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Les reptiles ont apparu pendant la période « Carbonifère ». Des reptiles sont des animaux qui ont des écailles, produisants des oeufs durs sur la terre. Aujourd'hui les reptiles se trouvent assez bas par rapport à la chaine alimentaire. Ils ont une histoire évolutionnaire très diverse. Ils comptent des succès évolutionnaires comme les dinosaures.

Les reptiles ont évolué des amphibiens pendant la période « Carbonifère ». Une pression évolutionnaire élevée a fait que les amphibiens sont devenus de plus en plus basés sur la terre. La sélection environnementale a lancé le développentt de certain traits comme des squelette renforcés, des muscles et une peauprotectricee qui sont devenus plus favorables. L'évolution des poumons et des jambes sont les étapes transitoires principales vers les reptiles, mais le développent du dur oeuf externe, remplaçant les oeufs marins des amphibiens est le caractéristique dominant des reptiliae. Quoique la taille de leurs cerveaux soit petite en comparaison avec des mammaire et des oiseaux, ces améliorations ont été vitales pour les stratégies de chasse employées par les reptiles.

L'animal le plus vieux connu qui aurait pu être un reptile (au lieu d'un amphibien avancé) est « Casineria ». Une série de marches trouvée à Nova Scotia, datée à il y a environ 315'000'000 ans montre des pieds reptiliens typiques. Cette série de marches sont attribuée à « Hylonomus », le plus vieux example connu non-questionable d'un reptile.

Notes regarding film shown in class. Life began in monocular form. It then developed to multicellular life. Because of all of the photosynthesis of the plants, the massive quantity of oxygen produced changed the atmosphere from a metallic base to an oxygen based one. Macroscopic life → developed from multicellular life. Macroscopic life is life that is viable to the human eye, in contrast with microscopic life. Earth covered in ice. Dead planet. -50°. All earth like antarctic. Threatened life with extinction. Followed by massive heat. 50°. Life survived due to evolution. After last period of total ice, life became multicellular. Then came macroscopic life. Life continued to complicate.

Life under ice. Glaciers moved rocks, i.e. large rocks in Central park. The presence of bizarre rocks means that a glacier once inhabited that place. During last ice age, only north and south covered, most earth not. Unaffected areas hardly affected. Small particles in lava point towards magnetism whilst liquid, once solidified, they remain in the state they were when the lava was liquid. i.e. they become inanimate.

Earth spent many years under ice. During which time it looked like a giant snow ball. The ice could attain a height of 1(km). Temp. dives to -50°. Vegetation disappears → food chain is destroyed; herbivores and carnivores cannot survive. Oceans froze to 1km depth. Photosynthetic plants cannot survive because the ice blocks the light of the sun. How could such events arrive? One often speaks of gas which raises the planet's temp. but one ought not forget that without these gases, the temp. of the planet would plunge to -18°.

In swamps, bacteria produce flammable gases. One thinks that these bacteria lived in all oceans and produced a gas which enabled the planet to retain her heat. It has been shown that even without CO2, the bacteria's gas could have maintained the temp. of the earth above 0°.

At the beginning, bacteria produced metal based gases until one plant bacterium developed which could photosynthesise. It is therefore life which maintained the temp. of the Earth and thus life which maintained itself.

In warm springs in the middle of icelands, bacteria survive. The water is heated by the centre of the earth. This is how bacteria survived during the ice ages. The heat coming from the centre of the earth is the key to the survival of these bacteria.

When macroscopic animals first appeared, they sprang up very quickly.

The build up of CO2 produced under the ice caused the earth to warm from -50° to 50°; this caused a rapid melting of the ice.