Tadpole Shrimps - Evolutionary Giants or 250-million-year pieces of stagnant organism?
398186
Notostracans (often just called Triops, tadpole shrimp or shield shrimp) are small crustaceans in the Branchiopoda group. Triops have internal compound eyes and a flattened shield covering the head and leg-bearing segments of the body. The order contains a single family, with only two extant genera. Their external morphology has not changed since the Triassic (appearance of Triops cancriformis around 220 million years ago). Triops cancriformis may therefore be the "oldest living animal species on earth" (Kelber, 1999).\n\nTadpole shrimps usually live near the ground of astatic pools, where they move with their ventral side down. However, lack of oxygen can force them to swim upside-down with their gill-like legs close under the surface of the water. Notostraca are omnivorous; they dig around in the mud using the frontal part of their shield, looking not only for plankton but also for larger prey such as worms, chironomid larvae and even weak tadpoles. Anostracans, often associated with notostracans, can also be a considerable part of their prey (especially when weak or dying).\n\nNotostracans sometimes even cannibalize freshly moulted members of the same species. In northern and central Europe, with few exceptions, all tadpole shrimps are female, whereas sex ratios in southern and western Europe as well as in northern Africa are near unity. These "females" possess hermaphroditic glands, but instead of selfing, parthenogenesis takes place. Modified appendages of the 11th pair of limbs bear the ovisacs with the mature eggs.\n\nTriops evolved to survive in naturally temporary ponds all over the world. As inhabitants of such, there has never been any pressure for them to become long-lived creatures. These ponds usually dry up during certain times of the year when there is no rainfall. Although the adult Triops die during these droughts, the embryos remain in a state of diapause (suspended animation) until the rains return and fill up the temporary ponds once again, making it safe for them to hatch.\n\nThe maximum life spans in the lab agree with data from field observations on Triops survival. In the lab, T. longicaudatus has a maximum lifespan of about 50 days and T. cancriformis a maximum lifespan of about 90 days, with some individuals beginning to die off as soon as 2 weeks after hatching. Secondarily, some may suffer premature deaths from moulting complications or other reasons.
1024565
Complexity? Other than extinctions, most species still exist as they have. We have observe no mutations of single celled creatures, no transition phases in the fossil record, or anything else that would support evolutionary theory.\n  The evolutionary course of the horse for instance is still found in the tapir of South America. I could go on , and on.\n  Did you know the tooth they based Peking man on was actually from an extinct pig?!? However school books have not been revised. Evolutionist are still presenting this as "proof".
25529
I believe so. I think they have just evolved into smaller things like iguanas, gheckos, lizards....etc.
1123642
I think the word YET needs to enter your train of thought. 10 years ago there was no evidence to suggest that the Archaeopteryx wasn't the ancestor of all birds, now we know more and find that there is something that pre-dates it. In 20 years time there might well be eveidence to pre-date it yet further.\n\nWho knows what will turn up? Do you think this find discredits the theory of evolution or is it just the established theory of the evolution of birds that, until more evidence is discovered, has been undermined?
100140
Dinosaurs died 100,000,000 years ago. \nThey're gone! Get over it.
24541
We can't really prove it. All their insides were decayed, so the only evidence of them being reptiles is their bone structure. But for all we know, they could have been fuzzy, warm blooded, dinosaurs. There is no way to determine either way scientifically, because we can't see a live one.
851769
We do not find countless transitional fossils for the same reason we do not find countless non-transitional fossils.  Fossilization is a VERY rare occurrence.  We are actually very fortunate to have the number of transitional fossils we do have.\n\nOne reason you do not see intermediary species everywhere is because the vast majority of species don't evolve.  They go extinct.  Evolution is fueled by environmental pressures.  When the environment changes drastically in a short period of time, it's far more likely for species to go extinct than for a lucky member to be born with some favorable mutation that allows it to mate and disperse it's dominant genetic traits into the gene pool.\n\nAt the same time, when the environment changes slowly, over millions and millions of years, the evolutionary changes can be so subtle that it can be difficult, if not impossible, to determine where one species ends, and another begins.  These ARE the "innumerable transitional forms" to which you refer.  Even today there are thousands of different insect species that, to the untrained eye, appear to be the same, but are not.\n\nI recommend a good way for you to sort out the facts from the misinformation would be by reading Evolution and the Myth of Creationism by Tim M. Berra.  It's an easy to follow, introductory guide to the basic facts of evolutionary theory.
1023108
The fossil history is false. The scientists don't know what they are talking about. Radiometric dating is flawed. Everything is a lie except the Bible. I am trying out the other side of this argument. It's pretty weak I must say.
431352
Snakes lost their legs on land, not in the sea as previous scientists thought, according to new research by professor of biology S. Blair Hedges and postdoctoral fellow Nicolas Vidal.\n\n"Everyone agrees that snakes evolved from lizards and are close relatives to lizards," Hedges said. "What is controversial is the specific group, whether on the land or in the sea."\n\nScientists estimate that snakes evolved 150 million years ago, Vidal said. For many years, they believed in the terrestrial or land theory, which says that snakes evolved from lizards that burrowed underground.\n\nThen, seven years ago, the discovery of a fossilized marine snake with tiny hind legs fueled the marine hypothesis that snakes lost their legs in the sea. The marine snakes called mosasaurs are now extinct, but their closest cousins, the monitor lizards such as the Komodo Dragon, are still alive today.\n\nHedges and Vidal chose two genes and compared them in lizards and snakes to see how closely they are related. From statistical analysis of these gene sequences, they created a family tree.\n\n"These two genes have accumulated different mutations in the different species," Vidal said. "These differences between the species are used to build the evolutionary trees. Snakes are not closely related to the monitor lizards, which means that they cannot have marine origins."\n\nHedges and Vidal's research is significant because of the comprehensive scope of the snakes and lizards studied. They collected DNA from 64 species representing all 19 families of living lizards and 17 of the 25 families of living snakes, Vidal said.\n\n"We mostly acquired DNA from the soft tissues, blood, shed skin, scales and tips of the tails of the animals," he said. "A very small amount is needed, so we can get the sample without killing the animal."\n\nHedges and Vidal acquired samples from other colleagues, their own collections, fieldwork in South America and pet stores that trade exotic animals, Hedges said.\n\nSome of the samples were difficult to acquire because some snakes and lizards are limited to certain parts of the world, such as remote islands, but it was crucial to their study.\n\n"We felt it was important to analyze genes from all the lizard groups, because almost every lizard family has been suggested as being the one most closely related to snakes," Hedges said. "If we had failed to include genes from even one of the lizard families, we could have missed getting the right answer."\n\nA possible theory to explain why snakes dropped their legs on land is that limbs are not conducive to their burrowing habits, Vidal said.\n\n"The idea is that if you have limbs sticking out, it's difficult to get into small openings," Hedges said. "It's more advantageous, because it enables snakes to get more food and offers safety from predators."\n\nHedges and Vidal did not find the closest lizard relative to snakes, but they did succeed in eliminating the monitor and marine lizards as possibilities.\n\n"This study doesn't answer all the questions," Hedges said. "In most fields, questions aren't answered all at once. They're answered in increments, and in this study, we've ruled out the marine theory, but that still leaves a lot of possibilities."\n\nHedges and Vidal said they hope to find the closest relative to snakes in the next year.\n\n"The work by Dr. Hedges and Dr. Vidal is a tremendous contribution to the body of knowledge," said Bryan Fry, deputy director of the Australian Venom Research Unit at the University of Melbourne in Australia. "Their data provides strong evidence for the terrestrial loss of limbs."
559225
Much of the support for the idea that snakes evolved at sea is their close phylogenetic relationship with the extinct group of marine reptiles, the mosasaurs.\n\nBoth snakes and mosasaurs share a number of unique characters, such as a hinge in the middle of the lower jaw, loss of the symphysis joining the two halves of the lower jaw, and the stabilization of the spinal column (the zygosphene-zygantra articulation).  These adaptations seem to have been a major evolutionary success, and led to adaptive radiations of the mosasaurs, snakes and the aigialosaurs (another extinct related group).\n\nIf the group (often called the Pythonomorpha) evolved at sea, it would explain a lot of the other adaptations (such as reduced or modified limbs) that these groups show.  However, more and more the fossil evidence seems to indicate that the Pythonomorpha probably evolved on land, and then each group developed adaptations ideal for marine environments totally separately.\n\nThis solution is not as elegant as it would be if all of the adaptations in the Pythonomorpha occurred at the same time, but it appears that sometimes evolution does not occur as elegantly as we might like.\n\nA terrestrial origin for snakes does explain some of the other unusual features of snakes, such as their eyes which show signs of having been reduced or completely lost at one point, and then an entirely new visual anatomy developed as they re-emerged from a subterrainean existence.
589339
The earth is 4.6 billion years old. The sun is close to 5 billion. Liquid water did not exist on earth until about 4 billion years ago. Life seems to have appeared 3.8 billion years ago. By 3.5 billion years ago, we have fossilized stromalites which are IDENTICAL to the ones still made today by prokayote blue-green algae in the Indian ocean.\n\nThe first eukaryote organisms (with cells structures like ours) first show up 1 billion years ago. Within 500 millions years from then, complex forms can be found in the fossil record which are ancestral to modern lineages. But here are NO fish, amphibians, reptiles, mammals or birds. These all arise later in sequence by evolutionary modification as the fossil record clearly shows.\n\nThe bottom line is that only evolution provides a comprehensive argument that explains what we see in the fossil record. The Intelligent Design people are frauds who misrepresent the data and are no more credible that the Gish/Morris combine of liars that plaugued us in the 70s and 80s.\n\nI (Dr. Art Sippo) am a 53 year old cradle Catholic with a BS in Chemistry (Magna cum laude)from St. Peter's College, an MD from Vanderbilt University, and a Masters in Public Health from Johns Hopkins. After Catholic apologetics, paleontology is my favorite hobby. I have been studying it since I was a kid in the 1950s.\n\nWith regard to "macroevolution" that term is actually passe. It is still touted by Creationoids so that they can say they support microevolution but not macroevolution. These terms were used around 30 years ago before the discovery of the complexity of eukaryote genetics. Microevolution was what happened when there were single alterations either in DNA sequences or protein sequences due to mutations. There were other mechanisms that worked in bacteria (eg., conjugation, plasmids) but their utility in eukaryotes was questionable. At that time it was assumed that prokaryote (eg, bacterial) genetics was directly applicable to eukaryotes (eg, mammals). We now know that this is not so.\n\nEukaryote genetics is so complicated that it has not been fully elucidated. There is modification of the transcription of DNA to messenger RNA, a further cropping of m-RNA into introns and extrons, and further modification of the proteins for which they code. None of this happens in prokaryotes.\n\nAlso eukaryotes use a "homeo box" generalized assembly kit which is functionally identical in all lineages and which can with slight tweaks make large changes in how the genotype (DNA data) is expressed into a phenotype (external structure). \n\nAlso, eukaryotes use chromosomes which rearrange themselves spontaneously in several different ways. This helps to contribute to evolution in the absence of any DNA mutations.\n\nAll of these mechanisms -- and more -- contribute to evolution. In fact everything that is necessary for what had been called "macroevolution" is present in these more complex genetic systems.\n\nWith regard to the changes in species of higher animals, many Creationoids have said that there were large systematic gaps between major taxa. They are right, In the linnean system there are large SYSTEMatic gaps, but these gaps are due to the system of classification, and do not correspond to real biological differences. Linnaeus was a Creationoid. He thought that each species was distinctly made by God. So he created a complex classification system that emphasized distinctions and did not assume common descent. In reality, his classifications were merely man-made conventions that limped badly. For example, the Class Reptilia included not only lizards but snakes (some of which bear live young and don't lay eggs), turtles, crocodiles (that all have 4 chambered hearts), dinosaurs (some of which have feathers), ichthyosaurs, mososaurs, plesiosaurs, and pterosaurs (some of which have fur). The problem with fish is even more complex.\n\nIn many cases, an organism does not fit into the Li
339373
There are two theories to explain how the Platypus has evolved into what it is today. The first (theory B) shows that relatives of monotremes formed their own evolutionary branch that was completely different from development of both marsupials and placentals. This change is thought to have occurred 135 million years go, the beginning of the Cretaceous period. The marsupials and the placentals divided at some point 135-65 million years ago.\n\nThe Second (theory A) was proposed by Gregory (1947) and was not popular until the 1970s. He said that between 135-65 million years ago, the placentals and marsupials separated to their own way then later the monotremes and the marsupials went their own way.\n\nEvidence for this theory is that the reproductive systems of monotremes and marsupials are extremely similar. The embryos of both have some stage of encased shells in the gestation period. The only difference is that monotremes have the encased shells throughout the entire gestation period, whereas marsupials only have the encased shells for about two thirds of the gestation period.\n\nAre you denying that evolution exists at all?
291260
Adaptation? Evolution?
794255
A lot of vertebrate metamorphosis study outside of amphibians is aimed at fish. Fish to look up include lamprey and flatfish. Vertebrate metamorphosis tends to be attributed to thyroid hormones. Unfortunately a lot of articles are in journals rather than online. The online stuff tends to be summaries/abstracts.\n\nAn introduction to the whole idea. It starts with invertebrates, but shows how the systems evolve up to vertebrates:\nhttp://www.thyroidmanager.org/Chapter1/index.html\n\nSpecific articles on the subject, mainly focusing on fish:\nhttp://www.sgnis.org/publicat/papers/az37_441.pdf\nhttp://findarticles.com/p/articles/mi_qa3746/is_199804/ai_n8798333\nhttp://www.ciwemb.edu/labs/schreiber/index.php\nhttp://www.findarticles.com/p/articles/mi_qa3746/is_199712/ai_n8778286\n\nA scientific journal article that might be useful if you can find it:\nWald, George (1958) The significance of vertebrate metamorphosis. Science 128:1481.\n\nYou may find more of interest in the references sections of the links provided.
864911
Probably not (and you probably mean "ancestors.")\nIt may have been some other lobe-finned fish, or some other fish with limb-like fins.
1135377
You have to look at evolution as a series of slight beneficial changes that are passed down through generations.  The steps from single to double circ are unknown to me, but it is more than a single big jump.
320406
There are many things that support the theory of evolution.  Mainly, the fossil record and the fact that you are here, though if natural selection holds true, you will not be working in any fied of science any time soon. \nThe tide example that you state does not disprove evolution because it's false; the amount of water in the world has not change as you suggest.  There is no reason to believe that any change in tides would work increasingly to cover the earth with water.  There are fluctuations in the level of the seas that follow geological and thermal events over the course of centuries and millenia, like the ice ages. In second place, evolution is not about the age of the earth, it's about natural adaptation to the environment. Examples to prove it can be found anywhere in nature.  Sea iguanas in Galapagos are one of the best-known examples of adaptive development.   If there was no evolution, these iguanas would be terrestrial like all of the other species of iguana in the world.  But they're not, they have evolved an adaptation to marine environments.  Think of that as a microcosm of what happens in the rest of nature.\nWhy do we have a residual tailbone?  Why do whales have residual fingers?  We don't have tails and we don't need them, but the tailbone is there...  If someone meant for us to have a tail, they would have given us a tail or none altogether.  The fact that we have a bone structure that serves no apparent purpose but to cause pain when you fall on your but and break it proves that there is an ongoing process that we are a part of.\nEvolution does not exclude creation, it just makes creation dynamic and alive at a much broader scale.  That creation cannot be a process driven by biology instead of a stagnant  pile of events is not written anywhere in any holy book.