Leo Baker Geometric Timeline

Cambrian Period

541 BCE

This period lasted 55.6 million years and brought a big change in evolutionary life referred to as the 'Cambrian Explosion'. During this time there were many hard shelled organisms (Chordates) and arthropods which are the ancestor of some present day organisms.

Ordovician Period

485 BCE

The Ordovician period lasted 41.2 million years. Its most notable feature was its large diversity of underwater life including trilobites, types of algae and many, many others. The temperature was mild and the atmosphere was full of moisture.

Silurian Period

443 BCE

The Silurian picture is the third period in the Paleozoic era and during this time the earth's sea levels were rising. In this period Agnatha were a common fish in the earth's oceans. They had no jaws and are similar to the modern Hagfish and Lampreys. The ocean's predators were a horseshoe crab-related creature called eurypterids. Most importantly during the Silurian period the first plants started to colonize land. These plants were most likely Lichens.

Devonian Period

416 BCE

This period lasted 60 million years and is referred to often as the "Age of Fishes". There's evidence showing that at this time there were 2 groups of fish with actual teeth, bones, swim bladders, and gills. Similar to the fish we have today. Insects like millipedes, centipedes and arachnids were also becoming more diverse. The Tiktaalik roseae also existed in the mid devonian. The second big Mass Extinction also took place, wiping out 70% of species at that time.

Carboniferous Period

359 BCE

This period occurred during the Paleozoic Era and is best known for its immense swamp forests. During this time amphibians were evolving and diversifying. Predators similar to today's crocodiles lived along with other evolving amphibians. The Amniote egg also came to be and earth's continents were moving together and soon to become Pangea.

Permian Period

298 BCE

This period began with the merging of the supercontinent Pangea. Due to the vast size of pangea, it caused extreme climates and environments. The swamps were replaced with different plant life better suited to the new earth. Huge cold blooded reptiles roamed the harsh land and later Therapsids (a mammal-like reptile) evolved and was better suited to Pangea. Unfortunately in the end one of the biggest mass extinctions took place, wiping out 90% of all marine species and 70% of land animals.

Triassic Period

251 BCE

The Triassic Period is the first period in the Mesozoic Era, following the great mass extinction. This time is often referred to as the "Age of Reptiles". There wasn't a lot of marine life after the extinction but some reptiles did go back into the oceans afterwards. The Lystrosaurus was a reptile during this time, and fossils of this creature predate the mass extinction but are also commonly found in early Triassic strata. Early mammals also began evolving during the end of the Triassic period.

Jurassic Period

201 BCE

This period lasted nearly 55 million years. During this time Pangea started to split apart. For plant life Fern and Ginkgos were dominant. They had roots are vascular tissue. The Jurassic period is rightfully known as the "Age of Dinosaurs" for its abundant amount of them. They developed strong skeletal structures and produced amniotic eggs. Both plant and meat eating dinosaurs evolved such as the Brachiosaurus and the Allosaurus. Small early mammals also lived among these giant lizards.

Cretaceous Period

145 BCE

This period is the last in the Mesozoic Era and lasted about 79 million years. During this period Pangea continued to drift apart and change the land. Ancient birds also starting flying in this period alongside the pterosaurs. Towards the end of the period large herded herbivore dinosaurs were said to flourish. The temperature was overall pretty warm and many tropical plants existed.

Tertiary period

65 BCE

The Tertiary period was the first of the Cenozoic Era. It lasted 64.4 million years. Mammal dominance was on the rise during this time. They began to evolve and grow bigger relatively quick, including ancestors of modern deer and horses. Also monkey ancestors.

Quaternary Period

2 BCE

The Quaternary period lasted barely over 2 million years. Almost this entire period is considered an ice age.Mammals continued to evolve, bring about animals like the mammoth, mastodon, giant bison woolly rhinoceros and others. Man also started evolving. Being in the form of Homo Erectus and neanderthals and homo so-on's.