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.
Just to add: if anyone is interested in learning more about the sudden appearance of extremely varied life, this event is called the “Cambrian explosion” and makes for some very interesting reading.
Cambrian Explosion is a bit of a misnomer because it leads people to think it was unique with respect to evolutionary processes. There is a push to call it the Cambrian Radiation [0]. Throughout complex life's time on Earth there have been multiple periods of rapid evolutionary development similar to the Cambrian. A blurb about the Cambrian Radiation appears in my coffee table picture book [1].
"Radiation" sounds more unique than "explosion" to me (not an evolutionary biologist). It sounds like it means there was some unusual atomic radiation causing mutations at that time, so I think it will lead to more misunderstanding by laypeople rather than less. Why did they decide not to have multiple "explosions"?
"Radiation" is meant to suggest that the evolution advanced in many very different directions, like the rays that diverge from a point.
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.
Yes I understand what it means, but the word "radiation" has other much more well-known meanings, one of which directly connects to having more mutations than usual, so it's bound to be misunderstood.
You are right about the risk of misunderstanding the word "radiation".
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.
This book looks fantastic - just perfect to capture the interest of the layman. If it ever get translated to my language it is going on my coffee table as well.
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?
A printed version costs about $150 to produce, which includes $15 that goes to the illustrators. Translating to other languages would be a technical challenge. I didn't coin the term Cambrian Radiation; you can find the phrase referenced by biologists many times throughout the book's bibliography:
The number of domains/kingdoms/empires/superkingdoms of living things is actually much more of a matter of debate amongst taxonomists than people realize.
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)
This shouldn't have been downvoted; external digestion, usually known as "cooking", is one of the most important features of human biology, explaining why our intestines are so short.
An animal’s gut is also arguably “external”, in the sense that the gastrointestinal tract means an animal is a topological torus, and the contents of the gut are also “outside” of the body. It’s an open question how the closed digestive tract evolved, but it presumably came from a digestive surface of some sort folding over on itself, since it must have evolved in creatures that were previously able to digest. The same general phenomenon presumably produced lungs by cavitating a gas-exchange surface to increase surface area.
Well, a digestive surface is necessarily external in that sense, since the only things you want to digest originate outside the body. The options are that you have a digestive surface that is open to the world, or that you have one which is protected within your interior, but nevertheless topologically external.
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.
If you have further reading material on these two developments, I'd be thrilled to go over them. The subject is fascinating, but layman subject matter is scarce and I already have a profession.
I agree that cooking is a form of digestion, but that is not what I was thinking when I made my comment. We are walking tubes. The cavity inside of the tube is still external to the tube itself.
This is a video that partially explains the concept.
The kingdoms Protozoa and Chromista include some former algae that have also motile 'spermatozoan like' forms in its lifecycle. The were plants before, but in some parts of this lifecycle they act like microscopic animals.
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.
Wow, that’s a lot of extrapolation from one comment.
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.
There was recently a discussion here on HN about the billion years of lost sediments on earth, and one article mentioned that that the crushing of that sediments into the sea lead to much more minerals in the sea and to the Cambrian explosion.
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.
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.
"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. "
I think science is interesting enough in its own right that you don't need to oversell it. It is not a 'massive creature', but it's fascinating nonetheless when explained in context and without the clickbaity headline.
Massive for its time. Average creature being a pinky finger (why didn't they just say a number), so about 5 cm. Half meter is 10x that. Something 10x bigger than me is not a giant, it's a titan.
It makes sense to me that body shapes were all over the map in the Cambrian. Life had just begun to fit into ecological niches. It was the wild west! A life form only had to have some small advantage to explode onto the scene. Even more so when the niche was empty, so competition was slight.
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!
If I had a time machine, the Cambrian and the period immediately preceding it would be the first place I'd go.
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.
"Hoyle and Wickramasinghe viewed the process of evolution in a manner at variance with the standard Darwinian model. They speculated that genetic material in the form of incoming pathogens from the cosmos provided the mechanism for driving the evolutionary engine"
previous stages of any exponential process look very slow from the late stages of it. The process of producing and complicating the single cell life [from nothing] in these 3-3.5B have tremendous complexity on its own.
>> 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.
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.
Not being familiar with Canadian museum names' abbreviations, the phrasing "ROM palaeontologists" from the subtitle sent my mind trying to remember which science-fiction series this reminded me of ... but it failed.
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.
A interesting footnote is the presence of possible chordate animals yet in that fauna (we are chordates as any other vertebrate). They were probably preyed upon by this creatures and at 5 cm long would seen this animal as huge an terrifying, for sure.
I would suggest getting through your first cup of coffee before you hit this article. It speaks of "ROM-based Ph.D. students" and "giant swimming heads."
It is "mind-boggling" compared to the size of similar animals at the time. Half a meter might sound short, but I'd say it would be mind-boggling to find a half-meter long ant, spider or bee in a forest, for example. Not so big compared to all animals that ever existed, but massive compared to similar animals at the time.
No, it was not mind-boggling. Read the first two sentences of the very next paragraph.
"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".
Arguably the two most iconic dinosaurs, T. Rex and the Brontosaurus family, are far larger and more aggressive than the rest of the group. Iconic does not imply representative.
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.
It's all relative I suppose, no? They were fairly clear on the scale right in the section you quoted, right at the top:
> 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.
you left out the part of the quote that gives it context. "compared to most animals that lived in the seas at that time, most of which barely reached the size of a pinky finger."
Yes, but with the headline and the guy talking 'massive'... they could have included a 'relative to' or something? I was expecting some kind of deep sea leviathan.
The relation was made in the headline. It stands to reason that a massive half billion year old animal would be massive relative to other animals from a half billion years ago.
Does the average person have a good sense of how big animals were 500 million years ago vs. 250-300 million years ago? The latter of which was quite big, and any 'massive' from there on would be fitting by modern standards.
The average interested person would have, yes. That would include anybody who's watched any of the relevant PBS Nova programming, or any of David Attenborough's work, etc. - you don't need to have kept your head in the journals to be informed at that level.
I didn't say it wasn't interesting. But it would have probably been even more interesting without building it up as 'massive creature' that's actually the size of my cat.
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.