Were There Any Poisonous Dinosaurs?

Ever since a slightly short Dilophosaurus (or two) spat black gooey poison at Dennis Nedry in Jurassic park people at large have not only have to deal with large meat eating dinosaurs but with the knowledge that there were also poisonous dinosaurs to deal with as well as those claws and teeth.

There is currently no evidence of venomous or poisonous dinosaurs in the fossil record. This does not discount the possibility. However, archosaurs have not been discovered to use poison.  One heavily disputed exception is Sinornithosaurus, which was suggested to have venom sacs and grooved teeth capable of poisoning.

So although there is no concrete evidence for poisonous dinosaurs yet discovered We take a look at the earliest animals that did have poison, and maybe one dinosaur that opened up the whole debate. .

So according to science there is currently no proof that poisonous dinosaurs existed in the 200 millions years dinosaurs were on the planet. However an absence of proof is not proof itself, at least not when it comes to dinosaurs and our information changes all the time, literally week to week! So we look at some of the contenders for poisonous dinosaurs and when the first recorded poisonous animals that do actually have proof.

Were There Any Poisonous Dinosaurs?

As we mentioned above, there is currently no evidence to suggest that there were poisonous dinosaurs. We may see them in movies, they may even look like other poisonous animals we see today, but we cant prove it. Although… there might be a contender for poisonous dinosaur that was discovered in 1999 in China, and looked at again in 2009.

Sinornithosaurus holds a claim, although disputed, to being the first and so far only poisonous dinosaur. However there are some things we need to know about this claim.

In 2009 a paper was published saying that a poisonous dinosaur had been discovered, however sinornithosaurus was actually discovered in 1999, what they meant was they had discovered some new information about it.

This information centered around the skull, and in particular the jaw. they stated that there was a space in the jaw that could have help a venom sac, and it was above some longer teeth that were angled back like those of a snake. Those teeth also had grooves on to allow the poison to drip, flow onto the teeth before being stabbed into some poor unsuspecting prey.

If those facts were true then sinornithosaurus would be the first and only known poisonous dinosaur!

here is the but…

  • They suggested that most other feathered members of the sinornithosaurus family would have had similar venomous traits, and they have not been found as of yet, or not for the reasons given.
  • Grooves on teeth are fairly common, but they could also be to help pull teeth out of prey ( break the seal / air pressure) -Although these groves are towards the back of the tooth which is another characteristic of venomous animals.
  • Holes in dinosaurs heads are pretty common, so its not certain this space was for a venom sac
  • and finally although the teeth of sinornithosaurus were curved back like a snake or lizard, it may have been as they came loose during fossilization and in fact they were much less angled when the dinosaur was alive.

The debate surrounding poisonous dinosaurs is fierce. The thought is that although ther eis not enough proof that poisonous dinosaurs did exist it doesn’t mean they didn;t. We have to just keep digging and find that proof.

sinornithosaurus poisonous Dinosaur

What would a dinosaur need to be poisonous?

There are a few characteristics of a venomous animal, we will look at the ones for land animals as poisonous sea animals often deliver their poison through contact, or eating or other ways. Most land animals ( not all) need to get it to their prey or attacker by biting or stinging them.

  1. A place to store the venom or poison. Often a venom sac in the jaw
  2. A way to get the venom or poison to the teeth or sting. Which might be by grooves or by hollow tubes in teeth
  3. Something sharp enough to inject or put the venom into the target. this is often teeth or a sting.

It is also useful to know the difference between poisonous and venomous. Although they are used in place of each other there are some important differences. Lets put it simply. Venomous animals have to bite or stab or you to get their venom inside, whereas you have to touch or eat a poisonous animal.

However the effects they have are pretty much the same once the poison, or venom is inside you!

What was the First Known Animal To be Poisonous?

When you think of venomous animals your mind is likely to go straight towards spiders and snakes. They pretty much have cornered the market in recent years. However there are plenty of other animals that carry poison inside them, from jelly fish in the sea to even mammals like the Duck billed platypus. (it is a mammal, we had to check)

However these animals were not the first known venomous animal on earth. This title goes to a 500 million year old tiny marine animal called a “conodont” they had tiny teeth less than 1 mm long. they were long and had deep groves in them. These grooves are very commonly found in animals that need to deliver poison. like in Arrow worms.

Scientists have suggested that the poison would have likely been a neurotoxin similar to puffer fish, and the blue ringed octopus that live today. Even though poison is common in Snakes and Insects they were not the first to use it.

First Land Animal to be Poisonous

If you had to guess it would likely be a reptile, snake or lizard. however the first poisonous land animal that we know about is none of these. It is actually a distant relation to mammals. It was called “Euchambersia mirabilis” and was about the size of a small dog.

it was a therapsid (not a  synapsids like Dimetrodon) as its legs were positioned more vertically. However, its legs were not the part that gathered the attention. its fossilized jaw has a large gap in it. Large enough for a venom gland. This space linked to its canine teeth which were sharp enough to cut into flesh.

Euchambersia mirabilis poison

That covers the three factors that are used to define a poisonous animal. it has the space for venom, the way to get it on to the teeth, and sharp enough teeth to get it into prey.

All this in an animal that lived before the dinosaurs about 260 million years ago. Seeing as the first snake has been dated to 167 million years ago it means, for the moment at least, that the first animal to have poison on Earth was in fact a mammal!

Will there ever be a poisonous dinosaur?

Well not a new one of course, they went extinct 66 million years ago! However there is a chance that more, or at least more definite proof will be unearthed at some stage. There is a new dinosaur being names on average about once a week.

Surely its just a matter of time till one of those will be a poison dinosaur! (venomous- i-raptor maybe! )


As of yet there is just not enough proof to say that there were dinosaurs that were poisonous. However this also means there is not enough proof to say there was not a poisonous dinosaur alive during the Dinosaurs 220 million or so years as the dominant lifeform on the planet.

There were animals with poison and venom in the sea 500 million years ago, there were poisonous relatives of mammals on the land 30 million years before the first dinosaur was even born.

15 years ago there were no swimming dinosaurs, then Spinosaurus showed us its oar like tail, no one thought dinosaurs could every fly until microraptor and sinornithosaurus came along. So at some point, even though their family tree isn’t full of poison, we think a poisonous dinosaur will be discovered.

Just don”t bet on it being a venom spitting, labrador sized Dilophosaurus though!









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