Herpetology

herpetology

study of amphibians and reptiles (polyphyletic)

Polyphyletic

group of organisms that have been grouped together but do not share an immediate common ancestor

Batrachology

study of amphibians

Gladwyn Kingsley Noble

textbook on amphibians

KP Schmidt

curator of american museum of natural history

checklist of reptiles + amphibians of NA accepted by itchyologists + herp society

notes on snake bite symtpoms

Roger Conant

first comprehensive field guide on herps in eastern US

Hobart Smith

major herpetologist, manuscripts on fauna

James R Dixon

300 manuscripts, texas herpetofauna descriptions

Mary Cynthia Dickerson

described 20+ new reptile species

Joan Beauchamp Procter

first curator of reptiles at the london zoo

Bernard Martoff

chair of zoo department at ncsu, first guide to herps of carolinas

type(s)

refers to a specific specimen

holotype

museum type specimen used to describe/represent a species

neotype

replaces a holotype if missing

syntype

multiple specimens to describe a species, no single representative

paratype

holotype + additional speciments

allotype

holotype of opposite sex

Superclass Tetrapoda

arise during devonian ~385 mya from

Actinistia

coelocanths (sarcopterydians)

2 extant species (latimeria)

Dipnoi

lungfish (sarcopterydians) —> evolved to tetrapods based on skeleton and presence of choana

lungs homologous to first tetrapods

6 extant species

choana

nostrils connect nasal cavity to mouth - allows for closed mouth breathing

Eusthenopteron

Class sarcopterygii

385 mya - northern hemisphere

skeletal fin features = appendicular bones

ambush predator in shallow, heavily vegetated, low o2 water

Romer’s Gap

360-345 mya lack of fossils described by Alfred Romer

Panderichthys

Class sarcopterygii

380 mya - Latvia

best known transitional prototetrapod

flat head, long snout, dorsally positioned eyes

dorsoventrally flattened tetrapod-like humerus

fin rays (not digits)

Elpistostege

Late devonian - Canada

Skull + backbone fragments

Most close to Tiktaalik

estuarine environment

Tiktaalik

375 mya - Canada

significant fossil discovery in 2004

wrist bones, arm like structures, flat body, revised dorsal eyes, wide skull + mobile neck, pectoral girdle separate from skull

Acanthostega

365 mya - Greenland

best known tetrapod, changed early understanding of evolution

had 2/3 of 41 unique tetrapod characteristics

freshwater rivers

8 digits (first digits) - came before walking on land

Ichthyostega

375-360 mya - Greenland

original transitional fossil

hind limb with 7 digits

primarily rely on lungs, completely leave water temporarily

freshwater streams

Tulerpeton

365 mya - Russia

no gills, less aquatic, marine but capable of terrestrial movement

6 digits

more robust petoral girdle

5 Pre-Adapted features to transition

respiration

movement

feeding

skin

sense organs

Respiration Adaptations

lungs appear in bony fish evolution, predecessors to swim bladder

led to buccal and costal pumping mechanisms

buccal pumping

using muscles to push air down

Costal pumping

changing volume of thorassic cavity to create negative pressure

Movement adaptations

limbs —> move to land

rowing —> bottom walking required bending of fin-limb

fin rays lost, replaced by short, robust digits

pectoral girdle disconnected from skull (mobile neck)

vertebral column more robust

limb girdles become supportive

Feeding adaptations

head movement (predation)

shallow water or out of water advatage

elongate snout + jaw

Skin adaptations

increased epidermis layers

increased keratinization

protect against abrasian, desiccation

Sense organ adaptations

lateral line + electric organ function only in water, lost except in larval stage of aquatic species

hearing and middle ear structure appeared

eye structure for aerial vision

dual channel nasal passages for respiration and olfaction

Biogeography

distributions of organisms across the planet and through timefather of

Alfred Russel Wallace

father of biogeography, theory of evolution + natural selection, developed idea separate from Darwin

Ecological Biogeography

geographic patterns in community structure

descriptions of biomes + regions = ecological categories

Historical biogeography

relationships + origins of taxa, reinvented in the late 20th century (dna discovery)

molecular clocks, phylogeography

emphasizes how phylogenetic affinities relate to distributional pattern history of a species/group

Cladograms

vicariance (change) - an ancestral species' range splits into separate parts due to a new physical barrier

dispersal

area cladograms - geographical distributions

Amphibian and reptile biogeography

plate tectonics

major divergence since break up of pangaea (200 mya)

late cretaceous (100-66mya) amphibians may have experienced diversification inconsistent with current tectonic theory

Order Anura species + hotspots

South america, west africa, eastern US

7935

Amphibian characteristics

ectothermic

pectoral girdle not attached to skull

pectoral+pelvic anchor arms and legs

vertebral column suspended between girdles, requiring special joints for stability and flexibility

Amphibian reproduction

most lay eggs in/near water

~30 different modes of reproduction

most undergo metamorphosis (larvae with gills, adult w lungs)

direct development - frogs, salamanders, caecilians

live young (ovoviparous, viviparous) - frogs, salamanders, caecilians

Amphibian respiration

lungs primitive, lack a true diaphragm, use buccal pumping

cutaneous

lunglessness - lost/vestigal, one frog, salamander family plethodontidae

Amphibian nervous system

brain less developed but still advanced

limb-opercular - vibrations felt through legs + sent to ear

lateral line in most tadpoles

pair of sensory papilla in inner ear

double auditory transmission channels in the middle ear

columnar (air filled sac in anurans)/stapes

opercular made of protein senses vibrations

amphibian vision

color, depth of focus

4 specialized receptors in the retina

green and red appearing rods (anurans only have green) sight of G+B

sensitive to all wavelengths

register only presence/absence of light

single + double cones (for movement), color vision/sensitive to narrow wavelengths

amphibian skin

2 layers: epidermis and dermis

epidermis

stratum corneum (outermost) (ecdysis)

keratinization present

stratum germanitivum

dermis

location of pigment production and glands

stratum spongiosum (DCU)

stratum compactum

Chromatophores

pigment-producing cells

dermal chromatophore unit in stratum spongiosum

Xanthophores: yellow-red

iridophores: white-blue

melanophores: black-red

fixed shape

color change = dispersion or aggregation of granules within

Mucous glands

dermis

moistens skin, optomizes oxygen exchange, protection from desiccation

Granular glands

dermis

secretes poison (paratoid)

poison typically requires a precursor

lipid glands

dermis

waxy coating (phyllomedusa sunscreen)

hatching glands

dermis

around snout, secretes enzymes to break down egg casing in larvae

hedonic glands

dermis

caudata and some reptiles

pheremones for courtship

merkel glands

mechanoreceptors ?

flask glands

salt and water balance ?

ecdysis

skin shedding

stratum corneum only

Caecillian teeth

pedicellate (sit on pedestal)

bicuspid

evolution of amphibia

upper mississippian/lower pennsylvanian fossils reappear (335mya)

12+ clades - anthracosaurs

amniotes

lack amniotic membrane

temnospondyli

“cut vertebrae”

vertebrae divided into 3 parts

possibly ancestors of modern amphibians

wide range of environments / every continent

lepospondyli

early amphibians/reptiles? polyphyletic?

triassic

250-200 mya

7 amphibian groups (including lissamphibia)

small to large

mostly aquatic

most disappear by mid jurassic

fossils say frogs came before caecilians

triadobatrachus

oldest true frog

250 mya

madagascar

Order Gymnophiona (apoda)

diverged first - poor fossil record

10 families, 231 species

pantropical distribution - south america, australia

majority fossorial except typhlonectidae (aquatic)

no limbs/limb girdles

tail reduced or absent

no ear openings, but do have collumella bones (stapes)

annuli present - ring-like divits in skin - segments with single vertebrae

paired tentacles between eyes and nostrils

smell derived from tear duct + extrinsic eye muscles

eyes vestigial and skin covered - sense light vs dark

dermal scales (often) layers of fiber tissue covered by mineralized nodules

vertebrae are amphicoelous

skull heavily ossified - aids in digging/burrowing

dual jaw closing mechanism

Order Caudata species + hotspots

828

North carolina, Eastern US

Order Gymnophiona species + hotspots

231

South America

Subclass Lissamphibia

~9k species

~8k assessed by IUCN

41% threatened

Salamanders most threatened (agriculture)

monophyletic

an organism and all its descendants

paraphyletic

an organism and some of its descendants

Eocaecilia

Earliest caecilian fossil

200 mya jurassic

legs, good vision

Amphicoelous

concave on anterior and posterior side of centrum (allows movement in all directions)

concertina and undulatory locomotion

gymnophiona dual jaw mechanism

masseter adductor mandibulae pulls lower jaw up

masseter interhyoideus posterior pulls down on processus retroarticularis (used for extra help, unique to this order, necessary bc of ossified skull)

Expatation

existing structure develops a new feature

Order caudata (urodela)

10 families

holoarctic with exception of some plethodontidae in neotropics

well developed tails, cylindrical/elongate bodies

distinct head, well developed limbs

reduced skull elements

model systems for regeneration

varied reproductive models (cryptobranchidae + sirenidae external fert)

derived lineages (internal fert, spermatophore deposited by male, collected with female cloaca, eggs deposited in damp areas)

external development (mostly directly to juvenile, some via larval stage)

heterochrony

Karaurus

first true salamander (caudata)

150 mya

Major synapomorphies of caudata

ossification sequence of skull

remodeling of palate during metamorphosis

absence of middle ear/cavity (only have a few ossicles)

presence of gill slits/external gills in aquatic larvae

heterochrony

change in timing of developmental events

Neoteny

larval appearance with reproductive maturity - somatic development slowed down

paedomorphosis

retention of ancestral juvenile traits in ontogenic stages of descendants

paedogenesis

speed up of reproductive, somatic development stays the same

ontogeny

development of organism from zygote to adult

obligate neoteny

organism will not metamorphose in nature due to external conditions or stimuli

inducible obligate neoteny

organism can be forced to metamorphose through manipulation of thyroid in a lab

facultative neoteny

may metamorphose in nature due to external stimuli (predators, drying of environment)

thyrokine

hormone that induces metamorphosis, produced by pituitary gland

Sirenidae

6 species

coastal southeastern north america and mississippi river valley

aquatic, muddy substrates with dense vegetation

moderately slender, eel-like

small forelimbs, hind and pelvic girdle absent

up to 0.9 m total length

all neotenic (obligate): external gills, gill slits, no eyelids

costal grooves present, nasiolabial absent

lungs present but small

fert presumed external

females lack spermathecae, males lack repro glands in cloaca

interventicular septum present in heart (almost 4 chamers, separates oxy and deoxy blood)

Cryptobranchidae

suborder cryptobranchoidea

6 species

asiatic giant salamanders, hellbenders

east-central china, japan, app + ozark mntns in US

clear, cold, mountain streams - aquatic

largest living salamanders

short, well developed limbs

heavy, laterally compressed tail

neotenic obligate traits

almost all respiration through skin → wrinkly

no costal grooves or nasolabial

lungs present but vestigal

external fert, females lack spermathecae

lack typical courtship displays

Ambystomatidae

suborder salamandroidea

33 species, 1 genus

north american to southern rim of mexican plateau

mole salamander

mostly terrestrial, return to water for repro

forest floorplains - upland forests

heavy bodied and tailed

4 short, well developed limbs

adults lack gills + slits

moveable eyelids

inducible obligate or facultative

costal grove present, nasiolabial absent

well developed + functioning lungs

internal fert

males have 6 sets of cloacal glands

courtship present

winter breeders

Salamandridae

103 species, 21 genus

holoarctic - europe, eastern to central russia

aquatic to terrestrial, most return to water for repro

less than 200 mm

slender to robust bodies

limbs well developed and moderately short

most adults lack gills/slits

moveable eyelids

eastern newt has triphasic life cycle: aquatic larvae, terrestrial efts, aquatic adults - may remain neotenic

costal grooves + nasolabial absent

lungs present and functional

internal fert, males have 5 sets of glands

courtships

more granular/rugose skin due to abundance of poison glands

most toxic of all salamanders

proteidae

6 species, 2 genus

eastern half of NC, eastern adriatic coast of europe

olms, mud puppies, waterdogs

aquatic

moderately robust bodies, short + well developed limbs, laterally compressed tails

obligate neoteny

external gills

costal and nasolabial grooves absent

lungs present but small

internal fert, males 6 sets of glands

Some surface dwellers, some cave dwellers, one in groundwater systems

amphiumidae

southeastern us

heavy bodied, tiny weak limbs

aquatic, eel like

direct internal fert, 5 sets glands

obligate neotenic - lose external gills during partial metamorphosis

eyelids and tongues absent

costal grooves present, nasolabial absent

lungs present

courtship, females protect eggs

plethodontidae

433 species, 25 gen

americas, southern canada to southwestern brazil, southern europe and korea

lungless salamanders - lungs absent

25-320 mm

diversity of body shapes, all have 4 limbs

adults lack gills and gill slits, have moveable eyelids, except in paedomorphic taxa

costal and nasolabial present

internal fert, 6 sets of glands

courtship

4 subfamilies

Order Anura (salienta)

cosmopolitan except extreme northern latitudes

geroabtrachus 290 mya in texas

triadobatrachus 250 mya (triassic) madagascar

body form evolved for saltatory movement

short, tailless body, broad flat heads, long muscular hind limbs

external fert, few exceptions, males amplex females, cloacae juxtaposed to ensure fert

indirect dev common, direct also widespread

major reorganization of anatomy and physiology during metamorphosis

contrasting body form + lifestyle partially explain lack of neoteny

taxonomy under rapid growth + change

inguinal amplexus

grabs hips

axillary amplexus

grabs shoulders