Sentences with phrase «animal phyla appeared»

The fossil record suggests complex multicellular life emerged about 600 million years ago in a relatively short period termed the «Cambrian explosion,» during which most major animal phyla appeared.

Not exact matches

Except for the Ediacaran biota, most animal phyla (some that persist and some that did not) appear in the fossil record rapidy and essentially simultaneously at the base of the Cambrian period, some 570 million years ago, an event known as the Cambrian Explosion.

Given that sexual reproduction is widespread among animals and sperm production appears to be present in all major phyla of metazoan animals, it raised a question whether any male - biased reproductive gene could be exempt from such selective pressure and remain conserved through extended evolutionary distances.

In any case the indisputable testimony of the geologic column reveals that in the last 500 million years (since the Cambrian explosion when most of the modern phyla appeared and Ediacaran phyla disappeared) and animals started crawling out onto land the CO2 level in the atmosphere has, most of time, been 10 to 20 times greater concentration than today.