South China shows the first three-foot giant

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Take it fast

• A 436 million years old Fossils of bony fish have helped researchers better understand them Vertebrate evolution.

• Before this discovery, the Lack of Silurian fossil record A huge data gap was created.

• Another fossil discovery A hall of mystery that has been around since 423 million years ago Old teeth.

I read Lulu Miller’s for the first time Why fish do not exist In 2024. Interspersed with her own personal exploration of the purpose of discovery, Miller recounts the story of David Starr Jordan, who named and described more than 2,000 fish species (an estimated 20% of the known species at the time). What fascinated me the most was how complex the biological hierarchy of “fish” really is. Miller explained the fascinating biology of fish, for example, that longfish are more closely related to humans than salmon! To learn more about the evolution of fish, I studied everything fish-related I could find: how bony fishes are the evolutionary ancestors of nearly all vertebrates, how ray-finned fishes are the ancestors of 99% of fish today, and how lobe-finned fishes are the precursors of tetrapods like amphibians and humans, reptiles.

Despite everything I’ve learned, I still have questions: What did fish look like before the ray-fin and lobe-finned split? Were ancient fish different from each other? Did they share the same characteristics seen in fish today? In 2026, a team from the Chinese Academy of Sciences’ Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) published research on two bony fish fossils found in southern China. A fossil, nom Eosteus of ChongqingThe oldest is a nearly complete, articulated bony fish fossil. This rare discovery is revealing a host of new information about evolutionary change.

History of fish

Although some scientists argue that bony fish diverged into ray-fin and lobe-fin fish at the end of the Silurian period, the general consensus is that the divergence occurred during the early Devonian period, approximately 419 and 339 million years ago. In fact, the Devonian period is sometimes called the “Age of Fishes.”

Ray-finned fish, part of the superclass Actinopterygii, have thin, webbed fins spread over bony spines. They make up the vast majority of fish, accounting for 30,000+ species in the world today. If you’ve heard of catfish, sturgeon or tuna, you know at least one ray-finned fish. Lobe-finned fish such as coelacanths in the Sarcopterygii superclass have fish fins. There are also significantly fewer lobe-finned fish than ray-finned fish.

Before this division, bony fishes were known as ostethians. Although scientists still use the term today, osteichthyans now include tetrapods in addition to bony fish.

A better understanding of ancient ostriches can reveal how this common ancestor laid the foundation for the evolution of animal life. The problem is that the fossil record is relatively incomplete. As the IVPP authors point out in their first published study, “Osteichthyans…dominate modern vertebrate biodiversity, yet their pre-Devonian fossil record remains rare and fragmentary.”

In other words, almost all the fossils we find come from the Devonian period. This is probably because animals in the Silurian period had softer bodies. Because soft tissues as well as shells or bones are not preserved, soft-bodied organisms are rare in the fossil record. This does not mean that soft-bodied animals cannot fossilize, just that the probability of that fossilization is low.

what is Eosteus of Chongqing?

Although only discovered in 2019, China’s fossil site Chongqing Lake State has become famous for its well-preserved fish fossils. In the past, fossils found in the area include shark-like cartilaginous fish Shenacanthus vermiformis including large, armored chest plates and Xiushanosteus is amazingAn armored jawed fish.

e. Chongqingensis It was found in the same area. As this small fish measured only 3 centimeters (about 1.2 inches) in length, it was certainly not one of the top predators of its time. The fossil dates to 436 million years ago, predating other fossils and microfossils of its type.

Researchers noticed that e. Chongqingensis There was a mix of different features, including:

• A generalized bony fish body, but without any bony fin rays

• Caudal fulcrums, ossified (hard/hard) spines or scales

• Single dorsal fin behind

• An anal fin spine is commonly found in placoderms (old armored fish like Duncleosteus) and cartilaginous fish.

essentially, e. Chongqingensis Many evolutionary traits that we see now are sorted into separate lineages. More importantly, the scientists noted that features associated with bony fish, such as dorsal fins and body shape, appeared earlier than they thought.

The authors note, “The 50% majority rule consensus of Bayesian inference and maximum-parsimony analysis places the new fish in the osteichthyan stem, while the strict consensus leaves its position unresolved.” In less scientific language, they are saying that some place analysis e. Chongqingensis Relatively before bony fishes appeared. However, this is not fully proven.

Another quest

IVPP researchers also identified the head and trunk bones of another Silurian-period fish Megamastax amblioduswhich lived about 423 million years ago. They found it M. Amblyodus Fossils in the city of Kujing, located in Yunnan Province, China. opposite e. Chongqingensis, M. Amblyodus was big At one meter long, or about 3.3 feet, it was the largest Silurian vertebrate from that geologic time period. This means possibility M. Amblyodus was a top hunter.

In the past, researchers found fragments M. Amblyodus fossil. While this provided a general overview of the fish’s existence and rough shape, there were still many questions about the creature. Researchers believed at first M. Amblyodus Can be lobe-finned fish.

About ten years later, the authors, who published their findings NatureFound the right advanced imaging and 3D reconstruction techniques to use M. Amblyodus‘ Head and trunk material to learn more about its anatomy.

Megamastax ambliodus had a unique anatomy. First, the researchers discovered that its main blood vessels resemble those of cartilaginous fish. M. Amblyodus There were also many archaic anatomical features such as the anterior upper jaw bone. But, perhaps most interestingly, Megamastax ambliodus In fact, early bony fish showed more characteristics, including:

• Extrascapular bones, or small bones in the neck area/back of the head

• Evidence of tooth resorption and replacement

• Two rows of cushion-like teeth sitting on blunt, individual bases

Importance of teeth

M. Amblyodus‘ The teeth are important because they show what early bony fish teeth looked like. According to the research team, “Phylogenetic analysis places Megamastax Within the Osteichthyan stem, close to the Osteichthyan crown-group node.” In other words, M. Amblyodus The bony fish was a near direct precursor to the early stages of evolution.

But the tooth also solved a scientific mystery. For decades, scientists in Europe’s Baltic region have been finding well-preserved tooth plates in Silurian rocks. It is now clear that they were not isolated fossils, but parts M. Amblyodus‘ Jaw. Additionally, these fossils show how widespread osteatheons were during the Silurian period.

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