An Occasional Series
Introduction:
This is the first in a series of background pieces for the Testament d20 setting published by Green Ronin It is being presented in the hope it adds to your Testament campaign, or other campaigns.
Our story begins with a disaster. Around 300 million gears ago the Siberian and European plates slammed into each other. Between the two some two million square miles (maybe more) of sea bottom were thrust up to become the broken lands usually referred to as Siberia. Along with this there came a long term series of eruptions known as the Siberian Traps. The greatest series of volcanic eruptions since the evolution of muticellular life
About this time the supercontinent of Pangaea was forming. Along with the change in world climate caused by the new land mass, the Siberian Traps produced much in the way of volcanic ash, which served to place the Earth in a sort of volcanic winter. The dominant vertebrates of the period and other large animals were not able to adapt to the changed conditions. So it was that the therapsids and thecodonts passed away, to be replaced after a period of transition by descendents of the thecodonts we would come to know as dinosaurs.
As the early dinosaurs grew in size, the therapsids found refuge by becomig smaller. Adopting a nocturnal life style helped as well, for the earliest of the dinosaurs were preferentially diurnal.
Other changes occurred among the therapsids as well. As they came to rely more on their sense of smell the olfactory bulb grew in size and importance. The frontal lobe became large and more complicated as well, the better to handle the information brought in by the nose. (The dinosaurs, in contrast, relied more on their sight, so in their case the parietal lobe became better developed. Which is why birds (descendents of dinosaurs) have the sort of brains they do.)
In addition there were changes in limb and jaw structure among the therapsids at this time, giving us the erect stance and the jaw of the modern mammal.
[sidebar]Therapsids belonged to a group of reptiles known as 'Synapsids', a group that also included the pelycosaurs. Synapsid is usually taken to mean, "one hole" since the early synapids had a single hole in the skull through which jaw muscles could attach to the animal's brain case, a more efficient way of doing it than the anapsid's (turtles, terrapins, tortoisis, and tuatra). The ealy diapsids (lizards, snakes, dinosaurs, and crocodiles) had two holes in the skull, which performed essentially the same function as the synapsid's single defenestration (a term for 'window' in the skull).
However, there were synapsids with two holes in the skull later on, as well as diapsids with single holes (formed with the merging of the original two over the generations. The big difference between the two groups lay in where the jaw muscles were attached to the brain case. In the case of the diapsid reptiles the jaw muscles attach to a point on the brain case past the bones of the reptilian jaw hinge. In the case of the synapsid reptiles the muscles attach to a point before the bones of the reptilian jaw hinge. As the generations passed an jaw muscles shifted their point of attachment to the brain case the reptilian jaw hinge among the synapsids had to move as well. Over time a new jaw hinge developed, derived from the proximal (near) end of the expanding dentary bone. When this new mamallian jaw hinge entirely supplanted the old reptilian version is when the first mammals appeared.[/sidebar]
The first mammals are now thought to have appeared in the Jurassic. Splay-legged, reptile brained, egg layers, they showed little promise. But from these first proto-mammals would come such as you and I.
Next up: Multituburculates, marsupials, and the early placental mammals.
Introduction:
This is the first in a series of background pieces for the Testament d20 setting published by Green Ronin It is being presented in the hope it adds to your Testament campaign, or other campaigns.
Our story begins with a disaster. Around 300 million gears ago the Siberian and European plates slammed into each other. Between the two some two million square miles (maybe more) of sea bottom were thrust up to become the broken lands usually referred to as Siberia. Along with this there came a long term series of eruptions known as the Siberian Traps. The greatest series of volcanic eruptions since the evolution of muticellular life
About this time the supercontinent of Pangaea was forming. Along with the change in world climate caused by the new land mass, the Siberian Traps produced much in the way of volcanic ash, which served to place the Earth in a sort of volcanic winter. The dominant vertebrates of the period and other large animals were not able to adapt to the changed conditions. So it was that the therapsids and thecodonts passed away, to be replaced after a period of transition by descendents of the thecodonts we would come to know as dinosaurs.
As the early dinosaurs grew in size, the therapsids found refuge by becomig smaller. Adopting a nocturnal life style helped as well, for the earliest of the dinosaurs were preferentially diurnal.
Other changes occurred among the therapsids as well. As they came to rely more on their sense of smell the olfactory bulb grew in size and importance. The frontal lobe became large and more complicated as well, the better to handle the information brought in by the nose. (The dinosaurs, in contrast, relied more on their sight, so in their case the parietal lobe became better developed. Which is why birds (descendents of dinosaurs) have the sort of brains they do.)
In addition there were changes in limb and jaw structure among the therapsids at this time, giving us the erect stance and the jaw of the modern mammal.
[sidebar]Therapsids belonged to a group of reptiles known as 'Synapsids', a group that also included the pelycosaurs. Synapsid is usually taken to mean, "one hole" since the early synapids had a single hole in the skull through which jaw muscles could attach to the animal's brain case, a more efficient way of doing it than the anapsid's (turtles, terrapins, tortoisis, and tuatra). The ealy diapsids (lizards, snakes, dinosaurs, and crocodiles) had two holes in the skull, which performed essentially the same function as the synapsid's single defenestration (a term for 'window' in the skull).
However, there were synapsids with two holes in the skull later on, as well as diapsids with single holes (formed with the merging of the original two over the generations. The big difference between the two groups lay in where the jaw muscles were attached to the brain case. In the case of the diapsid reptiles the jaw muscles attach to a point on the brain case past the bones of the reptilian jaw hinge. In the case of the synapsid reptiles the muscles attach to a point before the bones of the reptilian jaw hinge. As the generations passed an jaw muscles shifted their point of attachment to the brain case the reptilian jaw hinge among the synapsids had to move as well. Over time a new jaw hinge developed, derived from the proximal (near) end of the expanding dentary bone. When this new mamallian jaw hinge entirely supplanted the old reptilian version is when the first mammals appeared.[/sidebar]
The first mammals are now thought to have appeared in the Jurassic. Splay-legged, reptile brained, egg layers, they showed little promise. But from these first proto-mammals would come such as you and I.
Next up: Multituburculates, marsupials, and the early placental mammals.
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