traits zoology unit 2

★ Tetrapodomorpha

• within Sarcopterygians

• contains Stegocephalia

• stem group more closely related to Tetrapods than Dipnoi

• sister clade to Dipnoi (extant lungfish)

• early Devinian (~409)

• many simultaneous changes due to terrestrial life

• 4 muscular limbs or fins

• humerus w/ convex head w/ glenoid fossa

• choanae

★ Eusthenopteron

• within Tetrapodomorpha

• global distribution in Devonian period

• diphycercal caudal tail

• labyrinthodont teeth

• bony scales (no enamel/dentin layers)

• possessed shoulder, humerus, radius, ulna, & fin rays

• pectoral girdle & pelvic fins

★ Tiktaalik roseae

• within Tetrapodomorpha

• late Devonian (~375 mya) lived in Canada (at the equator)

• river floodplains & shalllows

• mosaic of fish & tetrapod qualities

• lost supracleithra, had mobile neck

• retained fin rays, scales

• lacked ischium, operculum

• finger-like bones, humerus, radius, ulna

• probably had lungs & mobile wrists

• mobile shoulder

★ Tetrapoda

• first Stegocephalians to have 4 limbs with digits

• 370 mya (middle-late Devonian, Romer’s Gap)

• loss of pectoral attachment to head, allowed more cranial mobility

• girdles & limbs become stronger, more robust & more ossified

• fins replaced by digits

• had to adapt to support weight on land (arch-like spinal column, vertebrae with extra processes & support elements, robust/longer limb bones, more robust pelvic/pectoral girdles)

• keratinized skin (prevents damage/water loss)

★ Acanthostega

• within Tetrapoda

• ~365 mya

• primarily aquatic

• paired limbs, no fin rays

• fin rays in caudal fin

• weak pelvis

• lacks olecranon process

• 8 digits each limb

★ Ichthyostega

• within Tetrapoda

• 365-360 mya

• primarily aquatic

• paired limbs, no fin rays

• fin rays in caudal fin

• robust pelvis & ribs

• strong forelimbs

• 7 digits each limb

★ Lissamphibia

• within Temnospondyli

• contains Batrachia & Gymnophiona

• pedicellate, bicuspid teeth

• loss of bones present in fish ancestors (postparietal)

• 2 occipital condyles (convergent with mammals)

• highly permeable skin, capable of cutaneous respiration

• mucus & poison glands in skin

• metamorphosis from aquatic larva to terrestrial adult

★ Temnospondyli

• within Tetrapoda

• contains Lissamphibia

• Carboniferous - Cretacecous (350-120 mya)

• first successful group of vertebrates on land, though still amphians

• cut vertebrae, weaker, more time spent in water

★ Gymnophiona

• within Lissamphibia

• contains Caecilians (naked snake)

• limbless

• fossorial & secretive

• eyes reduced, poor vision

• strong skulls for digging

• tentacles between eyes & nostrils (likely for olfaction)

• smooth skin, maybe scales beneath

• left lung smaller than right (convergent with snakes)

• some fully aquatic, with laterally compressed body & tail for swimming

• some fully terrestrial, strong skulls to aid in digging

• one species lungless, relies on cutaneous respiration

• only Lissamphibians to use internal fertilization via male phallodeum

• ~25% oviparous & 75% viviparous

• some provide maternal care (milk-like substance from cloaca, maternal dermatophagy)

★ Batrachia

• within Lissamphibia

• contains Anura & (Caudata →) Urodela

• monophyletic clade, including all descendants of common frog/salamanders ancestor

• has levator bulbi muscle (may assist in buccal pump/ventilation method)

• used to refer to all amphibians, reduced in late 1800s

★ (Caudata →) Urodela

• within Batrachia

• crown group within Caudata total group

• contains Cryptobranchidae, Sirenidae, Plethodontidae, Ambystomatidae, Salamandridae & Proteidae

• possess tail as adult

• lack secondary palate, tympanic membrane, scales

• possess 4 limbs (sometimes secondarily lost)

• high degree of neoteny in many lineages (external gills in aquatic species)

• all predators

• largest genomes of any vertebrate

★ Cryptobranchidae

• within Urodela

• giant salamanders, hellbenders

• all vulnerable, threatened, or endangered

• lateral skin folds (more surface area for cutaneous resspiration)

• angular bone fused with prearticular in mandible

• paternal care of eggs

• no gill slits in adults, gill arches remain internally

★ Hellbenders

• within Cryptobranchidae

• vulnerable due to disease & habitat loss

• possess lungs, rarely use however

• lives 30 years, takes 5 years to mature

• presence indicates good water quality

★ Sirenidae

• within Urodela

• neotenic aquatic salamanders

• hindlimbs & pelvic girdle lost

• lack teeth, keratinized beak-like jaw

• highly paedomorphic, no metamorphosis, retains external gills, lateral line system, no eyelids

• retain gills as adults, but obligate air breathers (terrestrial ancestry?)

★ Plethodontidae

• within Urodela

• long-tailed, seal, slimy, red, southern dusky, & four-toed salamanders

• lack lungs, exchange gasses cutaneously or through tissues in mouth/throat

• nostrils open onto upper lip via nasolabial groove

• no free-living larval stage or metamorphosis

• tongue projection feeding

★ Ambystomatidae

• within Urodela

• mole salamanders, pacific giant salamanders

• skulls broad, short snout

• lack nasolabial grooves

• 10 costal grooves

• eyes not moveable

• vomerine teeth transverse, not parallel to maxillae

★ Salamandridae

• within Urodela

• true newts & salamanders

• many multicellular poison glands, tetrodotoxin

• aposematic coloration, defensive postures

• premaxillae fused

• internal fertilization, spermatophore

★ Proteidae

• within Urodela

• mudpuppies, waterdogs, olms

• permanent paedomorphosis (neoteny or slowed somatic growth)

• external gills (3 pairs), no maxillae, functional lateral line system, caudal fin

• functional lungs & gills

• 4 digits on fore & hind limbs, other families have ancestral 4 forelimb & 5 hindlimb digits

★ Anura

• within Batrachia

• crown group within Salientia total group

• contains Bufonidae, Ranidae, Hylidae, Microhylidae, Dendrobatidae, & Pipidae

• lack dentary teeth

• lack tail as adult

• short vertebral column (8-9 presacral, jumping adaption)

• forelimb shorter than hindlimb

• fused forearm (radioulna) & lower leg (tibiofibula)

• elongated pelvis, hindlimb, tarsals (especially astragalus & calcaneum)

• ribs reduced, or lost

• tympanum & columella (stapes)

★ Bufonidae

• within Anura

• toads

• parotid glands

• warty, glandular, dry skin

• toothless

• horizontal pupils

• visible tympanum

• primarily terrestrial

★ Ranidae

• within Anura

• “true” frogs

• teeth on upper jaw only (maxilla & premaxilla)

• lack parotid glands, cranial crests

• extensive hindfoot webbing

• primarily aquatic or semi-aquatic

★ Hylidae

• within Anura

• tree frogs

• teeth on upper jaw only (maxilla & premaxilla)

• lack parotid glands, cranial crests

• adhesive toe pads, moderate hindfoot webbing

• arboreal or semi-arboreal

★ Microhylidae

• within Anura

• narrow-mouthed frogs

• teeth usually absent

• lack toe pads, parotid glands, cranial crests

• often skin folds

• terrestrial or fossorial

★ Dendrobatidae

• within Anura

• poison arrow/dart frogs

• small, aposematic coloration, potent skin alkaloids

• no parotoid glands, smooth skin

• parental care, guarding/carrying tadpoles

• diurnal, terrestrial rainforest species

★ Pipidae

• within Anura

• includes Xenopus & Pipa

• tongueless frogs

• entirely aquatic, dorsoventrally flattened body

• no tongue or eyelids, lateral line system retained

• fully webbed feet with sensory tips on toes

• females of Pipa embed eggs in back

★ Amniote

• within Tetrapoda

• contains Sauropsids & Synapsida

• reproduction out of water, protected embryo (shelled eggs, uterus, viviparity), no distinct larval stage

• second cervical vertebra

• astragalus bone

• > 1 sacral vertebra

• waterproof skin

• penis

• metanephric kidney

• costal ventilation

• tracheas with cartilaginous rings

• no otic notch

• different head-width : length proportion than amphibians

★ Labyrinthodonts

• within Amniote

• tetrapods

• dominated early Carboniferous

• reptile like, but not like modern reptiles

★ Reptiliomorph

• within Amniote

• tetrapods

• early ones gained sacral ribs, sternum & astragalus

• reptile like, but not like modern reptiles

★ Diadectomorpha

• within stem Amniote or stem Synapsid

• Carboniferous & early Permian

• teeth smooth

• wide variability in lifestyles/morphologies

• uncertain reproductive mode

• large otic notch

• specialized teeth & secondary palate

• bulky body (possibly enlarged gut for herbivory)

★ Seymouria

• within stem Amniote

• transitional between Amphibia & Amniota

• 5 digits typical

• no astragalus

★ Limnoscelis

• within stem Amniote

• transitional between Amphibia & Amniota

• 5 digits typical

• no astragalus

★ Hylonomus

• within stem Amniote

• less related to modern reptiles than mammals

• 5 digits typical

• no astragalus

★ Reptiliomorph

• within stem Amniotes

• total group of amniotes = Reptiliomorpha

• Carboniferous tetrapods

• closer related to Amniota than Amphibians

• pleurocentrum dominates vertebra

★ Sauropsida

• within Amniotes

• contains Lepidosauria & Archelosauria

• stem groups of fossil lizard-like taxa

• reptiles evolved within clade Diapsida

★ Archelosauria

• within Sauropsida

• sister clade to Lepidosauria

• contains Archosauria & Testudines

• some secondarily aquatic (Ichthyosauria)

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★ Lepidosauria

• within Sauropsida

• sister clade to Archelosauria

• contains Squamata & Rhynchocephalia

• crown group present by early Triassic (~252 mya)

• stem group found in late Permian (~259 mya)

• diapsid skulls

• sprawling gait, sinusoidal trunk & tail movement

• sliding joint between coracoid & sternum

• pleurodont dentition

★ Diapsida

• within Sauropsida

• numerous stem groups

• paraphyletic due to birds

★ Rhynchocephalia

• within Lepidosauria

• sister clade to Squamata

• contains (Sphenodontidae →) Sphenodon

• extinct species with global distribution, Triassic to Cretaceous

• has 1 extant species in New Zealand, Tuatara

• ventral gastralia (abdominal ribs)

• acrodont teeth

• complete lower temporal bar

• beak-like premaxilla

• 2 rows of upper teeth

• lack hemipenes

★ Tuatara

• within (Sphenodontidae →) Sphenodon

• endemic to New Zealand

• 2 upper & 1 lower row of teeth (palatal dentition)

• large parietal eye (Pineal gland/epithalamus)

• amphicoelous vertebrate (fish-like, unique among Amniotes)

• very slow growth rate, long lifespan

• threatened by habitat loss & invasive rats

★ Squamata

• within Lepidosauria

• sister clade to Rhynchocephalia

• contains Gekkota, Scincomorpha, & Episquamata

• many have secondarily lost their hindlimbs and/or forelimbs

  • pectoral girdle may be fully present, lost, or in-between

  • pelvic girdle never completely lost

• some secondarily aquatic

★ Gekkota

• within Squamata

• Gold dust day gecko, Jaragua dwarf gecko

• worldwide distribution

• no eyelids, possess transparent brille to cover eyes

• most nocturnal, excellent night vision (no rods, has special cones)

• toe pads can adhere to almost any surface

★ Scincomorpha

• within Squamata

• skinks & relatives

• cone shaped heads, with osteoderms

• limbs reduced or lost

• no distinct neck

• many viviparous, show parental care

★ Episquamata

• within Squamata

• contains Laterata & Toxifera

• forked tongue

• Jacobson’s organ well developed (vomeronasal organ)

★ Laterata

• within Episquamata

• sister clade with Toxifera

• contains Amphisbaenia, Lacertidae, & Teiidae

• non venomous

★ Amphisbaenia

• within Laterata

• “legless lizards”, but not the only legless lizards

• vestige of pelvic girdle in all species

• some (Bipes) retain forelimbs

• reduced eyes, enlarged stapes

• rings of scales

• most very small (<15 cm) long

★ Lacertidae

• within Laterata

• “true lizards”

• mostly insectivorous, wide variety in habitats

• some species parthenogenetic

• very small (<9 cm long)

★ Teiidae

• within Laterata

• whiptails, racerunners, tegus

• transverse rows of large rectangular scales on venter

• some species entirely female, reproduce with parthenogenesis

★ Toxifera

• within Laterata

• contains Iguania, Anguimorpha, & Serpentes

• lots of species (~60% of extant Squamata)

• defined genetically, no morphological synapomorphy

• includes all venomous reptiles, but not all members are venomous

★ Iguania

• within Toxifera

• Iguanas, chameleons, anoles, ect

• worldwide distribution

• pleurodont dentition (ancestrally, some secondarily acrodont)

• many have tongues useful for prey capture (entoglossal process of hyoid)

★ Anguimorpha

• within Toxifera

• contains Varanidae, Helodermatidae, & Anguioidea

• postorbital-squamosal arch absent

• pterygoids, palatines lack teeth

★ Varanidae

• within Toxifera

• monitors, komondo dragon, goannas

• strongly recurved quadrate

• posteriorly displaced choanae (internal nares)

• elongated cervical vertebrae

★ Helodermatidae

• within Toxifera

• beaded lizards

• venemous

• rugose osteoderms, on head

• grooved maxillary teeth for venom delivery

• tail used for fat storage

★ Anguioidea

• within Toxifera

• legless lizards, glass lizards, alligator lizards

★ Serpentes

• contains Boidae, Colubridae, Elapidae, Pythonidae, & Viperidae

• Jurassic period, between 167-143 mya

• limbless, external ear openings, tympanum lost

• elongation of body & increased vertebral count

• highly kinetic skull with double-hinged quadrate

• internal organs asymmetrical, one side nonfunctional

★ Boidae

• within Serpentes

• boas & anacondas

• nonvenomous

• retain vestigial pelvic elements (cloacal spurs)

• bilateral lung function

• less kinetic skull than most snakes, rely on constriction to kill prey

• ovoviviparous

★ Colubridae

• within Serpentes

• largest & most diverse snake family (no morphological synapomorphies)

• pelvic vestiges lost

• only right lung functional

• lack infrared pits

• most species nonvenomous

• BUT the venomous ones have rear fangs & are very dangerous

★ Elapidae

• within Serpentes

• cobras, mambas, sea snakes

• fixed hollow fangs in front of mouth

• pelvic vestiges lost

• only right lung functional

★ Pythonidae

• within Serpentes

• pythons

• retain vestigial pelvic elements (cloacal spurs)

• bilateral lung function

• multiple labial or facial heat-sensing pits

• constriction as main prey killing mechanism

★ Viperidae

• within Serpentes

• vipers & pit vipers

• long hinged front fangs, fold back when mouth closed

• pit vipers have infrared pits between eyes & nostrils

• many viviparous

★ Ichthyosauria

• within Squamata

• phylogeny uncertain, maybe within Diapsida

• secondarily aquatic

• fish or dolphin body shape (convergent evolution)

★ Mosasauria

• within Squamata

• phylogeny uncertain (hypotheses say Varanoidea or Serpentes)

• ~91 genera from Mesozoic

• secondarily aquatic

★ (Sauropterygians →) Plesiosaurs

• within Squamata

• contains Plesiosauromorphs & Pliosaurs

• Mesozoic

• secondarily aquatic

★ Plesiosauromorphs

• within (Sauropterygians →) Plesiosaurs

• sister clade to Pliosaurs

• long slender neck with small head

★ Pliosaurs

• within (Sauropterygians →) Plesiosaurs

• sister clade to Plesiosauromorphs

• short neck with large head

★ Thalattosauria

• within Squamata

• uncertain phylogeny

• Triassic

• most have downturned snouts & teeth adapted for crushing

★ Testudines

• within Archelosauria

• sister clade to Archosauria

• contains Pleurodira & Cryptodira

• anapsid skull

• edentulate

• dorsal carapace & ventral plastron form shell (made of keratin)

• incorporates vertebrae, ribs, gastralia (abdominal ribs) sternum

• 8 cervical vertebrae