eemb_113_lecture_3_notes - Lecture 3 \u25cf Extant orders in Amphibia(Lissamphibia \u25cb Caudata(ca 755 species \u25cb Anura(ca 7,259 species \u25cb Apoda(ca 214

eemb_113_lecture_3_notes - Lecture 3 u25cf Extant orders...

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Lecture 3 Extant orders in Amphibia (Lissamphibia) Caudata (ca. 755 species) Anura (ca. 7,259 species) Apoda (ca. 214 species) Definitions Monophyletic: Taxonomic group containing all descendants of a common ancestor Polyphyletic: Taxonomic group whose members do not share the same ancestor Paraphyletic: Taxonomic group that does not contain all descendants of a common ancestor Amphibian and Lissamphibia The majority of diversity in the Amphibia is in the distant past All three extant groups (Lissamphibia) are represented in the fossil record by 150 mya Uncertain relationship to ancestral amphibians…ongoing controversy Who were the Temnospondyls? Known from Carboniferous to Cretaceous (~340 – 140 mya) Widespread, found on all continents Diverse >90 genera Generalized tetrapod body form Significant skull diversity 20cm to 3 meters in length Ecologically diverse Aquatic, semi-aquatic, terrestrial, fresh and saltwater, arborea Dissorophoid origin for all Lissamphibia/Dissorophoid origin for Batrachia Stereospondyl origin for Apoda Two hypotheses
Frogs, salamanders, and caecilians from same clade Frogs and salamanders from one clade and caecilians from another Take home messages Majority of amphibian diversity in the past Temnospondyls very diverse ecologically Extant lineages are small, fresh water and terrestrial species Two with highly derived morphology: Apoda and Anura One with generalized morphology: Caudata There are features which unite the Lissamphibia (what do we call these?) Characteristics of extant amphibians (not exhaustive) 1. Eggs lack amnion and shell 2. Ectothermic 3. Skin structure Moist permeable skin (H2O, O2, CO2) Mucous glands and granular (poison) glands in skin 4. Three chambered heart 5. Carnivorous as adults 6. Diverse larval stage, Many have free-living larva 7. Dentition: Pedicellate teeth (homodont) 8. Ear structure Anamniote eggs versus Amniote eggs Anamniotic egg Can only live in water Does not have a barrier that can do gas exchange without water exchange as well Amniotic egg Can sit and stay viable in dry environment Ectothermy and Body Temperature Regulation cold blooded versus warm blooded: but many reptiles have very high body temps poikilothermic versus homeothermic: (= variable versus constant): but amphibians and reptiles can keep temp constant for long periods, some mammals and birds vary body temps ectothermic versus endothermic: (= heat source external versus internal) Note: we are not going to use the first two terms! Just ectothermy Extant Amphibian Characteristics Skin is moist and permeable (to varying degrees): Can act as respiratory organ subcutaneous scales in some Caecilians Skin glands
Serous glands, aka granular glands produce poison

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