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Author Topic:   Quick Questions, Short Answers - No Debate
kuresu
Member (Idle past 2513 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 121 of 653 (498129)
02-08-2009 9:53 AM
Reply to: Message 120 by Coragyps
02-08-2009 9:35 AM


Re: uplift???
I'll see if I can dig up the soil types around here. Unfortunately I no longer have my grandfather to ask, as he was a geologist/civil engineer with a Swedish firm (not sure if he actually worked for the swedish gov't, though). On the plus side, Uppsala is known for its sciences, so I'm sure there's someone/thing with relevant info.
Thanks.

This message is a reply to:
 Message 120 by Coragyps, posted 02-08-2009 9:35 AM Coragyps has not replied

  
BMG
Member (Idle past 209 days)
Posts: 357
From: Southwestern U.S.
Joined: 03-16-2006


Message 122 of 653 (508161)
05-11-2009 1:51 AM


Polar Bears?
Interior Secretary Ken Salazar announced that the Obama administration will leave in place an unpopular Bush rule on the protection of polar bears. The decision comes despite an outcry from Democrats, environmental activists and scientists alike, who promised to push to overturn the rule in court.
Obama Leaves Polar Bears Out in the Cold
The Polar Bear seems doomed, regardless of our efforts, but must we kick it while it's down? Or nonchalantly step over it while it lies helpless under our feet? Am I overreacting?
Edited by Admin, : Reduce length of long link.

  
Modulous
Member
Posts: 7801
From: Manchester, UK
Joined: 05-01-2005


Message 123 of 653 (508495)
05-14-2009 10:03 AM


titles in the Bible
From Message 256:
...and the tendency is to refer to {ancient near eastern works} by the first significant noun or action in the work.
But not when translated? Or is this just a quirk of English translations?
I don't know the history of putting titles to works, but I feel confident that some 'blame' belongs to the Greeks. So, for the moment, let's call it a quirk of the Greeks that the Romans and subsequently the rest of the world inherited.
One assumes that the Greeks used their own convention because either they were unaware of the near eastern one - or perhaps more likely, they preferred their own convention. "And He called" doesn't tell a person what the book is about, which seems to be what the Greeks aimed for in their titles.
Edited by Modulous, : No reason given.

  
BMG
Member (Idle past 209 days)
Posts: 357
From: Southwestern U.S.
Joined: 03-16-2006


Message 124 of 653 (509913)
05-26-2009 2:42 AM


Birds=Reptiles?
I have recently finished an intro to Bio course, and the class text, Biology: Concepts And Connections: Sixth Edition (sorry, don't feel like looking up the correct form for citing sources) claims that, on page 398, that,
quote:
Birds are feathered reptiles with adaptations for flight.
On the previous page, 397, it reads
quote:
The clade of amniotes called reptiles includes lizards, snakes, turtles, crocodiles, and birds,...
.
However, wikipedia quotes Colin Tudge below;
quote:
Mammals are a clade, and therefore the cladists are happy to acknowledge the traditional taxon Mammalia; and birds, too, are a clade, universally ascribed to the formal taxon Aves. Mammalia and Aves are, in fact, subclades within the grand clade of the Amniota. But the traditional class reptilia is not a clade. It is just a section of the clade Amniota: the section that is left after the Mammalia and Aves have been hived off. It cannot be defined by synapomorphies, as is the proper way. It is instead defined by a combination of the features it has and the features it lacks: reptiles are the amniotes that lack fur or feathers. At best, the cladists suggest, we could say that the traditional Reptila are 'non-avian, non-mammalian amniotes'.[6]
Bold mine.
A few weeks ago, speaking to some friends, I mentioned that birds were actually feathered reptiles. Was I accurate in repeating my text's claim?
I would really appreciate any feedback. Thank you.

Replies to this message:
 Message 125 by Dr Adequate, posted 05-26-2009 5:28 AM BMG has replied
 Message 126 by Coragyps, posted 05-26-2009 5:50 AM BMG has replied
 Message 127 by Percy, posted 05-26-2009 6:44 AM BMG has not replied
 Message 128 by caffeine, posted 05-26-2009 7:18 AM BMG has not replied
 Message 130 by Blue Jay, posted 05-26-2009 1:39 PM BMG has replied

  
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 125 of 653 (509920)
05-26-2009 5:28 AM
Reply to: Message 124 by BMG
05-26-2009 2:42 AM


Re: Birds=Reptiles?
I guess if you define reptiles as aminotes which aren't birds or mammals, then you can't say that birds are reptiles. Dinosaurs, yes ... but wait, aren't dinosaurs reptiles? Well, according to that definition, only the ones that aren't birds.
So what's Caudipteryx ... ?
Edited by Dr Adequate, : No reason given.

This message is a reply to:
 Message 124 by BMG, posted 05-26-2009 2:42 AM BMG has replied

Replies to this message:
 Message 129 by BMG, posted 05-26-2009 1:36 PM Dr Adequate has not replied

  
Coragyps
Member (Idle past 734 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 126 of 653 (509923)
05-26-2009 5:50 AM
Reply to: Message 124 by BMG
05-26-2009 2:42 AM


Re: Birds=Reptiles?
The term "reptiles" includes "lizards, snakes, turtles, crocodiles, and birds,..." but it is a more-or-less obsolete term. Turtles are anapsids, and may not belong with those others, which are all diapsids. And we synapsids are descended from "mammal-like reptiles," which isn't very helpful in deciding if mammals are still reptiles or not.
A situation in flux, from my understanding. Birds are closer kin to crocodiles than to lizards, if that helps at all.

This message is a reply to:
 Message 124 by BMG, posted 05-26-2009 2:42 AM BMG has replied

Replies to this message:
 Message 131 by BMG, posted 05-26-2009 1:48 PM Coragyps has not replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 127 of 653 (509930)
05-26-2009 6:44 AM
Reply to: Message 124 by BMG
05-26-2009 2:42 AM


Re: Birds=Reptiles?
Unlike Dr. Adequate and Coragyps, I am largely ignorant of the issues and problems of biological classification, and so I can give an answer with almost complete confidence.
Birds are not reptiles. Birds are dinosaurs, which are descended from reptiles.
Mammals are not reptiles. Mammals share a common ancestor with reptiles.
Reptiles are not amphibians. Reptiles share a common ancestor with amphibians.
If my uninformed answer is sufficiently controversial then someone should propose a new thread.
--Percy

This message is a reply to:
 Message 124 by BMG, posted 05-26-2009 2:42 AM BMG has not replied

  
caffeine
Member (Idle past 1024 days)
Posts: 1800
From: Prague, Czech Republic
Joined: 10-22-2008


Message 128 of 653 (509933)
05-26-2009 7:18 AM
Reply to: Message 124 by BMG
05-26-2009 2:42 AM


Re: Birds=Reptiles?
It's just a matter of definition. Reptile in the traditional usage would not include birds, but if you wanted to define it as a monophyletic clade it would have to. Which to use is just personal preference.

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BMG
Member (Idle past 209 days)
Posts: 357
From: Southwestern U.S.
Joined: 03-16-2006


Message 129 of 653 (509978)
05-26-2009 1:36 PM
Reply to: Message 125 by Dr Adequate
05-26-2009 5:28 AM


Re: Birds=Reptiles?
Thanks for the replies, everyone.
So what's Caudipteryx ... ?
Hmmm, currently, according to wiki,
quote:
The consensus view, based on several cladistic analyses, is that Caudipteryx is a basal (primitive) member of the Oviraptoridae, and the oviraptorids are nonavian theropod dinosaurs.
It gets better. A little futher down, from the same source,
quote:
Halszka Osmolska et al. (2004) ran a cladistic analysis that came to a different conclusion. They found that the most birdlike features of oviraptorids actually place the whole clade within Aves itself, meaning that Caudipteryx is both an oviraptorid and a bird. In their analysis, birds evolved from more primitive theropods, and one lineage of birds became flightless, re-evolved some primitive features, and gave rise to the oviraptorids
Bold mine.
So birds evolved from theropods, which were small, two-legged dinosaurs; well, most were small, I suppose, for, again, wiki claims that theropods
quote:
were the sole large terrestrial carnivores from the Early Jurassic until the close of the Cretaceous, about 65 Ma. Today, they are represented by the 9,300 living species of birds, which evolved in the Late Jurassic from small specialized coelurosaurian dinosaurs.
Thanks, DA.

This message is a reply to:
 Message 125 by Dr Adequate, posted 05-26-2009 5:28 AM Dr Adequate has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 130 of 653 (509979)
05-26-2009 1:39 PM
Reply to: Message 124 by BMG
05-26-2009 2:42 AM


Re: Birds=Reptiles?
Hi, BMG.
Forgive me for drawing this out, but I felt I had some additional insight to help answer the question.
The classification of organisms used to be categorical, such that animals could be placed into different groups based on whether or not they had a requisite array of defining characteristics. The system works just fine if your intent is just to group things by appearance. However, there is always the question of why you would want to group them that way.
But, modern biology uses evolution as the guide for classifying animals, such that true ancestry and relatedness are more important than morphological features. So, modern taxonomists will group everything that evolves from a reptile as a reptile, and will only distinguish two reptiles from one another by means of subgroups placed within the group "reptiles." Thus, birds would appropriately be considered a subgroup of reptiles, for instance.
This system works well because evolution is considered central to modern biology, and it provides a clearer picture of the history of life, so we are better able to see what factors shape the processes of life. Furthermore, it gives us some predictive ability: we can anticipate some of the ecological traits of some species based on what we know about closely related species, because closely related species are often affected similarly by similar environmental factors.
The problems come in when you start mixing terms from the categorical system with terms from the cladistic system. The word "reptile" is essentially meaningless in terms of evolution-based classification, because it groups things in terms of something other than evolutionary ancestry, and you'll only confuse people by trying to use both classification systems at once.
So, before even bothering to use a term such as "reptile," it's important to understand why you want to use it and what the term is going to convey to the person you're using it for.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 124 by BMG, posted 05-26-2009 2:42 AM BMG has replied

Replies to this message:
 Message 132 by BMG, posted 05-26-2009 2:14 PM Blue Jay has not replied
 Message 133 by roxrkool, posted 05-28-2009 9:59 AM Blue Jay has not replied

  
BMG
Member (Idle past 209 days)
Posts: 357
From: Southwestern U.S.
Joined: 03-16-2006


Message 131 of 653 (509980)
05-26-2009 1:48 PM
Reply to: Message 126 by Coragyps
05-26-2009 5:50 AM


Re: Birds=Reptiles?
The term "reptiles" includes "lizards, snakes, turtles, crocodiles, and birds,..." but it is a more-or-less obsolete term. Turtles are anapsids, and may not belong with those others, which are all diapsids. And we synapsids are descended from "mammal-like reptiles," which isn't very helpful in deciding if mammals are still reptiles or not.
In essence, it sounds as if I should simply stay away from the term "reptile" all together. Anapsids have skulls that lack openings near the temples. Diapsids have two openings on their skulls, one on each side("di").
Again, from wiki, about synapsids
quote:
At the same time, the term "reptiles", which traditionally denoted all cold-blooded amniotes, is now re-defined to include only the sauropsids (a class that unites the anapsids and the diapsids to the exclusion of the synapsids, because these first two groups are more closely related to each other than to the third one). Hence the term "mammal-like reptiles" for the synapsids is considered obsolete under this terminology.
And synapsids have a single hole behind each eye orbit.
A situation in flux, from my understanding. Birds are closer kin to crocodiles than to lizards, if that helps at all.
Yes, it does. I guess I may have had it right when I started this post; I think I will stay away from the term reptile altogther.
Thanks, Coragyps.

This message is a reply to:
 Message 126 by Coragyps, posted 05-26-2009 5:50 AM Coragyps has not replied

  
BMG
Member (Idle past 209 days)
Posts: 357
From: Southwestern U.S.
Joined: 03-16-2006


Message 132 of 653 (509984)
05-26-2009 2:14 PM
Reply to: Message 130 by Blue Jay
05-26-2009 1:39 PM


Re: Birds=Reptiles?
Thanks Percy, Caffeine, and Bluejay for the replies.
I'm less knowledgable than all three of you, I'm sure, in biology, so let's see if I have this straight. The term "reptile" was borne from the outdated, morphological system of classification, and the new form of classification, based on evolution, determines, as Bluejay has put it, "true ancestry and relatedness".
A work in taxonomic progress, I suppose. Birds belong to the Aves clade, mammals to the mammalia clade, and both are subgroups within the larger clade, Amniota. So, are most or all of the animals formerly known as reptiles undergoing a taxonomic classification upgrade, and being allocated to their respective clades? A wait-and see-approach for those interested in the subject?

This message is a reply to:
 Message 130 by Blue Jay, posted 05-26-2009 1:39 PM Blue Jay has not replied

  
roxrkool
Member (Idle past 988 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 133 of 653 (510174)
05-28-2009 9:59 AM
Reply to: Message 130 by Blue Jay
05-26-2009 1:39 PM


Re: Birds=Reptiles?
Great post! That was very informative.

This message is a reply to:
 Message 130 by Blue Jay, posted 05-26-2009 1:39 PM Blue Jay has not replied

  
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 134 of 653 (517842)
08-02-2009 11:04 PM


Bacteria Evolving Loss Of Function --- Example Please?
I presume that if you took bacteria which could synthesize some chemical necessary to their metabolism, and you grew them in a culture rich in this chemical, they would eventually stop making it for themselves.
Does anyone know of such an experiment?

Replies to this message:
 Message 144 by Parasomnium, posted 09-02-2009 4:08 PM Dr Adequate has replied

  
Itinerant Lurker
Member (Idle past 2655 days)
Posts: 67
Joined: 12-12-2008


Message 135 of 653 (517940)
08-03-2009 11:52 AM


Population genetics question
How are genetic markers dated? What I mean is, when genetic markers are used to track population movements throughout human history like this one,
National Geographic - 404
How are the dates associated with the various populations arrived at?

Replies to this message:
 Message 136 by Dr Adequate, posted 08-03-2009 11:43 PM Itinerant Lurker has replied

  
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