Interesting find announced today - a foot long, segmented worm from the Ediacaran, the period that came before the Cambrian explosion. Paper here:
https://www.nature.com/articles/s41586-019-1522-7
Popular article here:
https://www.nytimes.com/2019/09/04/s...ortichnia.html
It's an important find. We've found one or two bilateral animals in the Ediacaran. And we've found a lot of tracks made by mobile animals. But the two didn't match up - the animals we knew about couldn't make tracks like the ones we saw. The new animal end that - they actually found a track leading right up to the body of one, so there was no doubt this was the source. And it definitively shows there were mobile bilateral animals before the Cambrian.
Separate from the news, it's also relevant to one of Lee's threads, where he was arguing that the arthropods of the Cambrian having eyes and a brain showed that these features appeared suddenly instead of evolving. So, this thing is clearly not an arthropod, since arthropods are defined in part by the presence of eyes and a brain. And there's a chance it's an annelid, like many present-day segmented worms. But the discoverers of this fossil see things that might be like insect legs on the segments. In which case this would have a subset of arthropod features, and therefore be a strong candidate for the sort of creature that would be an arthropod precursor.
In which case Lee's argument would be even worse than it was at the time.
(Sorry i can't be bothered to find the original discussion. Was a bit of a car crash, and i'd rather not have looking at it set off some sort of internet-driven PTSD....)
https://www.nature.com/articles/s41586-019-1522-7
Popular article here:
https://www.nytimes.com/2019/09/04/s...ortichnia.html
It's an important find. We've found one or two bilateral animals in the Ediacaran. And we've found a lot of tracks made by mobile animals. But the two didn't match up - the animals we knew about couldn't make tracks like the ones we saw. The new animal end that - they actually found a track leading right up to the body of one, so there was no doubt this was the source. And it definitively shows there were mobile bilateral animals before the Cambrian.
Separate from the news, it's also relevant to one of Lee's threads, where he was arguing that the arthropods of the Cambrian having eyes and a brain showed that these features appeared suddenly instead of evolving. So, this thing is clearly not an arthropod, since arthropods are defined in part by the presence of eyes and a brain. And there's a chance it's an annelid, like many present-day segmented worms. But the discoverers of this fossil see things that might be like insect legs on the segments. In which case this would have a subset of arthropod features, and therefore be a strong candidate for the sort of creature that would be an arthropod precursor.
In which case Lee's argument would be even worse than it was at the time.
(Sorry i can't be bothered to find the original discussion. Was a bit of a car crash, and i'd rather not have looking at it set off some sort of internet-driven PTSD....)
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