The first animals on Earth had no skeletons and that changes everything

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Earth’s first sponges were soft, skeleton-free pioneers—rewriting the origin story of animal life. The earliest sponges were soft-bodied creatures without the mineral skeletons seen in their modern relatives, which explains their missing early fossils. Credit: Shutterstock Sponges rank among the oldest known animals on Earth, yet scientists have struggled to pinpoint exactly when they first appeared. DNA from living sponges and chemical traces preserved in ancient rocks indicate they emerged at least 650 million years ago. The findings are reported in Science Advances. That early date has sparked debate because it predates the oldest confirmed sponge fossils by at least 100 million years. To resolve this long standing conflict, an international research team led by Dr. M. Eleonora Rossi of the University of Bristol's School of Biological Sciences took a closer look at how sponge skeletons evolved. The Fossil Record and the Missing Spicules Modern sponges contain skeletons made of countless microscopic, glass-like structures called spicules. These durable elements fos
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