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Mini T-Rex found

 
 
Reply Fri 18 Sep, 2009 06:29 am
Interesting article on an ultra-small TRex discovered in China.

Apparently the basic body plan for the full sized TRex developed originally as a 9' tall animal and evolved into a creature almost 100 times its mass.

Why did some dinosaurs become so large when their basic body plan stayed the same. Was it due to a feeding behavior which gave then enough food to maximize their size (and avoid predation)?

Also it was interesting that this was another fossil discovery to come from archived fossil collections. It seems that some of the best places to make discoveries are the basement collections of museums and private collectors.

http://img16.imageshack.us/img16/1283/artraptorexeightcourtes.jpghttp://img41.imageshack.us/img41/451/artraptorexsevencourtes.jpg
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Type: Discussion • Score: 8 • Views: 3,363 • Replies: 30
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Setanta
 
  2  
Reply Fri 18 Sep, 2009 06:34 am
I saw a piece on this on BBC last night . . . very cool . . . China is proving to be a treasure trove for fossils . . . and not just in the Politburo . . .
rosborne979
 
  1  
Reply Fri 18 Sep, 2009 06:37 am
@Setanta,
Setanta wrote:

I saw a piece on this on BBC last night . . . very cool . . . China is proving to be a treasure trove for fossils . . . and not just in the Politburo . . .

I wish I could find stuff like that around here. On the other hand, I'm glad I don't live in the Gobi desert.
sozobe
 
  1  
Reply Fri 18 Sep, 2009 07:58 am
@rosborne979,
Yeah, saw that yesterday... very cool!

I had thought that evidence was starting to point towards T-Rexes being scavengers rather than hunters... now this points the other way again.
Setanta
 
  1  
Reply Fri 18 Sep, 2009 08:55 am
There is nothing which precludes hunters from being scavengers and vice-versa. The use of special lighting photography at night has revealed, for example, that lions are not necessarily the great hunters we have assumed they are. It has revealed that hyenas are very successful hunters, and that lions frequently drive them off their kills, and that, in fact, lions will stalk packs of hyenas for the express purpose of stealing their kills.
sozobe
 
  1  
Reply Fri 18 Sep, 2009 09:00 am
@Setanta,
True, but what I had read (not necessarily up-to-date -- sozlet had a major dino phase which she's not necessarily over but for a while I was reading about a book a week on dinos, not all current) was that the T-rex might have been only/ primarily a scavenger, and didn't really have the ability to be a predator as previously thought. (Lions definitely can be predators, even if they're not only predators.)
edgarblythe
 
  1  
Reply Fri 18 Sep, 2009 09:05 am
Are these direct ancestors to T-Rex. How can we know?
farmerman
 
  1  
Reply Fri 18 Sep, 2009 09:51 am
@edgarblythe,
bingo. Allosaurus and several others are close enough in body plan , and the finding of this one doesnt allow any conclusions. On the other hand,like the Wrangle Island and Catalina Island mini Mammoths of the early Holocene shows that animals can adjust their body dimensions wrt resources in a few generations. It doesnt take a lot of major diddling with genetics to alter structure.

in the "treatise of Vertebrate Paleo..." are several forms of T's in the early to mid and late Cretaceous. Too bad we dont have any genes to mess with
Setanta
 
  1  
Reply Fri 18 Sep, 2009 10:15 am
@sozobe,
Verra intersting . . . i didn't know that . . . scavenger still fills the belly, though . . .
sozobe
 
  1  
Reply Fri 18 Sep, 2009 10:21 am
@Setanta,
Went to look it up -- found this, still not sure how current/ reputable it is. Farmerman would know. It's the kind of thing I'm thinking of anyway:

Quote:
A current topic in paleontology that has received much popular press is the question of whether T.rex (or other Tyrannosauridae in general) were predators or scavengers. Let's explore this issue.

Paleontologist Jack Horner of the Museum of the Rockies (Bozeman, MT) has proposed that T.rex could not have been a predator. His arguments against predation include its small eyes (needed to see prey), small arms (needed to hold prey), huge legs (meaning slow speed) and that there is no evidence for predation " bones have been found with tyrannosaur teeth embedded in them or scratched by them, but so far no study has shown that tyrannosaurs killed other dinosaurs for food (a bone showing tyrannosaur tooth marks that had healed would be strong evidence for predation).

His evidence supporting scavenging include its large olfactory lobes (part of the brain used for smell), and that its legs were built for walking long distances (the thigh was about the size of the calf, as in humans). Vultures have large olfactory lobes and are good at soaring to cover long distances.


(Emphasis mine.)

http://www.ucmp.berkeley.edu/diapsids/saurischia/tyrannosauridae.html
rosborne979
 
  1  
Reply Fri 18 Sep, 2009 11:19 am
@sozobe,
sozobe wrote:
I had thought that evidence was starting to point towards T-Rexes being scavengers rather than hunters... now this points the other way again.

I was wondering if successful scavenging (lots of food) was one of the contributing factors for becoming very large. Scavengers don't need to be fast and agile, they just need to be able to dominate a carcass (size would be a key advantage).
0 Replies
 
rosborne979
 
  1  
Reply Fri 18 Sep, 2009 11:24 am
@farmerman,
farmerman wrote:
bingo. Allosaurus and several others are close enough in body plan , and the finding of this one doesnt allow any conclusions.

We might infer from this fossil that many of the other large predatory theropods (Allosaurus) originated as smaller versions also.
0 Replies
 
rosborne979
 
  1  
Reply Fri 18 Sep, 2009 11:30 am
@sozobe,
sozobe wrote:

Went to look it up -- found this, still not sure how current/ reputable it is. Farmerman would know. It's the kind of thing I'm thinking of anyway:

Quote:
Paleontologist Jack Horner of the Museum of the Rockies (Bozeman, MT) has proposed that T.rex could not have been a predator.

Then of course there's the fact that all these large dino's went through a growth phase. And it's possible that the juveniles were predators (as well as scavengers) when they were smaller, and then settled on scavenging as they reached adulthood.

It would be interesting to know how long it took a TRex to grow from birth to 90% of it's eventual adult weight. A Year? Ten Years? 20 years?

What was the lifespan of a TRex and at what age did they begin to reproduce?
Merry Andrew
 
  1  
Reply Fri 18 Sep, 2009 12:30 pm
@rosborne979,
rosborne979 wrote:

Setanta wrote:

I saw a piece on this on BBC last night . . . very cool . . . China is proving to be a treasure trove for fossils . . . and not just in the Politburo . . .

I wish I could find stuff like that around here. On the other hand, I'm glad I don't live in the Gobi desert.


I have climbed Mt. Monadnock several times during my lifetime, ros (I believe that's not too distant from where you live), and never stumbled across anything except the occasional empty beer or soda can.
rosborne979
 
  1  
Reply Fri 18 Sep, 2009 08:54 pm
@rosborne979,
rosborne979 wrote:

It would be interesting to know how long it took a TRex to grow from birth to 90% of it's eventual adult weight. A Year? Ten Years? 20 years?

What was the lifespan of a TRex and at what age did they begin to reproduce?

There was a discussion of the Mini-Rex on NPR Science Friday this afternoon (pure chance that I happened to catch it). They were interviewing the scientist who reported this specimen.

Based on bone fusion they were able to determine the age of the mini-individual, and it was a full grown adult at about 10 years old. In comparison, the large T-Rex's were adolescent at 15 and full grown at 20. The T-Rex specimen they named "Sue" was 28 years old and considered geriatric in T-Rex lifetimes.

The scientist also made a pretty good case for this specimen being very close to the ancestral line of T-Rex's, and not something else like an Alosaurus. He talked about the small front limbs in particular and said that some very particular ratio's between the front limb design and other anatomical features made this mini-rex very likely to be very close to the ancestral line of the bigger T-Rex's.

He fielded questions ranging from whether this mini-rex was a juvenile, or possibly an entirely different species exhibiting convergent evolution or whether it might just be a single-occurrence "freak" animal (none of which held up as well as an ancestor). They talked about the strata the fossil was embedded with as well as the formation conditions.

It was a very interesting NPR Science Friday show Smile
0 Replies
 
rosborne979
 
  1  
Reply Fri 18 Sep, 2009 08:55 pm
@Merry Andrew,
Merry Andrew wrote:
I have climbed Mt. Monadnock several times during my lifetime, ros (I believe that's not too distant from where you live), and never stumbled across anything except the occasional empty beer or soda can.

Monadnock's not far from here. But there isn't a fossil to be found on that mountain.
Merry Andrew
 
  1  
Reply Fri 18 Sep, 2009 09:27 pm
@rosborne979,
rosborne979 wrote:

Merry Andrew wrote:
I have climbed Mt. Monadnock several times during my lifetime, ros (I believe that's not too distant from where you live), and never stumbled across anything except the occasional empty beer or soda can.

Monadnock's not far from here. But there isn't a fossil to be found on that mountain.



Yeah, that's what I just said. I think.
rosborne979
 
  1  
Reply Sat 19 Sep, 2009 06:08 am
@Merry Andrew,
We agree.

Once when I was a kid I found a large chunk of black obsidian (volcanic glass) while hiking in the woods in Vermont. Since there are no volcano's in Vermont, I always wondered how it got there. (not a fossil I know, but my only "found something" story from a hike in this area)
Setanta
 
  1  
Reply Sat 19 Sep, 2009 10:10 am
@rosborne979,
Volcanoes can hurl their ejecta incredible distances. The volcano which erupted to create Baja Grande, an astoundingly large dormant caldera south of Los Alamos, New Mexico, heaved rocks as far as eastern Kansas and southwest Missouri. I'd suggest your obsidian in Vermont may have arrived there in a similar manner.
0 Replies
 
littlek
 
  1  
Reply Sat 19 Sep, 2009 03:33 pm
Mini? At nine feet! I guess it's all relative.
0 Replies
 
 

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