Naming fossils can be tricky. The titles are meant to be permanent, evoking something of where the ancient species was found, who uncovered it, or some essential facet of its nature. In 1933, for example, paleontologist W. Gross looked at a particularly large example of an armored fossil fish called Bothriolepis and named it as a new species - Bothriolepis maxima, the greatest species of its Devonian ilk. Clearly Gross expected the superlative to stick. What Gross couldn't have known is that there were larger Bothriolepis out there, yet to be found, waiting to be uncovered among the chilly outcrops of Nunavut, Canada.

Paleontologist Jason Downs and colleagues, needing something a tier above maxima, have named their fossil fish Bothriolepis rex. There's no fish quite like it alive today. This 370 million year old swimmer was encased in a suit of armor plates, wearing the bony part of its skeleton on the outside. This new species is far larger than its next challenger, however. Downs and coauthors estimated that Bothriolepis rex was about five and a half feet long, or about thirty percent larger than Gross' B. maxima.

But why all the armor? Downs and colleagues review a couple of possibilities. One is that all those thick bones acted as ballast. Bothriolepis was a big fish and a likely grubbed around in the mud for little plant morsels. At such size, Downs and coauthors note, dense armor plates would have helped B. rex stay closer to the bottom with less effort. On top of that, the thick bones of B. rex likely acted as protection. The Devonian was a fish-eat-fish world, and other fossils found near Bothriolepis rex give away the presence of coelacanth relatives - called sarcopterygians - with piercing teeth and possibly king-sized appetites.

B. rex site
Paleontologists Jason Downs (left) and Ted Daeschler (right) at the B. rex discovery site. Credit: Drexel University

Fossil Facts

Name: Bothriolepis rex

Meaning: "Pitted scale king."

Age: Devonian, about 370 million years old.

Where in the world?: Nunavut, Canada.

What sort of critter?: An armored fish known as an antiarch.

Size: About five and a half feet long.

How much of the creature’s body is known?: Plates of the external armor.


Downs, J., Daeschler, E., Garcia, V., Shubin, N. 2016. A new large-bodied species of Bothriolepis (Antiarchi) from the Upper Devonian of Ellesmere Island, Nunavut, Canada. Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2016.1221833

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The Rio do Rasto Tooth
Bob Weir's Otter
Egypt's Canine Beast
The Vastan Mine Tapir
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The Dawn Megamouth
The Genga Lizard
The Micro Lion
The Mystery Titanosaur
The Echo Hunter
The Lo Hueco Titan
The Three-Branched Cicada
The Monster of Minden
The Pig-Footed Bandicoot
Hayden's Rattlesnake Demon
The Evasive Ostrich Seer
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