Reptilia · Squamata
Petrosaurus mearnsiStejneger, 1894
Banded Rock Lizard
Photograph by Matthew Zarzeka, CC BY, via iNaturalist
A day-active, omnivorous lizard from the Nearctic region, reaching 106 mm snout to vent.
Once published as Streptosaurus mearnsi, Uta mearnsi — those names reach this page.
Reptilia › Squamata › Phrynosomatidae › Petrosaurus
- Grows to
- 106mm
- greatest recorded
- Eats
- Omnivorous
- Active
- Diurnal
- Lives
- Saxicolous, terrestrial
Longer than 76% of all species in Phrynosomatidae anyone has measured.
The bar is the rank itself: its length is the share of the family this animal exceeds. The chart below is the family’s real spread, on a logarithmic scale because body length here runs from 47 to 175 mm. The solid rule is this animal. Every bar is a count of real species, and nothing on this figure is estimated.
What is known
40 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
- Conservation status
- Least Concern
- Status assessed · the year the Red List last looked
- 2007
- Population trend
- Stable
The animal itself
- Limbs
- Four legs
- Venomous
- No
- Fangs
- None
- Body temperature when active · measured in the wild
- 36°C97 °F
- Body temp in the wild · mean, when active
- 36°C
mean body temperature of active individuals in nature
body temperature of active animals in nature
Size
- Length snout to vent · greatest recorded
- 106mm4.25 in
- Length snout to vent · adult female mean
- 76mm3 in
- Largest female · snout to vent
- 76mm3 in
- Hatchling length · snout to vent
- 32.55mm1.25 in
- Largest juvenile · snout to vent
- 32.6mm1.25 in
- Body mass · greatestcomputed
- 36.88g1.3 oz
- Body mass · adult female, meanmeasured
- 12.42g0.44 oz
max 106 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
- Diet
- Omnivorous
- Active
- Diurnal
- Where it lives
- Saxicolous, terrestrial
- Habitat
- Desert, Forest, Rocky, Shrubland
- Biome
- Deserts & Xeric Shrublands
- Active season · months of the year
- 7–12months
- Region
- Nearctic
- Mainland or island
- Mainland
- Highest it lives · above sea level
- 2000m
- Range size
- 24,624km²
- Home range · largest recorded
- 850m2
(Stebbins 2003, Alaniz-Garcia and Valdez-Villavicencio 2008, Stebbins and McGinnis 2018), "Generally omnivorous, P. mearnsi preys on various invertebrates as well as on small vertebrates like juvenile lizards, but will also feed on plant parts like leaves, blossoms or buds", Schulze Niehoff 2018); arthropods, juvenile lizards and flowers (Jones and Lovich 2009), arthropods, but also small lizards (Heimes 2022)
Crepuscular and Diurnal / strictly diurnal, but times of day changes seasonally (Schulze Niehoff 2018), diurnal (Heimes 2022)
Terrestrial and Saxicolous / saxicolous (Schulze Niehoff 2018), saxicolous (Heimes 2022)
Breeding
- Reproduction
- Oviparous
- Average clutch
- 4eggs
- Eggs or young per clutch
- 2–7eggs
- Mean clutch
- 4eggs
- Clutches a year
- 1per year
- First breeds at
- 24months
up to 6 (Lemm 2006, Grismer and Grismer 2022), 2-6 (Alaniz-Garcia and Valdez-Villavicencio 2008, Stebbins and McGinnis 2018), 2-6, max 7 (Schulze Niehoff 2018), 2-7 (Heimes 2022)
Naming and history
- Suborder
- Sauria
- Infraorder
- Pleurodonta
- Subspecies
- No
- Described by
- Stejneger
- Moved to another genus · since it was first described
- Yes
- Described in
- 1894
- Type locality
- USA
Keeping one
16.5 in × 16.5 in × 10.5 in(42 × 42 × 27 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 4.25 in (106 mm), at 4 × 4 × 2.5 times it, following the German federal welfare standard — how this is worked out.
Active animals measured in the wild averaged 97 °F (36 °C).
Mean body temperature of active individuals measured in nature. A measurement of the animal, not a setting for a thermostat.
Feeding
A prey item should be no wider than the space between the animal's eyes.
Widely used across reptile husbandry references. The stated reason is that the gap approximates the width of the throat, so wider prey is associated with impaction. This is established practice, not a measurement.
5kJ per day
Worked out for an animal of 37 g, the heaviest recorded for Banded Rock 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 at hatching
- — Longest recorded life
- — Preferred body temperature · chosen in a laboratory gradient
- — Eats arthropods
- — Eats vertebrates
- — Eats plant matter
- — How it hunts
- — How the young develop
- — Gestation or incubation
- — Clutches in a year
- — 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
- — Colour on the back
- — Pattern on the back
- — Pupil
- — Sex decided by
- — Red List criteria
- — Density · lowest recorded
- — Density · highest recorded
- — Active in
- — Lowest it lives · above sea level
Others in Phrynosomatidae
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). Petrosaurus mearnsi. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/petrosaurus-mearnsi
@misc{petrosaurus_mearnsi_2026,
title = {Petrosaurus mearnsi},
author = {{The Reptile & Amphibian Encyclopedia}},
year = {2026},
url = {https://www.allanglescreatures.com/species/petrosaurus-mearnsi}
}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.