Lurker, I think I figured out the evolutionary divergence point. My guess is that the planet had/has more than one moon or the moon was far closer at the same point than on Human Earth. With a higher gravity the six legged anphibians would be closer faster and more able to get prey... like the less legged anphibians. On Human Earth the four legged ones could survive on less food and breed faster as it was easier for them to get enough spare weight to produce offspring.
Either something hit the moon (or one of them) and knocked it away (farther from the planet or into the distance) and/or the offending projectile (possiblely a smaller moon also) ended up bombarding the planet and making it have a debris field around it. Either way the planet has less gravity now (or at least temporary super strength would have been mentioned) this debris could be the source of the high (relative to the human world's levels) of magic. Or it could be just like what I subspect happened in the third homeworld... its really, really close to Limbo or someother highly chaotic plane, say D&Ds etheral plane level close.
Though the Nekokai could also have caused the lack of human magic users. They apparently like to build large magic constructs on weak points between the worlds. Gateways to the human Earth and blocking runic structures on the 3rd races gateways. Those kind of things take lots of power to keep active. Since I can only guess that a nomadic people would set up a self substaning system so they didn't have to stand around watching it all the time... the easiest way to power it is to have it suck energy out of some large source of power... like the portals to the land full the 3rd race. To keep the sights from blowing it self up the easiest way is to take the excess magic power and dump it somewhere like the atmosphere. The blocking runic things mulch anything that wants to come through ending the unwanted intrusions in their world. If this is the case the they are probablely using the same type of thing to power the gateways and keep them stable when active. This either means they are draining power from their world or the human world. President says the humanside is where the power would come from... which would turn the non local side of the gateways into the magical equivalent of a gravity well... and would leave that sight a magically active zone in the human world. Thus all magic power comes from the third world and its been set up like this so long the NekoKai people forgot this is what is going on. At least on the large scale, if one set of mostly non nomadic people are maintaining these things and they don't remind peole or no one bothers to ask. Basically they turned there planet into a giant magic battery. Leylines being the magic power influx powerline for the portals.
By the same token the litterbond could be because the mother is ritually/habituatually in an empathic bond with her unborn. Which sticks behind like some kind of mental drug. The extreme gender dismorphic things is because they caused the males to deevolve/alternately evolve in womb from a now subcontious cultural point, like the general sex fixation. Also I doubt they have much of a written language of there own, written language being originated for keeping track of debt and supplies for businesses that occures from agricultural settlments. They are basically tribal as a race, with the possible exception of the gateway/ruined gate keepers, which may by and large be those half dragons in the first place. Any non magical written language (the prides will have runes of power for enchanting orsuch) is likely to be closely related to the whatever humans are on the otherside of the gates. History is likely either verbal or stored with the gate buildings and largely uncared about.
To be consistant if random brother of the brother/sister literbonds die off and the sister joins a different one of those bonds any offspring are probably going to contain smarter males as they actually have examples to think about in the first place. Also those Human Earth dwellers are probalby wearing a pendant or belt or armlet that acts as a magical batery or a shrinelike piece of furniture will have to be made so they don't lose their powers and end up undisguised in public... the shrine battery would also cause random people that had magic potential to suddenly develope powers or will have bizzarre things happen to them as a result of a charge from being in proimity... which is going to make any roomates have strange lives. In the case of the jewerly anyone standing around them to long.
Again any city or settlement with infrastructure is going to be at these gate sights, mostly the ones to human Earth. If they have any trade intertribal its going to be at these sights. You also wont have mines that arent operated by import humans (didnt see any mentioned, other species arent really developed enough to tell if theyd have them).
The strangely similar species are a red herring really. For animals and plants and the like form is closely related to function of the species. The same basic form of creature pops up over and over again, their were dinosaur equivalents of wolves only they had for instance scales and a solar fin rather than fur. Genetically some species of mole (pygmy shrew I think) has the closest genetic realatice being something like a grizzly bear. Genetics is bizzarrely unrelated to the form of the animals at least. Two near identical species visually could be completely unrelated genetically and two species random species that look vastly different could be first cousins, say pigs and elephants (this could be South Parks fault for the example, I saw the program on this five years or so ago). Basically they are doing the ancient Greek version of identification rather than genetic or other more useful comparisons.
Either something hit the moon (or one of them) and knocked it away (farther from the planet or into the distance) and/or the offending projectile (possiblely a smaller moon also) ended up bombarding the planet and making it have a debris field around it. Either way the planet has less gravity now (or at least temporary super strength would have been mentioned) this debris could be the source of the high (relative to the human world's levels) of magic. Or it could be just like what I subspect happened in the third homeworld... its really, really close to Limbo or someother highly chaotic plane, say D&Ds etheral plane level close.
Though the Nekokai could also have caused the lack of human magic users. They apparently like to build large magic constructs on weak points between the worlds. Gateways to the human Earth and blocking runic structures on the 3rd races gateways. Those kind of things take lots of power to keep active. Since I can only guess that a nomadic people would set up a self substaning system so they didn't have to stand around watching it all the time... the easiest way to power it is to have it suck energy out of some large source of power... like the portals to the land full the 3rd race. To keep the sights from blowing it self up the easiest way is to take the excess magic power and dump it somewhere like the atmosphere. The blocking runic things mulch anything that wants to come through ending the unwanted intrusions in their world. If this is the case the they are probablely using the same type of thing to power the gateways and keep them stable when active. This either means they are draining power from their world or the human world. President says the humanside is where the power would come from... which would turn the non local side of the gateways into the magical equivalent of a gravity well... and would leave that sight a magically active zone in the human world. Thus all magic power comes from the third world and its been set up like this so long the NekoKai people forgot this is what is going on. At least on the large scale, if one set of mostly non nomadic people are maintaining these things and they don't remind peole or no one bothers to ask. Basically they turned there planet into a giant magic battery. Leylines being the magic power influx powerline for the portals.
By the same token the litterbond could be because the mother is ritually/habituatually in an empathic bond with her unborn. Which sticks behind like some kind of mental drug. The extreme gender dismorphic things is because they caused the males to deevolve/alternately evolve in womb from a now subcontious cultural point, like the general sex fixation. Also I doubt they have much of a written language of there own, written language being originated for keeping track of debt and supplies for businesses that occures from agricultural settlments. They are basically tribal as a race, with the possible exception of the gateway/ruined gate keepers, which may by and large be those half dragons in the first place. Any non magical written language (the prides will have runes of power for enchanting orsuch) is likely to be closely related to the whatever humans are on the otherside of the gates. History is likely either verbal or stored with the gate buildings and largely uncared about.
To be consistant if random brother of the brother/sister literbonds die off and the sister joins a different one of those bonds any offspring are probably going to contain smarter males as they actually have examples to think about in the first place. Also those Human Earth dwellers are probalby wearing a pendant or belt or armlet that acts as a magical batery or a shrinelike piece of furniture will have to be made so they don't lose their powers and end up undisguised in public... the shrine battery would also cause random people that had magic potential to suddenly develope powers or will have bizzarre things happen to them as a result of a charge from being in proimity... which is going to make any roomates have strange lives. In the case of the jewerly anyone standing around them to long.
Again any city or settlement with infrastructure is going to be at these gate sights, mostly the ones to human Earth. If they have any trade intertribal its going to be at these sights. You also wont have mines that arent operated by import humans (didnt see any mentioned, other species arent really developed enough to tell if theyd have them).
The strangely similar species are a red herring really. For animals and plants and the like form is closely related to function of the species. The same basic form of creature pops up over and over again, their were dinosaur equivalents of wolves only they had for instance scales and a solar fin rather than fur. Genetically some species of mole (pygmy shrew I think) has the closest genetic realatice being something like a grizzly bear. Genetics is bizzarrely unrelated to the form of the animals at least. Two near identical species visually could be completely unrelated genetically and two species random species that look vastly different could be first cousins, say pigs and elephants (this could be South Parks fault for the example, I saw the program on this five years or so ago). Basically they are doing the ancient Greek version of identification rather than genetic or other more useful comparisons.