No more frogs dating Cam4 men iowa
The split between Anura and Caudata was estimated as taking place 292 million years ago, rather later than most molecular studies suggest, with the caecilians splitting off 239 million years ago.In 2008, Gerobatrachus hottoni, a temnospondyl with many frog- and salamander-like characteristics, was discovered in Texas.It had many frog-like features, but had 14 presacral vertebrae, while modern frogs have nine or 10.
The earliest known salientians (see below), closer to the extant frogs than to the extant salamanders, are Triadobatrachus massinoti, from the Early Triassic of Madagascar (about 250 million years ago), and the fragmentary Czatkobatrachus polonicus from the Early Triassic of Poland (about the same age as Triadobatrachus).
The structure of the salientian pelvis and hind limb was probably developed for swimming rather than jumping.
From the structure of the vertebrae, the group appears not to be monophyletic.
Another molecular phylogenetic analysis conducted about the same time concluded the lissamphibians first appeared about 330 million years ago and that the temnospondyl-origin hypothesis is more credible than other theories.
The neobatrachians seemed to have originated in Africa/India, the salamanders in East Asia and the caecilians in tropical Pangaea.