Massive animal species discovered in half-billion-year-old Burgess Shale
rom.on.ca
rom.on.ca
This book is an amazing read and will explain it, if you're interested: https://www.bookdepository.com/Wonderful-Life-Stephen-Jay-Go...
The Burgess Shale contains fossils from some of the earliest complex multi cellular life. Prior to this, for billions of years life was single cell or collections of single cell organisms. This is the time when complex life first appeared on earth, and the animals that evolved then were startlingly weird. And yes, most of them were very small.
What seems to have happened, is that "one day" (in geological terms) there was nothing but single cell organisms, and essentially "next day" (again, in geological time frames) there was an absolute explosion of complex life/animals.
Most interesting about life at this time is not just the diversity of life, but the diversity of fundamental types of animals. For some reason at this time evolution was free to come up with entirely new types of "animal designs", not just modifications of previously existing body types.
Today, all animals on earth are classified into a very small number of basic types of animal - (perhaps only 5?). but many of the fossils found in the Burgess Shale are so strange that it's not clear that they belong to any known family of animals. This implies that back then there might have been many, many fundamental types of animal, today we are left with only a handful of basics types.
There's even the suggestion that there are creatures that can't really be classified into plant or animal - it's not clear what they are at all.
Forgive me if I get the above wrong - I'm no expert, just an enthusiast. Maybe others can provide more information about the basic types of animal and how this relates to the Burgess Shale.
The Burgess Shale is a window into the absolutely most interesting time of earths history.
An animal the size of a dog might have been the largest animal on earth.
[0]: https://impacts.to/bibliography.pdf#page=41
[1]: https://impacts.to/downloads/lowres/impacts.pdf#page=15
Your book looks really interesting!
Such "radiations" have happened every time when there was little competition either because a new place or environment was invaded or because a catastrophe had eliminated the former incumbents.
The result of evolution "radiations" was that some group of animals that previously had been more or less uniform because they were adapted to a certain niche, after the "radiation" event became diversified in a large number of groups adapted to very different conditions of life and having much less resemblance between themselves than before.
However, the same risk applies to "explosion".
It is probably better to not use metaphors like "radiation" or "explosion", but to just say something like "diversification event".
However, "radiation" already has a long history of being used in the biological literature with this particular meaning, of divergent evolution, so for those familiar with the jargon, it seems an appropriate choice, even if it might not be the best word to use in something intended for the general public.
The "radiation" events are not events when the rate of mutations was higher (even if it is likely that the mutation rate during Cambrian was a little higher than today, due to higher ambient radioactivity because less of the primordial radioactive nuclides had already decayed by then).
The "radiation" events were events where a much larger proportion of mutants survived enough to have descendants, because of less competition that would have otherwise eliminated them.
This allowed a chain of neutral or bad mutations to lead eventually to improved organisms for certain conditions of life, while in the times of high competition it would have been impossible to escape local optima.
So while the rate of "raw" mutations was about the same as in other times, the rate of successful mutations, that persisted in the DNA of the descendants, was higher.
Did you coin the term Cambrian Radiation? Though I agree that the term Cambrian Explosion may mislead, I fear that the term Cambrian Radiation might confuse. If a new term is to be coined, wouldn't Cambrian Diversification be an obvious choice?
I have surmised the OP actually meant Cambrian Radiance, not radiation. Autocomplete might have been complicit.
Could you expand on that at all? It sounds really fascinating.
There's things that look like ferns, and are attached to the sea floor. But they lived at such a depth that the sunlight would not have been able to reach them so they could not have been plants.
https://en.wikipedia.org/wiki/Charnia
"The living organism grew on the sea floor and is believed to have fed on nutrients in the water. Despite Charnia's fern-like appearance, it is not a photosynthetic plant or alga because the nature of the fossilbeds where specimens have been found implies that it originally lived in deep water, well below the photic zone where photosynthesis can occur. "
Compared to the average size of creatures of the time, then, this thing would be like the biggest ever moose to us.
No plant or animal, but alive. How strange, rare and exotic ... like a mushroom?
(Mushrooms are not a plant nor animal either, but if you look close enough, mushrooms are indeed strange and exotic, though)
https://www.iberdrola.com/sustainability/biology-kingdoms-li...
https://www.iberdrola.com/wcorp/gc/prod/en_US/comunicacion/r...
Taking our classification schemes as a fact about biology is confusing the map for the territory.
But you are correct that mushrooms (which is the fruiting body of some types of fungi) are separate from plants (and actually more closely related to animals. They're basically animals that digest things externally instead of having a stomach to digest things internally)
Or, I guess, that you have a topologically external surface which does nothing but create vacuoles around food, which then get transmitted to a topologically internal digestive surface. (Similar mechanisms do exist for other purposes; one thing that may happen to a splinter embedded in your finger is that the body applies a protective coating to the splinter and then expels it.)
Starfish seem like an interesting case here, in that they have an ordinary internal stomach which they extrude, when they're eating, for the purpose of external digestion.
Our ancestors probably started as insectivores / frugivores / egg eaters
This is a video that partially explains the concept.
There are fungal spores pretty much everywhere, healthy animals are just particularly good at keeping they’re active forms at bay.
That you didn’t see this, make me think that some cultures have more use of irony than others. I can imaging that in a potpourri of cultures like the USA irony can often be misunderstood and therefore is less used than in other countries.
First of all, TheSpiceIsLife is Tasmanian according to their bio.
Second, even if they were American to then assume that all Americans can’t pick up on irony or sarcasm because one person on the internet missed an instance of it is quite the stretch.
Anyone know what the ~5 types are?
I think that he could be confusing animals with the five groups of vertebrates. IMAO, Is common in English to use animals mostly for big animals with bones and critters or bugs or "somethingsomething-fish" for everything else.
If we need to choose just five, among the really, really successful types of animals (in a very broad sense) we have Mollusca, Artropoda, Cnidaria, Chordata and... lets see, I would dobt between Platyhelminths because most vertebrates are hosts of several of them, or maybe Nematoda because they are hugely influential and everywhere in the soil in large amounts.
But we have also a lot of other groups: Annelida, Porifera, Echinodermata, Brachyopoda, Bryozoa, Priapulida etc... Definitely more than five big types of animals.
Niches themselves gyrated wildly as life forms evolved, each being an opportunity for some other life form to capitalize on. Rock, paper, scissors, Spock and on and on!
It took a long time to settle, and for life to start 2nd and 3rd-order optimizations to their niche. It became harder to 'move about' in the evolutionary landscape, when spaces started filling up. Certain body types became 'popular' and took over from some of the stranger ones. It became important not to have too many 'sports' e.g. body details that were expensive and not too useful.
I imagine the Cambrian as a sort of 'initial condition' game of chance for life on Earth. Change things a little back then, and we might have tentacles or pincer mouths!
Meeting one of these would be quite uncanny, as it's very different from the animals that live today.
It’s huge (for the time) but reconstructions of its various cousins (the other radiodonts) look way, way weirder.
It's so incredibly interesting that whatever happened caused the first proper multicellular life to arise after 3-3.5 billion years of just single celled life.
Well, from the perspective of their subjective experience.
From our perspective, if we are already seeing the effects...
Paleontology reporters, you have one job.
https://cdn.cnn.com/cnnnext/dam/assets/210907153715-03-titan...
A statement that is equally true today. We live in a time of giants (modern whales are the largest creatures ever) but the vast majority of creatures in the ocean remain very small.
Also, and on-topic, it's amazing how they can go from the actual fossil to so much understanding/theory about an ancient animal's shape and features.
> "half a meter"
Even scientists are doing clickbait titles these days
"Evolutionarily speaking, Titanokorys belongs to a group of primitive arthropods called radiodonts. The most iconic representative of this group is the streamlined predator Anomalocaris, which may itself have approached a metre in length."
If the most iconic representative of a group is twice the size of this new discovery, the size of the new discovery is not "mind boggling" or "massive".
Though I do agree that this creature wouldn't seem mind-boggling to those only familiar with the period's "iconic" species, in fact this creature would be mind-boggling to the vast majority of creatures alive at the time.
...
> With an estimated total length of half a meter
I suppose for specialists who understand what was floating around back then it's impressive, but that seemed a bit underwhelming to me.
> With an estimated total length of half a meter, Titanokorys was a giant compared to most animals that lived in the seas at that time, most of which barely reached the size of a pinky finger.
Yes, it's still fascinating and mind boggling if you know a little of the background.