_-VOIU8CqI/AAAAAAAAE0s/Fa4PQVRPj1U/s1600/sino.jpg
 
OH I CAN'T WAIT TO GET THE BOOK!
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Offline Stratos

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Re: Halbred's Paleo-News Thread
« Reply #207 on: June 04, 2010, 11:12:28 PM »
Diabloceratops makes me think of the Diablos from Monster Hunter. Though they look completely different. More of the Monster hunter creatures need to look like dinosaurs.

Wow, that's awesome. I just got back from a week-long trip, so I'm behind on my paleo-news. I didn't have access to my email, either. I just checked it, and I found a ton of papers that friends sent me. I'll be catching up for the next few days!

What can you tell me abouut the Solutrean solution?

Here's an article on it I found online. Sounds like its a few years later than Halbred's specialty area. ;)

Quote
The Solutrean Solution--Did Some Ancient Americans Come from Europe?
by Dennis Stanford and Bruce Bradley

For half a century, archaeologists have assumed that ancestors of the Clovis people - long considered the first Americans - crossed the Bering Land Bridge from northeast Asia some 14,000 calendar years ago, then spread southward across the continent. But there is something wrong with that picture.

Years of research in eastern Asia and Alaska have produced little evidence of any historical or technological connection between the Asian Paleolithic (Stone Age) and Clovis peoples. Also, the southeastern United States has produced more Clovis sites than the West, and a few radiocarbon dates suggest some of them may predate those in the western states. If correct, that hardly fits the notion that Clovis technology originated in northeast Asia or Alaska.

Over the years, various scholars have noted similarities between Clovis projectile points and "Solutrean" points, the product of a Paleolithic culture on the north coast of Spain between 22,000 and 16,500 years ago. Little credence has been given to suggestions of a direct connection between these technologies because of the 4,500-year time gap between the last of Solutrean and the first of Clovis, and because of doubts that people of the Upper Paleolithic could navigate the Atlantic Ocean.

But indirect evidence for Paleolithic ocean travel has been mounting. Although no boats have been found, we now know that by at least 40,000 years ago, watercraft carried a founding population to Australia. By 28,000 years ago, flintknappers were collecting raw materials from islands far off the Japanese coast. And closer to Spain, Paleolithic peoples inhabited some of the Mediterranean islands at least 14,000 years ago.

Solutrean peoples could have used this knowledge of watercraft to travel and exploit marine resources, which would have been especially important during the last glacial maximum, about 18,000 years ago, when most of Europe was covered with ice and competition for diminishing land resources must have been intense. Given these facts, we believe the hypothesis of a western Old World ancestry for Clovis should be reconsidered.

To determine whether the idea was worth additional study, we examined archaeological collections in Spain, France, and Portugal, looking for technological affinities between the European Upper Paleolithic and Clovis. Our cursory examination revealed an amazing correspondence between Solutrean and Clovis; in fact, Solutrean has more in common with Clovis than with Paleolithic technologies that followed it in Europe.

Solutrean and Clovis flintknappers used nearly identical stoneworking technologies. We observed a high degree of correspondence between stone and bone tools, as well as engraved limestone tablets, and caching of extra large bifaces and other tool stock. The Solutrean toolkit is, with a few exceptions, nearly identical to that of Clovis. Although some of the Solutrean concave-base projectile points are heavily thinned, none that we saw exhibited a well-developed Clovis-style flute. Clovis assemblages lack shouldered points and the Solutrean laurel-leaf knife.

A Solutrean origin for the Clovis culture seems a more parsimonious explanation of the evidence than an Asian ancestry. Certainly, if Solutrean industries were found in Siberia, no one would question their historical relationship with Clovis.
The ultimate test of this hypothesis may be found in genetic research on ancient human remains. Michael Brown and colleagues reported in 1998 that mitochrondrial-DNA haplogroup X (a genetic marker of population groups) is found in low frequencies in both European and Native American populations, but not among Asians. This indicated to them that some of the American founders may have come from Europe between 36,000 and 12,000 years ago.

Regardless of whether a Solutrean-Clovis link is eventually proven, exploring this hypothesis should increase our understanding of the development of technological innovations and broaden our knowledge of early peoples of the New World
________________________________________
When this article first appeared in Discovering Archaeology, DENNIS STANFORD is Chairman of the Anthropology Department at the National Museum of Natural History, Smithsonian Institution.
BRUCE BRADLEY is President of Primitive Tech Enterprises, Inc., in Cortez, Colorado, and Adjunct Professor at Augustana College in Sioux Falls, South Dakota.


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« Last Edit: June 04, 2010, 11:14:23 PM by Stratos »
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #208 on: June 05, 2010, 01:15:36 AM »
It is not impossible, but I would call it far from parsimonious.  For one thing, we know similar technologies have appeared independently.  Secondly, we have no other instances of advanced ocean-going in the west until around 3,000 B.C.E.   at the earliest when we see trade between Crete and Near East, and even those handling the relatively tiny distances and much calmer weather of the Eastern Mediterranean was difficult.  There was more advanced ocean-going ships in the far East, but even there widespread ocean travel did not happen until around that time.

So in order to accept that hypothesis would require ship-building technology that was somehow lost and not seen again for about 10,000 years. 

Add to that the question of why they only ended up in North America.  That makes a lot of sense if we assume a southward migration over land, but if we assume there was a culture that had advanced enough ships to cross the entire Atlantic Ocean it makes far less sense.  The first to make the trip that we know of were Norse, but that was not until 1,000 AD and even with the technology of the day they still island-hopped from Iceland to Greenland to the Islands of Newfoundland in what is now Canada.  That trip would have been practically impossible because all of those areas were covered with ice.  The very pressures that the article claim would have prompted them to move would also have posed a practically impassible barrier to such movements. 

You could claim they went south, but that leads to its own problems.  For instance if they went south you would expect signs of the Clovis culture to appear in South America prior to North America, and Appear in Western Africa and particularly the Canary Islands before that.  They also would have easily colonized more remote Mediterranean Islands that were not inhabited until much later.  It doesn't really make much sense that they would skip over unpopulated, resource-rich, war, relatively safe and sheltered islands just to travel across the ocean with no sign of there being anywhere they could end up.  This isn't like the south Pacific where there are lots of islands and thus a reasonable expectation of finding more.

So although I think all in all they need a lot more than some similarities in arrowhead styles to prove a link.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #209 on: June 05, 2010, 02:27:58 AM »
Yeah, I am familiar with this theory. I don't really buy it. Like Blackcat says, the evidence is almost entirely based on arrowheads. I'd want to see other archaeological similarities before I come to any kind of informed conclusion.

Also, who cares? Did you see all those awesome horned dinosaurs?!? :-P
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Offline Kytim89

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Re: Halbred's Paleo-News Thread
« Reply #210 on: June 06, 2010, 06:23:59 PM »
Here is an article about the Solutrean Solution that I wrote for my history class:
 
Arguing Against the Clovis Theory

            Imagine yourself as a prehistoric hunter during the last ice age, known as the Pleistocene, which occurred about 20,000 years ago. Your main food source consists of mega fauna such as the woolly mammoth, species of bison, tapir, and several other animals that eventually went extinct.   Due to climatological factors, a giant ice shelf that once blocked your path is now open for you to travel through to follow herds of game. Eventually you come to a new area where after several generations your descendants have populated the entire continent. Archeologists have come to call these people the Clovis culture and since the 1930s many believed that these were the ancestors to modern day Amerindians and the first inhabitants of the new world after several spear points were discovered in Clovis, New Mexico. However, there has been much opposition to the notion of the Clovis hunters being the progenitor of modern Amerindians, most of it is controversial to this day because it postulates that the Clovis people were not the first inhabitants of the new world and that earlier people existed before they came along.  According to James Dixon, author of Coastal Navigators: the First Americans May Have Come by Water, “A growing body of evidence indicates that the pathway between the great glaciers of the last Ice Age was closed—in fact, the way south may have been blocked until centuries after the dawn of Clovis.”(34) Contrary to the popularity of the Clovis defenders theories about the peopling of the Americas, there are several alternative arrival hypotheses to their claims that will disprove the notion of the Clovis culture being the first people to the Americas. 
            One alternative arrival hypothesis that could be used to counter the theory of Clovis Culture is the idea that the first inhabitants may have come to the Americas via the surrounding oceans. “Some researchers believe humans may have crossed the vast expanse of the Pacific and colonized South America before anyone reached North America. Support for this theory is based on sites such Monte Verde in southern Chile and Tiama –Tiama in northern Venezuela, which may be older that the oldest sites in North America. Biological evidence suggests some of the earliest skeletons in South America may share similarities with inhabitants of Polynesia and Australia.” (Dixon 34) What is interesting about these two sites is the fact that they are located near the ocean, they are coastal sites and in other words, they were left wide open for any sea going peoples to reach and use as a hub for establishing some form of civilization. It has been proven that Aborigines of Australia had reached that country at about 60,000 years ago, well enough time for them to spread across the country and eventually sea fare their way to South America and establish a significant presence on the continent long before the supposed Clovis culture had dawned in North America. However, the inhabitants of the land bridge called Beringia in the Bering Strait may have traveled down the pacific coast via boats to North America during the last ice age, but there is still little evidence for this point of view to be accepted because the sea levels have raised enough since the last ice age to cover up any evidence of coastal to make any credible guess as how they settled in the Americas.
            A second alternative arrival hypothesis is the so called Solutrean solution.  The Solutrean solution postulates the Clovis people learned their stone making techniques from a group of prehistoric Europeans that inhabited the Iberian Peninsula called the “Solutreans” who may have reached North America by traveling along the ice sheets of the North Atlantic Ocean. Dennis Stanford and Bruce Bradley, authors of The Solutrean Solution:Did Some Anchient Americans come  from Europe? Say, “Our cursory examination revealed an amazing correspondence between Solutrean and Clovis, in fact, Solutrean has more in common with Clovis than with the Paleolithic technologies that followed it in Europe.” So, some of the European migrated to the Americas and must have passed on their stone working techniques to the Clovis people.  Although the Solutrean Solution is a controversial theory in regards to the first people to the Americas, there is proof in the genes of some modern day Amerindians.  “The ultimate test of this hypothesis may be found in the genetic research on ancient human remains. Michael Brown colleagues reported in 1998 that mitochondrial DNA haplogroup X(a genetic marker of population groups) is found in low frequencies in both Europeans and Native American populations, but not among Asians. This indicated to them that some of the American founders may have come from Europe between 36,000 and 12,000 years ago.” (Stanford and Bradley 55) Although the Solutrean Solution has not been officially proven, the fact that some Amerindians share a haplography that is exclusively found only in Europeans, the presence of halo group X in low frequencies of Amerindian populations proves that the Europeans had a place in the founding of the Americas.
            The third and final alternative arrival hypothesis is the genetic and linguistic evidence of the South American continent. Micael B. Collins, author of Clovis Second: Time is Running Out for an Old Paradigm, says about the genetic evidence, “And the earliest human skeletal remains in the Americas do not have the Mongoloid traits that would be expected for a people who came from Siberia.”(50) The Clovis defenders have postulated that the Clovis people traveled from Siberia in Asia, crossed the Bering Strait land bridge and after several thousand years populated the Americas. However, the fact that skeletal remains much older than the Clovis must shine light on the possibility that the Clovis defenders defensive stance on the topic may be in vain. But, we must also include the linguistic, or language, of the peoples of the region. “Linguist cannot account for the great diversity found among Native American languages in the limited time afforded by the Clovis model.”(Collins 51) Apparently the Clovis people did not have enough time in the Americas to establish a language that would be carried down by their descendants, so, in a sense; some people must have existed before Clovis arrived   and their language must have diversified long before the dawn of Clovis culture.
             In conclusion, no matter what you stance on the topic of how the Americas became populated, one thing must be kept in mind, which is time. In the words of Jack L. Hofman, author of The Clovis Hunters, “Once thought to span thousands of years, the Clovis era is now dated to a few hundred, roughly from 11,400 to 10, 900 radiocarbon years.”(43) In my own mind, I don’t follow the Clovis theory because my own hunch about the topic figures that sources of human settlement in the Americas came from several different sources that ranged from the Australian Aborigines, Asians, Europeans, and possibly African and that these people eventually crossed genetically, culturally and technologically over a period of time and once the spigot turned off for their migration from their source to the new world, they eventually developed their own identity which carried onto today’s native populations of North, Central and South America via genetic drift. However, like any other part of history, there are those who accept a theory and those who oppose it. Therefore, regardless of whether the Clovis theory is accepted or not, the battle for which the earliest inhabitants of the new world were may go on forever.
   
 
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #211 on: June 06, 2010, 09:47:26 PM »
It has been proven that Aborigines of Australia had reached that country at about 60,000 years ago, well enough time for them to spread across the country and eventually sea fare their way to South America and establish a significant presence on the continent long before the supposed Clovis culture had dawned in North America.
Travelling the fairly short distance from island to island from southeast Asia to Australia is trivial matter compared to colonizing the much wider-scattered islands of the South Pacific, which didn't happen until fairly recently, and that is nothing compared to covering over half the pacific in one shot.  It would require ship-building technology that far exceeds even that of Rome, Greece, or the Polynesians, not to mention people living 15,000 years ago, and then have that technology completely forgotten with no trace of evidence left for about 10,000 years.  Also, if this was true you would expect islands in the Eastern pacific like the Galapagos to have similar artifacts, which I don't think is the case.

However, the inhabitants of the land bridge called Beringia in the Bering Strait may have traveled down the pacific coast via boats to North America during the last ice age, but there is still little evidence for this point of view to be accepted because the sea levels have raised enough since the last ice age to cover up any evidence of coastal to make any credible guess as how they settled in the Americas.
This is by far the most plausible.  It requires only very simple ships traveling very short distances following prey.  I find it amusing though that the author considers this hypothesis to be the only one that has "little evidence", despite the fact that it doesn't require any technology beyond what we know people at the time possessed and there is no less evidence for this than anything else.  It would seem this author is trying to push these fairly extraordinary hypotheses and for that reason is downplaying the much more likely but mundane explanation for the evidence seen.  This explanation can explain everything the other explantions can but doesn't require any unsupported assumptions, so by definition this is the parsimonious explanation if overland route was indeed blocked.

So, some of the European migrated to the Americas and must have passed on their stone working techniques to the Clovis people.
"Must"?!  I think there are other explanations that fit just as well.

“The ultimate test of this hypothesis may be found in the genetic research on ancient human remains. Michael Brown colleagues reported in 1998 that mitochondrial DNA haplogroup X(a genetic marker of population groups) is found in low frequencies in both Europeans and Native American populations, but not among Asians. This indicated to them that some of the American founders may have come from Europe between 36,000 and 12,000 years ago.” (Stanford and Bradley 55)
Other people studying the genome disagree with this, and think it is clear that modern native Americans share a common genetic heritage with Asians.  For instance there are a number of haplogroups that are found only in the Americas and East Asia, such as Haplogroups A and B (which are much older than haplogroup X).  What is more, Haplogroup X is not found at all in South America, it only appears in North America, which is pretty much impossible to explain if you say that Europeans are the original ancestors of all Native Americans.  X is also much more common in eastern Europe and the Near East than it is in western Europe where the Solutrean hypothesis said it originated.  Further, the Native American version of the that halpogroup is most similar to those in southern siberia and central, in fact that version is more similar to the american version than the european version.  It appears this version split off from the others very early on, and considering version of X are found in Africa still it is not implausible that the version now found in the Americas originated there or shortly after a group migrated out, meaning the population that is responsible for that haplogroup is probably not from Europe.

However, the fact that skeletal remains much older than the Clovis must shine light on the possibility that the Clovis defenders defensive stance on the topic may be in vain. But, we must also include the linguistic, or language, of the peoples of the region. “Linguist cannot account for the great diversity found among Native American languages in the limited time afforded by the Clovis model.”(Collins 51) Apparently the Clovis people did not have enough time in the Americas to establish a language that would be carried down by their descendants, so, in a sense; some people must have existed before Clovis arrived   and their language must have diversified long before the dawn of Clovis culture.
Even if that is true, island-hoping along the bearing straight can explain this.
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Offline Kytim89

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Re: Halbred's Paleo-News Thread
« Reply #212 on: June 07, 2010, 01:09:13 AM »
When I wrote that article my professor gave me a score of ninty-percent.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #213 on: June 07, 2010, 01:16:55 AM »
Oh, I somehow missed the part where you wrote it.
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Offline Kytim89

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Re: Halbred's Paleo-News Thread
« Reply #214 on: June 07, 2010, 01:47:46 AM »
Oh, I somehow missed the part where you wrote it.

It has my real name and instructor's name on it, sorry.
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Offline ThePerm

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Re: Halbred's Paleo-News Thread
« Reply #215 on: June 07, 2010, 06:00:45 AM »
i always figured the Bering strait opened and closed several times, but with long time distances. Long enough for each population on the other side to forget about the other.

Studying DNA is good, but because people are constantly moving its really hard to be exact. Also, sampling will for a very long time will be limited. It takes 5 years(give or take) to walk across the United State by foot. If the Bering strait were open for more than 1000 years any number of people could travel from one side to the other, competition, genocide, movement can all make the data inaccessible. The largest and dominating group were an Asian group. DNA is tricky though, because only those that breed survive, and a lot is based on Y chomosomal study. Y chromosomes eat other ones. Not to mention if there was another group between them, it would just throw DNA off.
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Offline ShyGuy

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Re: Halbred's Paleo-News Thread
« Reply #216 on: June 07, 2010, 10:56:52 AM »
Are you guys talking about Kennewick Man? He lived down the river from me.

Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #217 on: June 11, 2010, 03:38:06 PM »
Turtles might be back to being parareptiles. A new paper in Biology Letters posits an ancestral turtle, a fossil that's been known for over a century but largely overlooked: Eunotosaurus africanus. This contradicts relatively new molecular and biological data that has supported placement among diapsids.
 
Eunotosaurus is certainly an interesting choice: although incompletely known, its ribcage conforms to an expected ancestral turtle bauplan: they are laterally expanded in the way that turtles' ribs are, and look similar to those of the most basal turtle known, Odontochelys.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #218 on: June 28, 2010, 07:44:23 PM »
A recent article in science based on oxygen isotope data indicates that two of the groups of the large mezozoic marine reptiles, namely plesiosaur and icthyosaurs, were warm-blooded (endothermic) like modern mammals and birds.  In other words they can regulate their metabolism to maintain a constant warm internal temperature.  This supports more circumstantial evidence such as lifestyle and apparent hunting tactics.  They also looked at the third group of large marine reptiles from the era, mososaurs, but the evidence for them was inconclusive.  They may have been "gigantothermic", animals with low metabolic rate like modern non-avian reptiles that can still maintain warm internal temperatures due to their large size (as an animal gets larger its mass increases faster than its surface area, meaning it loses heat more slowly).  Giant leatherback turtles today can do this, and many mososaurs were much larger still.

There was an also an article on inconclusive evidence of pre-colombian polynesian contact with South America, but this would have occurred after  1200 AD, tens of thousands of years after the settlement of the new world and would have been fairly limited, mostly comprising a small exchange of tool shapes and a few words, the spread of chickens to the new world in isolated areas, and the spread of sweet potatoes across the pacific.  There was no mention of hypotheses about earlier contact, and even this later contact is highly controversial although it is gaining traction according to the article. 

They did state that there is a lot of debate about when the Polynesians started spreading to the farther islands in the Pacific, with the earliest pointing to a slow spread starting in about 500 BC and a much more rapid spread accompanying more advanced seafaring technology around 1000 AD.  The latter is considered the more popular hypothesis right now.  They spread to islands near Asia much sooner, but still only about 3000 BC at the earliest.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #219 on: June 28, 2010, 07:48:40 PM »
I've been meaning to post a comprehensive list of the new stories, but I haven't gotten around to it. Thanks, BlackCat! I'll also bring up the new ceratopsian volume, and I'll comment on all the papers in that.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #220 on: June 29, 2010, 09:41:45 PM »
There was also a recent Nature Communications article about a dinosaur nesting site.  It appears to have been used continuously over a long period of time.  What is interesting is that, at the time, the site was volcanically active, leading to acidic soil warmed by geothermal energy.  The dinosaur eggs apparently started off with super-thick shells that were slowly eaten away by the acid that leached it, resulting in an egg thin enough for the young dinos to break out of by the time they were reading to hatch.  The site was thought to have been chosen because the warmth would warm the eggs.  Most nests held under a dozen eggs, but some held almost 3 times that number.  No skeletons were found, so it is not yet possible to identify the species that made the nests.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #221 on: June 30, 2010, 01:24:26 PM »
Yeah, I just read about that yesterday. Probably saltasaurs, given the age and location.
 
Biblical Leviathan is real?
 
http://blogs.discovermagazine.com/notrocketscience/2010/06/30/behold-leviathan-the-sperm-whale-that-killed-other-whales/
 
Watch the video. LOOK AT THOSE TEETH!
« Last Edit: June 30, 2010, 02:30:52 PM by Halbred »
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #222 on: June 30, 2010, 06:41:00 PM »
Yeah, I thought the same thing the author did: "sounds like a mammalian megalodon".  Now we have to explain why two giant whale killers arose and then went extinct at around the same time.  The cold water argument for megalodon extinction doesn't work as well for a mammal.  Curiouser and curiouser.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #223 on: June 30, 2010, 07:19:27 PM »
Well, they lived in different places, so I don't think they were in direct competition. I never bought the cold-water theory, but environmental change may have negatively impacted the prey items, which would in turn impact the predators. It's entirely possible that Megalodon and Leviathan actually overhunted the largest whales and sort of caused their own extinction, although to really test that, you'd have to look at average fossil whale sizes from the Miocene onward. Even then, you're dealing with a tiny fraction of the actual population density, so we'll probably never know for sure.

It might also help to know when the modern "giant whales" arose.
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Offline ThePerm

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Re: Halbred's Paleo-News Thread
« Reply #224 on: June 30, 2010, 07:49:46 PM »
maybe a short term overhunting disrupted prey mating cycles

or maybe they were overhunted by intelligent Raptor fisherman :P
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