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Knob-Scaled Lizards: Xenosauridae

Behavior And Reproduction

These lizards stay hidden away most of the time. Individuals in some species, including the one known simply as the knob-scaled lizard, live alone and defend their homes. Males will even bite one another on the head, which can leave behind noticeable scars. Other species, like Newman's knob-scaled lizard, are much more welcoming. In this species, pairs of male and female lizards often live together in peace in the same crevices. Members of this family usually stay in the same area throughout their lives, which can be quite long. Newman's knob-scaled lizards, for example, can live to be at least seven years old.

Females in all species give birth to baby lizards, rather than laying eggs as many other lizards do. A typical clutch for a lizard from this family is one to three babies, but some of those in the knob-scaled lizard species can have six young at a time. Once the females have their babies, usually from June to August, some stay with their young. Scientists have found that mothers in Newman's knob-scaled lizard species and the species known as Xenosaurus platyceps remain with their babies in their hidden-away homes, often keeping the young farther inside the hole or crevice, while the mothers stay nearer the entrance as if guarding the babies from possible land predators.

Some reports indicate that the lizards are most active at dawn and dusk and during the night. Because populations are scattered, their numbers are low, and they usually stay out of sight, much about their behavior and reproduction is still unknown.


Many scientists once included the Chinese crocodile lizard as one of the species in the family of knob-scaled lizards. The Chinese crocodile lizard is very similar in appearance to the other knob-scaled lizards, which all live in Mexico and Central America. A 1999 study, however, compared their DNA and found that the Chinese crocodile lizard is different enough to have its own family, which is now called Shinisauridae. DNA is genetic material, essentially, an instruction booklet for making a living thing, that is passed down from parents to babies. By looking at differences in these "instructions," scientists can tell how closely two species are related.

Additional topics

Animal Life ResourceDinosaurs, Snakes, and Other ReptilesKnob-Scaled Lizards: Xenosauridae - Physical Characteristics, Habitat, Diet, Behavior And Reproduction, Knob-scaled Lizards And People - GEOGRAPHIC RANGE, CONSERVATION STATUS