Sunday, November 20, 2005

Grass And The Absence of Evidence

We don't have fossil evidence of grass past 55 million years ago, so it must not exist before that. (Or at least not be very prevalent.) Oops! It existed an additional 50 million years!

The thing is, scientists have no other choice but to rely on the fossil evidence, because otherwise they have no means of reconstructing what happened back then. But one should realize that it is always a tentative assessment. Perhaps fossils did not survive to this day for some reason, of there is some fossil they have missed. One new piece of evidence can cause them to rewrite pre-history, just as evidence of Biblical Aramaic is so sparse that new discoveries quite often cause people to rewrite Biblical Aramaic grammars.

Of course, now this fossilized dung is evidence, so people will say that this is a fact we know about grass on the basis of evidence, forgetting that until this point, there was lack of evidence and a different assumption.

The article:

So long scientists have held that grass growth on Earth gained ground only after the dinosaurs disappeared. But the large remnants of the Dino feces reveal a totally different picture. Now they view the probability that grass, not the only vegetarian component of a dinosaur meal eaten alongside other plants, served an important part of the early mammal's food. Caroline Strömberg of the Swedish Museum of Natural History and her team have many reasons to favor this view after studying mineral remnants preserved in the 65-67-million-year old dung fossils.
Today the grasses with their high silica content are not as easy to chew and possibly evolved to be so to avoid consumption by herbivores during large-scale grazing as a response to the patterns that existed in the Cenozoic era. But that theory points to the possibility that this defense was raised in response to grazing by dinosaurs. But with other small mammals that existed alongside the dinosaurs also likely to have been grass eaters, it is difficult to accord dinosaurs the sole blame for the development.
The discovery may also serve as a fillip to another mysterious mammalian existence of the period of the creatures termed as gondwanatherians that are understood to have had high-crowned teeth. Until now paleontologists believed these creatures of the Cretaceous period to have used the teeth to bite through wood since grasses were not known to have existed.

Now it is clear that they too savored a taste for grass like the dinosaurs and therefore had developed their own bodily tools to help them in this direction. While the earliest grass fossils trace their existence to 55 million years ago, the new discovery in Dinosaur dung traces them to nearly 100 million years ago.

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