Author Topic: Halbred's Paleo-News Thread  (Read 82428 times)

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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #175 on: March 28, 2010, 08:20:57 PM »
I'm looking at a live dinosaur right now, dude. ;-)

But seriously? I want a pet Homocephale. Not because it's my favorite dinosaur, but I think it'd be like a dog.
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Offline Kytim89

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Re: Halbred's Paleo-News Thread
« Reply #176 on: March 28, 2010, 10:17:46 PM »
I would pick a Spinosaurus for about one hundred dollars.
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Offline Stratos

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Re: Halbred's Paleo-News Thread
« Reply #177 on: March 29, 2010, 02:14:54 AM »
Get your butt up here before the summer and I'll see if I can't get you to the Colville River, which is way up north. That's where most of our dinosaurs come from. I've got no pull further south, though.

What type of time commitment are we looking at? A week? Two? And what sort of costs are involved?
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #178 on: March 29, 2010, 10:03:59 AM »
Probably two to three weeks. I'd have to get the specifics. You'd be living in a tent, eating food from cans or on a portable rangetop. Basically camping. I don't know the costs involved...if you really want me to, I can get the specifics.
 
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« Last Edit: March 29, 2010, 05:46:46 PM by Halbred »
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #179 on: March 29, 2010, 05:11:08 PM »
I would pick a Spinosaurus for about one hundred dollars.

It would probably eat food worth more than that in a day.

I would much rather have a sea scorpion.  Dinosaurs are over-rated.  I've already owned 3 live dinosaurs anyway.
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Offline Stogi

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Re: Halbred's Paleo-News Thread
« Reply #180 on: March 29, 2010, 06:10:44 PM »
I'm looking at a live dinosaur right now, dude. ;-)

But seriously? I want a pet Homocephale. Not because it's my favorite dinosaur, but I think it'd be like a dog.

That joke flew over my head...

And don't you mean "homalocephale"? ;)
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #181 on: March 29, 2010, 06:26:57 PM »
« Last Edit: March 29, 2010, 07:29:11 PM by Halbred »
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #182 on: March 30, 2010, 02:38:18 PM »
They figured out the coloration in another feathered dinosaur, specifically a late Jurassic therapod called Anchiornis huxleyi.  Thanks to an exceptionally well-preserved fossil, they were able to reconstruct its coloration in extreme, right down to the orange spots on its cheeks and black tips of its feathers.  This one is pretty ornate, if it wasn't for the tail and claws you might think it is a normal bird.  However, the feathers are fairly uniform in shape and contour even when they vary in size, unlike flying birds which have a wide variety of feathers with specialized shapes suited for various aerodynamic roles: Plumage Color of an Extinct Dinosaur




If you weren't told any different you might think it is a modern largely terrestrial hunting bird like a secretary bird:





They've also found what they think is the first Tyrannosaurid found in what was then the southern hemisphere (Autralia, in this case).  It is smaller and younger than its more famous cousins, but fir correct show they lived in a much larger area than there was previously evidence to support.  Unfortunately it was just a hip bone, so they can't give much in the way of details.  Although I strongly suspect this may be the abstract that the blog post Halbred just linked to is discussing, you can decide for yourself: A Southern Tyrant Reptile
« Last Edit: March 30, 2010, 07:25:04 PM by TheBlackCat »
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #183 on: April 01, 2010, 10:18:20 AM »
Brand new ankylosaur was published today. This is really wonderful news, because it's an extremely basal ankylosaur. It's from the Middle Jurassic of China, from the same formation you find guys like Gasosaurus and Mamechiosaurus. What's interesting is that this new guy, Xixianankyus (she-SHE-yan-kus) does not have the typical wide body and head full of osteoderms that later ankylosaurs have.

Rather, its skull is relatively free of osteoderms except for large scutes above the palpebral bones, which implies that that skull protection evolved to shield the eyes first before spreading around the rest of the head. The body is also covered in rows of small scutes, somewhat like the case in Scutosaurus, but they are larger than in that English taxon, and what's more, there are small triangular spikes arranged in a half-circle from shoulder to shoulder, across the back.

But that's not even the strangest thing: Xixiankyus was bipedal. Or at the very least, would not have found bipedality uncomfortable. It may have habituatially stood quadrupedally, but probably walked and ran bipedally. The really wierd detail is that Xixiankyus shows more skeletal similarities to basal ornithopods than to stegosaurs. Unless this is a case of rampant convergence, this fact renders the notion of a monophyletic "Thyreophora" moot. Stegosaurs and ankylosaurs are NOT closely related, and the later is closer to duckbills. I've only skimmed the paper, but this is pretty heavy stuff. The first specimen of Ankylosaurus was actually thought to BE a stegosaur, so...yeah. Weird.

If I find a good reconstruction, I'll post it (maybe I'll just draw my own), because this guy is rockin'!
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Offline ThePerm

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Re: Halbred's Paleo-News Thread
« Reply #184 on: April 01, 2010, 04:19:01 PM »
ooh i wanna make a reconstruction, give me specs yo. Any skeletal pics, related species, :o
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #185 on: April 08, 2010, 02:34:40 PM »
That last one, for those that didn't catch on, was an April Fool's joke.

New species of Australopithicus (sebida) were described from South Africa. They are nearly 2 million years old. It shows more derived features in common with early species of Homo than any other australopithicine, and suggests that early hominid evolution was very "crowded" indeed. Since so many species overlap in time, it's very clear that it's not a ancestor-descendant thing going on. Our lineage has LOTS of dead ends.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #186 on: April 08, 2010, 04:40:29 PM »
There is also a recent MtDNA analysis of some fossil hominid finger bones from Europe circa 40,000 BP.  They do not match either Neanderthals or modern humans, so assuming there wasn't a mistake it means that either some sub-populations of earlier hominids (like Homo erectus) lasted hundreds of thousands of years longer than expected or (as the researchers are saying) there was a fourth species of the genus Homo alive up until very recently (the other three being Homo neanderthalis, Homo sapiens, and Homo floresiensis).
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #187 on: April 08, 2010, 05:43:17 PM »
The finger bone story is full of holes. I'm gonna go out on a limb here and suggest that 40,000 year-old DNA is very incomplete and damaged. All the science blogs I've read about the subject (most notably The Loom) have suggested it's a neanderthal. More interesting is the suggestion that it's a neanderthal-modern human hybrid.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #188 on: April 09, 2010, 10:41:36 AM »
The finger bone story is full of holes. I'm gonna go out on a limb here and suggest that 40,000 year-old DNA is very incomplete and damaged. All the science blogs I've read about the subject (most notably The Loom) have suggested it's a neanderthal. More interesting is the suggestion that it's a neanderthal-modern human hybrid.


It was mitochondrial DNA, which you only get from the mother.  So if it was a hybrid (which the evidence is against happening to begin with), that still wouldn't cause any changes in mitochondrial DNA, which would be identical to the mitochondrial DNA from one of the two species (whichever one was the mother).  Besides, that is far from the first sample of that age they have extract mitochondrial DNA from, and it is has worked well from known human DNA samples from that time period.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #189 on: April 09, 2010, 10:56:37 AM »
Meh. I await further study. The burdon of proof is on those who would suggest it's some late-surviving basal hominid. I'm not saying that wouldn't be AWESOME, I'm saying that incredible claims require incredible evidence.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #190 on: April 09, 2010, 06:18:07 PM »
I agree, which is why I said "assuming there wasn't a mistake".  My point is simply that this is not the first time this technique was used. 

Also, the scientists were not claiming it was a late-surviving basal hominid, they were saying it was a fourth derived hominid.  But they didn't seem to adequately rule out the possibility that it was a basal hominid, which is why I included it.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #191 on: April 09, 2010, 11:21:17 PM »
I believe their suggestion was that this mystery hominid was a third branch-off from H. erectus.

HOWEVER, and this is a great time to bring this up: Paleoanthropologists haven't figured out what cladistics is yet. Nobody does the kind of phylogenetic analyses on hominids that you see done on EVERY OTHER GROUP OF FOSSIL ORGANISMS. I'm not sure if this is just immobility on the paleoanthropologists themselves, or the old problem of human exceptionalism. It's certainly a problem, though.

A real phylogenetic analysis might reveal that the Australopithecus genus is too broad, and could stand to be broken into two or more genera. Same for Homo. I mean, for pete's sake, there are only three major genera of hominid: Australopithecus, Ardipithecus, and Homo. Sure, you've got Paranthropus and Kenyanthropus, but the former used to be included in Australopithecus (and still is, sometimes) while the latter's exact phylogenetic position is unstable. I've read a suggestion that it's actually a non-hominid hominoid. Whatever it is, it's certainly basal to almost everyone else.

Somebody needs to do a broad phylogenetic anlysis of Hominoidea. This new hominid, Australopithecus sediba, provides a perfect excuse to do one.
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Offline ThePerm

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Re: Halbred's Paleo-News Thread
« Reply #192 on: April 10, 2010, 12:14:17 AM »
the human gene pool is exceptionally small, people are only 0.02% different from each other on average, that being said it is going to be very hard to figure out our genes backwards especially with extinct dead end species.
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Offline Stogi

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Re: Halbred's Paleo-News Thread
« Reply #193 on: April 13, 2010, 10:03:08 AM »
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #194 on: April 29, 2010, 12:25:32 PM »
FINALLY a worthwhile paleo news story.
 
Today, in the journal Nature, two new specimens of the basal oviraptorosaur Similicaudipteryx are briefly described, more for their plumage than their skeletons. One of the specimens is a juvenile, the other is a "teenager." There is a considerable size difference between them, but more importantly, their feathers are quite different.
 
The younger animal has a smaller tail fan and no pygostyle (which the authors conclude is age-related). It also has fewer arm feathers and tail feathers. Furthermore, the structure of the feathers seems different: in the teenager, the feathers are fully "modern," with a rachis and barbs. In the juvenile, however, the feathers are ribbon-like along most of their length, but become "feathery" toward the end. This kind of feather--where the gene responsible for producing barbs doesn't turn on--is also known in confuciusornid birds and scansoriopterygian theropods. However, it's not known in modern birds. The closest modern birds get is some birds of paradise, which have ribbon-like feathers that develop through different means.
 
The big idea here is that--not surprisingly--non-avian dinosaurs went through several "molts" just like modern birds. What's interesting, though, is that some molt stages include feather types that are "extinct" today. It would seem that feathers were much more variable in the Jurassic and Cretaceous than they are today. That's probably the result of pruning: modern birds stuck with only so many kinds of feathers, and everyone else went extinct. It is interesting, though, to see so many strange types of feathers in the fossil record.
 
For more on this, including a cool picture, see:
 
http://blogs.discovermagazine.com/notrocketscience/2010/04/28/dramatic-restructuring-of-dinosaur-feathers-revealed-by-two-youngsters-of-same-species/#more-1508
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #195 on: April 30, 2010, 09:59:22 AM »
That's probably the result of pruning: modern birds stuck with only so many kinds of feathers, and everyone else went extinct. It is interesting, though, to see so many strange types of feathers in the fossil record.
Why couldn't it be the result of just chance?  After all, the K/T extinction event was fairly indiscriminate for certain classes of animal (for instance birds survived, while other closely-related dinosaurs did not).  Couldn't it just have been that the birds that survived happened to not have those feathers?  When dealing with something like a mass extinction, I think the idea that lacking these feather types had some sort of adaptive significance is a hypothesis that needs specific support while dumb luck is the null hypothesis.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #196 on: April 30, 2010, 10:14:09 AM »
Well, modern bird groups originated during the Cretaceous, and they probably had the same four or five feather types as modern birds. But the extinction is what I meant by pruning. Everyone else went extinct.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #197 on: April 30, 2010, 10:51:03 AM »
I guess I see pruning as a more specific and gradual evolutionary process, where different branches of the family tree can't compete and die off over geologic time scales. 

I see the K/T extinction as more be akin to a blind person randomly swinging around a chain saw, which parts of the tree are cut off have little to do with how successful the lineage was and more to do with being in the wrong place at the wrong time.  I wouldn't really consider that sort of thing to be pruning, personally.
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Offline Halbred

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Re: Halbred's Paleo-News Thread
« Reply #198 on: April 30, 2010, 11:01:09 AM »
M'kay.

I do wonder about all the non-crown group birds at the end of the Cretaceous. Blind luck is one thing, but with so many different groups (enantiornithines, hesperornids, ichthyornids, etc.) blowin' up the avian family tree at the end of the Mesozoic, I'm surprised that only one group (ornithurines) made it through.
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Offline TheBlackCat

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Re: Halbred's Paleo-News Thread
« Reply #199 on: April 30, 2010, 02:45:22 PM »
I'm not sure why it is that surprising, that sort of thing seems fairly normal for mass extinctions as far as I can tell.  We see similar bottlenecks throughout metazoans during mass extinctions (and plants, I think, but I am not as familiar with the impact of mass extinctions on them).  Further, I would be surprised if there is anything that special about birds in general that would lead them to survive over very similar non-avian dinosaurs other than luck.
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