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Natural Sciences 360 Legacy of Life Lecture 13 Dr. Stuart S. Sumida

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Natural Sciences 360 Legacy of Life Lecture 13 Dr. Stuart S. Sumida. Living Amphibians – the Environmental Monitors REPTILES AND THEIR RELATIVES. Living Frogs and Salamanders (Batrachia) – the environmental monitors. Possible causes of amphibian declines include:

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Natural Sciences 360

Legacy of Life

Lecture 13

Dr. Stuart S. Sumida

Living Amphibians – the Environmental Monitors

REPTILES AND THEIR RELATIVES

slide3

Possible causes of amphibian declines include:

  • Changes in climate - acid rain, ultraviolet radiation, drought, ozone layer depletion, etc.
  • Loss of wetlands
  • Invasive predators (such as trout and bullfrogs)
  • Disease (bacteria, viruses, fungus) or parasites
  • Pollution - pesticides, fertilizers, heavy metals, etc.
slide5

What we used to think...

Mammals Birds

“Mammal-like Reptiles”

PRIMITIVE

REPTILES

Amphibians

slide6

Um.........NO.

Mammals Birds

“Mammal-like Reptiles”

PRIMITIVE

REPTILES

Amphibians

slide7

Panderichthyid Most Reptilia

Sarcoptrygians Amphibians Diadectomorpha Synapsida (including Aves)

slide8

Panderichthyid Most Synapsida Reptilia

Sarcoptrygians Amphibians Diadectomorpha (Mammals) (including Aves)

AMNIOTA (FOR SURE)

slide9

Panderichthyid Most Synapsida Reptilia

Sarcoptrygians Amphibians Diadectomorpha (Mammals) (including Aves)

AMNIOTA (FOR SURE)

Amniota?

slide10

Panderichthyid Most Synapsida Reptilia

Sarcoptrygians Amphibians Diadectomorpha (Mammals) (including Aves)

AMNIOTA (FOR SURE)

Amniota?

TETRAPODA

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Panderichthyid Most Synapsida Reptilia

Sarcoptrygians Amphibians Diadectomorpha (Mammals) (including Aves)

AMNIOTA (FOR SURE)

Amniota?

slide12

Amniotes: have four embryonic structures that reside outside the embryo to help it survive:

    • Amnion
    • Yolk sac
    • Chorion
    • Allantois
slide13

Other Sarcopterygians

Panderichthyids

Ichthyostegalia

Dissorophoids

Lissamphibia

Anthracosauria

Seymouriamorpha

Diadectomorpha

Amniota

Sarcopterygii

Tetrapoda

The road to reptiles

slide14

Diadectomorpha:

  • No intertemporal bone like other amniotes
  • Very terrestrially adapted
slide15

“Amphibia” Amniota

Seymouriamorpha Diadectomorpha Synapsida Parareptilia Captorhinidae Diapsida Archosauromorpha

Reptilia

Amniota

slide16

Amniotes: have four embryonic structures that reside outside the embryo to help it survive:

    • Amnion
    • Yolk sac
    • Chorion
    • Allantois
slide17

“Amphibia” Amniota

Seymouriamorpha Diadectomorpha Synapsida Parareptilia Captorhinidae Diapsida Archosauromorpha

Reptilia

Amniota

slide21

“Amphibia” Amniota

Seymouriamorpha Diadectomorpha Synapsida Parareptilia Captorhinidae Diapsida Archosauromorpha

Reptilia

Amniota

slide22

PARAREPTILIA Includes:

    • Mesosauria
    • Bolosauridae
    • Procolophonia
    • Paraiesauria
slide25

Eudibamuscursoris

The earliest known bipedal vertebrate

From the Early Permian (~280 million years old) of central Germany.

slide31

“Amphibia” Amniota

Seymouriamorpha Diadectomorpha Synapsida Parareptilia Captorhinidae Diapsida Archosauromorpha

Reptilia

Amniota

slide33

“Amphibia” Amniota

Seymouriamorpha Diadectomorpha Synapsida Parareptilia Captorhinidae Diapsida Archosauromorpha

Reptilia

Amniota

slide34

Basal Diapsid: Petrolacosaurus

Note: TWO holes (fenestrae) on side of skull

Known back to Late Pennsylvanian

slide35

Diapsida includes:

    • Many extinct forms
    • Squamata
    • Archosauromorpha
  • Squamata includes living lizards and snakes.
slide36

Squamata:

    • Lizards (including limbless lizards)
    • Snakes
slide51

“Amphibia” Amniota

Seymouriamorpha Diadectomorpha Synapsida Parareptilia Captorhinidae Diapsida Archosauromorpha

Reptilia

Amniota

slide52

Archosauromorpha Includes:

  • Crocodilians
  • Numerous other extinct groups
  • Pterosauria
  • Dinosaurs
  • Birds
slide54

Archosauria includes Crocodilians, Pterosaurs, Dinosaurs (including Birds), and a variety of other extinct groups.

slide55

Crocodylomorpha: Still extant - known from the Middle Triassic to present day.

  • In brief:
  • Low, flat skull.
  • All but a few marine forms have 24 vertebrae cranial to the hip and 2 sacral vertebrae for attaching to the hip.
slide58

Alligator mississippiensis

Note presence of bony “scutes” or osteoderms in skin.

slide60

Crocodilians are capable of a variety of types of locomotion: swimming; slow-sprawling walk; a moderate speed “high walk;” and even galloping in some young or smaller ones.

slide61

Nile crocodile

Some crocodilians have extremely complex social behavior and communication.

slide63

The Diversity of Extinct Marine Reptiles

Examples of Convergent Evolution

slide65

Mesozoic marine reptiles are not dinosaurs.

  • All are a variety of diapsid reptilies.
  • We will survey them from approximately more primitive diapsid derivatives to somewhat more derived diapsid derivatives.
slide66

“Amphibia” Amniota

Seymouriamorpha Diadectomorpha Synapsida Parareptilia Captorhinidae Diapsida Archosauromorpha

Reptilia

Amniota

slide67

Reall the Basal Diapsid: Petrolacosaurus

Note: TWO holes (fenestrae) on side of skull

slide68

Petrolacosaurus

A primitive diapsid reptile

Fenestrae color-coded green here

slide69

Mesozoic Marine Reptiles:

Diapsida

Sauropterygia

Placodontia

Nothosauria

Pleisosauria

Ichthyosauria

Squamata

Mosasauria

slide70

Diapsida

Sauropterygia

Placodontia

Nothosauria

Pleisosauria

Ichthyosauria

Squamata

Mosasauria

slide71

Diapsida

Sauropterygia

Placodontia

Nothosauria

Pleisosauria

Ichthyosauria

Squamata

Mosasauria

slide72

Placodonts were fusiform but large animals that lived in the Middle to Upper Triassic.

Similar to manatees in the niche they filled.

slide73

Placodus gigas

(type)

Large teeth and palatal teeth indicate that it probably ate molluscs.

slide76

Diapsida

Sauropterygia

Placodontia

Nothosauria

Pleisosauria

Ichthyosauria

Squamata

Mosasauria

slide77

Nothosauria:

  • Middle to Upper Triassic
  • Very short snout end of skull, relatively longer caudal (postorbital) region of skull.
  • Large, procumbent rostral (frontmost) teeth, often developed as fangs.
slide78

Often have elongate necks.

Humerus and femur longer than more distal elements.

slide79

Nothosaurus mirabilus

Reconstruction of skull and jaw musculature

slide81

Diapsida

Sauropterygia

Placodontia

Nothosauria

Pleisosauria

Ichthyosauria

Squamata

Mosasauria

slide82

Plesiosauria:

  • Much larger than nothosaurs.
  • Forelimbs and hindlimbs look much more similar.
  • EXTREMELY elongate necks, even more so than nothosaurs.
  • Note that despite paddle-like nature of hand (manus) and foot (pes), each still retains only five digits.
slide83

Plesiosaurs have

HYPERPHALANGY: additional segments to the digits of the fingers and toes.

slide84

Cryptoclidus (plesiosaurid)

Plesiosaurs have HYPERPHALANGY: additional segments to the digits of the fingers and toes.

Hydrothecrosaurus

(elasmosaurid)

slide85

Cryptoclidus (plesiosaurid)

Hydrothecrosaurus

(elasmosaurid)

slide86

Cryptocleidus

(about 30 meters long)

slide87

Liopleurodon

(about 80 feet long)

slide88

Diapsida

Sauropterygia

Placodontia

Nothosauria

Pleisosauria

Ichthyosauria

Squamata

Mosasauria

slide89

Ichthyosauria

  • Triassic to Cretaceous – However, more extreme members of group lived in Jurassic and Cretaceous.
  • Most highly specialized of marine reptiles. They converged on fish and cetacean forms.
  • Highly modified skull: large orbit, reduced cheek region, elongate snout.
  • Limbs modified into flippers; hyperdactyly.
  • Viviperous: gave birth to live young.
slide90

Mixosaurus reconstruction

  • Most highly specialized of marine reptiles. They converged on fish and cetacean forms.
slide91

Highly modified skull: large orbit, reduced cheek region, elongate snout.

Most highly specialized of marine reptiles. They converged on fish and cetacean forms.

Ichthyosaurus

slide95

Diapsida

Sauropterygia

Placodontia

Nothosauria

Pleisosauria

Ichthyosauria

Squamata

Mosasauria

slide96

Mosasaurs:

  • Not closely related to Sauropterygians or Ichthyosaurs.
  • Actually highly derived members of the lizard family Varanidae.
  • Late Cretaceous ecological replacements for Ichthyosauria.
slide97

Mosasaur Anatomy:

  • Extremely elongate tail, body narrower and slimmer than other groups surveyed. (Probably swam in a more eel-like fashion.)
  • However, neck, remains relatively short.
  • Limbs modified for steering as opposed to propulsion.
  • Have HYPER PHALANGY, but not hyerdactyly.
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