Herpetology Final - Big picture content, Crocodiles, Serpentes/Snakes , Rise of Lepidosaurs/Lizard Diversity

Sister clade

FIRST outgroup

Chelonian characteristics

-Carapace (dermal bones w/ fused ribs) +plastron (ventral shell)

-8 thoracic vertebrae

-Pectoral/pelvic girdle is MEDIAL to rib cage

Testudinidae

The tortoises - Stout limbs, high dome for protection. Gigantism is common!

Small clutch size, incubation is LONG. Protect nests. Smell/sight is important for these species.

Rhynchocephalians

Tuatara

Polyphyletic

Pertaining to a group of taxa derived from two or more different ancestors

Paraphyletic

Pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants.

Herp characteristics

Ectothermic - Do not produce their own heat, energy required to raise their body temperature comes from outer warmth (sun, etc.)

Highly efficient! Use 1/10th of the energy of birds/mammals, but are limited to certain areas/times of day due to being ectotherms.

Monophyletic group

Ancestor and ALL descendants

Amphibian characteristics

1. Hand (manus) w/ four digits and foot w/ 5 digits

2. Articular surface of atlas is convex (top-most vertebra is convex, allows for movement)

Lissamphibia characteristics

1. Pedicellate teeth

2. Columella + operculum

3. Green rods in retina

4. Two skin glands - mucous and poison

5. Levator bulbi in eye

6. Short, straight ribs

7. Skull bone reduction!

Anuran characteristics

1. Skulls extremely reduced

2. No teeth on mandible!

3. No tails! Urostyle is formed from fused caudals

4. Skin on head co-ossifies to skull

5. Greatly elongated hind limbs and feet

Anapsid

Skull condition in which there is NOT temporal fenestrae. TRADITIONAL view of turtles

Diapsid

TWO fenestrae, where other lizards/snakes are grouped. New data suggests turtles DO fall into the diapsid condition.

Testudines

ALL turtles + extinct relatives

Keratin scutes

DO NOT match bone sutures - this conveys greater strength!

Leatherback turtle

Second largest reptile on the planet

Marine turtles

Have longer forelegs than back , have elongated/broadened phalanges that cannot be moved independently

Pleurodires

Side-necked turtles

Cryptodires

Pull their necks back in cobra-style in a parasagittal plane

Cheloniodeans

The sea turtles - Hind flippers act like rudders. Takes 25+ years to reach reproductive age. They migrate by earth's magnetic field and sometimes travel 4000+ miles from nesting grounds!

Dermochelyidae

Dermochelys - NO epidermal scales (leatherback), instead has a carapace made w/ small ossicles.

They are INTERNAL homeotherms, meaning they can go into cooler waters. Heat is generated by muscles!

Amphibian diversity

6000 species

Reptile diversity

8000 species

Urodele

Salamander order!

380 species, mostly in Northern Hemisphere

Have three glands: Mucous, granular-poison, and mixed (pheromones)!

Anura

Frog/toad order!

ALL continents except Antarctica

Gymnophiona

Caecilian order!

170 species

Tails reduced/absent, limbs + girdles completely absent!

Left lung reduced, no external ear opening

Has fish-like scales

Testudines

Turtle order

285+ Species!

Squamates

Lizard/snake order

Crocodilians

Alligators/crocodiles

Chelonian characteristics

1. Carapace - dermal bones fused w/ ribs

2. 8 thoracic vertebrae

3. Pectoral and pelvic girdles are medial to rib cage

Lepidosauria characteristics

1. Transverse cloacal slits

2. Skin shedding!

3. Caudal autonomy

Rhynchocephalian characteristics

1. Caniniform teeth, diastema

2. Acrodonty

3. Heterodonty

Squamata characteristics

Contains lizards, snakes + amphisbaenians

1. Hemipene

2. Jacobson's organ

3. Kinetic skulls

4. Limb reduction is common!

Serpentine characteristics

1. Ligamental symphysis between dentaries

2. 120+ precloacal vertebrae

3. Prokinetic joint

Snake diversity

2900 species, all continents except Antarctica

Crocodilian characteristics

1. Dermal scutes and osteoderms

2. Thecodont teeth

3. Polyphyodonty

Crocodylus porosus

Largest living reptile - the saltwater crocodile

Crocodilian characteristics

-Has dermal scutes with osteoderms that provide protection and thermoregulation

-Thecodont (in sockets) dentition

-Polyphyodonty, takes weeks to a year to replace teeth

Crocodile senses

Have dome pressure receptors to sense vibrations in water

Have pits for osmoregulatory function.

Salt glands are present in tongues of non-alligatoroids, which explains why crocodiles have wide distributions

Alligatoridea: Alligatoridae

Alligators and caimans

Teeth of lower jaw fit into pits in upper jaw and CANNOT be seen when jaw is closed. Scales on underside of body have no sensory pits.

NO lingual salt glands

Alligatorinae

"True" alligators. TWO species. Both live in areas where seasonal temps drop below freezing!

Crocodyloidea

Notch in upper jaw accomodates 4th tooth of lower jaw. Sensory pits in scales on underside of body.

HAVE salt glands - wide distribution!

Crocodylidae

True crocs. 1st mandibular tooth often penetrates the premax. Some have broad snouts while some are slender.

C. porosus

Saltwater crocodile. Largest living reptile. 7m, 2000+ lbs.

Snake characteristics

-Ligamental symphysis between dentaries

-120 or more precloacal vertebrate

-Prokinetic joint

-All are carnivorous

-Pelvic girdle is only present as spurs

Snake biology

-Oviparous (external eggs) and viviparous (live birth)

-Genetic sex determination

-Females are usually larger, males have larger pelvic spurs

Snake efficiency

They can go long periods of time w/o eating - longer shape is great for picking up heat, allowing for more energy efficiency

Jacobsen's organ

Snake's smell is highly developed. Combined w/ a forked tongue and this specialized organ, they can "taste" their environments.

Snake hearing

Can hear faint vibrations through ground/water and some airborne sounds as well!

Trigeminal nerve endings

Used by snakes as infrared radiation to sense heat - evolved independently as the pit organs in boas and a single pit in crotalines.

Water snakes

-Flatten head to mimic vipers when threatened

-Viviparous

-Gives off musk

-Some feed on fish and other small creatures when trapped after tide goes out (Mangrove water snake)

Colubrinae

Largest clade, have enlarged back fangs w/ or w/o significant venom

Boiga

Brown tree snake - introduced in Guam, wiped out many beautiful endemic birds :(

Venomous colubrids

Killed a famous herpetologist w/ bite. Are rear-fanged, must chew to get venom.

Elapidae

Fixed-front fang snakes - extremely venomous. Have proteroglyph dentition w/ long maxilla that is only fairly rotatable.

Naja and Hemachatus

Can spit venom, may cause temporary blindness.

Lepidosauria

Transverse cloacal slits, regular skin shedding, caudal autonomy

Rhynchocephalia

Order of tuataras

Sphenodontidae

Tuatara family - Display teeth on top of jaws (arcodonty) and different tooth forms (heterodonty)

Squamata

Lizards/snakes/amphisbaenians

Evertible hemipenes, Jacobson's organ, kinetic skulls.

Limb reduction

Has occurred at least 62 times in squamates, often associated with fossoriality

Acrodont

Teeth set in shallow groove, adults are permanent.

Pleurodont

Attachment occurs lingually and are replaced throughout life - Thought to be ancestral in squamates.

Autotomy

Fracture occurs within specific vertebrae - NOT regenerated as new vertebrae.

Pseudoautotomy

Fraction occurs between vertebrae

Amphisbaenidae

Limbless (except for one w/ front legs). Body is annulated. Right lung is reduced, skulls are heavily ossified.

Helodermatidae

GILA MONSTER! Blunt tail used for fat storage, venomous! Eats small vertebrates and eggs - odd due to the fact they have grooves in teeth (why?)

Varanidae

Monitors!

Varanus komodoensis

Largest extant lizard. Found in Indonesia.

Vomeronasal organ

Tongue flicking w/ deeply forked tongue to get airborne cues. "Tasting" the environment - Also known as Jacobson's organ.