”These discoveries pose a problem for the idea that the Cambrian ancestors were too small to survive in the fossil record. The sedimentary rocks that preserve the fossilized cyanobacteria and single-celled algae are far older and, therefore, far more likely to have been destroyed by”
but they HAVE been preserved, and they HAVE been found. why do you spend pages and pages on dealing with the problem.. that has been solved already?
Stephen, you are History major, so naturally you speak of history. Do not speak of current affairs with your knownledge of history. You do not do so well.
”Yet few such precursors have been found.”
and you know about them! and since 90´s when you last checked, a lot more have been found. Whole lectures of Ediacaran biota can be found. Paleontologist know a lot of them these days, so your claim is already old, and false.
What does a real paleontologist stay?
"Now, a million years is certainly a long period of time by some standards, but it is an eyeblink in geologic history. Events occurring within less than a million years' time can create patterns of abrupt change in the fossil record" - (Eldredge, N. and Tattersall, I., The Myths of Human Evolution Columbia University Press, 1982, p. 57)
Now starts the Smoke and mirrors part:
”First, some paleontologists have questioned whether soft-bodied ancestral forms of the hard-bodied Cambrian animals would have even been anatomically viable. They argue that many animals representing phyla such as brachiopods and arthropods could not have evolved their soft parts first and then added shells later, since their survival depends upon their ability to protect their soft parts from hostile environmental forces."
Survival depended on their hard parts... so if an animal developed some hard parts... would that really increase it´s changes on survival?
You stephen just debunked yourself!!! OMG!
but that part sounds reasonable until you start to read it with a thought.
continue:
" Instead, they argue that soft and hard parts had to arise together.17 As paleontologist James Valentine, of the University of California, Berkeley, has noted in the case of brachiopods, “The brachiopod Bauplan [body plan] cannot function without a durable skeleton.”
WTF? I CANNOT SURVIVE WITHOUT MY SKELETON! because that´s how i am built. That´s how I have evolved.
Does that statement somehow indicate that brachiopods ancestors could not in any way function if they were smaller or somehow did not have these hard parts???
NO!!
" Or as J. Y. Chen and his colleague Gui-Qing Zhou observe: “Animals such as brachiopods . . . cannot exist without a mineralized skeleton. Arthropods bear jointed appendages and likewise require a hard, organic or mineralized outer covering."
TRUE, but it does not mean they did not evolve from soft bodied animals that found great advantage from harder body parts. SMOKE AND MIRRORS!
”It should be pointed out that this argument cannot be made for all Cambrian animal groups and, in my view, does not achieve the standing of a “proof” in any case.”
FINALLY Stephen agrees! you are not without hope!
and as Eldredge said, a lot can happen in million years, especially with short lived cambrian animals. evolution from shoft bodied into hard bodied CAN happen in ONE million years, fossil records have many evolution explosion eras, so Cambrian is no way special in that accord. think of mammals.
Mammalian evolution was hindered by the presence of dinosaurs. Any time they started to increase in numbers, they were eaten. But when meteor killed anything that were too large, could not hide underground or fly, very small mammals found that they could multiply and fill the land like moses taught them (sorry for the pun) they filled the land rapidly and started a very quick speciation and growth and diversion. Mammals inherited the land. evolution slowed down when they could no longer multiply without limit because other mammals started to hunt and kill each others.
”Thus, it seems unlikely that these interdependent subsystems would evolve independently first without an exoskeleton, only to have the exoskeleton arise suddenly as a kind of accretion atop an already integrated system of soft parts at the end of a long evolutionary process.”
I agree. Thingsdo not appear suddenly atop an integrated system of soft parts ant the end of a long evolutionary process.
animals living in the sea usually do not have bones, they have Cartilage. Bones are harder and ... well, more evolved than cartilage. would anyone believe that some animal suddenly developed hard bones just because it needed those to survive on dry land? that´s basically what you suggest.
Never thought that hardening of the exoskeleton would be a gradual process and we just do not have enough fossils to show the difference of a little harder skin of a little less soft ancestor? we might not ever be able to prove it but it does not make it possible, logical, unavoidable.
”This, again, makes it reasonable to expect that at least some rudimentary arthropod hard parts would have been preserved in the Precambrian if arthropods were present then.”
You are absolutelly right. do you think such a things exist...?
WIKIPEDIA:
ø Evidence suggests that significant diversification had already occurred before trilobites were preserved in the fossil record, easily allowing for the "sudden" appearance of diverse trilobite groups with complex derived characteristics
Ø Phylogenetic biogeographic analysis of Early Cambrian Olenellidae and Redlichidae suggests that a uniform trilobite fauna existed overLaurentia, Gondwana and Siberia before the tectonic breakup of the super-continent Pannotia between 600 million years ago and550 million years ago.[6] Tectonic breakup of Pannotia then allowed for the diversification and radiation expressed later in the Cambrian as the distinctive olenellid province (Laurentia, Siberia and Baltica) and the separate Redlichid province (Australia, Antarctica and China).[6][19] Breakup of Pannotia significantly predates the first appearance of trilobites in the fossil record, supporting a long and cryptic development of trilobites extending perhaps as far back as 700 million years ago or possibly further.[19]
Any creationist can tell you that this only proves that wikipedia is not reliable source because it can prove you wrong!!
”As paleontologist George Gaylord Simpson noted in 1983, even if it’s true that Precambrian ancestors were not preserved simply because they lacked hard parts, “there is still a mystery to speculate about: Why and how did many animals begin to have hard parts—skeletons of sorts—with apparent suddenness around the beginning of the Cambrian?”
First, mystery is what drives scientists, second,why can I find this quote ONLY on christian sites?
and as a side note, George was raised christian, and his education and discoveries made him an agnostic.
Ei kommentteja:
Lähetä kommentti