Lizard Development

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Anolis carolinensis (green anole) mating.
Australian water skink embryo

Lizards and snakes represent scaled reptiles (squamata). Lizard development involves an amniotic egg, that evolutionary (~320 million years ago) freed the vertebrates from their aquatic (water) to a terrestrial (land) environment. The Galápagos Islands marine iguana was also made famous by Charles Darwin's historic evolution studies.

The genome of the lizard Anolis carolinensis (green anole) from southeastern United States has a karyotype of 18 chromosomes, comprising six pairs of large macrochromosomes and 12 pairs of small microchromosomes, and has recently been sequenced[1]. Interestingly, almost all reptilian genomes also contain "microchromosomes", very small chromosomes less than 20 Mb in sequence size. (More? Genome)

Lizard links: lizard | 1904 Sand Lizard | 1932 Twinning | Category:Lizard

Animal Development: axolotl | bat | cat | chicken | cow | dog | dolphin | echidna | fly | frog | goat | grasshopper | guinea pig | hamster | horse | kangaroo | koala | lizard | medaka | mouse | opossum | pig | platypus | rabbit | rat | salamander | sea squirt | sea urchin | sheep | worm | zebrafish | life cycles | development timetable | development models | K12
Historic Embryology  
1897 Pig | 1900 Chicken | 1901 Lungfish | 1904 Sand Lizard | 1905 Rabbit | 1906 Deer | 1907 Tarsiers | 1908 Human | 1909 Northern Lapwing | 1909 South American and African Lungfish | 1910 Salamander | 1951 Frog | Embryology History | Historic Disclaimer

Some Recent Findings

  • Egg incubation temperature influences the growth and foraging behaviour of juvenile lizards[2] "After laying their eggs, oviparous reptiles are reliant on the external environment to provide the required incubation conditions for successful embryonic development. Egg incubation temperature can impact the behaviour of various species of reptiles, but previous experiments have focused on the impact of incubation environment on hatchlings, with only a limited number of studies focussing on the longer-term behavioural consequences of incubation environment. This study investigated the effects of developmental environment on bearded dragon lizards (Pogona vitticeps) that were incubated at different temperatures within the natural range; half of them were incubated at a 'hot' temperature (30 ± 3 °C) and half at a 'cold' temperature (27 ± 3 °C). The growth and foraging behaviour of the lizards was then compared over 18 weeks of development. Although the lizards incubated at a cool temperatures grew more quickly, those incubated at the hotter temperature completed the foraging task more often and had significantly faster running speeds. These results show that egg incubation temperature impacts the foraging behaviour of juvenile lizards and suggest a potential trade-off between growth and foraging speed, which could influence an animal's life history trajectory." DOHAD
  • skull Development, Ossification Pattern, and Adult Shape in the Emerging Lizard Model Organism Pogona vitticeps: A Comparative Analysis With Other Squamates[3] "The rise of the Evo-Devo field and the development of multidisciplinary research tools at various levels of biological organization have led to a growing interest in researching for new non-model organisms. Squamates (lizards and snakes) are particularly important for understanding fundamental questions about the evolution of vertebrates because of their high diversity and evolutionary innovations and adaptations that portrait a striking body plan change that reached its extreme in snakes. Yet, little is known about the intricate connection between phenotype and genotype in squamates, partly due to limited developmental knowledge and incomplete characterization of embryonic development. Surprisingly, squamate models have received limited attention in comparative developmental studies, and only a few species examined so far can be considered as representative and appropriate model organism for mechanistic Evo-Devo studies. Fortunately, the agamid lizard Pogona vitticeps (central bearded dragon) is one of the most popular, domesticated reptile species with both a well-established history in captivity and key advantages for research, thus forming an ideal laboratory model system and justifying his recent use in reptile biology research. We first report here the complete post-oviposition embryonic development for P. vitticeps based on standardized staging systems and external morphological characters previously defined for squamates. Whereas the overall morphological development follows the general trends observed in other squamates, our comparisons indicate major differences in the developmental sequence of several tissues, including early craniofacial characters. Detailed analysis of both embryonic skull development and adult skull shape, using a comparative approach integrating CT-scans and gene expression studies in P. vitticeps as well as comparative embryology and 3D geometric morphometrics in a large dataset of lizards and snakes, highlights the extreme adult skull shape of P. vitticeps and further indicates that heterochrony has played a key role in the early development and ossification of squamate skull bones."
  • yolk sac development in lizards (Lacertilia: Scincidae): New perspectives on the egg of amniotes[4] "Embryos of oviparous reptiles develop on the surface of a large mass of yolk, which they metabolize to become relatively large hatchlings. Access to the yolk is provided by tissues growing outward from the embryo to cover the surface of the yolk. A key feature of yolk sac development is a dedicated blood vascular system to communicate with the embryo. The best known model for yolk sac development and function of oviparous amniotes is based on numerous studies of birds, primarily domestic chickens. In this model, the vascular yolk sac forms the perimeter of the large yolk mass and is lined by a specialized epithelium, which takes up, processes and transports yolk nutrients to the yolk sac blood vessels. Studies of lizard yolk sac development, dating to more than 100 years ago, report characteristics inconsistent with this model. We compared development of the yolk sac from oviposition to near hatching in embryonic series of three species of oviparous scincid lizards to consider congruence with the pattern described for birds. Our findings reinforce results of prior studies indicating that squamate reptiles mobilize and metabolize the large yolk reserves in their eggs through a process unknown in other amniotes. Development of the yolk sac of lizards differs from birds in four primary characteristics, migration of mesoderm, proliferation of endoderm, vascular development and cellular diversity within the yolk sac cavity. Notably, all of the yolk is incorporated into cells relatively early in development and endodermal cells within the yolk sac cavity align along blood vessels which course throughout the yolk sac cavity. The pattern of uptake of yolk by endodermal cells indicates that the mechanism of yolk metabolism differs between lizards and birds and that the evolution of a fundamental characteristic of embryonic nutrition diverged in these two lineages. Attributes of the yolk sac of squamates reveal the existence of phylogenetic diversity among amniote lineages and raise new questions concerning the evolution of the amniotic egg."
More recent papers  
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Search term: Lizard Embryology | Lizard Development | Reptile Embryology

Older papers  
These papers originally appeared in the Some Recent Findings table, but as that list grew in length have now been shuffled down to this collapsible table.

See also the Discussion Page for other references listed by year and References on this current page.

  • Identifying the evolutionary building blocks of the cardiac conduction system[5] "The endothermic state of mammals and birds requires high heart rates to accommodate the high rates of oxygen consumption. These high heart rates are driven by very similar conduction systems consisting of an atrioventricular node that slows the electrical impulse and a His-Purkinje system that efficiently activates the ventricular chambers. While ectothermic vertebrates have similar contraction patterns, they do not possess anatomical evidence for a conduction system. ... Mammalian and avian ventricles uniquely develop thick compact walls and septum and, hence, form a discrete ventricular conduction system from the embryonic spongy ventricle. Our study uncovers the evolutionary building plan of heart and indicates that the building blocks of the conduction system of adult ectothermic vertebrates and embryos of endotherms are similar."
  • tooth development in a model reptile: functional and null generation teeth in the gecko Paroedura picta[6] "This paper describes tooth development in a basal squamate, Paroedura picta. Due to its reproductive strategy, mode of development and position within the reptiles, this gecko represents an excellent model organism for the study of reptile development. ...We show evidence for a stratum intermedium layer in the enamel epithelium of functional teeth and show that the bicuspid shape of the teeth is created by asymmetrical deposition of enamel, and not by folding of the inner dental epithelium as observed in mammals."
  • Patterns of interspecific variation in the heart rates of embryonic reptiles[7] "New non-invasive technologies allow direct measurement of heart rates (and thus, developmental rates) of embryos. We applied these methods to a diverse array of oviparous reptiles (24 species of lizards, 18 snakes, 11 turtles, 1 crocodilian), to identify general influences on cardiac rates during embryogenesis. Heart rates increased with ambient temperature in all lineages, but (at the same temperature) were faster in lizards and turtles than in snakes and crocodilians. We analysed these data within a phylogenetic framework. Embryonic heart rates were faster in species with smaller adult sizes, smaller egg sizes, and shorter incubation periods."
  • Reptilian spermatogenesis: A histological and ultrastructural perspective[8] "Until recently, the histology and ultrastructural events of spermatogenesis in reptiles were relatively unknown. Most of the available morphological information focuses on specific stages of spermatogenesis, spermiogenesis, and/or of the mature spermatozoa. No study to date has provided complete ultrastructural information on the early events of spermatogenesis, proliferation and meiosis in class Reptilia. Furthermore, no comprehensive data set exists that describes the ultrastructure of the entire ontogenic progression of germ cells through the phases of reptilian spermatogenesis (mitosis, meiosis and spermiogenesis)."


Iguana - historic drawing

root; cellular organisms; Eukaryota; Opisthokonta; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Sarcopterygii; Tetrapoda; Amniota; Sauropsida; Sauria; Lepidosauria

Squamata (squamates) - snakes and lizards.

  • Iguania (iguanian lizards) - arboreal with primitively fleshy, non-prehensile tongues, highly modified in the chameleons.
    • Acrodonta
    • Iguanidae (iguanid lizards)
  • Scleroglossa
    • Amphisbaenia
    • Anguimorpha (anguimorph lizards)
    • Gekkota - all geckos and the limbless Pygopodidae.
    • Scincomorpha (scincomorph lizards)
    • Serpentes (snakes)
  • unclassified Squamata
Links: Taxonomy Browser Lizards

Development Overview

Australian Water Skink


Anolis carolinensis (green anole) mating.

Anolis carolinensis (green anole)

The genome of the lizard Anolis carolinensis (green anole) from southeastern United States has a karyotype of 18 chromosomes, comprising six pairs of large macrochromosomes and 12 pairs of small microchromosomes, and has recently been sequenced.[1] Interestingly, almost all reptilian genomes also contain "microchromosomes", very small chromosomes less than 20 Mb in sequence size.

It is a model organism for laboratory-based studies of organismal function and for field studies of ecology and evolution. This species was chosen for genome sequencing in part because of the ease and low expense of captive breeding, well studied brain, and sophisticated color vision. It is also well suited for studies involving the role of hormones in development and adult nervous system plasticity. (modified from Genome)

Search PubMed Genome: Lizard


  1. 1.0 1.1 Alföldi J, Di Palma F, Grabherr M, Williams C, Kong L, Mauceli E, Russell P, Lowe CB, Glor RE, Jaffe JD, Ray DA, Boissinot S, Shedlock AM, Botka C, Castoe TA, Colbourne JK, Fujita MK, Moreno RG, ten Hallers BF, Haussler D, Heger A, Heiman D, Janes DE, Johnson J, de Jong PJ, Koriabine MY, Lara M, Novick PA, Organ CL, Peach SE, Poe S, Pollock DD, de Queiroz K, Sanger T, Searle S, Smith JD, Smith Z, Swofford R, Turner-Maier J, Wade J, Young S, Zadissa A, Edwards SV, Glenn TC, Schneider CJ, Losos JB, Lander ES, Breen M, Ponting CP & Lindblad-Toh K. (2011). The genome of the green anole lizard and a comparative analysis with birds and mammals. Nature , 477, 587-91. PMID: 21881562 DOI.
  2. Siviter H, Deeming DC & Wilkinson A. (2019). Egg incubation temperature influences the growth and foraging behaviour of juvenile lizards. Behav. Processes , 165, 9-13. PMID: 31170461 DOI.
  3. Ollonen J, Da Silva FO, Mahlow K & Di-Poï N. (2018). Skull Development, Ossification Pattern, and Adult Shape in the Emerging Lizard Model Organism Pogona vitticeps: A Comparative Analysis With Other Squamates. Front Physiol , 9, 278. PMID: 29643813 DOI.
  4. Stewart JR & Thompson MB. (2017). Yolk sac development in lizards (Lacertilia: Scincidae): New perspectives on the egg of amniotes. J. Morphol. , 278, 574-591. PMID: 28168721 DOI.
  5. Jensen B, Boukens BJ, Postma AV, Gunst QD, van den Hoff MJ, Moorman AF, Wang T & Christoffels VM. (2012). Identifying the evolutionary building blocks of the cardiac conduction system. PLoS ONE , 7, e44231. PMID: 22984480 DOI.
  6. Zahradnicek O, Horacek I & Tucker AS. (2012). Tooth development in a model reptile: functional and null generation teeth in the gecko Paroedura picta. J. Anat. , 221, 195-208. PMID: 22780101 DOI.
  7. Du WG, Ye H, Zhao B, Pizzatto L, Ji X & Shine R. (2011). Patterns of interspecific variation in the heart rates of embryonic reptiles. PLoS ONE , 6, e29027. PMID: 22174948 DOI.
  8. Gribbins KM. (2011). Reptilian spermatogenesis: A histological and ultrastructural perspective. Spermatogenesis , 1, 250-269. PMID: 22319673 DOI.


Murphy BF & Thompson MB. (2011). A review of the evolution of viviparity in squamate reptiles: the past, present and future role of molecular biology and genomics. J. Comp. Physiol. B, Biochem. Syst. Environ. Physiol. , 181, 575-94. PMID: 21573966 DOI.

Dzialowski EM, Sirsat T, van der Sterren S & Villamor E. (2011). Prenatal cardiovascular shunts in amniotic vertebrates. Respir Physiol Neurobiol , 178, 66-74. PMID: 21513818 DOI.

Gamble T. (2010). A review of sex determining mechanisms in geckos (Gekkota: Squamata). Sex Dev , 4, 88-103. PMID: 20234154 DOI.


Lu HL, Wang J, Xu DD & Dang W. (2018). Maternal warming influences reproductive frequency, but not hatchling phenotypes in a multiple-clutched oviparous lizard. J. Therm. Biol. , 74, 303-310. PMID: 29801642 DOI.

Desfilis E, Abellán A, Sentandreu V & Medina L. (2018). Expression of regulatory genes in the embryonic brain of a lizard and implications for understanding pallial organization and evolution. J. Comp. Neurol. , 526, 166-202. PMID: 28891227 DOI.

Sanger TJ & Kircher BK. (2017). Model Clades Versus Model Species: Anolis Lizards as an Integrative Model of Anatomical Evolution. Methods Mol. Biol. , 1650, 285-297. PMID: 28809029 DOI.

Wise PA, Vickaryous MK & Russell AP. (2009). An embryonic staging table for in ovo development of Eublepharis macularius, the leopard gecko. Anat Rec (Hoboken) , 292, 1198-212. PMID: 19645023 DOI.

Noro M, Uejima A, Abe G, Manabe M & Tamura K. (2009). Normal developmental stages of the Madagascar ground gecko Paroedura pictus with special reference to limb morphogenesis. Dev. Dyn. , 238, 100-9. PMID: 19097047 DOI.

Storm MA & Angilletta MJ. (2007). Rapid assimilation of yolk enhances growth and development of lizard embryos from a cold environment. J. Exp. Biol. , 210, 3415-21. PMID: 17872995 DOI.

Fabrezi M, Abdala V & Oliver MI. (2007). Developmental basis of limb homology in lizards. Anat Rec (Hoboken) , 290, 900-12. PMID: 17415759 DOI.

Sanger TJ & Gibson-Brown JJ. (2004). The developmental bases of limb reduction and body elongation in squamates. Evolution , 58, 2103-6; discussion 2107-8. PMID: 15521466

Muthukkaruppan V, Kanakambika P, Manickavel V & Veeraraghavan K. (1970). Analysis of the development of the lizard, Calotes versicolor. I. A series of normal stages in the embryonic development. J. Morphol. , 130, 479-89. PMID: 5437480 DOI.

Mohammed MB. (1984). Development of the lizard limb as shown by the distribution of [35S]sulphate incorporation. J. Anat. , 138 ( Pt 3), 399-403. PMID: 6429113


Herrick CJ. The Brain of the Tiger Salamander (1948) The University Of Chicago Press, Chicago, Illinois.

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Search PubMed: Lizard development | Anolis carolinensis


Fig. 343. Head of a Lizard Embryo (Sphenodon punctatum Hatteria)

Schwalbe (1891) points out the significant fact that in reptiles that lack an external ear (lizard and turtle) there occur distinct hillocks in the embryo, resembling those in vertebrates that develop an auricle. These hillocks undergo degeneration and are reduced to the level of the surrounding skin. He finds in both birds and reptiles hillocks corresponding to the tragus and antitragus hillocks of His. These animals have one hillock (Auricularkegel), situated dorsal to the first cleft, which seems to represent a more primitive apparatus than is present in mammals, although it may be related to the helix system. In Salachians it possesses a spiracle.

(From Contributions to Embryology No.69)

Sand Lizard 1904

Normal Plates of the Development of Vertebrates 4 - Sand Lizard (Lacerta agilis) by Karl Peter

The Brain of the Tiger Salamander 1948

Herrick CJ. The Brain of the Tiger Salamander (1948) The University Of Chicago Press, Chicago, Illinois.

Part I. General Description and Interpretation 1. Salamander Brains | 2. Form and Brain Subdivisions | 3. Histological Structure | 4. Regional Analysis | 5. Functional Analysis, Central and Peripheral | 6. Physiological Interpretations | VII. The Origin and Significance of Cerebral Cortex | VIII. General Principles of Morphogenesis Part 2. Survey of Internal Structure 9. Spinal Cord and Bulbo-spinal Junction | 10. Cranial Nerves | 11. Medulla Oblongata | 12. Cerebellum | 13. Isthmus | 14. Interpeduncular Nucleus | 15. Midbrain | 16. Optic and Visual-motor Systems | 17. Diencephalon | 18. Habenula and Connections | 19. Cerebral Hemispheres | 20. Systems of Fibers | 21. Commissures | Bibliography | Illustrations | salamander

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