It can be assumed that as the species procreates whether with humans or other hybrids it evolves and improves with each generation. A female member of the species, albeit with remnants of human DNA. The real reason may lie with the low success of the Species film franchise as a whole. The bipedal form is a male version of Sil and Eve's. Sara Daughter of Eve and Patrick Ross in her alien form. The mouth has two mandibles similar to that of the Predalien and they possess hair-like tentacles that are similar to the Yautja.
Sil's Species
He had an extendable tentacle-penis which attempted to enter Sara's mouth, similar to the tentacle described above.
However each generation share similar physical characteristics. It is also stipulated that they were a "cancerous" race that visited Mars millions of years ago when its surface was similar to that of Earth, and annihilated all life on its surface before leaving remnants of their DNA in its soil. A female member of the species, albeit with remnants of human DNA.
