016 Fanged + Venomous Snakes

8/2/2019 016 Fanged + Venomous Snakes

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Venomous

snakes in Illinois

and elsewhere.



The early evolution of venomous snakes is notwell understood because of the variety of tooth

types and a dearth of fossil material showingmaxillary bones with fangs in place.

The oldest fossils I have located are from the

Early Miocene (ca 5 my BP), which is not toolong ago. Both viperids and elapids are known,but they are very similar to living forms, so onecould presume they have had an extended

earlier history.



Venomous Snakes

There are three major types of venomous snakes in the world, if

mildly venomous types, such as Heterodon, are excluded.Categorization has mainly been based on the shapes of theirmaxillary bones and the positions of the fang-like teeth on themaxillaries. Se below for those considered more ancestral(Opisthogyphous) to those believed more specialized (Protero. &

Soleno.) :

Opisthoglyphous (Rear-fanged snakes)

Proteroglyphous (Front-fanged snakes: cobras, sea snakes,coral snakes, mambas, kraits)

Solenoglyphous (Moveable-fanged snakes: (vipers, pitvipers) rattlesnakes, copperheads, cottonmouths,bushmasters)

:



Rear-fanged snakes are generally believed

to have been be the earliest venomous

snakes, but there is no fossil evidence for

this. However, if we assume this to be the

case, then the following slide shows how

this might have happened.



Rear-fanged

snakeMaxilla is movable

and rotates on this

surface

To change to asolenogyphus snake

would need to

shorten maxilla



We have three rear-fanged snakes in

Illinois, the 1) Ring-necks, the 2) Flat-headed, and 3) the Hognoses. None of

these are known to bite people, so they

are not considered dangerous. Seebelow.



Few people in this area know that Ringneck

snakes are rear-fanged. The genus Diadophis

occurs over much of the eastern U. S. (see

map below), but I don’t think a bite from this

snake has ever been reported. It never gets

more than about 15 inches long, and usuallyis quite common, especially in rocky,

limestone regions. There are two subspecies

in Illinois, the Prairie Ringneck, D. punctatusarnyi and the Northern Ringneck, D. p.

edwardsii.







Diadophis skullshowing slightlyenlarged rear fang



Northern

Prairie



The rear-fanged snakes of the genus

Tantilla include a very large group, butmost of the species are found to the

southern and western U. S. They are all

small snakes not known to bite, so theycan be easily handled without fear. Only

one species occurs in IIIinois, and it is on

the endangered species list, so it is a rarity

in the state.



Flathead snake: Tantilla gracilis





The Hognosed snakes of the genus Heterodon,

are known colloquially as “Puff Adders,” because

they can flatten their neck somewhat like a

cobra. There are two species in the state, one

that used to be common in this area (H.

platyrhinos), and the other which is found only in

very sandy areas (H. nasicus). Both species haveenlarged rear “fangs” (see below) with which

they puncture their toad prey. Again, this is a

snake that rarely bites, so it usually can be

handled with impunity. Very few bites have beenreported for either species, and those that have

been bitten indicate that the venom is not very

toxic.



Eastern hognose snake: Heterodon platyrhinos








Heterodon nasicus



Western hognose snake: Heterodon nasicus





Serpentes

Scolecophidia

Alethinophidia

Macrostomata

Caenophidia

Colubroidia

Living snake

families



Solenoglyphous snakes in

IllinoisCopperheads

Cottonmouth

Massasauga

Timber Rattlesnake



Northern Copperhead: Agkitrodon contortrix mokasen



Southern Copperhead : Agkistrodon contortrix contortrix



A. c. mokasen A. c.contortrix



There are five copperheadsubspecies in the U.S. Only twoof which occur in Illinois:

Agkistrodon contortrix contortrix and A. c. mokasen. Interestingly,the females of all the subspecies

are more colorful than the males.



Cottonmouth: Agkistrodon piscivorus






A juvenile cottonmouth with yellow tail..



Note: None inMadison Co.

Monroe Co., nrFults. Now gone?





Note the 9enlarged head

scales in the genus

Sistrurus.



9 enlarged head scales in genus Sistrurus



Eastern Massasauga: Sistrurus catenatus



Clinton Co.,near. CarlyleLake

Used to be in Madison

Co.





Timber rattlesnake: Crotalus horridus



Still in Effingham area





Illinois Snakes

Worm snakes

Mud snake

Racers

Kingsnakes

Rat snakes

Green snakes

Bull snake

Colubrine Snakes







C. a. helenae

nr Chester

C. a. vermis





Black Racer: Coluber constrictor priapus







C. c. flaviventris

C. c. priapus





Monroe Co.

















E. o. spiloides

Now Pantherophis, not Elaphe





















Now Liochlorophis vernalis

N t i i snakes



Natricine snakesGarder snakes (2)

Ribbon snakes (2)

Water snakes (6)

Queen snake

Crayfish snake

Brown snake

Redbelly snake

Lined snake

Earth snake

Kirtland‟s snake















































Mississippi Green water snake: Nerodia cyclopion





Kirtland‟s snake: Clonophis kirtlandi









Venomoussnakes in

Illinois

Scolecophidia



Serpentes

Alethinophidia

Macrostomata

Caenophidia

Colubroidia

Living snake

families



Rear-fanged

snakeMaxilla is movableand rotates on this

surface

To change to a

solenogyphus snake

would need to

shorten maxilla



Hognosed snakesor

Puff “adders”



















There are five copperheadsubspecies in the U.S. Only twoof which occur in Illinois:Agkistrodon contortrix contortrix

and A. c. mokasen. Interestingly,the females of all the subspeciesare more colorful than the males.










Note: None inMadison Co



Madison Co.






Note the 9enlarged head

scales in the genus

Sistrurus.









Clinton Co.,near. CarlyleLake










Rear-fanged

snakeMaxilla is movableand rotates on this

surface

To change to a

solenogyphus snake

would need to

shorten maxilla

Class Reptilia



Class Reptilia

Sublass DiapsidaInfraclass Lepidosaurimorpha

Superorder Lepidosauria

(Includes Rhynchocephalians)

Order Squamata

(includes lizards, amphisbaenids, and snakes)

Suborder Serpentes or Ophidia

(Incudes only snakes)





A principle adaptation in snakes

is their ability to feed on largeprey. Everything we see in snakeanatomy seems pointed toward

this end. Because they cannotchew, their prey must beswallowed whole. Note the slides

below which shows how they dothis.





Note that cartilaginous rings surround

the trachea so that it remains open

for inhalation and exhalation duringthe swallowing process. Snake lungsare very elongate and internally

diverse.



ectopterygoid

supratemporal

The major changes we see in snakes when compared with lizards are

associated with large-sized food objects which must be swallowed whole.

Starting anteriorly and moving posteriorly we see:



Starting anteriorly and moving posteriorly we see:

1) The two mandibles are not fused medially, but are attached by a stretchable

symphysial ligament so the mouth can be opened widely.

2) The premaxillae are fused medially and are not rigidly attached to the rostrum as

in lizards.

3) The maxillaries, palatines, and pterygoids are all movable and have teeth.

4) The teeth are longer, curved posteriorly (to embed more deeply when the prey

attempts to escape), and are on movable bones (to increase contact with prey

when in the mouth).

5) The braincase is completely surrounded by bone (for isolation from the prey as it

moves down the anterior esophageal area).

6) Elongate supratemporal bones with quadrate bones attached posteriorly (forshifting the gape farther back and increasing its size).







vomeronasal organ = Jackobson’s

Palate



symphysial

ligament

Lizards

Lower jaw

Developmentally, snakes are similar to



p y,other vertebrates, but as time passes

they begin to coil and lengthen (seenext slide). During this lengtheningphase the viscera in the body cavityalso lengthens, so when snake viscera

is examined it appears quite elongated,and different from what lizard viscerawould look like (see below).

Stage 18 Stage 20 Stage 26



Trunk starts short, thenincreases in length.

Somite

Snake viscera in

two parts.



Nerodia ?

anterior posteriorHeart









How snakes move



How snakes move

Lateral undulation

concertina

sidewinding

rectilinear

(See below)



Lateral undulatory

locomotion



Concertina locomotion

Sidewinding





In heavy-bodied snakes such as boas,pythons, and vipers.



Rectilinear locomotion

interscutali



superior costo-cutaneous

Ventral scale

inferior costo-cutaneous

Gliding snake from East Indies



Hind limb vestiges in living snakes




A considerable number of living snakes havevestiges of hind limbs. When this character ispresent, systematists generally consider it anancestral trait, and thus, those snakes that

have it as more primitive. See the slide belowfor two examples of this.

Eyelash boa



3 wormsnakes

pubis

ilium

femur

Immovable

maxilla

Braincase only

partly covered

posteriorly



maxilla

Immovable

palatines &

pterygoids

mostly without

teeth

Teeth not

recurved

Primitive skullroof

Epipterygoid present

Supratemporals thin

sheets on lateral edge

parietals

Tegu lizard

Tupinambis

nigropunctatus

Teeth on maxilla

Teeth on palatines



Teeth on pterygoids

supratemporalquadrate

recurved teeth

Python argus

Enclosed braincase

Maxilla, palatines,and pterygoids all

movable.

No epipterygoid

Intramandibular joint

Fossil snakesPachyrhachis problematicus (late Cretaceous of Israel)



Pachyrhachis problematicus (late Cretaceous of Israel)

Hassiophis terrasanctus (late Cretaceous of Israel)

Yurlunggur camfieldensis (Late Oligo. to E. Mio. Australia)

Wonambi naracoortensis (Pleistocene of Australia;Eocene rest of world)

Dinilysia patagonica (late Cretaceous of S. America)



Living

snakes





Pachyrhachis problematicus (Late Cretaceous of Israel)



Pachyrhachis , another interpretation

Dinilysia



yFrom late Cretaceous (± 70 my BP)

of South AmericaA primitive snake

No recurved maxillary teeth ?

Maxillaries not moveable

Supratemporals in lizard-

like position

Palatines and pterygoidsnot moveable, but

toothed

dorsal view

ventral view

Late Oligoceneto early



Miocene of

Australia



Yurlunggur camfieldensis (E Miocene of Queensland Australia

SynapomorphyIf a shared homologue is found in (or inferred to occur in) a

common ancestor, and if it is thought to have originated in that




ancestor and not in an earlier ancestor, then the shared

homologue is termed a synapomorphy.

According to cladistics, only synapomorphic characters can be

used in phylogenetic reconstruction.

Symplesiomorphy

If the shared homologue is found in (or inferred to occur in) the

common ancestor of the subject taxon, but is thought to have

originated as an evolutionary novelty in an earlier ancestor, then

the homologue is termed a symplesiomorphy.

According to cladistics, symplesiomorphic characters cannot be


Serpentes Scolecophidia



Alethinophidia

Macrostomata

Caenophidia

Colubroidia

Living

snakefamilies

S l hid G l



Scolecophidea: Gr. s colec +

ophidea = worm + snake

Alethinophidea: Gr. aleth +

ophidea = real or authentic +

snake .



ScolecophidiaBlind or Worm Snakes

Includes three families:

Anomalepididae

Leptotyphlopidae

Typhlopidae



The “worm” snakes are very

specialized, and probably are not

ancestral (although they are touted

as such by some) to the

Alethinophidia (or normal snakes)

Most of the fossil snakes found do

not show any of the scolecophidianspecializations.



Typhiophis squamosus

QuadrateWorm Snake

Very specializedskull



A Scolecophidian skull

Scolecophidae





Anomochilidae

1) No teeth on premaxilla, palatines, or pterygoids.

Synapomorphies



2) Dentary and maxillary teeth short, with stout bases.

3) Ectopterygoid element reduced to a small splint within the

pterygo-maxillary ligament.

These are derived, not primitive snake characters!

So I disagree with the phylogeny in the text.Content: Two Species.- Anomochilus leonardi (Malaysia

and Sabah in Borneo) and

A. weberi (Sumatra and Kalimantan

in Borneo)

A very specialized skull





Anomochilus weberi



Aniliidae1) Angular and splenial elements of lower jaw absent.

Synapomorphies



2) Tips of hemipenial lobes dicoidal.

3) Eye reduced in size and covered by a transparent scale.

4) Posterior superficial palate strongly bilobed and turned dorsally into

orbitonasal trough.

5) Lacrimal foramen entirely within posterior wall of prefrontal.

Content: One species.- Anilius scytale (A burrowing snake that is a

specialized feeder) Feeds on elongate vertebrates, primarily caecilians,

amphisbaenians, eels, and other snakes.

Distribution: See map below



Anilius scytale



Uropeltidae

Synapomorphies



1) Hemipenis undivided (?).

2) Sulcus spermaticus unforked.

3) Premaxillary teeth absent.

4) Broadened cultriform process of basisphenoid.

5) Vomerine processes of premaxilla reduced.

6) Fovea dentis of occipital condyle reduced or absent.

Content: 2 subfamilies, 9 genera and ca 55 species.




Cylindrophis rufus

This is a lizard-like

Quadrate and

supratemporalMaxilla not loose



supratemporal

Palatines and

pterygoids not

movable



Uropeltis m. macrolepis



Boidae1) Supraorbital element present.

2) Levator anguli oris muscle lost

Synapomorphies



2) Levator anguli oris muscle lost.

Content: 3 subfamilies, ca 20 genera, and ca 74 species

Subfamilies: Boinae (9 genera, 33 species)

Pythoninae (ca 8 genera, 26 species) Southern Africa,southern Asia from India, eastward throughout the Indoaustralian

Archipeligo and Australia.

Erycinae (3 genera, 15 species) Central and northern Africa,

southern Europe, and southwestern Asia











Jaw articulation far

back.



Elongate quadrate

widens gape by moving

jaw articulation

posteriorly..



posterior





Young copperhead using wiggling tail

as a lure (Can you ID the anuran?).

Areas where snakes are not

found.



There are no colubrid snakes in

Greenland, Iceland, Ireland, New

Zealand, Tasmania, or southern SouthAmerica.



Illinois SnakesColubrine Snakes



Worm snakes

Mud snake

RacersKingsnakes

Rat snakes

Green snakes

Bull snake

Colubrine Snakes







C. a. helenae

nr Chester

C. a. vermis










C. c. flaviventris



C. c. priapus





Monroe Co.

















E. o. spiloides


























Ribbon snakes (2)Water snakes (6)

Queen snake

Crayfish snake

Brown snake

Redbelly snake

Lined snake

Earth snake

Kirtland‟s snake



























































RINGNECK SNAKES



RINGNECK SNAKES

Genus Diadophis










The Hognosed snakes of the genus Heterodon, are

known colloquially as “Puff Adders,” because they

can flatten their neck somewhat like a cobra.

There are two species in the state one that used



There are two species in the state, one that usedto be common in this area (H. platyrhinos), and

the other which is found only in very sandy areas

(H. nasicus). Both species have enlarged rear

“fangs” (see below) with which they puncture

their toad prey. Again, this is a snake that rarely

bites, so it usually can be handled with impunity.

Very few bites have been reported for either

species, and those that have indicate that the

venom is not very toxic.









Heterodon nasicus








Serpentes

Scolecophidia



Alethinophidia

Macrostomata

Caenophidia

Colubroidia

Living snakefamilies

Solenoglyphous snakes in

Illinois

Copperheads



Copperheads

Cottonmouth

Massasauga

Timber Rattlesnake









A. c. mokasen A. c.

contortrix

There are five copperhead

subspecies in the U S Only two



subspecies in the U.S. Only twoof which occur in Illinois:Agkistrodon contortrix contortrix

















Note the 9

l d h d



enlarged head

scales in the genus

Sistrurus.









Clinton Co.,

near. CarlyleLake

Used to be in Madison

Co.












Illinois Snakes

Worm snakes

Colubrine Snakes



Worm snakes

Mud snake

Racers

Kingsnakes

Rat snakes

Green snakes

Bull snake







C. a. helenae

nr Chester

C. a. vermis










C. c. flaviventris



C. c. priapus





Monroe Co.

















E. o. spiloides
























Ribbon snakes (2)

Water snakes (6)



Queen snake

Crayfish snake

Brown snake

Redbelly snake

Lined snake

Earth snake

Kirtland‟s snake



























































Venomous

snakes in



snakes in

Illinois

Serpentes

Scolecophidia



Alethinophidia

Macrostomata

Caenophidia

Colubroidia

Living snakefamilies

To change to a

solenogyphus snake

would need toshorten maxilla



Rear-fanged


and rotates on thissurface

Hognosed snakes

or



or

Puff “adders”

















There are five copperheadsubspecies in the U.S. Only twoof which occur in Illinois:A ki t d t t i t t i



Agkistrodon contortrix contortrix














Monroe Co., nr

Fults. Now gone?



Note the 9

enlarged head



g

scales in the genusSistrurus.









Clinton Co.,near. Carlyle

Lake








To change to a

solenogyphus snake

would need toshorten maxilla



Rear-fanged


and rotates on this

surface

Class ReptiliaSublass Diapsida

Infraclass Lepidosaurimorpha

Superorder Lepidosauria



(Includes Rhynchocephalians)

Order Squamata

(includes lizards, amphisbaenids, and snakes)

Suborder Serpentes or Ophidia(Incudes only snakes)



A principle adaptation in snakesis their ability to feed on large

prey. Everything we see in snakeanatomy seems pointed toward



anatomy seems pointed towardthis end. Because they cannotchew, their prey must beswallowed whole. Note the slidesbelow which shows how they dothis.



Note that cartilaginous rings surroundthe trachea so that it remains open

f i h l ti d h l ti d i



for inhalation and exhalation during

the swallowing process. Snake lungsare very elongate and internally

diverse.

ectopterygoid

supratemporal



The major changes we see in snakes when compared with lizards are

associated with large-sized food objects which must be swallowed whole.Starting anteriorly and moving posteriorly we see:

1) The two mandibles are not fused medially, but are attached by a stretchable

symphysial ligament so the mouth can be opened widely.

2) The premaxillae are fused medially and are not rigidly attached to the rostrum as

in lizards.

3) The maxillaries, palatines, and pterygoids are all movable and have teeth.



4) The teeth are longer, curved posteriorly (to embed more deeply when the prey

attempts to escape), and are on movable bones (to increase contact with prey

when in the mouth).5) The braincase is completely surrounded by bone (for isolation from the prey as it

moves down the anterior esophageal area).

6) Elongate supratemporal bones with quadrate bones attached posteriorly (for

shifting the gape farther back and increasing its size).







vomeronasal organ = Jackobson’s

symphysial

Palate

Lizards



y p yligament

Lizards

Lower jaw

Developmentally, snakes are similar toother vertebrates, but as time passesthey begin to coil and lengthen (see

next slide). During this lengtheningphase the viscera in the body cavityalso lengthens, so when snake viscera



g ,is examined it appears quite elongated,

and different from what lizard viscerawould look like (see below).

Stage 18 Stage 20 Stage 26



Trunk starts short, then

increases in length.

Somite

Snake viscera intwo parts.

Nerodia ?

anterior posteriorHeart



Snake vertebrae are only slightly different from lizardvertebrae, but with lengthening there’s a lot more of

them. Two additional processes, the zygosphene

and zygantrum have been added to stabilize the

long vertebral column dorso-ventrally. When a snaket d it k b d t l t h



extends its neck or body out a long way to reachanother purchase, the two above processes keep it

from sagging too much in the middle.







How snakes move

Lateral undulation

concertina

(See below)



sidewinding

rectilinear



Lateral undulatorylocomotion

Concertina locomotion



Sidewinding





In heavy-bodied snakes such as boas,

pythons, and vipers.



Rectilinear locomotion

superior costo-cutaneous

Ventral scale

inferior costo-cutaneous

interscutali



Gliding snake from East Indies




A considerable number of living snakes have

vestiges of hind limbs. When this character ispresent, systematists generally consider it anancestral trait, and thus, those snakes that



, ,have it as more primitive. See the slide below

for two examples of this.

Eyelash boa

pubis

ilium

femur



3 wormsnakes

Immovable

maxilla

Braincase only

partly covered

posteriorly

Teeth not

recurved

Primitive skull

Epipterygoid present

Supratemporals thin

sheets on lateral edgeparietals



Immovable

palatines &

pterygoids

mostly without

teeth

Primitive skull

roof Tegu lizard

Tupinambisnigropunctatus

Teeth on maxilla

Teeth on pterygoids

Teeth on palatines

supratemporal

Enclosed braincase

Maxilla, palatines,

and pterygoids all

movable.



supratemporal

quadraterecurved teeth

Python argus

No epipterygoid

Intramandibular

joint

Fossil snakesPachyrhachis problematicus (late Cretaceous of Israel)

Hassiophis terrasanctus (late Cretaceous of Israel)

Yurlunggur camfieldensis (Late Oligo to E Mio Australia)

Dinilysia patagonica (late Cretaceous of S. America)



Yurlunggur camfieldensis (Late Oligo. to E. Mio. Australia)

Wonambi naracoortensis (Pleistocene of Australia;Eocene rest of world)

Living

k



snakes





Pachyrhachis problematicus (Late Cretaceous of Israel)



Pachyrhachis , another interpretation

DinilysiaFrom late Cretaceous (± 70 my BP)of South America

A primitive snakeSupratemporals in lizard-

like position

dorsal view



No recurved maxillary teeth ?

Maxillaries not moveable

Palatines and pterygoidsnot moveable, buttoothed

ventral view

Late Oligoceneto earlyMiocene ofAustralia





Yurlunggur camfieldensis (E Miocene of Queensland, Australia

Synapomorphy

If a shared homologue is found in (or inferred to occur in) a


ancestor and not in an earlier ancestor, then the shared

homologue is termed a synapomorphy.

According to cladistics, only synapomorphic characters can be


S l i h



Symplesiomorphy

If the shared homologue is found in (or inferred to occur in) the

common ancestor of the subject taxon, but is thought to have

originated as an evolutionary novelty in an earlier ancestor, then

the homologue is termed a symplesiomorphy.

According to cladistics, symplesiomorphic characters cannot be


Serpentes Scolecophidia

AlethinophidiaLiving

k



Macrostomata

Caenophidia

Colubroidia

snake

families

Scolecophidea: Gr. s colec +

ophidea = worm + snake



Alethinophidea: Gr. aleth +

ophidea = real or authentic +

snake .

ScolecophidiaBlind or Worm Snakes

Includes three families:



AnomalepididaeLeptotyphlopidae

Typhlopidae

The “worm” snakes are very

specialized, and probably are not

ancestral (although they are touted

as such by some) to the



y

Alethinophidia (or normal snakes)Most of the fossil snakes found do

not show any of the scolecophidian

specializations.



Typhiophis squamosus

Quadrate

Worm SnakeVery specializedskull



A Scolecophidian skull

Scolecophidae





Anomochilidae

1) No teeth on premaxilla, palatines, or pterygoids.

2) Dentary and maxillary teeth short, with stout bases.

3) Ectopterygoid element reduced to a small splint within the

pterygo-maxillary ligament.

These are derived, not primitive snake characters!

So I disagree with the phylogeny in the text

Synapomorphies



So I disagree with the phylogeny in the text.

Content: Two Species.- Anomochilus leonardi (Malaysiaand Sabah in Borneo) and

A. weberi (Sumatra and Kalimantan

in Borneo)

A very specialized skull





Anomochilus weberi



Aniliidae1) Angular and splenial elements of lower jaw absent.

2) Tips of hemipenial lobes dicoidal.

3) Eye reduced in size and covered by a transparent scale.

4) Posterior superficial palate strongly bilobed and turned dorsally into

orbitonasal trough.

5) Lacrimal foramen entirely within posterior wall of prefrontal.

Synapomorphies



Content: One species.- Anilius scytale (A burrowing snake that is a

specialized feeder) Feeds on elongate vertebrates, primarily caecilians,

amphisbaenians, eels, and other snakes.




Anilius scytale



Uropeltidae1) Hemipenis undivided (?).

2) Sulcus spermaticus unforked.

3) Premaxillary teeth absent.

4) Broadened cultriform process of basisphenoid.

5) Vomerine processes of premaxilla reduced.

6) F d ti f i it l d l d d b t

Synapomorphies



6) Fovea dentis of occipital condyle reduced or absent.

Content: 2 subfamilies, 9 genera and ca 55 species.




Cylindrophis rufus

This is a lizard-like

Quadrate and

supratemporalMaxilla not loose

Palatines and

pterygoids not

movable





Uropeltis m. macrolepis



Boidae1) Supraorbital element present.

2) Levator anguli oris muscle lost.

Content: 3 subfamilies, ca 20 genera, and ca 74 species

Subfamilies: Boinae (9 genera, 33 species)

Pythoninae (ca 8 genera, 26 species) Southern Africa,

Synapomorphies



y g p

southern Asia from India, eastward throughout the Indoaustralian

Archipeligo and Australia.

Erycinae (3 genera, 15 species) Central and northern Africa,

southern Europe, and southwestern Asia











Elongate quadrate

Jaw articulation far

back.



Elongate quadrate

widens gape by moving jaw articulation

posteriorly..



posterior





Young copperhead using wiggling tail

as a lure (Can you ID the anuran?).

There are no colubrid snakes in

Greenland, Iceland, Ireland, New

Zealand, Tasmania, or southern South

Areas where snakes are notfound.



America.



Illinois Snakes

Worm snakesMud snake

Racers

Colubrine Snakes



Kingsnakes

Rat snakes

Green snakes

Bull snake





C. a. vermis



C. a. helenae

nr Chester










C. c. flaviventris



C. c. priapus





Monroe Co.

















E. o. spiloides
























Ribbon snakes (2)

Water snakes (6)

Queen snake

Crayfish snake



Brown snake

Redbelly snake

Lined snake

Earth snake

Kirtland‟s snake



























































RINGNECK SNAKES

Genus Diadophis












The Hognosed snakes of the genus Heterodon, areknown colloquially as “Puff Adders,” because they

can flatten their neck somewhat like a cobra.

There are two species in the state, one that used

to be common in this area (H. platyrhinos), andthe other which is found only in very sandy areas

(H. nasicus). Both species have enlarged rear

“fangs” (see below) with which they puncture

their toad prey Again this is a snake that rarely



their toad prey. Again, this is a snake that rarelybites, so it usually can be handled with impunity.

Very few bites have been reported for either

species, and those that have indicate that the

venom is not very toxic.









Heterodon nasicus










Coral snakes are proteroglyphous (front-fanged



Coral snakes are notfound near Illinois, but

as Milk snakes are oftenbanded with red, sothey have been

f d i h d



confused with andconsidered coral snakes

by some.



Texas Coral Snake: Micrurus fulvius tener





Rear-fanged snakes

(Opisthoglyphous)



Rattlesnake striking. Note mouth is wide open



Fangs are pointing almost straight at prey

canal



Proteroglyphous

snake

Fixed-fanged snake

(maxilla does not move)



African Spitting Cobra

Naja nigricollis





Mozambique spitting cobra: Naja ??









Australian Death „adder‟: Acanthophis antarcticus



Australian Tiger-Snake: Notechis niger



Pelagic Sea Snake: Pelamis platurus





Azemiops feae

The most primitve living viper



The pit vipers are different from the true vipers

in having a heat (infrared) sensitive pit (or hole)

between the eye and the nostril (see slide

below). The group occurs in both the old and

new worlds (see map below). Old world genera

have been considered more ancestral than New

World because they are still oviparous, whereas

all New World members (except theb shmaster) are i iparo s There are fe



( pbushmaster) are viviparous. There are few

other additional ancestral features to separate

the two groups.



Bushmaster mouth: long fangs!



Solenoglyphous

snake



Crotalus ruber ruber

Red Diamond Rattlesnake



30 Rattlesnake SpeciesFrom the New World (North, Central and South America)

2 genera:

Crotalus and Sistrurus

plus

51



subspecies (if you recognize)

For a total of 81 taxa in all



Ridge-nosed Rattlesnake: Crotalus willardi



Eastern Diamondback rattlesnake: Crotalus adamanteus





Western diamondback rattlesnake: Crotalus atrox



Rock Rattlesnake: Crotalus lepidus



The Bushmaster is the onlyNew World pit viper

(Crotalinae) that lays eggs.

All others (rattlesnakes,

copperheads, cottonmouths),

are viviparous However,



are viviparous. However,most Old World pit vipers

still lay eggs.



Bushmaster mouth: long fangs!



Bushmaster: Lachesis muta ssp

The fangs of venomous snakesare never bare as shone in

many commercialpublications. They are covered

with a thin epithelial

membrane which is a part of



membrane which is a part of

the oral cavity.

















Rhinoceros viper: Bitis nasicornus

from Africa



Horned viper: Bitis nasicornus



The Burrowing Asps: genusAtractaspis, appears to be a groupof solenoglyphus snakes not very

closely related to the true vipers.They don’t have a viper -like head,and they don’t look very viper -like.

They have very elongate venomglands which apparently are not



glands which apparently are notconsidered homologous toDuvernoy’s glands.



Burrowing asps: Atractaspis

Family Atractaspidae



Burrowing asps: genusAtractaspis



Mole viper: Atractaspis engaddensis



Burrowing asp: Atractaspis microlepidota

Heat sensitive organsin snakes











Documents

016 Fanged + Venomous Snakes