Unit 2: Amphibians and Reptiles
Synapsid
-Mammals -Single fenestrum behind orbit
Anapsid
-Pre-amniotes -No fenestrum
Diapsid
-Reptiles* & Birds -Two fenestrae behind orbit
External frog and salamander characteristics
1. cranial crests 2. parotid gland 3. tarsus (shank) 4. dorsolateral folds 5. femoral area (thigh) 6. toes with digital discs 7. toes without digital discs 8. tympanum
Crocodylia
An order of large reptiles that appeared 83.5 million years ago in the Late Cretaceous period. They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria. Members of the crocodilian total group, the clade Pseudosuchia, appeared about 250 million years ago in the Early Triassic period, and exhibited a wide diversity of forms during the Mesozoic era. The order Crocodilia includes the true crocodiles, the alligators and caimans and the gharials. Although the term 'crocodiles' is sometimes used to refer to all of these, a less ambiguous vernacular term for this group is 'crocodilians'.
Lamellae
thin plate like structures on feet for gripping
Spectacle
transparent scale over eye in some Squamates
Facultative parthenogenesis
'sometimes parthenogenic'; under appropriate conditions, some species are able to produce viable offspring without males
Femoral pores
emit pheromones, found on ventral side of body/on legs of some lizards
Hemipenes
paired male organ used in copulation in Squamates; many have hooks or lamallae, can be forked
Caudal Autotomy
self-amputation of tail, used in escaping predators
Nictitating membrane
transparent 3rd eyelid that covers the eye but still allows for vision in Testudines & Crocodylians
Poisonous or Venomous? THERE IS A DIFFERENCE
venomous is applied to organisms that bite (or sting) to inject their toxins, whereas the term poisonous applies to organisms that unload toxins when you eat them. This means that very few snakes are truly poisonous.
Subclass Lepidosauria
• "Scaled Lizards" • All reptiles with overlapping scales • 2 orders: Rhynchocephalia & Squamata • Order Rhynchocephalia • Tuataras and relatives • 1 sp., Sphenodon punctatus • New Zealand • Characteristics: • Medium-sized, lizard-like reptiles • Pronounced, photoreceptive parietal eye aka 'third eye' • No external ears • Spiny crest along back • 2 rows of teeth on upper jaw, 1 row on lower • 1st confirmed successful wild breeding in 200 yrs was in 2008 - 9 • Sexual dimorphism • Temperature-dependent sex determination [higher temp=male] • Leathery eggs
Euryapsids
-Extinct! -A subclass of reptiles that have a single, upper temporal opening behind the eye. The subclass includes the Plesiosauroidea, Nothosauria, and Placodontidae.
Archosauromorpha
-taxonomic infraclass within the subclass Diapsida — the dinosaurs, pterosaurs, and the modern crocodiles. -major group of diapsids, differentiated from the other diapsids by the presence of single openings in each side of the skull, in front of the eyes (antorbital fenestrae). Continues the tetrapod trend of the reduction of skull bones by the fusion of multiple bones and the opening of fenestrae in the skull. Helps to lighten the skull, provide more room for muscles and other tissues, and allows more skull flexibility (kinesis) when eating. Also include another opening in the lower jaw (mandibular fenestra), a high narrow skull with a pointed snout, teeth set in sockets (called thecodont tooth implantation), and a modified ankle joint. -The ancestral archosaurs probably originated some 250 million years or so ago, in the late Permian period. Their descendants dominated the realm of the terrestrial vertebrates for a majority of the Mesozoic Era. Only the birds and crocodilians exist to provide a glimpse into the past glory of archosaurs.
Reptilia—(including turtles, lizards, snakes, crocodilians and birds)
4 Orders, >10,000 sp.; HIGHLY ENDANGERED • Order Testudines • Order Rhynchocephalia • Order Squamata • Order Crocodylia • Characteristics: • Have 4 limbs or descended from 4-limbed ancestors • Amniotes; Diapsida • Most oviparous, some viviparous • Eggs laid on land • No aquatic larvae/metamorphosis • Ectothermic • Breathe through lungs primarily • Most species extremely long-lived • Epidermis thin, covered in scales, scutes or osteoderms • Undergo ecdysis
Testudine Morphology
Carapace (Outer layer): keratinous scutes of the epidermis-upper half -covered by 5 unpaired vertebral scutes, bordered by 4 pairs of pleural scutes and 10-12 pairs of marginal scutes (up to 38 separate scutes) -Notice that the keratinous scutes do not coincide in number or position with the underlying bones-38 scutes vs. 59 bones Plastrons (Outer layer): keratinous scutes of the epidermis-lower half-covered by a series of 6 pairs of scutes (12 individual scutes) -Notice that the keratinous scutes do not coincide in number or position with the underlying bones-12 scutes vs. 9 bones
Frog Skeleton
Has a vertebral column consisting of only nine vertebrae and a urostyle
Lepidosauromorpha
Largest group of non-avian sauropsids - with ~10,100 species • Including ~ 6,500 lizards, ~3,600 snakes, 1 tuatara • Two groups -ECTOTHERMS (and so are testudines and most fishes) • They rely on external sources of heat to raise their body temp (ectothermy) • Ultimately gain heat from the sun (heliothermy) via: - Direct - Reflected - Conduction - Convection • Lose heat though - Conduction - Convection - Evaporation - Breathing • Physiological processes (e.g., vasodilation) can speed up heating or slow down coolingdiapsids (many derived lepidosaurs have modified the "textbook" diapsid condition) • The following characters define the group: - 1. Bodies are covered in keratinous scales (derived from the epidermis) and are relatively impermeable to water• Outer layer of epidermis is shed periodically as growth occurs (cyclical shedding)• Growth is also determinate (grow ceases at a certain size) (vs. indeterminate as in testudines and some other groups of tetrapods) - 2. Transverse cloacal slit (vs. vertical slit in other "reptilian" groups) - 3. Internal fertilization but achieved via different means in the group• No copulatory organ in Tuatara• Paired hemipenes (pl.; hemipenis sing.) in squamates
Squamata
Massive group with ~10,100 species • Commonly referred to as snakes and lizards• Incredible diversity of body shapes, body sizes - reflects the diversity of life histories in this group • The phylogenetic relationships amongst the groups of squamates are highly debated - • There are currently 42 families of "lizards" and 24 families of snakes (Serpentes) Squamate skulls: -Modified diapsid condition • All squamates lack the temporal bar () , which forms the ventral border of the lower temporal fenestra (*) • This bar is formed by the jugal(purple) bone and the quadrate(pink) bone in the tuatara and stem group lepidosaurs - The temporal bar is absent in all squamates because the jugal is reduced in size or absent (as in some snakes)
Snake head shape
Non-venomous snakes have a rounded head, venomous snakes have a more triangular-shaped head. The shape of a venomous snake's head may deter predators. However, some non-venomous snakes can mimic the triangular shape of non-venomous snakes by flattening their heads. This can help them appear more dangerous to potential predators.
Copperhead
Scientific name: Agkistrodon contortrix Order: Squamata Suborder: Serpentes Family: Viperidae (Vipers and Pitvipers) Genus: Agkistrodon -Species Distribution in Texas: Three subspecies based on color pattern and distribution occur throughout Texas except the Panhandle. -Family Distribution: Worldwide except Antarctica and Arctic regions. -Venomous, with a rotating fang apparatus that allows long fangs that are erected when biting and fold against the palate when mouth is closed. Most have robust bodies and distinctly triangular heads. Infrared receptors ("pits") occur in the subfamily crotalinae, the pitvipers. The left lung is usually absent or reduced when present.
American Alligator
Scientific name: Alligator mississippiensis Order: Crocodylia (Crocodiles and Alligators) Family: Alligatoridae (Alligators and Caimans) Genus: Alligator -Species Distribution in Texas: East Texas and Texas Gulf Coast to the Rio Grande. Interestingly, the species has never been found in Mexico. -Family Distribution: Southern USA, South America, and one species in China. The Chinese Alligator is the most critically endangered crocodilian in the world. -Broad snout, teeth of the lower jaw fit into pits inside the upper jaw. Like all crocodylia, these have osteoderms in the skin, an external tympanum, a longitudinal opening for the cloaca, and a functionally four-chambered heart. Nostrils dorsally located at tip of snout with valves to shut them while diving; secondary palate separates buccal cavity and nasal passages, webbed feet, keeled tail. Have ability to adjust peripheral and core blood flow in response to needs of diving and thermoregulation. Temperature-dependent sex determination.
Tiger Salamander
Scientific name: Ambystoma tigrinum Order: Caudata Family: Ambystomatidae Genus: Ambystoma -Species Distribution in Texas: Western subspecies, A. t. mavortium Barred Tiger Salamander occurs from the panhandle south to Big Bend and in Rio Grande Valley; Eastern Tiger Salamander A. t. tigrnium can be found in east Texas. -The systematics of tiger salamanders is complex; eastern and western subspecies and races occur in most of eastern and western USA and southern Canada. -Family Distribution: North America to the southern rim of the Mexican Plateau. -Heavy-bodied, heavy-tailed salamanders with 4 well-developed limbs. Most adult ambystomatids lack gills and gill slits and do have eyelids. Some paedomorphic forms like the Mexican Axolotl retain larval characteristics as adults. All species have costal grooves and well-developed lungs. Fertilization is internal.
Green Anole
Scientific name: Anolis carolinensis Order: Squamata Clade: Iguania Suborder: Lacertilia Lizards Family: Dacyloidae Genus: Anolis Clade Iguania Family Dactyloidae: -1 genus; >450 species. -Species Distribution in Texas: Green anoles occur in the eastern half of Texas -Family Distribution: Southeastern USA through Central America and West Indies almost to tip of South America -Extremely speciose group of primarily arboreal lizards. Relatively small lizards (25 - 120 mm snout-vent length) with morphologies adapted for climbing. Have pleurodont teeth, which distinguishes them from agamids and chamaeleons. Several synapomorphies diagnose the family, including endolymphatic sacs penetrating the nuchal musculature; and strongly bicapitate, bisulcate hemipenes. Anolis, (largest and most diverse reptile genus ~ 420 species), has posterior extension of the dentary, a reduced angular, the presence of subdigital lamellae bearing setae (toe pads similar to but less developed than that of gekkos), and reticular lingual papillae (= netlike arrangement of bumps on tongue). Far posterior extension of dentary gives appearance of triangular shaped head. External ears. Toepads expanded.
Spiny Softshell
Scientific name: Apalone spinifera Order: Testudines Family: Trionychidae (Softshell turtles) Genus: Apalone -Species Distribution in Texas: Eastern 2/3 of Texas, as well as Pecos and Rio Grande River drainages in West Texas -Family Distribution: North America, Africa, Southeast Asia, and the Indo-Australian Archipelago. -Trionychidae contains about 25 species with 12 genera. All species are aquatic but bask near water. The carapace of these turtles lacks scutes and is covered instead with a leathery skin. Superficially, can be distinguished by their dorsoventral compression, leathery shells, and elongate snout. Much of the carapacial skeleton is lost, resulting in ribs with free ends. Numerous characters diagnose the Trionychidae, including lack of articulation between the centra of the last cervical and first thoracic vertebrae, claws present on only the medial three digits, and fleshy lips covering the usual keratin beak. These specialized aquatic turtles are able to absorb significant amounts of oxygen from the water through the skin covering the carapace and their buccal cavity.
Dwarf Salamander
Scientific name: Eurycea quadridigitada Order: Caudata Family: Plethodontidae Genus: Eurycea -Lungless salamanders -Species Distribution in Texas: East Texas Family Distribution: Southern Canada to Southwestern Brazil. Oddly, a few forms are found in Mediterranean Europe and Korea. -Small (generally less than 60 mm in SVL); very slender body shape; possess distinct narrow grooves between each nostril and the upper lip; males often have protuberances on the upper lip associated with the nasolabial grooves and a mental gland located beneath the mouth; costal grooves are pronounced; generally have four fingers and five toes; toes are widely separated; aquatic and terrestrial; lungless. -Fertilization is internal. Plethodontids have elaborate mating rituals and employ chemosensory stimulants during courtship.
Texas Map Turtle (Endemic to Texas)
Scientific name: Graptemys versa Order: Testudines Family: Emydidae (Pond Turtles) Genus: Graptemys -Species Distribution in Texas: The Texas Map Turtle is Endemic to the Edwards Plateau region of Central Texas. -Family Distribution: Europe to the Ural Mountains and North America southward to Eastern Brazil, with a disjunct species in eastern Argentina. Largest and most diverse turtle family with 53 species in 10 genera distributed throughout North America, northern South America, Europe, northwestern Africa, and Asia. Primarily freshwater species, though some species inhabit brackish waters (for example the Diamondback Terrapin, Malaclemmys terrapin) or are terrestrial, such as Box Turtles. Variable size (11 cm to 60 cm) carapace length. Coloration is also quite variable. The family does not have a distinguishing suite of superficial characters. In some species, the carapace is domed, while most have a low-arching carapace. The plastron is hinged and movable in some, while fixed in others. Unique skeletal features are few
Mediterranean House Gecko
Scientific name: Hemidactylus turcicus Order: Squamata Clade: Gekkota Suborder: Lacertilia Lizards Family: Gekkonidae Genus: Hemidactylus -Species Distribution in Texas: Exotic, occurs in most of the state. -Family Distribution: Contains 1300+ species distributed world-wide in warm latitudes. -Nocturnal, insectivorous, lizards with vertical pupils, and a transparent scale over the eye called a spectacle (no eyelids). The skin is soft with sparse horny tubercles. The toes usually have transverse rows of hooked lamellae that permit adhesion to smooth surfaces. The tail is used as a fat store, and is capable of autotomy. External ears. Caudal autotomy is common with fracture planes in each caudal vertebra.
Gulf Coast Toad
Scientific name: Incilius nebulifer Order: Anura Family: Bufonidae (True Toads, Harlequin Toads and relatives) Genus: Incilius -Species Distribution in Texas: East and South Texas to the Trans-Pecos. Not in Panhandle or West Texas. -Family Distribution: Worldwide except Antarctica and Australia. But the Cane Toad, B. marinus, which is native to extreme S. Texas to central Amazon and southeastern Peru lives in Australia. The Cane Toad may be the most abundant amphibian in the world because it was introduced to Australia and throughout the Pacific and is a harmful invasive species. -Skin is dry and warty; body is squat and plump; parotoid glands are very distinct and located behind the eyes; forelimbs are shortened; hindlimbs are used for walking or hopping; skull highly ossified (usually skin is ossified to the skull); teeth absent from upper and lower jaws; 2 rounded tubercles present on legs
Southern Leopard Frog
Scientific name: Lithobates sphenocephalus Order: Anura Family: Lithobates (True Frogs) Genus: Lithobates -Species Distribution in Texas: eastern half of Texas -Family Distribution: Worldwide except for southern South America and most of Australia -Ranids possess long legs with pointed toes, a narrow waist, smooth skin, and toes joined by webbing; typically have dorsolateral folds; upper jaw is toothed; tongue bicornuate behind. Most ranids are medium to large species; the Goliath Frog from West Africa is the largest frog in the world. Many species are typical pond breeders.
Alligator Snapping Turtle
Scientific name: Macrochelys temminckii Order: Testudines Family: Chelydridae (Snapping turtles) Genus: Macrochelys -Species Distribution in Texas: East Texas. The only other member of this family is the Snapping Turtle, Chelydra serpentina. It is a widespread species and occurs throughout Texas. -Family Distribution: southern 2/3 of North America east of the Rocky Mountains, parts of Mexico and Central America, and southward into Ecuador.
Texas Coral Snake
Scientific name: Micrurus tener Order: Squamata Suborder: Serpentes Family: Elapidae (Cobras, Kraits, Coral Snakes and allies) Genus: Micrurus -Distribution in Texas: The southeastern half of Texas, not in far western Texas, Panhandle, nor high plains areas. -Family Distribution: Southern North America to southern South America, Africa, southern Asia, Australia -Venomous with erect fangs. The familiar cobras, coral snakes, are typical representatives. Left lung is reduced or absent. Ventral scales transversely elongated.
Slender Glass Lizard
Scientific name: Ophiosaurus attenuatus Order: Squamata Clade: Anguimorpha Suborder: Lacertilia Lizards Family: Anguidae (Alligator lizards, Galliwasps, Glass Lizards, and allies) Genus: Ophiosaurus -Species Distribution in Texas: Eastern half of Texas -Family Distribution: Americas, Europe, Southwest Asia, southern Asia Species of anguids occur in xeric and tropical habitats. These include the legless lizards and limbs are absent and reduced in many forms. External ears. They have a lateral skin fold along the body. Osteoderms underlie the ventral scales. Rectangular scales make the skin appear armored. Several species of Anguidae are quite small and limbless, others are limbless but rather long, while still others (mostly gerrhonotines) have strong but short limbs and relatively large triangular heads with powerful jaws. Anguids range in size from less than 10 cm up to about 1-1.5 m.
Texas Ratsnake
Scientific name: Pantherophis obsoleta Order: Squamata Suborder: Serpentes Family: Colubridae (Colubrids) Genus: Pantherophis -The taxonomy of this cosmopolitan group is convoluted and unresolved. -Species Distribution in Texas: Eastern 2/3 of Texas -Family Distribution: Worldwide except Antarctica and the Arctic -The most structurally diverse group of snakes, containing 2/3 of all snake species. Lacking limbs, lacking moveable eyelids, lacking external ears. Ventral scales transversely elongated. Left lung greatly reduced or absent.
Texas Horned Lizard
Scientific name: Phrynosoma cornutum Order: Squamata Clade: Iguania Suborder:Lacertilia Lizards Family: Phrynosomatidae Genus: Phrynosoma Clade Iguania Family Phrynosomatidae: -9 genera with 163 species including Horned lizards, spiny lizards, earless lizards, and others -Species Distribution in Texas: Previously state-wide, but now rare East of Interstate Highway 35. Populations of our state reptile have declined and disappeared presumably due to a combination of factors: imported red fire ants, which they do not eat and which displace native ants; expanding agriculture; expanding urbanization. -Family Distribution: Southern half of North America to western Panama -Relatively small (most < 10 cm snout-vent length) lizards, and represent a diversity of forms. Have pleurodont teeth, many skeletal synapomorphies (e.g. absence of pterygoid teeth; reduction of the clavicular flange; the posterior process of interclavicle invested by the sternum anteriorly; a sink-trap nasal apparatus (with an elongate septomaxilla); other synapomorphies (enlarged posterior lobe of the hemipenes. Many have heavily keeled scales, and horned lizards have spines. External ears. Femoral pores.
Great Plains Skink
Scientific name: Plestiodon obsoletus Order: Squamata Clade: Scincomorpha Suborder: Lacertilia Lizards Family: Scincidae (Skinks) Genus: Plestiodon -Species Distribution in Texas: Western 2/3 of Texas. -Family Distribution: Nearly worldwide, except cold regions. -Scales around the body equal in size, overlapping, and smooth and shiny. Size ranges from small to large. External ears. Generally slender with relatively short limbs. Osteoderms under dorsal and ventral scales. Caudal autotomy very common but not universal. Highly diverse in terms of behavior, reproduction, and ecology.
Lissamphibia
The Batrachomorpha: includes extant amphibians (anurans, salamanders, and caecilians)
Testudine Inhalation/Exhalation Morphology
Transverse abdominus: -wraps around the back portion of the turtle's lungs -makes the turtle exhale during contraction Posterior limiting membrane: -Used to inhale -Pull on membrane via liver for negative pressure system Serratus: -composed of cervical and thoracic portions that originate from the cervical vertebrae and ribs and converge to insert on the medial surface of the scapula to form the sling support that suspends the thorax between the forelimbs. Abdominal oblique: -a muscle found on the lateral side of the abdomen. It is broad and thin. it forms one of the layers of the lateral abdominal wall along with external oblique on the outer side and transverse abdominis on the inner side. Its fibers are obliquely oriented hence the name. It helps maintain the abdominal pressure and movements of the trunk along with the other muscles. -Pectoralis: an intrinsic, fan-shaped muscle of the forelimb that usually runs from the sternum, clavicle and/or adjacent structures to the humerus and/or the scapula.-Its major actions are adduction, or depression, of the arm (in opposition to the action of the deltoideus muscle) and rotation of the arm forward about the axis of the body.
Testudines
Turtles belong to the Sauropsida and are the only extant amniotes with anapsid skulls • They are instantly recognizable because of their shell - this is an incredible structure! • They are not particularly diverse - there are only 346 extant species, distributed across 14 families • Nevertheless turtles are quite successful in both terrestrial and aquatic habitats
