Tag Archives: clade

http://www.youtube.com/watch?v=i4K5ocVhPtw&feature=plcp

Fossils can be fascinating windows into the past of our earth.
The fossils, visible in this film, represent different extinct plants of the groups Lycopodium (club moss) and Equisetum (horse tail, snake grass, puzzlegrass), which nearly all had the sizes of real recent trees in the period of the Carboniferous, about 370 million years ago.
A “Lagerstätte” for bituminous coal fossils is located in the South-West of Germany (e.g. Saarland).
These fossils in the film belong to my own collection and were found by my own in the Saarland at different localities.
Does a fossil represent a direct indication for evolution by its mere existence?
The answer is no!
Fossils can only contribute to a better understanding of the evolution of our organisms on earth, when they are interpreted in a phylogenetical context.
“Dinosaur-parks”, a modern way of entertaining the populace at a low level by just presenting fossils and dinosaur-replications without explaining coherences properly, therefore mostly do not represent educational institutions for an understanding of evolution, even though they sometimes claim this.
Phylogenetic trees of recent organisms can generally be reconstructed correctly without an involvement of fossils.
But in case researchers are able to match fossils to the stemlines of monophyletic groups, fossils can for example reveal the order of character transformations there.
Fossils e.g. prove that some dinosaurs (such as Oviraptor) had feathers, which must have had different functions than supporting wings to fly, because those dinosaurs primordially were unable to fly.
It can be stated in a simplified way that at least two different steps towards the evolution of birds can be named: at first feathers evolved, then –much later- feathered wings developed.
Of course characters such as the warm-bloodedness and a breeding behavior also evolved stepwise before featherwinged birds appeared.
Furthermore, fossils can contribute informations about different other aspects of the evolutionary biology (being helpful only in a phylogenetical context!).
For example:
The reconstruction of the historical biogeography depends often on fossil records. Using fossils and the recent distribution of species or other groups, it can be for example stated that some organisms evolved and dispersed already on the supercontinent Gondwana.
Another helpful function of fossils can be that they facilitate the decisions of researchers in regard of a possible homology of recent morphological strucures (e.g. compared between different organism groups).
Fossils also are needed to determine the age of evolutionary events.
But please note that they thereby mostly can only contribute a minimum age.

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