Lab #5: Lepidosauria Part 1: Shenodonta and Sauria

Lab #5: Lepidosauria 

Part 1: Shenodonta and Sauria

Introduction 

Eureptilia contains two extant lineages of reptiles, which are sister taxa.  These two extant lineages are Archosauromorpha and Lepidosauromorpha,  Some of the most iconic reptiles known to humans are contained within Lepidosauromorpha, which include:

• Sphenodontida (Extant Tuatara and Rhynchocephalian) 
• Sauria (Lizards)
• Serpentes (Snakes)

Lepidosauria all exhibit the following synapomorphies:

1.  Transverse cloacal aperture (vent)
2. Notched tongue (- lingul prehension)
3. Full-body ecdysis
4. Imperforate columella 
5. Teeth attached to jaws
6. Pelvic bones fused in adults
7. Fracture planes on septa within caudal vertebrae

Squamata

• Comprised of Sauria and Serpentes
• Contains over 8,000 species (5,019 species within Sauria alone)
• Inhabit all contents but Antarctica
• Found in hot and cold climates
• Found in high and low elevations 
• Found in dry and wet environments
• Found in freshwater and marine habitats
• Greatest diversity found in semiarid habitats 
• Characterized from their skeletal and soft anatomy 
• Defined by more than 50 synapomorphies

The following is a list of 12 reviewed synapomorphies discussed in lab exhibited by Squamates:

1. Fused premaxillae
2. Fused parietal
3. Reduced nasals
4. Lack of volmerine teeth
5. Specialized joints between ulna-ulnare and radius-radiale
6. Specialized ankle joints
7. WEll developed hemipenes
8. Saccular ovaries
9. Jacobson's organ (vomeronasal organ) seperate from nasal capsule
10. Lacrimal duct joining the vomeronasal duct
11. Femoral and pre-anal glands
12. Egg tooth at hatching

Anatomy of Skull in Varanus

Diversity Among Lepidosuaria

There are currently 19 extant families that have been recognized within Sauria, but may be as many as 36 families.  The greatest issue of debate over the number of families contained in Sauria pertains to the disagreement as to how large some families are and how inclusive family-level groups should be.  Ultimately there remains considerable debate over whether or not to elevate many lizard subfamilies to family-level status.  There is current consensus that the subfamilies within the family, Iguanidae, should be broken down into families.        

YELLOW ARE THE FAMILIES WE DISCUSSED IN LAB

Families Represented in Lab (alphabetical order):

Agamidae
(Angleheads, Calotes, Dragon Lizards, and Allies)

Classification: Squamata; Toxicofera; Iguania; Acrodonta; Agamidae.

Sister taxon: Chamaeleonidae.

Two Subfamilies: Agaminae and “Leiolepidinae.” 

Distribution: Africa, Asia, Australia, and Tasmania 

Droco volans 

-Have airfoil formed from ribs which is used gliding 

Anguidae

Alligator Lizards, Glass Lizards, and Allies

Classification: Squamata; Toxicophora; Anguimorpha; Anguidae.

Nine Genera: Abronia, Anguis, Barisia, Colop- tychon, Elgaria, Gerrhonotus, Mesaspis, Ophisaurus, and Pseudopus

Ophisaurus -glass lizard

no limbs 

           longitudinal fold

                                                            Chamaeleonidae

Chameleons

Classification: Squamata; Toxicofera; Iguania; Acrodonta; Chamaeleonidae.
Sister taxon: Agamidae.

Content: Ten genera, Bradypodion, Brookesia, Calumma, Chamaeleo, Furcifer, Kinyongia, Nadzikambia, Rhampho- leon, Rieppeleon, and Trioceros, with 186 species. Distribution: Africa, the Middle East, Madagascar, south- ern Spain, Sri Lanka, and India

• Acrodont teeth
• laterally compressed bodies
• prehensile tails
• head casques covering their necks 
• zygodacty- (feet fusion of sets of two and three digits, form-ing opposable, two-digited mitten-like fore and hind feet; manus fusion 1–2–3 and 4–5, pes 1–2 and 3–4–5) 
• projectile tongues
• independently movable eyes 

Gekkota

Eublepharidae
Eyelid Geckos
Classification: Squamata; Gekkota; Gekkomorpha; Eublepharidae.
Sister taxon: The ((Gekkonidae+Phyllodactylidae) Sphaerodactylidae) clade.
Content: Six genera, Aeluroscalabotes, Coleonyx, Eublepharis, Goniurosaurus, Hemitheconyx, and Holodac- tylus,  Distribution: Disjunct in southwestern North America and northern Central America, and sub-Saharan Africa and southern Asia 

Key Characteristics 

LACK TOE PADS

HAVE EYELIDS

     

Sphaerodactylidae

Dwarf Geckos
Classification: Squamata; Gekkota; Gekkomorpha; Sphaerodactylidae.

Sister taxon: The clade (Gekkonidae + Phyllodactylidae). Content: Twelve genera, Aristelliger, Chatogekko, Coleo- dactylus, Euleptes, Gonatodes, Lepidoblepharis, Pristurus, Pesudogonatodes, Quedenfeldtia, Saurodactylus, Sphaero- dactylus, and Teratoscincus     

-Small like their common name suggests(dwarf gecko)

-Have spectacles

Gekkonidae
Wall-Climbing Geckos
Classification: Squamata; Gekkota; Gekkomorpha; Gek- konidae.
Sister taxon: Phyllodactylidae.
Content: Fifty genera, Afroedura, Afrogecko, Agamura, Ailuronyx, Alsophylax, Asiocolotes, Blaesodactylus, Calodac- tylodes, Chondrodactylus, Christinus, Cnemaspis, Colopus, Crossobamon, Cryptactites, Cyrtopodion, Dixonius, Ebena- via, Elasmodactylus, Geckoella, Geckolepis, Gehyra, Gekko, Goggia, Hemidactylus, Hemiphyllodactylus, Heteronotia, Homopholis, Lepidodactylus, Luperosaurus, Lygodactylus, Matoatoa, Nactus, Narudasia, Pachydactylus, Paragehyra, Paroedura, Perochirus, Phelsuma, Pseudogekko, Ptenopus, Ptychozoon, Rhinogecko, Roptropella, Rhoptropus, Stenodac- tylus, Tropiocolotes, Urocotyledon, and Uroplatus, with 885+ species.
Distribution: Pantropic including islands. Introduced in temperate North and South America 

Most diverse group, they are large in size.
Have no eye lids but do have 14 sclerotic ossicles

Helodermatidae
Gila Monster and Mexican Beaded Lizard
Classification: Squamata; Toxicophora; Anguimorpha; Helodermatidae.
Sister taxon: The clade Xenosauridae + (Anguidae + Dip- loglossidae + Anniellidae).
Content: One genus, Heloderma, with 2 species. Distribution: Southwestern North America, from the Sonoran Desert southward along the Mexican Pacific coast to Guatemala

• large lizards (300– 500 mm adult SVL). 
• only lizards with well- developed venom glands. 
• thick skin with rows of rounded scales circling ----the body, giving them a beaded appearance
• pleurodont, and pterygoid teeth are present 
• synoptic fusion of dermal bones to skull table

Phrynosomatidae (North American Spiny Lizards) 

Classification: Squamata; Toxicofera; Iguania; Pleurodonta; Phrynosomatidae.

Sister taxon: All other Pleurodonta

Nine genera: Callisaurus, Cophosaurus, Hol- brookia, Petrosaurus, Phrynosoma, Sceloporus, Uma, Urosaurus, and Uta

Distribution: Southern half of North America to western Panama

Characteristics:

• Moderately sized lizards 
• Arid-adapted species
• Robust spiny-scaled body 
• Terrestrial and Semi-terrestrial 
• Occur in seasonal environments (reproduction strongly seasonal)

Iguanidae (Iguanas and Allies)

Classification: Squamata; Toxicofera; Iguania; Pleurodonta; Iguanidae                                Sister taxon: Crotaphytidae                                                                                                                 Eight Genera: Amblyrhynchus, Brachylophus, Conolophus, Ctenosaura, Cyclura, Dipsosaurus, Iguana, and Sauromalus                                                                             Distribution: Americas from southwestern United States to Paraguay and southern Brazil, West Indies, Galápagos, and west-central Pacific islands (Neotropics)

Characteristics:

• Typically large lizards
• Predominantly terrestrial
• Rarely descend into ground 
• Exclusively herbivorous

Corytophanidae (Casque-Head or Helmeted Lizards)

Classification: Squamata; Toxicofera; Iguania; Pleurodonta; Corytophanidae.
Sister taxon: Dactyloidae
Three genera: Basiliscus, Corytophanes, and Lae- manctus
Distribution: Southern Mexico to northern South America 

Characteristics: 

• Arboreal lizards 
• Casque-headed
• Slender bodies
• Long limbed
• Rarely ascend to ground, except to lay eggs, and forage

Dactyloidae (True Anoles)

Classification: Squamata; Toxicofera; Iguania; Pleurodonta; Dactyloidae.

Sister taxon: Polychrotidae.
One Genus: Anolis
Distribution: Southeastern United States through Central America and the West Indies to tropical and subtropical South America

Characteristics:

• Most speciose pleurodontan lizards
• Arboreal species, specialized foot morphology 
• Sexual dimorphism, males are larger
• Sit and wait predators on arthropods

Scincidae (Skinks)

Classification: Squamata; Scinciformata; Scincimorpha; Scincidae.
Sister taxon: Xantusiidae
Two subfamilies: Acontinae and “Scincinae”
Distribution: Nearly worldwide

Characteristics ("Scincinae"):

• Highly diverse group 
• Cylindrical bodies and tails
• Conical head
• well developed moderately short limbs
• Shiny, smooth scales 
• Others are short and robust with heavily keeled scales 
• Many are active foragers

Teiidae (Whiptail, Tegus, and Allies)

Classification: Squamata; Laterata; Lacertiformes; Teiidae.
Sister taxon: Gymnophthalmidae.
Two Extant Clades: Teiinae and Tupinambinae
Two Extinct Clades: Chamopsiinae and “Polyglyphanodontinae.”
Distribution: Americas, from northern United States to Chile and Argentina

  Characteristics:

• Small, granular dorsal and lateral body scales
• Rectangular, large, juxtaposed, transverse rows of ventral scales
• Many are terrestrial and forage on forest ground

Varanidae (Monitors and Goannas)

Classification: Squamata; Toxicophora; Anguimorpha; Varanidae.
Sister taxon: Lanthanotidae.
One Genus:Varanus
Distribution: Warm temperate and tropical Africa south of the Sahara, eastward through Asia to Australia and islands in the southwestern Pacific 

Characteristics:

• Large in size
• Thick skin with numerous rows of small, rounded scales circling body
• Ventral scales larger than dorsal scales
• Rectangular scales on ventral surface
• Very snake-like tongue 
• Relatively small heads with long necks and large robust bodies 
• Well enveloped limbs
• Long muscular tails 

Ohio Diversity within Lepidosauria

Within Ohio there are few native species of lizards.  the sate only contains two families and five species.  

1) Family: Iguanidae

Sceloporus undulates garmani (Northern Fence Lizard)

2) Family: Scincidae (Skinks)

Scincella lateralis (Ground Skink)

Plestiodon fasciatus (Five-Lined Skink)

Plestiodon laticeps (Broad-Headed Skink)

Plestiodon anthracinus (Northern Coal Skink)