Cambrian explosion, the unparalleled emergence of organisms between 541 million and approximately 530 million years ago at the beginning of the Cambrian Period. The event was characterized by the appearance of many of the major phyla (between 20 and 35) that make up modern animal life. Many other phyla also evolved during this time, the great majority of which became extinct during the following 50 to 100 million years. Ironically, many of the most successful modern phyla (including the chordates, which encompass all vertebrates) are rare elements in Cambrian assemblages; phyla that include the arthropods and sponges contained the most numerically dominant taxa (taxonomic groups) during the Cambrian, and those were the taxa that became extinct.
The beginning of the Cambrian Period is marked by the evolution of hard body parts such as calcium carbonate shells. These body parts fossilize more easily than soft tissues, and thus the fossil record becomes much more complete after their appearance. Many lineages of animals independently evolved hard parts at about the same time. The reasons for this are still debated, but a leading theory is that the amount of oxygen in the atmosphere had finally reached levels that allowed large, complex animals to exist. Oxygen levels may also have facilitated the metabolic processes that produce collagen, a protein building block that is the basis for hard structures in the body.
Other major changes that occurred in the Early Cambrian (541 to 510 million years ago) include the development of animal species that burrowed into the sediments of the seafloor, rather than lying on top of it, and the evolution of the first carbonate reefs, which were built by spongelike animals called archaeocyathids.
By the Early Cambrian the bulk of the biosphere was confined to the margins of the world’s oceans; no life was found on land (except possibly cyanobacteria [formerly known as blue-green algae] in moist sediment), relatively few pelagic species (biota living in the open sea) existed, and no organisms inhabited the ocean depths. Life in the shallow regions of the seafloor, however, was already well diversified. This early aquatic ecosystem included the relatively large carnivore Anomalocaris, the deposit-feeding trilobites (early arthropods) and mollusks, the suspension-feeding sponges, various scavenging arthropods, and possibly even parasites such as the onychophoran Aysheaia. Thus, it seems likely that a well-developed aquatic ecosystem was already in operation in the ocean shallows by this time.
Following the Cambrian Period, the biosphere continued to expand relatively rapidly. In the Ordovician Period (485.4 million to 443.4 million years ago), the classic Paleozoic marine faunas—which included bryozoans, brachiopods, corals, nautiloids, and crinoids—developed. Many marine species died off near the end of the Ordovician because of environmental changes. The Silurian Period (443.4 million to 419.2 million years ago) marks a time when a rapid evolution of many suspension-feeders in the oceans occurred. As a result, pelagic predators such as nautiloids became abundant. Gnathostome fishes, the oldest craniates, became common near the end of Silurian times.
From the Cambrian Explosion to the Great Dying
Precambrian Creatures: The First Animals
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Remember nerds, no current struggle session discussion here on the general megathread, i will ban you from the comm and remove your comment, have a good day/night :meow-coffee:
Cooking green beans and vegan burgers, yim yum. Wish I got paid tomorrow instead of thursday tho
no current struggle session discussion
Wait won't that mean no DC vs AC debates :sicko-wistful:
'fusion breakthrough' is the 'china bout to collapse' of the scientific world
I swear bro just increase our grant budget by $20 billion and it’ll be real just before the world starved to death due to soil erosion and massive climate change induced ecological collapse
Here here. At this point, humanity doesn’t survive without a massive source of clean, cheap energy.
They will shoot nanoparticles into the ionosphere before giving up oil
True, but they’ll also switch to cheaper energy that happens to be clean so they can use it to make other products out of those sweet sweet hydrocarbons. So long as it lines :porky-happy:’s pockets.
I posted recently about the cost of the Space Shuttle program, and while looking it up I realized that they could have had about two Space Shuttle programs and two Apollo programs for the projected cost of the F-35 program (before it rises again lmao).
if we'd given them 100 bil in the first place they'd already be done, the manhattan project cost 36 billion (today usd) and fusion has been getting thrown fractions and getting scapegoated for going so slow. my brother in christ your budget is the one they've had to work around! the US has spent more on fucking fighter planes!
At least it's a small step up from "we created a wormhole on microsoft powerpoint!!1"
Apparently the UK considers you “destitute” if you’ve gone without a necessity because of money more than twice in the past month.
TIL I’m destitute. I thought I was pretty well off. Guess people who are well off don’t have empty cupboards or bank accounts that spend 28 days of the month overdrawn.
:amerikkka:
I've since dug out of that hole, but there were times in my life when I didn't have food or money for a day and didn't know where I'd get either for the next day. Tough times.
yeah apparently i am "at risk of poverty" according to irish regulations because ive had to deprive myself of heating so i can pay rent and i cant afford one roast dinner a week (which is a weird standard)
Don't mind me, just teaching people theory in the /r/victoria3 threads about how terrible capitalism is
The good news is that this site is so dysfunctional that a 10% increase in traffic will instantly crash the site, keeping us all safe
Who needs a self destruct when the mere presence of a hostile majority destroys everything? :think-about-it:
Overheard without context, from a guest at the shelter.
"Nah man, I support the Communist Party of China."
Wish I had any idea what they were talking about.
For 2200/mo I expect to take the meds and then earnestly believe I am on a pokemon adventure. I fully expect to be a dragon tamer fighting in an episodic shonen adventure
Haha what if catching covid permanently compromised your immune system, both making it more likely for you to catch covid again as well as making you more seriously susceptible to myriad typically mild viruses haha. That sure would be bad for hard working restaurants and stores and movie theater owners haha. Thank goodness that definitely isn't the truth and increasingly supported by peer-reviewed research haha. My second favorite band is playing a sold out show next week, 300 people in a 300 square foot venue, tickets are only $180, so cheap!! I caught covid a couple weeks ago but luckily it was mild and my boss said i only needed to wear a mask if i felt like i needed to (which of course i didn't, even though i had kind of a bad cough for a week or so, that would have been so embarassing to wear a mask!). USA is the best I'm so glad I'm not an opressed china uyghur slave social credit -9000.
Lol sounds like woke movement crap watch this YouTube video of failed actor and new age lifestyle himbo ruselll brand on failed comedian turned political clown unwilling to read jimmy dores show talking about how china is an athoritarianist non free thinker place and also real journalistic free thinkers like them aren't allowed to say the truth which is this and that 45 minutes of this and that trust me just watch the video it will change you
Haha true. Do you think russel brand effectively utilized girl power when he stroked jimmy dores's's furry wall :eric-andre: 🤔
Hey thanks for the 's. This is why we need to unit with maga and why aoc makes me so mad
Boss makes a hundred, I make a buck, that's why I voice train in the company truck
download books from libgen and do not fuck with computers beyond that. only ever be marginally employed in part-time seasonal work with perks. find some way to combine surf and snowboard instructor into a person. then drop dubstep remixes on the weekends. do not ever "contribute to the economy" or try to "get ahead" in any meaningful way.
"What is art" is a trap philosophy question, once you find a good answer to it you will be punished forever by having to listen to other people answer it in extremely dumb ways.
One man's art is another man's trash. Just look for that which is another man's trash and that's art. This is an extremely good answer
I'm gonna try and start sleeping normal hours again
stays up till 3am playing video games
My non-binary student and my impoverished student that I was worried about getting a passing grade to both did very well on their last exam. So I don't have to do anything to sketch their grades through to passing I think. Very grateful for that.
When you image search Hexbear the results are pictures of guns and swords