Probably you have come across various species of lizards in your home, compound, fields, yards, or zoo and wonder if they have bones. How then are their body muscles supported? So, do lizards have bones?
The direct answer is, YES, all lizards are vertebrates that have bones that are interconnected together to help them in locomotion.
The bones of lizards are classified under either appendicular skeleton or axial skeleton. These bones offer support, protection of internal organs, and options for attachment of body muscles and cells. The number of each bone varies according to size and species of lizard.
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Lizards, like other reptiles, have bones. Their bones are classified under either appendicular skeleton or axial skeleton. The appendicular skeleton consists of the pelvic girdle, the pectoral, the limbs, and the bones of the front and hind legs.
The axial skeleton form the central axis of the lizard’s body. It comprises the skull, the dorsal/thoracic cage and the vertebral column.
The two skeleton structures are interconnected and plays a great role in protecting the inners body organs such as the heart, lungs, kidneys and intestines as well as the spinal cord (vital). Moreover, they provide suitable support of the body and enhances easier locomotion.
What are the functions of Bones in Lizards?
The following are main functions of bones in lizards:
- Protecting the spinal cord – the vertebral column bones.
- Protecting the brains and cerebral system – the skull.
- Protecting providing option for attachment of internal organs such as digestive organs, heart, kidney, liver and lungs (ribs).
- Provides option for attachment of the body muscles – axial skeleton, pelvic and pectoral girdle.
- Help in locomotion/movement – the appendicular skeleton – femur, tibia, fibula, humerus, scapula, metacarpals, and metatarsals.
- For grasping and grinding over the surface – the phalanges, metatarsals and metacarpals – including lizard teeth.
How Many Bones Does a Lizard Have?
Lizard species have different varying number of bones due to their difference in sizes. However, the skeleton of lizard has 28 specialized bones, which work collective to offer protection and locomotion effectively.
These bones include the vertebral column (caudal, sacral, lumbar, thoracic/dorsal and cervical vertebrae), the sternum, the scapula, the tarsals, metatarsal, carpal, metacarpal, tibia, fibula, ulna, radius, ribs, mandibles, maxilla and the phalanges.
Most lizards have 100 to 300 bones while large lizards such as Tree crocodile may have more. On the other hand, small lizards such as gecko may have less than 100 bones.
Do Lizards Have Bones in Their Tails?
Yes! Lizards have bones in their tail. The tail which is formed from the caudal vertebrae contain bones, ligaments, nerves, vasculature and tail muscles which gives it the tail power.
The tail of most lizards get detached easily when held. The Fracture of the tail vertebrae usually occurs at the fracture plane leaving behind flesh tail tissue to heal.
The cut tail is not easily returned in lizards – thus most of lizard species won’t grow their tail back (remain tailless) – check lizard tail bones regeneration.
Though a few lizard species show lateral growth of detached tail, the tail may not be as functional as the original tail. The First 3 bones in the lizard caudal vertebrae are fused to give it tail power. In case the tail detachment occurs past these three bones, there is normally no regrowth that can occur in most cases.
Lizards lack the tail autotomy and cannot be treated once their cut tail. Ensure you hold your pet lizard from below at the chest region (not lifting it by the tail).
a. Appendicular Skeleton.
The appendicular skeleton in lizards comprises of the bones that form the front and the hind legs plus the pelvic girdle and pectoral girdle from which the limbs are attached to the axial skeleton. These bones collectively coordinate the lizard’s movement.
1. Pectoral girdle.
This consist of two main bones, that is, the scapula and the collarbone also called clavicle. The clavicle is s-shaped bone, which articulates with the sternum at the front chest of the lizard. The clavicle also joins the scapula at the end of lizard’s shoulder.
Its main function is to support the scapula. Lizards have two collarbones – each jointed at the sternum and scapula. Scapula is a bone that articulates with humerus and aid in the shoulder movement of lizard.
Scapula has a wide v-shaped surface area that offers an option for attachment of the neck and back muscles that coordinates the movement of joints. Lizards have two scapula – one for each front leg/limb.
2. Front Legs.
Lizards have two front legs. Each leg has similar and equal number of bones as the other. Humerus (limb) joins scapula at the shoulder articulation point.
Then, the two leg bones (ulna and radius) join humerus at the sigmoid notch. At the end of ulna and radius lay carpal bones, which allow rotary movement of the arm.
The Carpals extent to form the metacarpal bones (bones at the palm of the arm) and phalanx bones (the bones that allows the folding of the arm). The phalanges are jointed to help the lizards when grasping the prey.
The bones at the front legs of lizards function to coordinate in the locomotion and grasping the prey. In addition, they provide option for attachment of front leg muscles.
3. Pelvic girdle.
The Pelvic girdle has three bones that provide an option for the attachment of the lizard’s hind legs. The three bones are the pubis (front), ischium (back) and ilium (wing). The pelvic girdle also provides the surface for attachment of back muscles.
Most lizard species have their pelvic girdle fused and linked to the axial skeleton at the caudal vertebrae except in large lizards such as Komodo Dragon and Tree Crocodile Monitor and bearded dragons do they eat tomatoes?.
In small lizards, the femur is connected directly to the axial skeleton through the ball and socket joint at the sacral vertebrae.
4. Hind legs.
Lizards have two hind legs. Each leg has equal number and similar bone type as the other. The Hind leg is joined to pelvic girdle at caudal vertebrae using the femur – which has the ball shaped end to allow the notch rotary motion.
At the end of femur, there is a patella bone, which helps form the knee joint. The leg is extended using two bones called tibia (larger) and fibular (smaller). These two bones function to support the weight of lizards and offer option for attachment of leg muscles.
At the end of tibia and fibula lay tarsal bones that allows two-way motion of the arm. These bones are connected to metatarsal bones (metatarsals are elongated bones and forms base of lizard’s foot). At the end of metatarsals are phalanx bones. The phalanges are jointed and form the toes, which help in grasping on the ground, trees or rocks when walking.
b. Axial Skeleton.
The axial skeleton comprises of the skull, the dorsal/thoracic cage and the vertebral column. Axial skeleton forms the central axis of the lizards. The major function of axial skeleton is to offer point for the attachment of the appendicular skeleton and protect the spinal cord (spinal cord is responsible for nervous system coordination).
1. The skull.
Skull is a bony structure, which forms the head. The lizard’s skull is divided into several bones, which include the facial bones, the cranial bones, the hyoid bone and auditory ossicles.
The skull also contain the lower jaw (mandible – the only movable bone) and maxillae. The meninges (head hard skin and muscles) grow and merge with the lizard’s body skin.
Major functions of the skull is to protect the brain – which is be most sensitive part of the body coordination system.
2. Cervical Vertebrae
The cervical vertebrae consist of vertebra found at the lizard’s neck region. The first two cervical vertebra (atlas and axis) are specialized to help the nodding of head (atlas) and rotary motion of the head (axis).
Other vertebra are fused making the neck region of lizard stiff while some advance to form thoracic vertebrae. The cervical vertebrae also offer option for attachment of neck muscles.
3. Thoracic/dorsal vertebrae.
The dorsal vertebrae, also called thoracic vertebrae, is found at the chest region of the lizards. The vertebra provides option for the attachment of the ribs (ribs protects internal organs such as lungs, heart and livers from external damage).
The end of each rid is attached to sternum (breastbone) that is located at the front chest region. The number of ribs and vertebra varies from one lizard species to another. Large lizards like Tree Crocodile monitor and Komodo Drago have 15 to 24 vertebra, the medium sized lizard lizards have 10 to 16 dorsal vertebra while small lizards such as savannah and chameleon lizards have 7 to 11 thoracic vertebrae.
Each dorsal vertebra is connected to two ribs (one on either side). The dorsal vertebral provides option for the attachment of the back muscles.
Related: Are Lizards Poisonous?
4. Lumbar Vertebrae.
Most lizard species do not have lumbar vertebrae apart from the large lizards such as Komodo dragon and Asian water monitor lizards. The lumbar vertebra do not have the ribs attached. This region is where the stomach lay and provides option for the lizards to coil effectively during attacks.
5. Sacral Vertebrae.
The sacral vertebrae are found at the sacral section (sacrum). The pelvic girdle is jointed with the sacral vertebrae and offers large surface area for attachment of back muscles. The Lizards have 1 to 7 sacral vertebra. However, larger species can have 3 to 5 more vertebra.
Small and middle-sized lizards such as Nike water lizards, savannah lards and house lizards have their sacral vertebra fused to form caudal vertebrae.
6. Caudal Vertebrae.
The caudal vertebrae, also called tail vertebrae, is what forms the tail of the lizards. Caudal vertebrae has bones that decrease in size up to the last one. Each vertebra has two short protruding ribs that provide surface for attachment of tail muscles.
The caudal vertebra has short spines and arches. Long-tailed lizards such as Basilisk, chameleon lizards and skinks have 10 to 32 caudal vertebrae while small-tailed lizards have 1 to 10 caudal vertebrae.
Related: Are Leopard Geckos Nocturnal?
Conclusions
All Lizard species have bones that are collectively linked to aid them in protection and locomotion. The bones are classified under either appendicular skeleton or axial skeleton.
Main functions of the bones include support, protection of internal organs and offer options for attachment of body muscles. The total number of bones vary according to size and species of lizard. Lizards have an average of 28 specialized bones.