Where are all the missing links?

Alligator scoots, dinosaur feathers and mammal hair are all made up of keratin, though of different weights. Dinosaurs, probably being endothermic, probabley had the same insulation needs as mammals. As such, downy feathers provide a much needed relief.However, there is still a large gap between flight feathers and down. An excellent research project was performed to establish how they could have developed at the Society for Vertebrate Paleontology(you'll need to search for that... I'm having no luck in finding the abstract). Birds flap their wings to generate lift to fly in the air. The funny thing is... this works on the ground just as well. Wings can perform the same function and allow for higher running speeds. The plus is that you can be a large carnivore and still benefit (hmmm... T-rex arms suddenly looking pretty handy now...). As such, given the prey size throughout the Mesozoic it seems logical that such a benefit would quickly emerge, and grant it's phenotypic host the benefit of increased breeding sucess.Of course it's pure speculation, but that would explain the diversity of theropod forms and sizes and why there doesn't seem to be a straight line to our avian friends.And... to the author of this innitial post... using the term "lesser forms" is misleading. Evolution does not make any value judgements on genomes. They are merely complex or simple to fit the needs of survival.Vale,
Theus

---

Veri Omni Veritas

Congratulations! You have found the reasonably esoteric "thread within a thread"! Size isn't the only factor involved. The arms are extremely muscular, and there is a non-vestigial third metatarsal used only for tendon connections to the other two exposed fingers. There certainly are indicators that it was used for something, but it may be specific to something we cannot measure, such as mating behavior. However, given the muscle strength it certainly is testable to determine if it could generate enough lift. Even a perceived "negligible" or small amount would be sufficient, if only to compete with other T-rexes. It was no problem for T-rex to outrun Triceratops or a Hadrosaur, but outrunning T-rexes in competition for food is something else entirely. And you are right, they are not built like raptor arms, the latter have much greater side-to-side movement and can certainly reach the mouth, even with their longer than normal necks.Excellent point on the feathers (downy vs. flight). However, I was referring to the initial functional jump, not the now-known path of it's development. There must be an additional selectional step to focus on downy feathers to push them toward feathers capable of flight.בתםים
Theus

---

Veri Omni Veritas