Oh, tetrapod. How Science Daily says you’ve changed. The first walkers, they’re saying, may have had more to do with floods than droughts:
University of Oregon scientist Gregory J. Retallack, professor of geological sciences, says that his discoveries at numerous sites in Maryland, New York and Pennsylvania suggests that “such a plucky hypothetical ancestor of ours probably could not have survived the overwhelming odds of perishing in a trek to another shrinking pond.”
…
“Remains of drying ponds and desert soils also are known and are littered with fossil fish, but none of our distant ancestors. Judging from where their fossils were found, transitional forms between fish and amphibians lived in wooded floodplains. Our distant ancestors were not so much foolhardy, as opportunistic, taking advantage of floodplains and lakes choked with roots and logs for the first time in geological history.”
Limbs proved handy for negotiating woody obstacles, and flexible necks allowed for feeding in shallow water, Retallack said.