I've never agreed with dinosaur to bird theory. Not since I began reading about it more indepth, realizing the serious discrepancies associated with the fossil timeline.
Fossils of birds in red. Fossils of dinosaurs in green.
Some scientists were and still are, so fixated on their high hopes they began claiming that "dinosaurs were probably warm blooded" because they were convinced, in their own mind, that birds and dinosaurs shared similar physiology.
There weren't any actual facts to support that supposition, "warm-blooded dinosaurs" but they presumed since birds are...
Since they "like" the dinosaur-bird theory (somewhat similar to YEC who "like" the idea of a magic god hand-designing all life (as it is, as it always will be) in 24 hours), well, they claimed dinosaurs had "warm blood" like birds.
YEC have an excuse. Scientists do not.
Now science has some research which suggests that dinosaurs were not warm blooded.
Dinosaurs were a failed evolutionary experiment, and they went extinct. Birds survived and diversified. It's just the Darwin way of things. Just the blood type alone tells me that birds and dinosaurs are only (very) distant cousins on the evolutionary tree of common ancestry of Archosaurs; between birds, crocodiles and dinosaurs.
Dinosaurs were not "warm blooded" like birds.
Birds are not descended from dinosaurs. It's difficult to know blood-type from mere fossil evidence.
That's a whole lot of supposing...
"...Dinosaurs have long been thought of as slow, lumbering, cold-blooded animals, akin to reptiles like the crocodile and the lizard – but there's been increasing signs in recent years that they may have been warm-blooded, as mammals and birds are..."
- An Old L.A. Times Article
Based on nothing more than the fact that birds, were warm-blooded.
Dinosaurs were not Warm Blooded.
(Source)
"...Dinosaurs are generally thought of as cold-blooded animals like reptiles. However, a new study from Australia provides evidence that dinosaurs were warm blood animals just like mammals and birds." The idea that dinosaurs could have been warm-blooded was proposed by Robert Bakker and John Ostrom in 1960s. A study supporting this hypothesis was published last year, where a team of researchers had studied growth lines on the dinosaurs' bones and found that dinosaurs had high metabolism rates and high growth rates, which meant they were warm-blooded."
(Source)
BBC News - Dinosaurs 'neither warm nor cold blooded'
Jun 12, 2014 - Warm blooded animals, like mammals and birds, need a lot of fuel and use .... has argued since the 1970s that dinosaurs were warm-blooded."
Alan Feduccia was one of the scientists suggesting the need for exercising caution in drawing premature conclusions. But the dinosaur-hypothesis crowd wanted to force the facts to fit the desired conclusion and Feduccia compared some of these darwinists(?) with creationists???
"With the advent of ‘feathered dinosaurs,’ we are truly witnessing the beginnings of the meltdown of the field of paleontology,"
(Source)
Amen on that.
USGS FAQs - Paleontology - Were dinosaurs warm-blooded?
United States Geological Survey Scientists have conflicting opinions on this subject. Some paleontologists think that all dinosaurs were 'warm-blooded' in the same sense that modern birds and ...
Links
- Scientists Say No Evidence Exists that Theropod Dinosaurs Evolved into Birds "...scientists say examples of flying reptiles remains a case of convergent evolution. "Similar design features exist in modern birds, which evolved them independently, say the scientists."
- Hollow bones helped high-flying reptiles stay aloft
Forget dinosaurs. All tetrapods go back to the amniotes (310 million years ago), and birds and mammals share a common ancestor, which mutually endowed birds and mammals with genes that enabled the development into warm-blooded species. THAT is my conclusion based on the evidence.
The rise of the ancestors of birds, crocodiles, mammals, turtles, dinosaurs, and many, many extinct groups, etc etc etc...
(Source), The Skeleton: Part 1, The Skull, ANAPSIDS, DIAPSIDS, SYNAPSIDS AND OTHERS)
"Do birds and mammals share a common endothermic reptile ancestor or did they develop their endothermies convergently?"
A REDDIT RESPONSE OF INTEREST: (Source) "There is a hypothesis that crocodilians actually descend from endothermic ancestors that became ectotherm secondarily. It is not very popular though. Even then, birds+crocs are more related to ectotherms like lizards, snakes and turtles than they are to mammals, so the common ancestors of all them had to be ectotherm."
(Ectotherm. Any so-called cold-blooded animal; that is, any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface.)
HAIR ENABLES WARM-BLOODED PHYSIOLOGY
"...The origins of hair date back 310 million to 330 million years ago to the last common ancestor of mammals, birds and lizards, according to a new study that discovered genes associated with hair production in living green anole lizards and chickens."
(Source)
Feathers, are modified scales, enabling birds to be warm-blooded.
"...A genetic explanation for the evolution of the feather; the modification of the reptilian scale.
Homology, Genes, and Evolutionary Innovation By Günter P. Wagner
Princeton University Press, Apr 13, 2014 - Science - 496 pages
(Source)
In spite of the fact that when we look at birds and see those scales on their feet and the modified scales that are feathers, the almost reptilian looking eyes of birds, the bird's egg-laying vs. mammalian livebirth (some snakes, who are undeniably close relatives, vary between egg-laying and live-birth (oviparous; egg-laying and viviparous; live birth) -- that's not leaving much of an argument) and all the primitive superficial appearances... it seems easy to say: "Birds have little in common with mammals and clearly, by appearances, seem to be closer related to the reptile" -- well done, for the oversimplified version, and what about the Pangolin? Do the scales its covered in differ so much from the scaley feet on chickens? Or its modified scale that became a soft down-like feather? The pangolin shares traits that make it look almost reptilian, covered in "scales."
So I say... mammals and birds are closer related by a common ancestor, than given credit.
"Like hair...Feathers (modified scales) enables birds to be warm-blooded. Therefore, the answer is "yes." -- a common ancestor endowed them with the genes, but convergent evolution lead to development of separate integumentary system that enable warm blooded physiology. Inherited genetic traits 310 mya -- though hair and feather for warm-bloodedness, was a result of convergent evolution.
-- Birds and mammals, are not a million miles apart on the evolutionary tree as some tend to think. No more than the Alligator is so drastically different from its ancestors who roamed 100+ million years ago.
“Reptiles don’t really have great press,” said Gordon M. Burghardt, a comparative psychologist at the University of Tennessee at Knoxville. “Certainly in the past, people didn’t really think too much of their intelligence. They were thought of as instinct machines.” But now that is beginning to change, thanks to a growing interest in “coldblooded cognition” and recent studies revealing that reptile brains are not as primitive as we imagined. The research could not only redeem reptiles but also shed new light on cognitive evolution.
Because reptiles, birds and mammals diverged so long ago, with a common ancestor that lived 280 million years ago, the emerging data suggest that certain sophisticated mental skills may be more ancient than had been assumed — or so adaptive that they evolved multiple times."
(Source, "Coldblooded Does Not Mean Stupid")
Birds and mammals have an innate intelligence. Mammals were never true reptiles, and there are many "gray areas" in evolution, including the diapsids. There is no "law" that says all diapsids were all "dumb reptiles". :-(
Which brings research that concludes *all intelligence* in birds and mammals, are necessarily, by some unknown law -- by default, all the result of "convergent evolution," and no benefit of the doubt, these genes, in some form were not derived from an ancient archosaurian common ancestor.
"More than 50 genes contributed to their convergent specialization and were enriched in motor control and neural connectivity functions. These patterns were not found in vocal nonlearners, but songbird RA was similar to layer 5 of primate motor cortex for another set of genes, supporting previous hypotheses about the similarity of these cell types between bird and mammal brains."
(Pfenning et al., "Convergent transcriptional specializations in the brains of humans and song-learning birds," Science, Vol. 346: 1256846-1 - 1256846-13 (December 12, 2014). )
Counter-argument by an I.D. proponent:
"So certain birds and humans use the same genes for vocalization -- but those genetic abilities are absent in non-human primates and birds without vocal learning? If not derived from a common ancestor, as they clearly were not,
REALLY?! IS THAT SO?
how did the genes get there? This kind of extreme convergent genetic evolution points strongly to intelligent design. The authors of the paper are, to be sure, not ID advocates. Yet they acknowledge how big the problem of convergent genetic evolution is becoming for evolutionary biology".
(Source)
As the article concluded about Reptile intelligence:
"...the emerging data suggest that certain sophisticated mental skills may be more ancient than had been assumed — or so adaptive that they evolved multiple times."
(Source)
Not omitting how many species can vocalize (Source) and "speak".
On the evolution of feathers and hair.
It's quite possible that since genes to grow hair were inherited from a common ancestor 310 million years ago -- and without hair, insulation, the warm-blooded can not survive in cold temperatures. Hair and feathers are necessary for the warm-blooded. There was a great ice age around 320-260 mya. And another cold season around 200 mya. It's quite possible the climate drove these changes.
Climate would provide a possible explanation behind the development of fur and feathers.
The new date some scientists have given for the rise of mammals is 220-201 mya.
"...We know that fur has to be ancient. The evolutionary tree of modern mammals is a very furry one, and the last time the three major lineages of today’s beasts – the monotremes, marsupials, and placentals – shared a common ancestor was in the Triassic, over 220 million years ago. There’s no indication that hair evolved more than once, so fur has to be at least that old."
(Source)
Dr. John A. Ruben offers a counter-argument to the suggestion that climate change, weather, and warm-blooded physiology lead to the development of fur and feathers (Source) Selective Factors Associated with the Origin of Fur and Feathers)
However, this is in contradiction to the conclusion arrived at elsewhere by his colleagues, in regard to Anchiornis huxleyi, a creature described by Dr. Feduccia as possessing "non-theropod sacral anatomy" and having "feathered feet" namely,"...illustrating also that it could not have been a terrestrial animal..." (Source) See the following excerpt.
Feathered feet, or the "snowshoe" in nature:
THE “SNOWSHOE EFFECT” OF THE FEATHERING ON PTARMIGAN FEET
"...Foot feathering clearly increases the bearing surface of the foot by about four times and reduces sinking of the foot in snow by about half. The demonstrated snowshoe function of the foot feathering surely is adaptive, for it must inevitably reduce the energy required for all leg movements on snow."
Department of Physiology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7. Accepted for publication 5 July 1976.
(Source)
Therefore it can be safely deduced that climate, snow, temperature does in fact have an impact on the development of fur and feathers.
No comments:
Post a Comment