About 360 million years ago, a shell-like fish, believed by many to be 9 feet long, ruled the seas in shallow subtropical waters above present-day Cleveland. Type Dunkleosteus terrelli It was Earth’s first vertebrate “super-predator” and lived during the Fish Age (Devon period), when North America was at a latitude close to what is now Rio de Janeiro. But in the nearly 150 years of research since the fossilized remains of prehistoric large fish were discovered on the shores of Lake Erie in 1867, scientists may have made some wrong assumptions about the shark’s size and shape. dunkleosteus

A scientist at Case Western Reserve University suggests in a study published this month that the length of this prehistoric predator may have been greatly exaggerated, meaning it was much shorter and bulkier.

Cleveland’s mascot and Ohio’s best fossil fish

“Dunkleosteus “It’s already a strange fish, but it turns out that old size estimates have overlooked many features that make this fish even more bizarre, such as a very tuna-like body,” said Russell Engelman, a graduate student at Case. Western Reserve. Biology and lead author of the study published in the journal Variation “Some of my colleagues called it ‘Chunky Dunk’ or ‘Chunkleosteus’ after seeing my research.

Engelman said she is aware of the reduction of iconicity. Dunkleosteus It can’t be good news because the big fish is “basically Cleveland’s mascot when it comes to paleontology” (the species even had a Twitter account for a few years). He said he had similar feelings at first as a Cleveland native.

Most studies of Dunkleosteus are based on specimens at the Cleveland Museum of Natural History, which has the largest and finest collection of relics. Dunkleosteus In the world. His name is honored by both the former museum curator (David Dunkle) and the local business owner (Jay Terrell) who discovered the fossil species.

Dunkleosteus An indigenous symbol proclaimed by the Ohio General Assembly in 2020 Dunkleosteus terrelli fish fossil status.

Despite this, little research has been done on fish since the 1930s, Engelman said.

“Without reliable size estimates, very little can be said about it. Dunkleosteus scientifically, ‘look at the big, scary fish!’ Except,” said Engelman. “These length estimates were an example of something that went unnoticed by everyone because this fish was thought to be well-studied.”

short head, short body

Most estimates of the length of the species are not based on strong evidence, Engelman said. The reason for this is Dunkleosteus It was an extinct species of fish called an arthropod. Unlike modern fish, such as arthrodia DunkleosteusThey had bony armored heads, but their internal skeleton was made up of cartilage. This means that only the heads of these animals are preserved as fossils, so the size and shape remain a mystery. The new study proposes an estimate of length based on a 24-inch head minus nose; this is believed to be a consistent measurement between groups of living fish and smaller fully known Dunkleosteus relatives. skeletons .

“The rationale for this study can be summed up in one simple observation,” Engelman said. Said. “Short fish usually have short heads, long fish have long heads.”

Based on this method, Engelman concluded: of Dunkleosteus It was only 11 to 13 feet long—much shorter than any previous researcher had predicted.

“Destructive balls” of the depths

“Dunkleosteus it has been reconstructed frequently, suggesting it had a shark-like body shape,” said Engelman.

But the shorter torso and body armor shape also meant: dunkleosteus, probably much larger.

“A 11-metre Dunkleosteus essentially the same weight as a 15-foot great white shark,” Engelman said. “These were built as wrecking balls. New proportions Dunkleosteus It may seem silly until you realize that it has the same body shape as a tuna fish and a mouth twice the size of a great white.

These new size estimates, Dunkleosteus in a broader scientific context Dunkleosteus It is part of a larger evolutionary history in which vertebrates progressed from small, inconspicuous bottom dwellers to gigantic giants.

“Even though it’s reduced in size Dunkleosteus It may seem like a disappointment, said Engelman, arguably the largest animal that ever existed on Earth. And these new estimates allow for a lot of analysis of Dunkleosteus that was never thought possible. It’s a bitter pill to swallow, so now we can move on to the fun stuff.”

Patricia Princehouse, deputy director of CWRU’s Institute for the Science of Origin, said it was exciting to see the new study.

“This new look at the legendary ‘sea monster’ Dunkleosteus shows that there are many new breakthroughs in the world of paleontology waiting to be discovered, even for known species,” Prinhaus said. Said. The multidisciplinary institute initiates and conducts scientific research in the field of genetics and supports the work of Engelmann and other students.