Related Experiment Video
Updated: Jul 11, 2026

Processing Embryo, Eggshell, and Fungal Culture for Scanning Electron Microscopy
Published on: August 16, 2019
Fossilized viscera in primitive echinoderms
Abstract:
Fossilized visceral organs in ancient echinoderms have anatomical features that were not inferred from the anatomy of extant relatives. The unique visceral anatomy of extinct echinoderms demonstrates the need to integrate paleontological and neontological analyses in order to fully evaluate this and other morphologically complex phyla. Comparative analysis of the visceral anatomy of extinct and extant echinoderms necessitates regrouping these animals into three new subphyla. Similar analyses for other metazoan groups could yield equally significant results.
Related Concept Videos
The Fossil Record
What is Evolutionary History?
The Evidence for Evolution
Cleavage and Blastulation
Diversity of Protists III
Eukaryotic Evolution
Contrary to the endosymbiont theory, the eukaryote-first hypothesis proposes that the simpler prokaryotic and...

