World's First Venomous Animals Identified

A paleobiologist has identified conodonts—a large group of tiny extinct marine animals that lived up to 500 million years ago—as likely being the world's first venomous animals.

These animals, which lived until about 200 million years ago, are considered to have been jawless vertebrates. Most of their fossilized remains are teeth.

(Four types of conodont teeth from different species mounted on a pin; Credit for both images: University of Leicester)

(Pile of conodont teeth, which are less than a millimeter long apiece)

Hubert Szaniawski of the Instytut Paleobiologii PAN in Poland analyzed such teeth and compared them with the teeth and other features of both extinct and living venomous and poisonous species. 

"In most of the early conodonts the elements were conical and strongly elongated," Szaniawski writes in his paper, published in the latest issue of the journal Acta Palaeontologica Polonica.

"Many of them are characterized by possession of a deep, longitudinal groove, usually associated with sharp edges or ridges," he added. "A comparative study of the grooved elements and venomous teeth and spines of living and extinct vertebrates strongly suggests that the groove in conodonts was also used for delivery of venom."

Szaniawski also found that the conodont teeth had a structure similar to the grasping apparatus found on some arrow worms.

(Arrow worm; Credit: Zatelmar)

Some arrow worm species carry the neurotoxin tetrodotoxin, so it's possible that conodonts could inject a similar substance into victims. This neurotoxin has no known antidote. Pufferfish, mola, porcupine fish, triggerfish, the blue-ringed octopus and rough-skinned newts all possess tetrodotoxin. 

You have to marvel at nature. Here we are, replacing technologies from last year, but this venom may have done the job well the first time starting at 500 million years ago, before dinosaurs even walked the earth.

Szaniawski mentions other venomous animals in his paper. It's always interesting to me that very few living mammals are venomous. A few species of shrews have poisonous saliva and the male duck-billed platypus has a venomous spur on its hind leg. All existent poisonous and venomous mammals "are regarded as being very primitive," he wrote. 

(Platypus; Credit: John Gould)