Lizards are usually thought of crawling on all fours. However, some special species of lizards have adapted the ability to run just on their hind legs. If you’re short on time, here’s a quick answer: Certain lizards like basilisks and frilled dragons can sprint short distances on only their back legs when trying to escape predators or chase prey.
In this article, we will explore several types of bipedal lizards, looking at their unique adaptations that allow them to run on two legs as well as reasons why they developed this ability. We’ll also overview care requirements in case their fascinating mode of movement makes you want one as a pet!
Famed Bipedal Lizards
Basilisks
Among lizards, basilisks are the sprinters that can literally run across water on their hind legs. These skillful reptiles can stay afloat by slapping their wide feet against the water’s surface, creating little air pockets that keep them from sinking.
Their iconic bipedal movement inspired their nickname – the “Jesus Christ lizard”.
There are five species of basilisk lizards found in Central and South America. The most well-known is the common basilisk (Basiliscus basiliscus), which grows up to 3 feet long. Male basilisks sport a large crest on their heads and backs to attract females.
These agile lizards can sprint short distances on water at about 5 feet per second.
Here’s a comparison of key traits for the two major basilisk species:
| Species | Size | Range | Speed on Water |
|---|---|---|---|
| Common Basilisk | Up to 3 feet long | Mexico to Ecuador | 5 feet per second |
| Brown Basilisk | Up to 2.5 feet long | Nicaragua to Northwest South America | 4.6 feet per second |
Researchers have studied these lizards to understand the physics behind running on water. Check out this National Geographic article to learn more about these reptiles’ fantastic talent.
Frilled Dragons
Frilled dragons are tree-dwelling lizards found in northern Australia and southern New Guinea. When threatened, these iconic lizards can stand up on their back legs and unfold the large frill around their necks – an intimidating sight!
There are three frilled dragon species. The most common is the northern frilled dragon (Chlamydosaurus kingii), which grows over 3 feet long. Frills frame their wide triangular heads and can expand to impressive diameters. These displays reveal bright red and yellow folds of skin to startle predators.
Frilled dragons perch in trees and ambush small birds and mammals as prey. They use their strong back legs to leap between branches. When resting, frilled dragons often stilt on their hind limbs while propped against tree trunks.
Beyond defense, standing tall allows them to scan the landscape and watch for meals!
Underneath the spectacle, frilled dragons are gentle creatures. Many online videos showcase them as playful pets when habituated to humans. Breeders have also developed striking color variants of frilled dragons for collectors.
Evolutionary Reasons for Bipedalism
Predator Evasion
Many lizards evolved bipedal running as a means of escaping predators more quickly. By running on two legs, these lizards can achieve speeds up to nearly 21 mph, giving them a significant advantage in outpacing predators.
According to research, bipedal lizards like the Australian frilled lizard and Asian basilisk can run up to 2.5 times faster on two legs compared to four. The increased stride length and speed comes from the lizards’ ability to move their hind legs independently without interference from front limbs.
This freedom of movement allows the back legs to reach farther forward with each stride.
This incredible speed boost gives bipedal lizards a survival edge. Lizards forced to dash away from hungry coyotes, foxes, snakes, and birds often owe their lives to their ability to spring up and sprint on two feet.
Studies of predator-prey interactions show bipedal lizards are much more likely to escape an attack than slower-moving quadrupedal lizards. Faster travel also allows lizards to cover more ground more efficiently when searching for food and mates.
Better Vision While Running
Another advantage of two-legged running is the ability to see farther ahead with greater clarity. Lizards running on all fours must watch the ground in front of them closely to avoid tripping over obstacles. Their field of vision is limited.
But species like basilisks and frilled lizards can look forward with less restriction of their sight line, allowing them to spot food, mates, or dangers further in the distance. With their head raised and eyes facing forward, bipedal runners can detect approaching threats sooner.
According to a 2008 study, bipedal basilisks have a visual field spanning nearly 360 degrees horizontally when running. This expanded visibility likely provides a critical advantage over quadrupedal lizards in avoiding surprise attacks and reacting quickly.
Energy Conservation
Running on two legs is generally more energy-efficient than running on four for lizards. By reducing the number of limbs in contact with the ground, bipedal runners minimize energy-draining friction and road resistance.
Their longer stride length also reduces the number of strides needed to cover a given distance, decreasing overall energy expenditure. Studies comparing the metabolism of bipedal and quadrupedal lizards have confirmed that two-legged runners use less energy per unit of distance traveled.
This efficiency advantage means bipedal lizards can sprint at top speeds for a longer time before tiring. They can cover more ground in search of food while exerting less effort. Endurance is extremely beneficial when running from predators over long distances.
Lizards with the energy savings of bipedalism can keep up sprints for extended periods to ensure escaping attacks. Their stamina also improves hunting success, allowing them to run down swift prey.
Anatomy & Physiology Allowing Bipedalism
Powerful Hind Legs and Tail
Certain species of lizards like basilisks and Jesus Christ lizards have muscular hind limbs and long tails that give them exceptional sprinting and leaping abilities. Their strong back legs allow them to propel themselves forward at high speeds, using their tails for balance and steering as they run on their hind feet across water.
Studies show the basilisk can run at a velocity of 1.5 m/s and accelerate faster than a free-falling skydiver thanks to the power in their back legs and sturdy tails.
Low Center of Gravity
To maximize speed and stability in an upright position, bipedal lizards have evolved a low center of gravity closer to their powerful hind limbs. Their lightweight upper bodies, S-shaped spines, and forward positioning of organs like the heart and lungs shifts their center of mass downward.
This makes them less prone to toppling over as they dash on two feet.
Keen Balance
Exceptional balance capabilities allow certain lizards to sprint quickly on two legs without falling over. Specializations like widened shoulder joints give them greater side-to-side stability, while tails act as counterweights when running.
Their inner ear structure with enhanced vestibular systems also contributes to precision balancing. Additionally, bipedal lizards can subtly adjust their limb positioning to maintain equilibrium as needed while in full stride.
According to references on Oxford Academic and the University of Michigan Museum of Zoology, anatomical and physiological adaptations give some lizards incredible bipedal running skills.
Care for Bipedal Pet Lizards
Habitat Requirements
Bipedal lizards like basilisks and frilled dragons need ample space to run around. An enclosure of at least 6 feet long and 3 feet wide is recommended. The habitat should include plenty of horizontal branches, vines, and rocks for climbing and basking.
Substrate options include reptile carpeting, coarser barks like orchid bark, or a mix of organic topsoil and play sand. Make sure the substrate is deep enough for burrowing (at least 2-3 inches). Provide a large bowl of fresh water changed daily.
Temperature & Humidity
These active lizards thrive at warmer temperatures from 85-95°F. Create a thermal gradient with basking spots reaching 100-110°F. The cool end can drop to 75-80°F at night. Measure temperatures with a reptile thermometer and adjust heat sources as needed. Ideal humidity levels are 50-70%.
Use under tank heaters, room humidifiers, and daily misting to maintain ambient moisture.
Dietary Needs
In the wild, bipedal lizards eat insects, small vertebrates, and fruit. Feed pet lizards a varied diet including:
- Crickets
- Roaches
- Mealworms
- Superworms
- Waxworms (treats)
- Pinkie mice
- Chopped fruit like mango and berries
Dust food with calcium + vitamin D3 2-3 times a week and a multivitamin 1-2 times a week. Feed babies and juveniles daily, adults can eat every other day. Always provide fresh, clean water.
Handling Precautions
While bipedal lizards may seem friendly, improper handling can stress them. Move slowly when interacting with these flighty reptiles. Scoop them gently, supporting the whole body. Never grab by the tail! Supervise young children and keep handling to a minimum.
Wash hands before and after touching your pet to prevent disease spread.
Conclusion
The ability to swiftly run on two legs gives certain lizards an key survival edge and fascinating appeal. By evolving muscular hindquarters and specialized physiques stabilizing bipedal motion, basilisks, frilled dragons and other lizards occupy a unique locomotive niche.
Their distinctive talent continues to wow both scientists and casual observers alike.
