From an explosion of Cambrians to 10 out of 10 great dying experience, this geological time period covers a lot. It is also mainly guesswork. The oldest Oceanic crust that we can create a deposition modal of and date is from the Mesozoic, in order to modal the topography of the Paleozoic, geologists have to guess, using structural relationships between plates, climate-sensitive sediments that only form under specific conditions, and of course, fossils. This is the time of organisms you could turn your human eyes to and recognise as a living organism, with more complex ecosystems to developing as a result. Inhabiting both marine, made up of shallow Epeiric Seas, the extent of which we can modal by looking at lithospheric transgression, and terrestrial environments made up of 6 main continents (Baltica, China, Gondwana, Kazahstania, Laurentia, and Siberia), several micro- continents, and island chains. These continents will change the most during the later stages of the Paleozoic The time of complex Eukaryotic organisms has come.

Cnidarians have been part of the fossil record since about 545 Million Years ago during the Late Ediacaran Period, diverging into groups that included the first Anthozoans at 541 Million years ago. These Anthozoans now comprise of the sessile organisms that include corals and anemones. The exact dates where these species diverged and formed the corals (Octocorallia and Hexacorallia being the coral classes of the Anthozoan subphylum) is still very nebulous. Or maybe I’m just bad at research, I’m three breakdown deep into this… article, so it is hard to tell. Much like fungi, corals are partial classified based on the formation of symbiotic relationships, so these need to also be established when looking at the fossil record and using molecular clocks to track proteins.

All in all it’s a bit like determining the head of ferret released into a bag on cat mint, among 10 other ferrets.

One of the first orders to evolve was Helcionelloida which has been interpreted as some of the early common ancestors for Mollusca.

Arthropods have an exoskeleton and therefore fossilise, giving us a more complete record of their evolution as before this time period most organisms were soft bodies, therefore much less likely to leave any fossil evidence. This doesn’t stop disagreements about what should be classed as an arthropod. The Cambrian signifies the start of two major lineages of arthropods, Chelicerata and Mandibulata, their descendants still living today having diversified into many different classes. The trace fossil Rusophycus which may have been the trail of an arthropod dates as far back as here.

The time that brings you the first non-vascular plants like moss, and water filled with arthropods and molluscs. Divided into seven stages, the information we have from this is by studying layers of rock and the composition of fossilized sea creatures. Geologists can also tell that plate tectonics shifted and changed a lot, due to the deposition of detrital and chemical sediments of the crust and cratons, while palaeontologists have noted Corals, Nortalids and Cephalopods undergoing a lot of radial evolution, at least in the areas that are studied. Mainly in Europe and North America. I’m not judging, just slightly disappointed, the scientific community as a whole loses one scholastic point, but gains it back again because in recent years more studies have been done in more places.

The Late Ordovician mass extinction occurred during the Ordovician – Silurian transition. Possibly initiated by glaciation, causing sea levels to drop. The species that had established niches along the marine–terrestrial divide would have either had to adapt or die, along with the change in sea temperature that proved too much for an estimated 60% of marine life. This event was a two pulse event, together eliminating about 85% of species. Glaciation isn’t the only theory for the driving force behind this mass extinction, volcanism is another theory, but the solid reason for this extinction event is temperature changes. Mainly affecting brachiopods, bryozoans, conodonts, trilobites, echinoderms, corals, bivalves and graptolites. Despite the huge plummet in species, the broad structures of species morphology and ecology didn’t change, niches largely stayed the same. Diversity would slowly recover over the next 5 million years.

Shoots and leaves are underpinned by a new vascular system of xylem and phloem beginning a huge diversification of new plant species. Being likened to the Cambrian explosion for Plantae.

If you wish to skip the nonsense of how fungi came about and the intricacies of phylogenetics and taxonomy here is where fungi start to show up in a larger diversity of species within the fossil records. The fossils are still very rare, but these fungi got big, the largest (prototaxites) appearing during the Late Silurian or Early Devonian reaching 8 meters.

Estimated to be around 407 to 397 years old, These fossils showed secondary xylem otherwise known as advent wood. The radiation of this evolutionary feature would lead to a huge number of new species and an extinction event owing to the ecological changed, because this tiny feature would be responsible for creating new environments and ecological niches that, to us, are synonymous with nature.

Trying to decipher what constitutes as the first amphibian is a bag full of ferrets on meth. Many of the specimens are fragments. Elginerpeton is one of the earlier fossils, made up of fragments from the scapular, femur, tibia and lower mandible from 368 million years ago, but there are other fossils from extinct genera of tetrapod-like Parmastega which has been dated to 372 million years ago. Which could be, at the very least, a transitional link between fish and amphibians, and classed as a tetrapod. These early tetrapods would evolve into the major fauna groups of mammals, birds, reptiles and modern amphibians. But where in the gradient these early tetrapods could be classed as an amphibian is hard to decipher. Paleo-genealogy is super hard.

The one with big ass bugs and a shit tone of coal. Woody plants really took off, but the decomposers of the ecosystems hadn’t quite adapted to this yet, which meant all this organic matter couldn’t be broken down, leaving us with the layer of coal. And why it is a finite resource, because every epoch since has had decomposers who can handle it. An interesting thing that is currently happening in the evolution of bacteria and decomposers, is that some bacteria can break down plastics, as a result of their being a resource in abundance. The old adage of “life finds a way” is ringing true presently, as it did 358.9 million years ago with this new resource called wood.

The first amniotes were a group of tetrapods that laid their already fertilized eggs on land or retained them inside their bodies. These species would diversify into many of our modern vertebrates, including mammals, birds and reptiles.

Pangaea forms from Gondwana and Euamerica, setting the stage for the dinosaurs that aren’t actually dinosaurs, therapsids. Which dominate the land. The ones with the big sails evolving first. It was the 3^rd of the main five mass extinction event that puts a stop to that and instead leads to dinosaurs.

Let’s face it, we all had a dinosaur and a mythology phase. Even if we weren’t a gender that actively encouraged these phases we still had them. Some of them lasted one singular moment when visiting a museum, others lasted years, and some of us never truly left them. Nor should you, but finding reliable information can be tricky. Films lie to you, the BBC’s “walking with dinosaurs” is out of date, and reference books cost the earth you stand on and your right kidney. So let me give you an outline that your 6-year-old self will be shocked you even need, because at the age of 23 the dementia is clearly kicking in and you’ve forgotten some of the broader details of what dinosaurs came when. For those of you who haven’t had your dinosaur phase yet, I don’t care how old you are, you are 6 years old again. Welcome to the age of reptiles! The death of Pangaea and the disintegration of Gondwana.

The fragmentation of Pangaea and the continuing shifts of the continents can be discovered by looking at the detrital and chemical sediments both as part of the crust and cratons, but also by looking at magnetic signatures from the oceanic crust. Rifts formed, notably between Laurasia and Gondwana, filling with seawater and creating an ocean basin that would become the Atlantic over millions of years. Mapping the movement of the globe’s mobile belts gives us an indication of how stable the geology was and how these shifts may have shaped the biosphere by separating populations and changing the climate, even allowing us to narrow down the causes for various extinction events.

During the mid-Triassic, we welcome Nyasasaurus Parringtoni. This is the closest to the common ancestor of all dinosaurs that we have found, part of the archosaur genus. The fossils were found in Tanzania comprising of fragments of an arm bone and some vertebrae. Very little is known about it, but its size can be estimated at around 100cm high, as well as its locomotion, being largely bipedal.

The Triassic-Jurrasic extinction event. Both terrestrial and aquatic fauna were affected, an estimated 23% to 34% of marine genera went extinct along with many archosaurs. There seemed to be a number of environmental and climatic changes. Rapid global warming of 3°^C to 4°^C. Stratification of the ocean basins with consequent decreased water circulation. Increased atmospheric pCO₂ inducing a perturbation, (deviation of movement in a normal system), in the carbon cycle. Sea levels fell. Carbonate productivity declined. Volcanic activity has been theorized to be the main cause for these changes, specifically the information gained from Central Atlantic Magmatic Province (CAMP), which has been attributed to the breaking up of Pangaea. This is another extinction event that has phases. Volcanism being the first set of events followed by marine anoxia and acidification of the oceans, our old friends.

The One with all the classics and when you realized that Hollywood was a lie. I’m talking about Tyrannosaurus Rex and the like. The last geological time period with what we would consider true dinosaurs, every species has its end. Until you hear and see a cassuary.

Likely the youngest of the polaris stars is α Umi Aa. There is some speculation at the age of this star, as there is with all things on this meandering journey of ours, but even with additional data and theories the age remains around the 50 to 70 million years mark.

Welcome to Asteriornis, the oldest fossil evidence of modern birds. Also dubbed the wonderchicken, as depending on the angle, it either looks like a duck or a chicken and palaeontologists are odd people. There were genera like archaeopteryx from the Late Jurassic and Ichthyornis of the Late Cretaceous, but these species retained many of their theropod characteristics such as teeth Asteriornis on the other hand was built differently, and would be recognisable as a bird to a modern ornithologist, albeit a confused ornithologist.

The shortest of Eras and abandoned by geologists in favour of using epochs to divide the time scale, because with an era this tiny, you might as well be more specific and use epochs. This is the journey of how mammals seemingly took over the land, seas and ventured into the skies, with birds diversifying alongside them. The very last remnants of the dinosaurs. Due to this Era being far more recent we are able to distinguish much more variety of the global climate, and not just in its general spiral from warm with few ice caps to widespread glaciation. Geological time periods may differ slightly depending on where in the world it’s being measured. In the past 30 years or so, more information about the world at a global scale has been discovered, published, and more widely distributed. So, from the rumbling shifts of the Orogenic Mobile Belts, the continental tilting, frozen expanses of glaciation, to the ongoing argument (or what my parents would call a “loud discussion”), about whether the Anthropocene is real. Let us explore our own geological era. Welcome to the second line of your temporal address.

For a species that is so prevalent, grass evolved pretty late. When it did, it did what the vascular trees did before it and created entire new ecosystems and many an aneurysm for gardeners the world over. With new species and ecological behavioural shifts, it is hard to picture our world without grasses down to our own agricultural practices with domesticated grass species and the aristocratic French bringing us the aneurysm-inducing lawns to the reason for some of the most spectacular migrations of animals on the planet. Grass became ubiquitous in many biomes.

Welcome to Sahelanthropus tchadensis, let’s hope we don’t regret it. Possibly roaming the earth at 7 million years ago around the present-day Sahara, Granny Sahelanthropus tchadensis was a bipedal apelike animal, with small canines. We only have a little data on the cranium, hence why I’m separating this as a species of note rather than a definitive species of early Homo. Ardipithecus ramidus was another species of note. Still very apelike, appearing in the fossil record around 4.4 Million Years Ago. It is thought to be one of the ancestor species for non-human hominins, but with no complete specimens, it remains a question. Palo-genetics is a difficult field to give certainty to with the specimens and technology we currently have. So, even though there are Ardipithecus ramidus specimens that are more complete than Lucy (an Australopithecus afarensis dated 3.9 to 2.9 million years old), they are still not a complete picture.

The first human species Homo erectus. This species stood upright and lacked the slightly ape-like feet and facial featured, with a flatter face and less prominent brow ridges, but still distinctly not to the degree of Homo sapiens and shared the planet with around 6 other species of human.