Guiyu | 3D Dinopedia

Guiyu

Period of life:

425 million years ago

Period:

Silurian period

Habitat:

Marine environment

Taxonomy:

Bony fish

Height:

0.11 m

Countries:

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Guiyu (425 million years ago)

Guiyu oneiros, which means “ghost fish” in Chinese, is one of the oldest known bony vertebrates. In fact, it may be the very first lobe-finned fish (Sarcopterygii)—the evolutionary branch that, hundreds of millions of years later, gave rise to amphibians and eventually to all land-dwelling vertebrates, including humans.

The remains of Guiyu were discovered in Yunnan Province, southern China, in marine deposits dating back about 425 million years to the Late Silurian Period—an era when life was only beginning to venture onto land. At that time, the oceans teemed with armored fish, ancient arthropods, and the first coral reefs. Within this vibrant ecosystem, Guiyu held its place as one of the early links in the grand evolutionary chain.

Imagine a fish about 30 centimeters long, with a streamlined body, shiny scales, and powerful fins. In shape, Guiyu resembled modern perch, yet it combined features of both ancient armored fishes (placoderms) and modern bony fishes. Its pelvic girdle included not only internal skeletal elements, like those of today’s fish, but also external bony plates—a remnant of ancient armor. Its fins bore large spines that likely helped defend it against predators.

The skull of Guiyu was covered with bony plates, and its body was protected by tough scales coated with ganoine—a glossy enamel-like substance still seen in sturgeons and garfish today. Behind the head were three large bony shields, remnants of a thoracic armor similar to that of placoderms. These features make Guiyu a true “living puzzle” for paleontologists, combining traits from several early vertebrate lineages.

Studying Guiyu helps scientists understand the transition from armored fish to bony fish—from slow, heavily plated creatures to agile swimmers that would eventually become the ancestors of all modern fish. These discoveries illuminate one of the most crucial stages in evolution: the emergence of the bony skeleton, a development that paved the way for countless species to flourish after the Silurian period.

Guiyu is more than just an ancient fish—it is a testament to nature’s early evolutionary boldness, the first step toward the complex organisms that, millions of years later, would include us.

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