Lizards & Snakes & Tuatara Part II
description
Transcript of Lizards & Snakes & Tuatara Part II
![Page 1: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/1.jpg)
Lizards & Snakes & Tuatara Part II
VERTEBRATE ZOOLOGY (VZ Lecture18 – Spring 2012 Althoff - reference PJH Chapters 13 &
14)
copperhead
![Page 2: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/2.jpg)
• Squamata (order) lineage ________ (suborder)
• Long-standing hypothesis: that snakes evolved from a subterranean lineage of lizards with greatly reduced eyes
followed by more recent extant species of surface-dwelling snakes where eyes “redeveloped” after nearly disappearing in earlier forms
• With recent fossil discoveries, there is still much uncertainty regarding the evolutionary history of snakes
Snakes
![Page 3: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/3.jpg)
• 3 infraorders: ScoleocophidiaAlethinophidiaColubroidea
• Out of ~2,900 species of snakes, most (~2,350) from the infraorder Colubroidea….
1,800+ in the family ______________ alone --sp. found on all continents
--many have venom to kill prey but lack specialized hollow teeth for injecting venom
Extant Snakes
eastern milk snake
![Page 4: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/4.jpg)
• Some species have remnants of pelvic girdle, others no trace of pelvic girdle
• General body form types: (A) slow-moving constrictors(B) longer-faster: visually-oriented snakes (C) arboreal—longer yet (D) small, rounded head with little distinction between head and tail, reduced eyesize (E) large head and stout body—to accommodate large prey (F) flattened tail (side-to-side) & valves that close the nostrils…for diving
Extant Snakes
![Page 5: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/5.jpg)
Fig. 13-4, p338 PJH
A
B
![Page 6: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/6.jpg)
Fig. 13-4, p338 PJH
C
E F
![Page 7: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/7.jpg)
• ____________________ important in most snakes: forked tongue, with widely separated tips than can move independently a) “collect” molecules from air or ground b) transfer those molecules from tongue, whenretracted, to the vomeronasal organs
• _________________________: typical of nonconstrictors that can move quickly, frequently raising the head to look around. Many arboreal species have enlarged eyes…and overall longer body length enables them to go to tips of branches to pursue prey
Detection of Prey
![Page 8: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/8.jpg)
parrot snake - Costa Rica
worm snake - Tennessee
BURROWING
ARBOREAL
![Page 9: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/9.jpg)
grass snake
Forked tongue
tongue
vomero-nasal organ
nerve brain
A
B
AB
_________________
_________________
![Page 10: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/10.jpg)
• Foraging behaviors very diverse among squamates (i.e., snakes and lizards)….
• Most feeding specializations are related to changes in the structure of the skull and jaws.
• Most of these specializations associated with a) loss of _____________________ b) loss of _________________ bone that
formed that lower temporal bar
Foraging & Feeding
![Page 11: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/11.jpg)
Fig. 13-6, p343 PJH
![Page 12: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/12.jpg)
Lowertemporalfenestra qj
sq
j “early” form (Permian Petrolacosaurus)
![Page 13: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/13.jpg)
qj
sq
j “modern” Tuatara
![Page 14: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/14.jpg)
qj
sq
j
“modern” collared lizardjqj
sq
![Page 15: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/15.jpg)
qjj
“modern” snake = loss of upper temporal arch,not one but two places
po
q
sq
![Page 16: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/16.jpg)
• They not only had a a) loss of lower temporal bar b) loss of quadratojugal bone that formed that lower temporal barthey also had the loss of a second temporal bar which was formed by a connection ________ the postorbital and squamosal bone
• Result even more flexibility of the skull• Additional increase in flexibility achieved by flexibility
of the joints between other bones in the palate and the roof of the skull
For snakes…
![Page 17: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/17.jpg)
• Among advanced snakes, their skulls are considerably more flexible than those of lizards
• Sometimes commonly referred to as “unhinging” of the jaw, snakes do not “unhinge” their jaws. They simply have a design that allows extreme movement of the jaws.
• Their skulls have ___ links, with joints between them that permit rotation of the jaw. The “links” are paired (each side of head) and they can function independent of the opposite side “paired” link. Coupled with the pterygoquadrate ligament and the quadrato-supratemporal tie, they can have considerable sideward movement and rotation.,
For snakes…
![Page 18: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/18.jpg)
Fig. 13-7, p344 PJH
LATE
RA
L VI
EWVE
NTR
AL
VIEW
1
23
4
5
6
17
7
8
8 “________” of flexibility
![Page 19: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/19.jpg)
• Mandibles, at the front end, are joined _____ by muscles and skin…not rigid bone like for lizards. Allows extreme spread sideways and forward and backwards independently.
also for snakes…
![Page 20: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/20.jpg)
• A—without fangs (ex. African python)
• B & C—OPISTHOGLYPHOUS—fangs in the rear of the maxilla (ex.false viper) (“behind” and “knife”)
• D—SOLENOGLYPHOUS—fangs on a rotating maxilla (ex. African puff adder) (“pipe”)
• E—PROTEROGLYPHOUS—permanently erect fangs at the front of the maxilla (“first”)
3 lineages of “venom” snakes---same function, different designanother example of __________ ___________
Dentition of snakes
![Page 21: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/21.jpg)
Fig. 13-9, p346 PJH
AB
C
D E
OPISTHOGLYPHOUS
SOLENOGLYPHOUS PROTEROGLYPHOUS
![Page 22: Lizards & Snakes & Tuatara Part II](https://reader036.fdocuments.in/reader036/viewer/2022081420/56815a93550346895dc80d1b/html5/thumbnails/22.jpg)
• OPISTHOGLYPHOUS—fangs in the rear of the maxilla, _____________________________ that may conduct saliva to wound
• SOLENOGLYPHOUS—fangs on a rotating maxilla, __________. Longer fangs allows deeper penetration. Venom kills & aids digestion. Prey often allowed to ‘escape’ and tracked down when dead.
• PROTEROGLYPHOUS—permanently erect fangs at the front of the maxilla, _________________
Dentition of snakes