Bichirs don't belong to the broad group of lobe-finned fishes
that gave rise to land-dwelling vertebrates.
Believed to be descended from lobe-finned fishes
, modern amphibians are divided into three groups--frogs and toads, salamanders, and caecilians.
One lineage led to the ray-finned fishes, or actinopterygians, and the other to lobe-finned fishes
, or sarcopterygians; the latter gave rise to land vertebrates, Bemis explained.
evolved legs while still in the water.
Around 400 million years ago, certain species of bony fish--called the lobe-finned fishes
for their muscular, fleshy fins--began to evolve features such as larger limbs with digits, which allowed them to move onto land.
But between the latest Devonian Period and the subsequent Carboniferous period, placoderms disappeared and ray-finned fishes rapidly replaced lobe-finned fishes
as the dominant group, a demographic shift that persists to today.
The tracks are also ten million years older than the oldest known fossils of lobe-finned fishes
called elpistostegids, which are widely considered to be transitional forms between fish and tetrapods.