|MadSci Network: Evolution|
An interesting question Justin, that I will answer in 2 parts. The 1st part is, are things the same today as they were in the past? We always look at evolution and realise that reptiles evolved from amphibians, that birds came from reptile's etc., but rarely do we think about bacteria in the same way. Let us think of the Dinosaurs you mention in your question. Are they here today? No thatís obvious, they all died. But we never consider bacteria. So are all the bacteria from that time also dead and therefore are the bacteria present today different from the ones then. Well again lets consider the Dinosaurs. There are surviving "Dinosaurs", the crocodiles and alligators. So there may be surviving bacteria. Without a time machine this is tough call. If there are bacteria today that were present then, they will have changed overtime but may be similar. To be more to the point on your question, is Salmonella the same today as it was then? Well Salmonella is predominantly found in the guts of 2 groups of organisms Mammals and Birds, neither of whom were hear in the past. Why do they like this environment? Well its warm and they like to grow at that temperature. Were the guts of dinosaurs warm? Well maybe. So we can't really say that Salmonella lived in the guts of Dinosaurs. To conclude organisms today are not like they were in the past, time does not freeze. Therefore bacteria today are probably not the same as in the past. All organisms adapt to live somewhere, Salmonella is the guts of warm organisms and the guts of dinosaurs may not have been that warm. So my gut feeling without the precise data, is that Salmonella is a relatively new organism, much older than we are (humans) but maybe not as old are as the Dinosaurs are. It probably appeared when warm-blooded organism became prevalent. So, no Salmonella did not infect Dinosaurs but other similar organisms probably did.
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