Design a plan to use morph. studies, biochemical evidence (molecular) and geological evidence(fossil)

Question

Snakes are a group of legless reptiles. Some scientists have raised the following question: Did snakes have a legged ancestor in their evolutionary history, and if so, how long ago? 

Design a plan to use morphological studies to obtain information that can help answer the question raised above. 

Design a plan to further study this question using biochemical evidence.  

Design a plan to further study this question using geological evidence.

Answer 1

So Vina M.,

Morphology wouldn't be easy, since there aren't a lot of intermediate species present today. Maybe some legless skinks, but that doesn't get you anywhere, does it. Though you could study all sorts of skeletal structures, etc. (including oviparous vs. viviparous) it might be difficult to infer timing?

Biochemical -- can study metabolic enzyme systems in general, but I think you'd want a genomic analysis, for enzymes present across reptiles in general, and maybe amphibians as well. Genomic divergence is well-characterized, if computationally intensive. There's probably a lot of data out there, that could get you the timing of first-snakes.

Geologic -- you'd have to find and identify time of first snake origins. You probably wouldn't find intermediate forms. More likely, you'd find radiation of snake species from an early snake critter. But this requires a considerable fossil database.

-- Cheers, --Mr. d.