The "Genesis Sphere" is causing some overgrowth effect on the biosphere there. Certain life forms would probably even be bigger if they emerged on an Earth-like planet, instead of this Super-earth world. The pictured aliens would be even leaner and taller if they spent enough time producing new generations on a less massive planet.
Although I agree, its perhaps too slender for the amount of G factor the planet displays. I'll either tweak the gravity and mass of the world later, or the alien concept and make it more bulky, beefy, hard.