Reptilia · Squamata
Xenosaurus rackhamiStuart, 1941
Rackham’s Knob-scaled Lizard
Photograph by Jorge Armín Escalante-Pasos, CC BY, via iNaturalist
A rock-dwelling, day-active lizard from the Neotropic region, reaching 120 mm snout to vent.
Reptilia › Squamata › Xenosauridae › Xenosaurus
- Grows to
- 120mm
- greatest recorded
- Active
- Diurnal
- Lives up to
- 5.8years
- Lives
- Saxicolous
What is known
29 sourced facts, each taken from a named scientific dataset. How to read these.
Cited from a dataset unless a row is marked otherwise.
Standing in the world
- Still living
- Extant
The animal itself
- Limbs
- Four legs
- Venomous
- No
- Fangs
- None
- Longest recorded life
- 5.8years
Slavens and Slavens, 1999. Reptiles and Amphibians in Captivity: Breeding - Longevity and Inventory, Slaveware, 400 p.
Size
- Length snout to vent · greatest recorded
- 120mm4.75 in
- Length snout to vent · adult female mean
- 110.9mm4.25 in
- Largest female · snout to vent
- 110.9mm4.25 in
- Hatchling length · snout to vent
- 45mm1.75 in
- Largest juvenile · snout to vent
- 45mm1.75 in
- Body mass · greatestcomputed
- 39.06g1.4 oz
max 120 mm SVL (Feldman et al. 2016)
snout-vent length; the source column mixes this with straight carapace length
computed from length by a family-level allometric equation, not weighed
How it lives
- Active
- Diurnal
- Where it lives
- Saxicolous
- Biome
- Tropical & Subtropical Dry Broadleaf Forests
- Region
- Neotropic
- Mainland or island
- Mainland
- Elevation · above sea level
- 830–840m
- Range size
- 18,920km²
Rodda 2020
Breeding
- Reproduction
- Viviparous
- Average clutch
- 4.5eggs
- Eggs or young per clutch
- 2–7eggs
- Mean clutch
- 4.5eggs
2-7, mean 4.5 (Zamora-Abrego et al. 2007, see also Woolrich-Pina et al. 2014), mean 4.5 (Zuniga-Vega et al. 2017)
Naming and history
- Suborder
- Sauria
- Infraorder
- Anguimoprha
- Subspecies
- No
- Described by
- Stuart
- Moved to another genus · since it was first described
- No
- Described in
- 1941
- Type locality
- Guatemala
Keeping one
19 in × 19 in × 12 in(48 × 48 × 30 cm)
Minimum length × width × height, for one animal. Bigger is always better.
The standard sizes ground-dwelling species at 4 × 4 × 2.5 times snout-vent length.
Lives on rock, so stable hard surfaces and basking ledges suit it.
Mindestanforderungen an die Haltung von Reptilien (Sachverständigengutachten), German Federal Ministry for Nutrition, Agriculture and Forestry, Animal Welfare Division, 10 January 1997. The standard states these floor areas are recommendations rather than binding limits.
From this animal’s own snout-vent length of 4.75 in (120 mm), at 4 × 4 × 2.5 times it, following the German federal welfare standard — how this is worked out.
No preferred body temperature has been recorded for Rackham’s Knob-scaled Lizard. Rather than repeat a number from a care sheet, this page leaves it out.
Feeding
5kJ per day
Worked out for an animal of 39 g, the heaviest recorded for Rackham’s Knob-scaled Lizard — so it is the top of the range, not a figure for a particular animal. Weigh yours and the number will be lower.
An upper estimate, not a feeding target, and not veterinary advice. The equation covers only what an animal burns staying alive, so a growing, gravid or recovering animal needs more — and it was measured on wild animals, which move far more than one in an enclosure. Body condition and a vet who knows the species are what a feeding decision should rest on. Where this comes from.
What nobody knows
These are not gaps in our research. No scientific dataset records them for this species — and saying so is information you cannot get from a reference that simply leaves a field out.
- — Length snout to vent · adult male mean
- — Length snout to vent · adult mean
- — Length nose to tail · greatest recorded
- — Female length · mean, nose to tail
- — Length nose to tail · adult male mean
- — Length nose to tail · adult mean
- — Largest male · snout to vent
- — Largest female · shell length
- — Largest male · shell length
- — Hatchling length · nose to tail
- — Largest juvenile · shell length
- — Egg length
- — Egg width
- — Body mass · a typical adult
- — Body mass · adult female, mean
- — Body mass at hatching
- — Preferred body temperature · chosen in a laboratory gradient
- — Body temperature when active · measured in the wild
- — Diet
- — Eats arthropods
- — Eats vertebrates
- — Eats plant matter
- — How it hunts
- — How the young develop
- — Gestation or incubation
- — Clutches in a year
- — Clutches a year · fewest
- — Clutches a year · most
- — First breeds from · youngest recorded
- — First breeds by · oldest recorded
- — Hatchling length · smallest recorded
- — Hatchling length · largest recorded
- — Age at first breeding · female
- — Mature from · youngest recorded
- — Mature by · oldest recorded
- — Size at maturity · smallest recorded
- — Size at maturity · largest recorded
- — Body temp in the wild · lowest mean recorded
- — Body temp in the wild · highest mean recorded
- — Colour on the back
- — Pattern on the back
- — Pupil
- — Sex decided by
- — Conservation status
- — Status assessed · the year the Red List last looked
- — Population trend
- — Red List criteria
- — Active season · shortest recorded
- — Active season · longest recorded
- — Density · lowest recorded
- — Density · highest recorded
- — Home range · largest recorded
- — Habitat
- — Active in
Others in Xenosauridae
- Arboreal Knob-scaled Lizard
- Chin-spotted Knob-scaled Lizard
- Flathead Knob-scaled Lizard
- Knob-scaled Lizard
- Mountain Knob-scaled Lizard
- Newman's Knob-scaled Lizard
- Pallid Knob-scaled Lizard
- Pena's Knob-scaled Lizard
- San Martin Knob-scaled Lizard
- Zacualtipá́n Knob-scaled Lizard
- Xenosaurus fractus
- Xenosaurus mendozai
Take this data
Everything on this page is available as data under CC BY 4.0 — use it freely, credit it, no permission needed.
This species as JSON · the whole dataset
Cite this page
The Reptile & Amphibian Encyclopedia (2026). Xenosaurus rackhami. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/xenosaurus-rackhami
@misc{xenosaurus_rackhami_2026,
title = {Xenosaurus rackhami},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/xenosaurus-rackhami}
}Sources
- Meiri, S. (2024). SquamBase — a database of squamate (Reptilia: Squamata) traits. Global Ecology and Biogeography. Public domain (CC0).
- Oskyrko, O. et al. (2024). ReptTraits: a comprehensive dataset of ecological traits in reptiles. Scientific Data. Used under CC BY 4.0.
- Catalogue of Life (dataset 3LR), used under CC BY.
- Moura, M. R. et al. TetrapodTraits: a database of 33,281 tetrapod species. Used under CC BY 4.0. Observed values only; this encyclopedia does not publish its imputed predictions.