The animal kingdom is divided into different evolutionary lines. These include, among others, the protostomes ("mouth first") and deuterostomes ("second mouth").

Most of the animal forms we're familiar with date back to what's called the Cambrian, which started about 540 million years ago. But the earliest animals appear before that, in a period called the ...

This is a simplified evolutionary tree of six representative animal phyla, illustrating differences in body form, habitat, and species numbers among them. Advanced Search. Home; ...

Researchers of the Siberian Branch of the Russian Academy of Sciences have reconstructed the likely appearance of an extinct group of comb jellies, one of the oldest known animal phyla. Their findings ...

Phylum vertebrata: New concepts based on advances in animal systematics. ScienceDaily . Retrieved June 2, 2025 from www.sciencedaily.com / releases / 2014 / 09 / 140917073112.htm ...

That prompted me to ask what kinds of sexual differences predominate across the entire animal kingdom, and why.” Daphne Fairbairn[/caption] Fairbairn spent three years mining the available literature ...