A new fossil discovered in France promises to shed light on the murky evolutionary history of spiders. The rare three-dimensional fossil of the new species shows that it is nearly, but not quite, a spider, lacking the key silk-spinning adaptation that defines spiders. This 300-million-year-old arachnid is our closest view yet of the ancestor to all spiders.
The extinct carnivore, Kolponomos, looked like a bear, and bit like a sabre-toothed tiger.
A group of carnivores that went extinct around 20 million years ago looked superficially like modern bears, but new research shows their bite was more similar to sabre-toothed cats. Known as Kolponomos, these extinct bears were thought to feed on shelled organisms, like modern otters, but with few fossils to go on, their diet and lifestyle has remained contentious.
What is the minimum amount of time it takes to fossilise something? (asked by Nick)
Fossils are defined as the remains or traces of organisms that died more than 10,000 years ago, therefore, by definition the minimum time it takes to make a fossil is 10,000 years. But, that is just an arbitrary line in the sand – it means very little in terms of the fossilisation process.
The fossil record is one of the most obvious pieces of evidence for evolution. Fossils have been known since human history began, and Aristotle first noted the similarity between fossils and living animals, leading him to conclude that fossils represented deceased creatures, a view supported by Leonardo da Vinci. By the 19th century, people were increasingly beginning to appreciate that some fossils represented extinct animals, and that their positioning in the rocks appeared to represent that passage of time. Now there is also ample evidence from molecular genetics and radiometric dating that the fossil record does represent the evolutionary history of life on Earth. Despite this, creationists still continue to argue otherwise. Some have suggested that the fossil record represents animals killed during one or more biblical floods, however this is incongruent with the evidence available.
Across the next 10 articles, I present a few of the quirky examples of evolution that we can readily observe in nature. It is by no means an exhaustive list, but merely a set of stories which I feel illustrate well the power of evolution to create complexity, and how we can see evidence for natural selection by looking carefully at the idiosyncrasies it has produced.
The examples I provided in this series can be broadly categorised into a few themes; coevolution (Fig Wasps and Hawk Moths), evolutionary constraints on adaptation (Pandas, The Human Eye), convergent evolution (Birds and Bats), adaptive radiation (Galapagos Finches, Ring Species) and homology (DNA and the Pentadactyl Limb). And within each of these categories, there are numerous other stories I could have told to illustrate my point. But the point I am trying to illustrate is that evolution is a real phenomenon. Charles Darwin’s theory of evolution by natural selection is one which explains the natural world around us in both a satisfying and verifiable way.
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