JD-man
Pachycephalosaurus
Posts : 318
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Join date : 2016-06-08
 | Subject: Career activity update #3.5 (It's a big 1)!  Mon Dec 18, 2023 5:24 pm | |
| I originally posted the following at deviantART ( https://www.deviantart.com/jd-man/journal/Career-activity-update-3-5-It-s-a-big-1-1003238346 ). For those who don't remember "my last career activity update": https://jurassicmainframe.forumotion.com/t1724-career-activity-update-3-it-s-a-big-1 - Quote :
- Hi everybody!
As you may remember, my last career activity update was back in 4/2020 ( https://www.deviantart.com/jd-man/journal/Career-activity-update-3-It-s-a-big-1-839828282 ). Since then, Covid-19 happened (which ended the Gallery SPARK program), I left Whole Foods, & I got my current job as a Bartell Drugs Cashier (+ a temporary Admissions job for Pacific Science Center's "Hockey: Faster Than Ever" exhibition: https://www.youtube.com/watch?v=cq_kTHwV3kE ). Also, in addition to adding to/editing the Interpretation parts of said update, I've since collected my thoughts on the non-dino exhibits in "Fossils Uncovered" (specifically, how I'd help friends/family interpret them, which is the main reason for this update). 1 more thing of note: When I say this/these/here, I'm pointing to something.
Cheers,
Herman Diaz
This is where the Archeology Gallery splits from the Paleontology Gallery. Many ppl think of archeology & paleontology as being the same thing, but they're not (*define archeology & paleontology*).
Our tour of the Paleontology Gallery begins here, in the Cambrian Period, ~540 MYA. This is "when animal life first diversified" ( https://archive.ph/fnt2z ). Before the Cambrian, there were only a few kinds of animals, & they were all "soft-bodied[...]like worms and jellyfish" ( https://morethanadodo.com/2019/08/01/meet-the-first-animals/ ). But then a bunch of new kinds evolved hard parts in a relatively short amount of time called the "Cambrian Explosion". They included trilobites like these, brachiopods like these, mollusks like these, & fish w/bony skeletons like this. Speaking of which...
...we're now in the Ordovician Period, ~480 MYA. This is when jawless fish 1st evolved. See how it has no jaws, just "an open circular mouth for filter feeding" ( https://quizlet.com/226959925/fish-bio-1-flash-cards/ ). Also during the Ordovician, there was an ice age that caused Earth's 1st mass extinction.
We're now in the Silurian Period, ~440 MYA. This is when life 1st moved onto land, beginning w/simple plants like this green algae, which later evolved into complex plants like this club moss, & then continuing w/invertebrate animals like spiders & millipedes, which fed on dead plants &/or each other. Also during the Silurian, fish like these 1st evolved jaws from "larger gill supports" ( http://web.archive.org/web/20200928222957/http://paleoporch.com/wp-content/uploads/2018/05/IMG_3845-e1527470430213.jpg
), so they could bite things.
We're now in the Devonian Period, ~410 MYA. This is when plants 1st evolved leaves like these, grew tall, & formed the 1st forests on Earth. The roots of these forests broke down "bare rock, creating the first soils" on Earth (See "Transcript": https://web.archive.org/web/20231215030345/https://www.pbs.org/video/when-it-was-too-hot-for-leaves-79gmfk/ ). Also during the Devonian, tetrapods (or 4-legged vertebrate animals) 1st evolved from lobe-finned fish like this. See the 4 lobbed fins, 2 here & 2 here? They were very strong w/bony internal supports, probably for ""walking" on the bottom of shallow water" areas ( https://www.livescience.com/43596-devonian-period.html ).
We're now in the Carboniferous Period, ~350 MYA. This is when swamp forests of giant club mosses like this & giant horsetails like this covered Earth's lowlands, which means there was "more oxygen[...& thus...], bigger bugs" ( https://www.dispatch.com/story/opinion/columns/2022/09/08/earths-oxygen-level-fluctuated-over-the-eons-life-too/65508564007/ ). There were dragonflies like this w/3ft wingspans & millipedes like this over 6ft long. The Carboniferous is also when early tetrapods split into 2 major groups:
-On the 1 hand, there were amphibians like this.
-On the other hand, there were amniotes like our ancestors. More on them later.
We're now in the Permian Period, ~290 MYA. This is when all the continents came together into 1 giant landmass called Pangea, which means there was less coastline & thus, hotter & drier conditions on land:
-These new conditions were good for seed plants like conifers & cycads b/c seeds can remain dormant for many years "until conditions are right for [them] to germinate" ( https://www.shmoop.com/study-guides/biology/plant-biology/plant-reproduction ). These new conditions were not-so-good for spore plants like club mosses & horsetails, which need water to spread their spores.
-These new conditions were also good for amniotes like our ancestors b/c amniotic eggs are shelled w/water inside. These new conditions were not-so-good for amphibians, which need water to lay their jelly-like eggs. Speaking of amniotes, the Permian is also when early amniotes split into 2 major groups:
-On the 1 hand, there were reptiles like the ancestors of dinos.
-On the other hand, there were synapsids, which include true mammals like our ancestors + their extinct relatives called proto-mammals. You can see the family resemblance in our skulls. Like us, proto-mammals have incisors, canines, & a single hole behind each eye for the jaw-closing muscles, which you can feel here (*the temple*) when you bite down.
Proto-mammals like this Lycaenops & this Dimetrodon dominated life on land until the End-Permian Mass Extinction, 252 MYA. It was "Earth's biggest mass extinction", killing off "over 90 percent of species" ( https://www.smithsonianmag.com/smart-news/ocean-acidification-could-have-driven-earths-biggest-extinction-event-180954938 ). However, it WAS good for some species. For example, a special group of reptiles called archosaurs, which split into 2 major groups shortly after:
-On the 1 hand, there were croc-line archosaurs, which include modern crocs + their extinct relatives like this guy called Revueltosaurus.
-On the other hand, there were bird-line archosaurs, which include modern birds + their extinct relatives like non-bird dinos & pterosaurs.
We're now in the Mesozoic Era, beginning w/the Triassic Period 252 MYA (See "Triassic stuff": https://www.deviantart.com/jd-man/journal/Career-activity-update-3-It-s-a-big-1-839828282 ).
Before we move on to the Jurassic Period, I should mention that the Triassic is also when "true mammals[...1st...]evolved from" small, hairy proto-mammals like this guy called Thrinaxodon ( https://themammallab.com/2020/07/mammal-origins-evolution/ ). Here's a replica of a Thrinaxodon skeleton & here's the original lower jaw of Thrinaxodon.
We're now in the Jurassic Period, beginning 201 MYA. This is when dinos became REALLY big & diverse. The Jurassic is also when Pangea began splitting into 2 smaller landmasses, Laurasia in the north & Gondwana in the south, which means there was more coastline & thus, cooler & wetter conditions on land. These new conditions led to a lusher, more tropical landscape "dominated by fern prairies[...]and coniferous forests" ( https://archive.ph/zWkJW ). Cycads like this guy called Zamites were also common. In fact, they might've been a favorite food of stegosaurs like this guy called Stegosaurus, which might partly explain why stegosaurs were so weird looking (See "Stegosaurus skeleton & Zamites cycad fossil": https://www.deviantart.com/jd-man/journal/Career-activity-update-3-It-s-a-big-1-839828282 ).
"Modern-style birds[...1st evolved...]in the Cretaceous Period" ( https://www.geol.umd.edu/~tholtz/dinoappendix/HoltzappendixWinter2010.pdf ), but before we move on to that, I should point out this nice display of ammonite fossils. IDK as much about ammonites, just that 1) they're a group of cephalopods closely related to squids, octopuses, & nautiluses like this, & 2) they were very abundant during the Mesozoic, so much so that experts "can determine the age of rocks based on the species of the ammonites found" ( https://epod.usra.edu/blog/2018/12/ammonite-fossil.html ).
We're now in the Cretaceous Period, beginning 145 MYA. This is when non-bird dinos were at their biggest & most diverse. The Cretaceous is also when the continents began moving to their modern locations. This led to more volcanic activity, which led to higher temps, which led to rising sea levels, especially here in North America, which was split in half by the Western Interior Seaway. The eastern half is called Appalachia & the western half is called Laramidia, which is where T. rex & Triceratops lived. Speaking of T. rex, this is an original skull "nicknamed the “Tufts-Love” T. rex after the two Burke volunteers who discovered it" ( https://www.burkemuseum.org/news/meet-tufts-love-t-rexs-biggest-little-fans ). As you can see here, T. rex had the strongest bite of any land animal ever (See "T. rex skull": https://www.deviantart.com/jd-man/journal/Career-activity-update-3-It-s-a-big-1-839828282 ).
Here's a reconstruction of what Triceratops might've looked like when alive (not the best one they could've used, but whatever: https://web.archive.org/web/20231215034412/https://www.alamy.com/stock-photo-triceratops-dinosaur-computer-illustration-87159859.html ). I especially like this display for showing that not all dinos lived at the same time. In fact, as you can see here, some famous dinos like T. rex & Triceratops lived closer in time to us than they did to other famous dinos like Stegosaurus.
Before we move on to my favorite Burke Museum fossil, I should point out this nice display of plant fossils (See "Cretaceous plant fossils": https://www.deviantart.com/jd-man/journal/Career-activity-update-3-It-s-a-big-1-839828282 ).
This skeleton is NOT from a dino, but is still really cool. It's from a type of mosasaur called Platecarpus. Mosasaurs were a group of marine lizards closely related to snakes. Platecarpus grew to ~24ft long. The largest known mosasaur, Mosasaurus itself, grew to ~50ft long, which is big, but not nearly as big as JW's Mosasaurus, which was Blue whale-sized in the 2015 movie, & has since basically become a kaiju. Also unlike "the movie Mosasaurus", which is covered in croc-like armor, "skin impressions show" that real mosasaurs were covered in snake-like scales ( https://dinomuseum.ca/2019/11/28/the-real-mosasaurus/ ).
Now we're at the Cretaceous-Paleogene or K-Pg Mass Extinction 66 MYA. AKA the End-Cretaceous Mass Extinction, it killed off 75% of Earth's species, including all the non-bird dinos, pterosaurs, ammonites, & mosasaurs. It was probably caused by an asteroid "the size of Mount Everest[...hitting...]Earth with the force of a billion" Hiroshima bombs ( https://archive.ph/lXWEb ), blowing up so much dust that the sun was blocked "for many years" ( https://www.biointeractive.org/sites/default/files/KT_Trail_of_Evidence_teacher.pdf ). This killed the plants (which need sunlight to make food), which in turn killed the large herbivores (which ate the plants), which in turn killed the large carnivores (which ate the large herbivores). By "large", I mean no land animal over 56lbs or so survived.
As you can see here, a layer of iridium was created by the asteroid impact. Iridium, a type of heavy metal, is rare on Earth, but abundant in asteroids. I especially like this display for showing the relative number of species in each group both before & after the asteroid impact. Obviously, dinos were hit hard, w/only modern-style birds surviving. Crocs & turtles, not so much, partly b/c they were smaller & more ectothermic (& thus, needed less food than the larger, more endothermic dinos) & partly b/c they lived in or near freshwater (& thus, "were buffered from the worst effects": https://royalsocietypublishing.org/doi/10.1098/rsbl.2022.0118 ). You can see more survivors of the asteroid impact around this corner, including paddlefish like this & marsupials like this, which still live in modern times. Speaking of which...
...we're now in the Cenozoic Era, which includes modern times. IDK as much about the Cenozoic, just that it began warm & wet, but gradually became cooler & drier, culminating in a series of ice ages, the last of which ended ~12,000 years ago. | |
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