Da, exact asta vedem, cum reptilele au suferit mutatii timp de milioane de ani, cum s-au redus trasaturile reptiliene pas cu pas si au crescut in numar cele aviene.
Daca fosilele arata asta, de ce, atunci, printre speciile supravietuitoare de astazi nu gasim specii intermediare intre reptile si pasari? Avem tot felul de reptile, avem tot felul de pasari, dar n-avem chiar dovada care ar confirma - sa zicem - presupunerea bazata pe marturia fosilelor. De ce trebuie sa va chinuiti cu o amarata de fosila Archaeopteryx, cand ar trebui sa aveti o sumedenie de specii in viata? (Tinand cont de mutatiile genetice si selectia naturala care au lucrat milioane de ani)
Raspunsul il stii si singur: pt. ca speciile se sting, nu supravietuiesc toate. Dupa cate stiu eu nici dinozauri nu mai exista, deci nu doar ca nu dispunem de specii intermediare, in cele mai multe cazuri nu mai dispunem nici de speciile originale. Stim insa ca aceste specii originale si "intermediare" au existat, dispunem de fosilele lor. Archaeopteryx nu a supravietuit pana azi, inseamna ca nu a existat?
Asadar: avem mii de specii de reptile supravietuitoare, avem mii de specii supravietuitoare de pasari, dar cand vine vorba de speciile supravietuitoare intermediare intre reptile si pasari, pauza. Desi tranzitia de la reptile la pasari s-a produs prin mutatii genetice si selectie naturala, in decursul a miliaone de ani. Normal ar trebui sa existe cel putin tot de ordinul miilor de specii intermediare. Culmea! E ca un facut!
Dar cum evolutionistii se agata de orice, iata ca il au pe Archaeopteryx - fosilizat, doar n-ati crezut ca viu!?
Corect era sa zici: avem mii de specii de
reptile dinozauri supravietuitoare, avem mii de specii supravietuitoare de pasari, dar cand vine vorba de speciile supravietuitoare intermediare intre
reptile dinozauri si pasari, pauza."
A, asa suna altfel, nu?
Avem dinozauri supravietuitori Daniel? Deci ca sa intelegem si noi astia mai prosti ca tine, folosind logica ta ilustra, faptul ca azi nu exista mii de cutare specii, inseamna ca ele nu au existat(!?). Nu avem azi mii de specii de dinozauri? Raspunsul: "Culmea! E ca un facut!
". Adica, dinozaurii n-au existat, nu-i asa academician Daniel?
Ca sa ne revenim un pic din logica asta ametitoare: nu ne trebuie specii in viata ca sa stim ca ele au existat mai demult. Avem fosilele lor,
deci stim ca au existat. Avand in vedere ca e atat de simplu, de ce perseverzi in ilogic? Pt. ca atunci cand vine vorba de fapte care ameninta existenta conceptuala a dzeului tau drag, faci scurt-circuit. Ai un blocaj mental care scurtcircuiteaza realitatea, logica, ratiunea.
Si apoi sunt convins ca din studiile tale amanuntite efectuate in directia asta, ai aflat ca fosilizarea e un eveniment extrem de rar, fiind nevoie de foarte multe "intamplari fericite" ca toti factorii necesari sa fie prezenti si deci sa aiba loc. Citeam intr-o carte ca fosilele de care dispunem azi reprezinta aproape 1% din toate speciile care se estimeaza ca au trait in trecut pe pamant.
Tu ai spus initial ca din fosile se observa cum reptilele au suferit mutatii timp de milioane de ani, cum s-au redus trasaturile reptiliene pas cu pas si au crescut in numar cele aviene.
Problema este ca nu aveti acoperire si-n realitate.
Problema este ca voi aveti tare multa ignoranta. Ia de-aici (luata de pe o pagina care porneste de la o publicatie Watchtower(!), o carte despre creatie care am impartit-o si eu la greu, prima data in studentie, unui prieten de la silvicultura care a ras cu curul dupa ce a citit din ea):
http://www.talkorigins.org/indexcc/CC/CC214.htmlMany new bird fossils have been discovered in the last couple of decades, revealing several intermediates between theropod dinosaurs (such as Allosaurus) and modern birds:
Sinosauropteryx prima. A dinosaur covered with primitive feathers, but structurally similar to unfeathered dinosaurs Ornitholestes and Compsognathus (Chen et al. 1998; Currie and Chen 2001).
Ornithomimosaurs, therizinosaurs, and oviraptorosaurs. The oviraptorosaur Caudipteryx had a body covering of tufted feathers and had feathers with a central rachis on its wings and tail (Ji et al. 1998). Feathers are also known from the therizinosaur Beipiaosaurus (Xu et al. 1999a). Several other birdlike characters appear in these dinosaurs, including unserrated teeth, highly pneumatized skulls and vertebrae, and elongated wings. Oviraptorids also had birdlike eggs and brooding habits (Clark et al. 1999).
Deinonychosaurs (troodontids and dromaeosaurs). These are the closest known dinosaurs to birds. Sinovenator, the most primitive troodontid, is especially similar to Archaeopteryx (Xu et al. 2002). Byronosaurus, another troodontid, had teeth nearly identical to primitive birds (Makovicky et al. 2003). Microraptor, the most primitive dromaeosaur, is also the most birdlike; specimens have been found with undisputed feathers on their wings, legs, and tail (Hwang et al. 2002; Xu et al. 2003). Sinornithosaurus also was covered with a variety of feathers and had a skull more birdlike than later dromaeosaurs (Xu, Wang, and Wu 1999; Xu and Wu 2001; Xu et al. 2001).
Protarchaeopteryx, alvarezsaurids, Yixianosaurus and Avimimus. These are birdlike dinosaurs of uncertain placement, each potentially closer to birds than deinonychosaurs are. Protarchaeopteryx has tail feathers, uncompressed teeth, and an elongated manus (hand/wing) (Ji et al. 1998). Yixianosaurus has an indistinctly preserved feathery covering and hand/wing proportions close to birds (Xu and Wang 2003). Alvarezsaurids (Chiappe et al. 2002) and Avimimus (Vickers-Rich et al. 2002) have other birdlike features.
Archaeopteryx. This famous fossil is defined to be a bird, but it is actually less birdlike in some ways than some genera mentioned above (Paul 2002; Maryanska et al. 2002).
Shenzhouraptor (Zhou and Zhang 2002), Rahonavis (Forster et al. 1998), Yandangornis and Jixiangornis. All of these birds were slightly more advanced than Archaeopteryx, especially in characters of the vertebrae, sternum, and wing bones.
Sapeornis (Zhou and Zhang 2003), Omnivoropteryx, and confuciusornithids (e.g., Confuciusornis and Changchengornis; Chiappe et al. 1999). These were the first birds to possess large pygostyles (bone formed from fused tail vertebrae). Other new birdlike characters include seven sacral vertebrae, a sternum with a keel (some species), and a reversed hallux (hind toe).
Enantiornithines, including at least nineteen species of primitive birds, such as Sinornis (Sereno and Rao 1992; Sereno et al. 2002), Gobipteryx (Chiappe et al. 2001), and Protopteryx (Zhang and Zhou 2000). Several birdlike features appeared in enantiornithines, including twelve or fewer dorsal vertebrae, a narrow V-shaped furcula (wishbone), and reduction in wing digit bones.
Patagopteryx, Apsaravis, and yanornithids (Chiappe 2002; Clarke and Norell 2002). More birdlike features appeared in this group, including changes to vertebrae and development of the sternal keel.
Hesperornis, Ichthyornis, Gansus, and Limenavis. These birds are almost as advanced as modern species. New features included the loss of most teeth and changes to leg bones.
Modern birds.
References:
Chen, P., Z. Dong and S. Zhen, 1998. An exceptionally well-preserved theropod dinosaur from the Yixian Formation of China. Nature 391: 147-152.
Chiappe, L. M., 2002. Osteology of the flightless Patagopteryx deferrariisi from the Late Cretaceous of Patagonia (Argentina). In Chiappe and Witmer, pp. 281-316.
Chiappe, L. M. and L. M. Witmer (eds.), Mesozoic Birds: Above the Heads of Dinosaurs. Berkeley: Univ. of California Press.
Chiappe, L. M., M. A. Norell and J. M. Clark, 2001. A new skull of Gobipteryx minuta (Aves: Enantiornithes) from the Cretaceous of the Gobi Desert. American Museum Novitates 3346: 1-15.
http://diglib1.amnh.org/novitates/i0003-0082-346-01-0001.pdfChiappe, L. M., M. A. Norell and J. M. Clark, 2002. The Cretaceous, short-armed Alvarezsauridae. In: Chiappe and Witmer, pp. 87-120.
Chiappe, L. M., S. Ji, Q. Ji and M. A. Norell, 1999. Anatomy and systematics of the Confuciusornithidae (Theropoda: Aves) from the Late Mesozoic of northeastern China. Bulletin of the American Museum of Natural History 242: 1-89.
http://diglib1.amnh.org/bulletins/i0003-0090-242-01-0001.pdfClark, J. M., M. A. Norell and L. M. Chiappe, 1999. An oviraptorid skeleton from the Late Cretaceous of Ukhaa Tolgod, Mongolia, preserved in an avianlike brooding position over an oviraptorid nest. American Museum Novitates 3265: 1-36.
Clarke, J. A. and M. A. Norell, 2002. The morphology and phylogenetic position of Apsaravis ukhaana from the late Cretaceous of Mongolia. American Museum Novitates 3387: 1-46.
http://diglib1.amnh.org/novitates/i0003-0082-3387-01-0001.pdfCurrie, P. J. and P. Chen, 2001. Anatomy of Sinosauropteryx prima from Liaoning, northeastern China. Canadian Journal of Earth Sciences 38: 1705-1727.
Forster, C. A., S. D. Sampson, L. M. Chiappe and D. W. Krause, 1998. The theropod ancestry of birds: New evidence from the Late Cretaceous of Madagascar. Science 279: 1915-1919.
Hwang, S. H., M. A. Norell, Ji Q. and Gao K., 2002. New specimens of Microraptor zhaoianus (Theropoda: Dromaeosauridae) from northeastern China. American Museum Novitates 3381: 1-44.
http://research.amnh.org/users/sunny/hwang.et.al.2002.pdfJi, Q., P. Currie, M. A. Norell and S-A. Ji, 1998. Two feathered dinosaurs from northeastern China. Nature 393: 753-761.
Makovicky, P. J., M. A. Norell, J. M. Clark and T. Rowe, 2003. Osteology and relationships of Byronosaurus jaffei (Theropoda: Troodontidae). American Museum Novitates 3402, 1-32.
http://diglib1.amnh.org/novitates/i0003-0082-3402-01-0001.pdfMaryanska, T., H. Osmólska and M. Wolsan, 2002. Avialan status for oviraptorosauria. Acta Palaeontologica Polonica 47(1): 97-116.
http://app.pan.pl/acta47/app47-097.pdfPaul, Gregory S., 2002. Dinosaurs of the Air. Baltimore: Johns Hopkins University Press.
Sereno, P. C. and C. Rao, 1992. Early evolution of avian flight and perching: New evidence from the Lower Creates of China. Science 255: 845-848.
Sereno, P. C., C. Rao and J. Li, 2002. Sinornis santensis (Aves: Enantiornithes) from the Early Cretaceous of Northeastern China. In: Chiappe and Witmer, pp. 184-208.
Vickers-Rich, P., L. M. Chiappe and S. Kurzanov, 2002. The enigmatic birdlike dinosaur Avimimus portentosus. In: Chiappe and Witmer, pp. 65-86.
Xu, X. and X. Wang, 2003. A new maniraptorian dinosaur from the Early Cretaceous Yixian Formation of Western Liaoning. Vertebrate Palasiatica 41(3): 195-202.
Xu, X. and X-C. Wu, 2001. Cranial morphology of Sinornithosaurus millenii Xu et al. 1999 (Dinosauria: Theropoda: Dromaeosauridae) from the Yixian Formation of Liaoning, China. Canadian Journal of Earth Sciences 38: 1739-1752.
Xu, X., Z. Tang and X. Wang, 1999a. A therizinosaurid dinosaur with integumentary structures from China. Nature 399: 350-354.
Xu, X., X-L. Wang and X-C. Wu, 1999b. A dromaeosaur dinosaur with a filamentous integument from the Yixian Formation of China. Nature 401: 262-266.
Xu, X., Z. Zhou and R. O. Prum, 2001. Branched integumental structures in Sinornithosaurus and the origin of feathers. Nature 410: 200-204.
Xu, X., M. A. Norell, X. Wang, P. J. Makovicky and X. Wu, 2002. A basal troodontid from the Early Cretaceous of China. Nature 415: 780-784.
Xu, X., Z. Zhou, X. Wang, X. Kuang, F. Zhang and X. Du, 2003. Four-winged dinosaurs from China. Nature 421: 335-340.
http://www.cals.ncsu.edu/course/zo501/4WingedDino.pdfZhang, F. and Z. Zhou, 2000. A primitive enantiornithine bird and the origin of feathers. Science 290: 1955-1959.
Zhou, Z. and F. Zhang, 2002. A long-tailed, seed-eating bird from the Early Cretaceous of China. Nature 418: 405-409.
Zhou, Z. and F. Zhang, 2003. Anatomy of the primitive bird Sapeornis chaoyangensis from the Early Cretaceous of Liaoning, China. Canadian Journal of Earth Sciences 40: 731-747.
Further Reading:
Chiappe, L. M. and G. J. Dyke, 2002. The Mesozoic radiation of birds. Annual Review of Ecology and Systematics 33: 91-124. (technical)
Dingus, L. and T. Rowe, 1997. The mistaken extinction: dinosaur evolution and the origin of birds. New York: Freeman and Company.
Padian, K. and L. M. Chiappe, 1998. The origin of birds and their flight. Scientific American 278(2) (Feb.): 38-47.
Paul, Gregory S., 2002. Dinosaurs of the Air. Baltimore: Johns Hopkins University Press.
Pojeta, John Jr. and Springer, Dale A., 2001. Evolution and the Fossil Record, American Geological Institute, Alexandria, VA.
http://www.agiweb.org/news/spot_06apr01_evolutionbk.htm ,
http://www.agiweb.org/news/evolution.pdf .
Prum, Richard O. and Alan H. Brush, 2003. Which came first, the feather or the bird? Scientific American 288(3) (Mar.): 84-93.
Wang, Justin, 1998. Scientists flock to explore China's 'site of the century'. Science 279: 1626-1627.