Trilobita
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Trilobitas são artrópodes extintos. Um dos parentes vivos mais próximos do trilobita é o caranguejo-ferradura (Limulidae). Os corpos dos trilobitas são divididos em três partes: um cefalon (cabeça), um tórax (corpo); e um pigídio (cauda). Os trilobitas são freqüentemente encontrados enrolados como insetos de hoje para proteção. Os trilobitas variam em comprimento de um milímetro a 70 cm. Os trilobitas viveram nas águas marinhas. A maioria sabia nadar, mas alguns não, então simplesmente rastejavam no fundo do oceano. Eles ainda não sabem ao certo por que foram extintos. A maioria dos cientistas pensa que os trilobitas podem ter se tornado a principal fonte de alimento quando surgiram os primeiros tubarões. Outros como eu acham que foi por causa do dilúvio de Noé e seus corpos estavam muito fracos para lidar com todo o mar agitado.
Anatomia
Todos os trilobitas têm as mesmas partes do corpo, uma cabeça (cefalão), um corpo (tórax) e cauda (pigídio). O corpo também pode ser dividido em três comprimentos, daí o nome trilobite. O espesso exoesqueleto dorsal é composto por uma estrutura complexa de quitina e proteína, espessada e endurecida pela calcita. Os artrópodes modernos têm um sistema circulatório aberto. Os olhos dos trilobitas são o sistema visual mais antigo conhecido. Os olhos são compostos como os olhos de crustáceos e insetos hoje em dia. Eles são compostos de muitas lentes minúsculas. Alguns trilobitas eram cegos. [1]
Olhos
Os trilobitas foram o primeiro grupo de animais do reino animal a desenvolver olhos complexos. Os trilobitas do Cambriano já possuíam um sistema visual altamente avançado. O número de lentes em um olho trilobita varia, alguns trilobitas tinham apenas uma, enquanto outros tinham milhares de lentes em um único olho. As lentes têm o formato de hexágonos, seis lados.
Existem três tipos de sistema de olhos trilobita:
O olho Holocroal
o olho esquizocroal
o olho abatocroal
Os dois primeiros são os tipos principais, a grande maioria dos trilobitas tem olhos holocroais.
Alguns trilobitas não têm lentes. Na verdade, alguns nem têm olhos.
Esta é uma parte importante para provar o criacionismo e que a arca de Noé era real. Seus olhos são tão complexos que eles não podem simplesmente ser assim, eles tiveram que ter sido criados por alguém (Deus). Os evolucionistas não conseguem explicar por que seus olhos são tão complexos uma vez que eles sabem que eles não podem ser tão primitivos, sem ter um criador.
[2]
Ecologia
Trilobitas só foram encontradas em leitos fósseis oceânicos. Nenhuma forma de água doce foi encontrada. Eles ocupavam muitos ambientes oceânicos diferentes, de bancos rasos e recifes, a fundos oceânicos mais profundos, e até mesmo a coluna de água, como plâncton flutuante ou formas de natação livre. Trilobitas de diferentes habitats frequentemente tinham formas especializadas. Partículas de comida eram agitadas pelas pernas e passadas para a frente até a boca, e como eles não tinham uma mandíbula inferior muito grande, eles obviamente tinham certeza de que não eram geralmente predadores, pois só podiam comer comida macia. [3]
Reprodução
Scientists think that Trilobites reproduced sexually,so do mostly all arthropods now day. No-one is quite sure how trilobites reproduced, although some fossils have been found that appear to have egg sacs attached to their bodies. other fossils have been found that show trilobites shed their exoskeleton several times as they grew up, adding a new segment to their abdomen and getting bigger each time, they molted their exoskeletons as they grew, as all arthropods today do. [4]
Desenvolvimento
There are three development stage periods for the trilobite.
1. A Protaspid Period
This is the Larva stage. It is composed of and uncompleted exoskeleton.
2. The Meraspid Period
This is when the body is only complete with two united segments. Every time it molts it will add another one or two.
3. The Holaspid Period
This is when no more of the segments can be added during molts. After this is completed it now is called a Holaspis. The major change is not in what it looks like, but if it will increase in size. [5]
Extinção
The Trilobites were said to have become extinct around 550-750 million years ago. They were said to have become extinct when the first sharks and other early fishes in the Silurian and Devonian periods. Trilobites may have provided a main source of food for them. Their low numbers and diversity at the end of the Permian, which probably added to their extinction during that great mass extinction event. There is also the possibility of it being from Noah's flood and that there little and weak bodies were to weak to handle the rough waters of the flood.
Distribuição fóssil
Trilobites appear to have been only marine organisms since the fossilized parts of trilobites are always found in a rock with fossils of other salt-water animals like brachiopods, crinoids, and coral, and they are found in a range of environments from extremely shallow water to very deep water. The tracks left behind by trilobites crawling on the sea floor are sometimes kept as trace fossils. Trilobite fossils are found worldwide. They were one of the first fossils to get attention, new species are being discovered every year. The Native Americans gave a name for the trilobite which means "little water bug in the rocks." A famous location for trilobite fossils in the United Kingdom is Wren's Nest, Dudley in the West Midlands.
The fossil is now on display to the public. Dr Graham Young said: "We have found a very unusual specimen that illustrates some of the diversity and weirdness of ancient life. A trilobite of this size really is an amazing discovery." In July 1998, a team of scientists went out to northern Manitoba hoping they would find fossils similar to the ones uncovered by the previous digs, like the 43-cm (17-inch) long trilobite found in the area a decade before. [7]
Visão evolucionista
The evolutionist believe that the Trilobites were alive millions of years ago (around 550-750 million years ago). They also believe that it had nothing to do with Noah's flood, which is one of the highest possibilities.
They don't really have an explanation to the complexity of the Trilobite eye. They think that as time goes on that creatures will get more and more complex and complicated, but that is not true. It really already began that way, we can tell because of the trilobite eye. They have a lot to do with how life began.[8]
Visão criacionista
The creationists believe that the Trilobites became extinct because of Noah's flood, they think that their bodies were to small and weak to curl up and defend themselves from the rough seas.
Most people think that the Trilobite is a very simple creature but it is not in fact. It is a very complex creature, especially it's eye which is so complex that it could not have evolved,especially since there are no transitional fossils that indicate an evolution. This goes to show that it must have had a Creator. This has only been discovered a couple years ago. [9] Evolutionists try to say that now the creatures are getting more and more complex and complicated as life goes on, but really it already had started out that way. [10]
Kurt Wise believes that the best extra-biblical evidence for creation would come from the design of a Trilobite eye and that this creation by God is the most reasonable hypothesis for the reason of the complexity of the trilobite’s schizochroal eye.
[11]
Videos
Galeria
Selenopeltis, a Moroccan trilobite.
small Flexicalymene meeki trilobite is in the classic "rolled" defensive position
Paraceraurus exsull, Russian Ordovician.
Ligações externas
- Trilobite Reproduction and Development Last revised 08 November 2007 by S. M. Gon III
- Trilobites David L. Alles Western Washington University Trilobite: Eyewitness to Evolution, Vintage Books (2000).
- Guide to Trilobites A Guide to the Orders of Trilobites Dr. Sam Gon III
- The Fossil Record Technical Journal 14(1):110–116 April 2000 by John Woodmorappe
- Trilobite technology: Incredible lens engineering in an ‘early’ creature by Charles Stammers. Creation 21(1):23–0. December 1998
- Un-Bee-lievable Vision by Frank Sherwin, M.A. February, 2006
- ‘My favourite evidence for creation!’ by Kurt Wise. Creation Ex Nihilo, Sept.-Nov. 1989, Vol. 11 No. 4, p. 29
- Invertebrates: animals without backbones by Dr. Gary Parker. Facts of Life Chapter 3: The fossil evidence
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