Friday, July 19, 2013

Anatomy and Physical Appearance of Bipedal Lizards

I will now describe the anatomy and physical appearance of these unknown large bipedal lizards. I will first describe the anatomy and diversity of lizards in general.

Introduction To Lizards

Lizards are a group of reptiles belonging to the suborder Lacertilia in the order Squamata. Their closest living relatives are the snakes, which are also members of the order Squamata, and the tuataras, which belong in the closely-related order Rhynchocephalia. Squamates are the second-most speciose order of vertebrates on Earth, second only to the Perciformes, and they live on every continent other than Antarctica. Lizards are a very diverse and incredibly successful group of animals that have managed to evolve and adapt to numerous habitats and ecosystems all across the world.

Within the lizards, there is great diversity in body size and shape, as well as behavior and lifestyles. For example, monitor lizards are large terrestrial apex predators, while iguanas are arboreal and mostly herbivorous. In the past, there existed even greater diversity than this. One example is the mosasaurs. These were gigantic, carnivorous lizards that were adapted to a marine lifestyle. They were among the top predators in the Cretaceous seas, and they are thought to have fed on fish, shellfish, plesiosaurs, and possibly even other mosasaurs. 

Therefore, it is clear that the lizards are a very adaptable and remarkably succesful group of organisms.

Leg Anatomy

Like all other living reptiles, most lizards walk predominately on four legs, with their legs sprawling out to the sides of their bodies. This is different from mammals, birds, and dinosaurs, who all have legs which are directly underneath their bodies. However, some species, such as the larger monitors, are capable of walking with their legs held in a semi-erect fashion beneath their bodies.

This is because, generally, lizards' legs have a tendency to become more erect the longer they are, and the larger the animal is. Therefore, large lizards with long legs can have limbs that appear and function just like the more erect limbs of mammals and birds.

In my last post, I wrote about how sightings of small carnivorous 'dinosaurs' in North and South America probably represent an unknown species of giant, predatory iguanid lizard that frequently walks on two legs. These animals appear to be capable of both quadrupedal and bipedal locomotion. However, as their front limbs appear to be much shorter than their hind legs, it appears to me that they are mostly bipedal, and occasionally drop down on all fours. This would make them more bipedal than any other lizards known to science. 

In addition, these creatures also appear to have much longer hind limbs than any other lizards known to science. This would presumably enable them to run quickly in pursuit of prey. And, indeed, this is what numerous sighting reports seem to indicate.

Teeth And Claws

These animals appear to be omnivores which eat both plants and meat. They use their sharp teeth and claws to  capture and kill their prey. Some sighting reports have indicated that they have especially long and sharp claws on their feet, like the extinct 'raptor' dinosaurs, or dromaeosaurs. I would presume that they would probably use these claws as weapons, possibly for predation. It is also possible that they could be used for self-defense, or for fights between males (male lizards, especially iguanas, tend to fight with each other a lot). 

It is unclear what purpose, if any, the relatively short forearms could be used for. It's possible that they could use their arms to grasp small prey items, but this is just speculation. We do know that they also have long, sharp claws on their hands, albeit not as long as the claws on the feet. 

They are also armed with powerful jaws full of long, sharp teeth. The teeth have large, bump-like serrations. Teeth that are serrated in this way are useful for both chomping on plants and slicing through flesh. Once again, this is presumably indicative of these animals' omnivorous diet. 

Skin And Coloration 

These animals are covered with scaly skin, like all other reptiles. Some eyewitnesses have reported seeing hair- or feather-like structures on the skin, especially on the back. I think that these are probably  just scales that resemble hair or feathers. Many iguana species have spikes on their backs, and it is possible that a confused witness could mistake them for fur or feathers. 

The color of the skin varies considerably according to the reports. However, most of the time, these animals are described as being either green, brown, or orange. Their bodies are covered with brown or black stripe-like markings, or splotches.


In conclusion, these giant bipedal iguanid lizards are about 9 to 10 feet long, and 4 to 5 feet tall when standing erect on 2 legs. They have long, erect hind limbs, and short arms. They have scaly skin with fur-like scales on the back, and they are adorned with stripe-like markings on their skin. They have sharp teeth with large, bumpy serrations, and very sharp and dangerous claws on the feet.

In my next few posts, I will discuss the behavior and habits of these animals, as observed from the sighting reports. I will try to identify what animals they prey on, what habitats they live in, and possibly also what methods cryptozoologists should use to try to search for them. 

Until then, cheers!


  1. Very interesting article. This was a very nice analysis of such reports, and I can't wait to read more from you.

  2. Btw: you should do some statistics on the commonly reported features for these reptiles in order to see what features are consistent and thus likely accurate. I've never really heard of bipedal lizard reports, so you should also share some references to information on reports or the original reports themselves. Keep up the great work.

    1. Well, a lot of the stuff in this article is actually mostly speculation. The stuff that the reports always consistently describe are this: large eyes, sharp teeth and claws, stiff tail, walks on two legs, has a long snout, and has the ability to run very fast.

      The large claws on the feet are based on one sighting in Georgia that I read on the Internet once (yeah, I know, not very reliable, huh?). I used to think this sighting was a misidentified monitor lizard, but after going through it again, I now think it is a genuine report of these unknown reptiles.

      Here is a link to the report:

  3. In the 1980s I lived in Arizona and the local 'river rats' (mainly prospectors and elderly people who lived in tents next to the Colorado river)told stories of a giant chuckwalla. This was clearly not the species from San Esteban Island normally called by this name as it was described as a dinosaur-like animal 3-4 feet tall that ran on two legs and lived in the desert. This seemed to be local folklore and I knew of nobody who actually saw one.

    It seems to me later this may have been a reference to these 'river dinosaurs' as a 'giant chuckwalla' seems to be a pretty good description by a layman of what is being seen.

    1. Wow, that is very interesting! Thanks for sharing!