BIOL10140 Deuterostomes II PDF

Deuterostomes II: The Tetrapoda  Echinodermata ANCESTRAL Cephalochordata...

Deuterostomes II: The Tetrapoda  Echinodermata ANCESTRAL Cephalochordata Chordates DEUTEROSTOME Urochordata Notochord Myxini Vertebrates Common ancestor of chordates Petromyzontida Chondrichthyes Gnathostomes Vertebrae Actinopterygii Osteichthyans Jaws, mineralized skeleton Actinistia Sarcopterygii Lungs or lung derivatives Dipnoi Lobed fins Amphibia Tetrapods Reptilia Amniotes Limbs with digits Amniotic egg Mammalia Milk Non-Vertebrate Deuterostomes Non-Vertebrate Deuterostomes  Agnathans Hagfishes and Lampreys Gnathostomes  Echinodermata Deuterostomes ANCESTRAL Cephalochordata Chordates DEUTEROSTOME Urochordata Notochord Myxini Vertebrates Common ancestor of chordates Petromyzontida Chondrichthyes Gnathostomes Vertebrae Actinopterygii Osteichthyans Jaws, mineralized skeleton Actinistia Sarcopterygii Lungs or lung derivatives Dipnoi Lobed fins Amphibia Tetrapods Reptilia Amniotes Limbs with digits Amniotic egg Mammalia Milk  Echinodermata Deuterostomes ANCESTRAL Cephalochordata Chordates DEUTEROSTOME Urochordata Notochord Myxini Vertebrates Common ancestor of chordates Petromyzontida Chondrichthyes Gnathostomes Vertebrae Actinopterygii Osteichthyans Jaws, mineralized skeleton Actinistia Sarcopterygii Lungs or lung derivatives Dipnoi Lobed fins Amphibia Tetrapods Reptilia Amniotes Limbs with digits Amniotic egg Mammalia Milk Tetrapoda A significant event in vertebrate evolution was the transition of one clade of lobe-fin fishes to terrestrial environments. This clade is the Tetrapoda. Despite not necessarily being aquatic, all tetrapods are members of the Sarcopterygii (lobe-finned fishes). Because all sarcopterygians are members of the Osteichthyes (bony fishes), then all tetrapods are bony fishes as well. This includes you. Cladograms and Nested Subsets Deuterostome Chordate Cladogram Vertebrate Echinodermata Cephalochordata Chordates Urochordata Myxini Vertebrates Petromyzontida You Chondrichthyes Gnathostomes Bony Fish Actinopterygii Osteichthyans Actinistia Sarcopterygii Dipnoi Amphibia Tetrapods Mammal Reptilia Amniotes Mammalia Venn Diagram Tetrapoda Key tetrapod adaptations: Four limbs and feet with digits (usually…) A neck, allowing separate movement of the head Fusion of pelvic girdle to backbone Absence of respiratory gills in non- aquatic species o However, skeletal elements for gills persist in all groups. Ears for detecting airborne sounds Tetrapoda: Origins Dipnoi We now know that Tetrapoda evolved Eusthenopteron wholly within the aquatic realm. Panderichthys Many early tetrapod taxa were decidedly ‘fishy’ in their appearance. Tetrapoda Tiktaalik Acanthostega Tulerpeton Limbs with digits Lissamphibia Key to limb bones Ulna Radius Amniota Humerus Silurian PALEOZOIC Devonian Carboniferous Permian Eusthenopteron foordi 415 400 385 370 355 340 325 310 295 280 265 0 From the Upper Devonian of Quebec, Canada (~385 mya) Time (millions of years ago) Tetrapoda: Origins Many early tetrapod taxa were decidedly ‘fishy’ in their appearance 2 1 3 Eusthenopteron foordi Bones of the pectoral fin, extending into the lobe. Numbered bones are homologous to the: 1 - humerus 2 - ulna 3 - radius of your arm. Tetrapoda: Origins Fish Tetrapod Characters Characters We see organisms in Scales Neck Tiktaalik roseae the fossil record that Fins Ribs have interesting Gills and lungs Fin skeleton mixtures of fish-like and Flat skull tetrapod-like traits. Eyes on top of skull Shoulder bones Ribs Neck Scales Head Eyes on top of skull Humerus Flat skull Ulna “Wrist” Elbow Watch the video on Brightspace Radius Fin Fin skeleton Tetrapoda: Today This contrasts with what Sarcopterygii Actinistia we think about tetrapods in the modern biota. Dipnoi One of the hallmark Lobed fins characters of the group that you will see in many Tetrapods Lissamphibia textbooks (as illustrated here) is “limbs with digits.” Amniotes Reptilia Limbs with digits Amniotic egg Mammalia We now know that this is a hallmark Milk of modern tetrapods. Not ALL tetrapods through ALL time. Tetrapoda Sarcopterygii Actinistia Dipnoi Lobed fins We will focus on this Tetrapods Lissamphibia group now: Lissamphibia Amniotes Reptilia Limbs with digits Amniotic egg Mammalia Milk  Lissamphibia ‘Amphibians’ Lissamphibia Commonly called “amphibians” radiated in the early Triassic (~ 210 mya). Lissamphibia is represented by approximately 8000 living species in three clades: Caudata (Urodela) salamanders Salientia (Anura) frogs Gymnophiona (Apoda) caecilians Lissamphibia Salamanders ~ 750 species. Northern Hemisphere distribution Some are aquatic, others live on land as adults. Some species are terrestrial throughout their entire life. Hellbender Cryptobranchus alleganiensis Palmate newt Lissotriton helveticus Lissamphibia Salamanders Many species entirely lack lungs (secondary loss of lungs). In these taxa, respiration takes place across the skin. Network of capillaries takes blood close to surface where gas exchange occurs. Red salamander Pseudotriton ruber Lissamphibia Salamanders Paedomorphosis is a common theme in salamanders, with many species retaining larval morphologies as mature adults. Three specimens, all from the genus Ambystoma; mole salamanders, endemic to North America Marbled salamander Marbled salamander Axolotl Ambystoma opacum Ambystoma opacum Ambystoma mexicanum Adult, Terrestrial Larva, Aquatic Adult, Aquatic Same species Lissamphibia Salamanders Paedomorphosis is a common theme in salamanders, with many species retaining larval morphologies as mature adults. Three specimens, all from the genus Ambystoma; mole salamanders, endemic to North America Marbled salamander Marbled salamander Axolotl Ambystoma opacum Ambystoma opacum Ambystoma mexicanum Adult, Terrestrial Larva, Aquatic Adult, Aquatic Same morphology Lissamphibia Frogs > 7,000 species Cosmopolitan distribution Lack tails (as adults) and have powerful hind legs for locomotion on land Frogs with leathery skin are called ‘toads’ – this is not an evolutionary group. Lissamphibia Frogs Some species even survive artic and subarctic conditions. The wood frog, Rana sylvatica, can survive being fully frozen. Use blood sugar and urea to limit the amount and size of ice crystals that form inside cells. The heart can be stopped for several months. Lissamphibia Caecilians ~200 species Distributed throughout the tropics, except Australia/New Guinea and Madagascar Most are terrestrial, burrow through leaf litter and soil. Lissamphibia Argentine caecilian Chthonerpeton indistinctum Caecilians Some caecilians, for example the rubber eels (Family Typhlonectidae), are semi-aquatic (like the Argentine caecilian Chthonerpeton indistinctum) or fully aquatic (like Kaup's caecilian Potamotyphlus kaupii). Kaup's caecilian Potamotyphlus kaupii Lissamphibia Caecilians Legless, nearly blind Loss of legs is a secondary adaptation Heavily ossified skulls for burrowing. Chemosensory tentacles – literally taste their way through the environment Lissamphibia Gymnophiona Morphology and molecular evidence supports monophyly of the Lissamphibia. Caudata There is some evidence for frogs and salamanders being more closely related to each other than to caecilians. Batrachia Salientia Life History and Ecology of Amphibians “Amphibian” = “both ways of life” (aquatic larva + terrestrial adult) Legs, lungs, external eardrums, (a) The tadpole (b) During metamorphosis and adaptations for carnivory arise during metamorphosis. This is the way frogs do things. (And it should be noted that not all frogs go through this bi-phasic life cycle.) (c) The adults return to water to mate.  Life History and Ecology of Amphibians Some frog species exhibit direct development – miniature adult frogs develop directly in the eggs (right). External fertilization; eggs require some moisture in the environment In some species, males or females care for eggs or tadpoles on their back, in their mouth, etc. (bottom). Amphibian populations are declining worldwide Scanning electron Fungal Pathogens micrograph of a zoospore of B. dendrobatidis Animals are generally less susceptible to parasitic fungi than plants – but not completely! The chytrid fungus Batrachochytrium dendrobatidis (amphibian chytrid fungus) is the cause of chytridiomycosis in frogs. A second species, Batrachochytrium salamandrivorans, has been found that causes chytridiomycosis in salamanders. Typical chytridiomycosis infection seen in a frog Amphibian populations are declining worldwide Fungal Pathogens Chytridiomycosis is a major (but not the only) factor in the recent decline in amphibian populations. The fungus attacks keratinized areas of a frog's body. Tadpoles are not heavily keratinized and are not severely affected. Adults have keratin-rich skin and die as a result. The fungus appears to have originated in East Asia and likely spread via the international pet trade (O’Hanlon et al. 2018. Science). Mountain Yellow-legged frogs (Rana muscosa) from California killed by B. dendrobatidis infection. Tetrapoda Sarcopterygii Actinistia Dipnoi Lobed fins Tetrapods Lissamphibia Amniotes Reptilia Limbs with digits We will focus on this Amniotic egg Mammalia group now: Amniota Milk  Amniota †Parareptiles Amniotes (formal name Turtles Amniota) are the clade of tetrapods whose living Crocodilians Sauropsids Archosaurs members comprise the †Pterosaurs ‘reptiles’, birds, and mammals. †Ornithischian dinosaurs Dinosaurs †Saurischian Saurischians Diapsids dinosaurs other than birds Birds †Plesiosaurs †Ichthyosaurs Lepidosaurs Tuataras Squamates (lizards and Synapsids snakes) Mammals Amniote Diversity The majority of living tetrapods are amniotes. More than 20,000 amniote species are currently recognized. They possess a rich fossil record as well, extending back over 300 million years.  Extraembryonic membranes Amniotic Egg Allantois Chorion Amniotic cavity with amniotic fluid Amniotes are named for the major derived character of the clade, the amniotic egg Embryo (also sometimes called the Yolk cleidoic egg), which (nutrients) contains membranes that protect the embryo. Shell Amniotic egg was a key Albumen adaptation to life on land. Amnion Yolk sac (‘Vitteline Membrane’)  Amniotic Egg The amniotic eggs of all birds, most reptiles and a few species of mammal have a shell. Shelled eggs are deposited externally; ‘oviparous’. Common blackbird (Turdus merula)  Amniotic Egg Even in amniote species with live birth the extraembryonic membranes are still there. There is simply no shell, and the amniotic ‘egg’ is ‘laid’ inside the uterus. The membranes form the placenta in some taxa. Eutherian mammals are the classic example of this, but many ‘reptiles’ are viviparous, as well. Common human (Homo sapiens)  Early Amniotes Living lissamphibians and amniotes split from a common ancestor about 350 million years ago Early amniotes were more tolerant of dry conditions than first tetrapods Seymoria Amniotic egg allowed for dryer terrestrial Edaphosaurus habitats to be exploited by vertebrates for the first time. Amniotes have other terrestrial adaptations, such as relatively impermeable skin and ability to use rib cage to ventilate the lungs.  Early Amniotes The earliest amniotes were predators with sharp teeth and long jaws. Dimetrodon In contrast to modern ecosystems, early terrestrial vertebrate communities were dominated by carnivores.  ‘Reptiles’ Emerald tree boa Corallus caninus The word ‘reptile’ is often used to mean any terrestrial vertebrate that is cold-blooded and covered in scales. This includes animals, such as lizards, snakes, turtles, crocodilians It also includes less well-known taxa such as, amphisbaenians, dibamids and tuataras. Many known extinct groups have also been called ‘reptiles.’  ‘Reptiles’ The word ‘reptile’ is often used to mean any terrestrial vertebrate that is cold-blooded and covered in scales. This includes animals, such as lizards, snakes, turtles, crocodilians It also includes less well-known taxa such as, amphisbaenians, dibamids and tuataras. Many known extinct groups have Spotted worm lizard Amphisbaena fuliginosa also been called ‘reptiles.’ But this is not a real evolutionary group! Tetraopd phylogeny based on the nuclear RAG-1 gene. Squamates (snakes, amphisbaenians and lizards) The last common Sphenodon (Rhynchocephalia) ancestor of all ‘reptile taxa’ Crocodilians Amniota Turtles Tetrapoda Mammals (= Synapsida) Lissamphibia Huggal et al. 2007. Syst. Biol. Tetraopd phylogeny based on the nuclear RAG-1 gene. Squamates (snakes, amphisbaenians and lizards) The last common Sphenodon (Rhynchocephalia) ancestor of all ‘reptile taxa’ Birds Archosaurs Crocodilians Amniota Turtles Tetrapoda Mammals (= Synapsida) Lissamphibia Huggal et al. 2007. Syst. Biol.  ‘Reptiles’ While you would traditionally group these types of tetrapods together as ‘reptiles’, to the exclusion of birds… Goldenscale anole Red-headed krait American alligator Baltimore oriole Anolis chrysolepis Bungarus flaviceps Alligator mississippiensis Icterus galbula ‘Reptiles’ Birds  ‘Reptiles’ …this is how they are actually related. Goldenscale anole Red-headed krait American alligator Baltimore oriole Anolis chrysolepis Bungarus flaviceps Alligator mississippiensis Icterus galbula Squamates Archosaurs Sauropsida Because crocodilians are more closely related to birds than they are to lizards and snakes, the term ‘reptile’ does not define an evolutionary group (clade). The group that unites all traditional ‘reptiles’ in addition to birds is called Sauropsida. ‘Reptiles’ Most ‘reptiles’ are ectothermic, that is, they absorb heat from the environment as the main source of body heat. Ectotherms regulate body temperature through behavioral adaptations. Reptiles have scales that create a waterproof barrier for their skin. Most lay shelled eggs, which are relatively water efficient, on land. Sand lizard, Lacerta agilis  Origin and Evolution of ‘Reptiles’ The earliest fossil evidence for ‘reptiles’ is approximately 310 million years ago during the late Carboniferous Period. First major group to emerge was the parareptiles A paraphyletic group, mostly large, stocky, quadrupedal herbivores Bradysaurus baini : ~ 260 mya from Australia  Origin and Evolution of ‘Reptiles’ Parareptiles dwindled in the late Permian (~255 mya) Diapsids diversified during this period. Diapsids consisted of two major lineages: lepidosaurs and archosaurs: Lepidosaurs - tuataras, lizards, snakes, and †mosasaurs, †ichthyosaurs Archosaurs - crocodilians, †pterosaurs, †phytosaurs and dinosaurs Modern reptiles are all diapsids – maybe…  Turtles The phylogenetic position of turtles remains uncertain Have a boxlike shell made of bone and keratin. Upper (carapace) and lower (plastron) shields are fused to the vertebrae and ribs Turtles have adapted to forests, shrubland, deserts, ponds, rivers, and even entirely marine environments Common box turtle, Terrapene carolina  Lepidosaurs Sphenodon punctatus One surviving lineage of lepidosaurs is represented by one species (Sphenodon punctatus) of lizard-like reptiles called tuataras. This is the last remnant of a once abundant diapsid group called Rhynchocephalia. Living tuataras are restricted to small islands off the coast of North Island, New Zealand. Pleurosaurus goldfussi An aquatic rhyncocephalian  Lepidosaurs The other major living lineage of lepidosaurs consists of the squamates: lizards, snakes, and amphisbaenians (plus some others…). Squamates are a very diverse group, with over 9,000 described species. Serpentes 3,000 of them are snakes. Serpentes (snakes) are one of many legless squamate groups. Water moccasin Agkistrodon piscivorus Carpet python Morelia spilota Serpentes Serpentes (snakes) are one of many legless squamate groups. Indeed, I have shown each of these photos in previous slides. Serpentes Serpentes (snakes) are one of many legless squamate groups. XNot a snake Totally a snake X Not a snake Serpentes All living snakes are carnivorous, and have adaptations to aid in the capture and consumption of prey including: Chemoreceptors Heat-detecting organs (some) Loosely articulated jawbones and elastic skin and connective tissues Indonesian pit viper Trimeresurus insularis, blue morph  Banded krait Bungarus fasciatus Serpentes Venom Let’s just get this out of the way: some snakes are venomous. And some venomous snakes are dangerous to humans. The krait (top) is VERY dangerous. Untreated bites from a krait are usually fatal. But the adder (bottom) will not kill you. The bite is described as ‘intensely painful’, but it is not normally fatal. To humans. Dogs are another story. Common European adder Vipera berus  Cape house snake Boaedon capensis Serpentes NOT ALL SNAKES ARE VENOMOUS! Or even dangerous for that matter. This has led to many species being exterminated in areas due to an assumption of their being dangerous. The two snakes to the right are neither venomous, nor particularly harmful to anything larger than a small rodent. Cuban giant dwarf boa Tropidophis melanurus  Archosauria Today, archosaurs consist of the ‘reptile’ group crocodilians, as well as birds. This is the most diverse tetrapod clade today. >12,000 species (and counting). This diversity is entirely due to birds. In addition, there are also many entirely extinct groups, including aetosaurs, rausuchians, phytosaurs, and pterosaurs Crocodylomorpha Crocodilians (alligators, gharials and crocodiles) belong to an archosaur lineage dating back to the late Triassic. The 25 living species of crocodilians are all restricted to warm regions. Crocodylomorpha Crocodilians (alligators, gharials and crocodiles) belong to an archosaur lineage dating back to the late Triassic. The 25 living species of crocodilians are all restricted to warm regions. This clade was much more diverse in the past. There were fast running, herbivorous and even fully marine crocodilians in the past. Dinosauria Dinosauria Dinosaurs originated in the Triassic Period, about 230 million years ago. They were the dominant terrestrial vertebrates during the Jurassic and Cretaceous Periods (~201 to ~66 million years ago). Tyrannosaurus rex Edmontosaurus annectens Dinosauria Dinosaurs diversified into vast range of shapes and sizes Small bipedal carnivores, like the 1 kg Microraptor (left) Huge herbivorous quadrupeds, like the 80,000 kg Argentinosaurus (right) Dinosauria Like, seriously huge. We have no modern analog for any terrestrial animal this large today. Much of the living biology of the truly large sauropods remains a mystery. Member of the excavation team posing nest to a femur in the field. Patagotitan mayorum at the Field Museum of Natural History, Chicago, USA Dinosauria Like, seriously huge. We have no modern analog for any terrestrial animal this large today. Much of the living biology of the truly large sauropods remains a mystery. H. William Menke on the Riggs Expedition to Member of the excavation team posing nest to the femur in the field. Grand Junction, Colorado, USA in 1900. Patagotitan mayorum at the Field Museum of Natural History, Chicago, USA Dinosauria There is abundant fossil evidence that many dinosaurs were social animals. Trackways preserving evidence of multiple individuals of the same taxon moving through the same space at the same time. Dinosauria There is evidence of extensive parental care in some dinosaurs. Death assemblages showing a parent covering eggs in a nest (left), and a mass death of juveniles and adults (right). Dinosauria Dinosaurs are not extinct. Birds are theropod dinosaurs, the group of bipedal carnivorous dinosaurs that includes T. rex, among others. Feathers are now known to exist on many species of non-avian dinosaur. Microraptor gui – NOT a bird. About 120 million years old. Common Chaffinch (Fringilla coelebs) – Definitely a bird.  Wing Dinosauria Toothed beak claw By 150 million years ago, birds coexisted alongside other dinosaur groups. Confuciusornis Hesperornis regalis A Cretaceous bird from China (about 120 A Cretaceous fossil bird from the USA (about million years old). 80 million years old). Airfoil wing Long tail with with contour many vertebrae feathers At ~ 150 million years old, Archaeopteryx is the oldest known bird. That is, birds did not come right after the dinosaurs. Birds are one kind of dinosaur that existed in the Mesozoic. There were many others in addition. Worst. Day. Ever. Dinosauria Birds are special with respect to other dinosaurs only insofar as they happened to make it through the end-Mesozoic mass extinction event. Lesser flamingo, Phoenicopterus minor, Lake Nakuru, Kenya Condamine, et al. 2021. Nature Communications. Dinosauria All living birds belong to the clade Neornithes There are >13,000 living species of bird. They have a worldwide distribution and occupy many terrestrial, aquatic and aerial niches. But there are massive ranges in size, form, degree types of parental care, etc. Common Ostrich, Struthio camelus. Bumblebee Humingbird, Flightless. Social. ~ 110 kg Atthis heloisa. Flier. Solitary. ~ 2.2 g  Mammalia Mammals are represented by more than 6,000 living species All living mammals have: Mammary glands, which produce milk Hair High metabolic rate, due to endothermy Taurotragus oryx Saimiri sciureus Mammalia Mammals are part of the larger clade Synapsida, which diversified in the Permian (298 – 252 Ma) Mammals first appear in the fossil record about 230 million years ago – only slightly after the appearance of dinosaurs. Dimetrodon, a Permian synapsid By the early Cretaceous, the three living lineages of mammals emerged: monotremes, metatherians, and eutherians. Mammals undergo a significant adaptive radiation in the wake of the End-Cretaceous Extinction Event. Hyracatherium, an Eocene horse Mammalia (extant) Monotremata (5 species) Monotremata (324 species) Metatheria ANCESTRAL Metatheria MAMMAL Proboscidea Sirenia Tubulidentata Afrotheria Hyracoidea Afrosoricida Macroscelidea (5,010 species) Theria Eutheria Xenarthra Xenarthra Rodentia Lagomorpha Primates Euarchontaglires Dermoptera Scandentia Carnivora Cetartiodactyla Perissodactyla Laurasiatheria Chiroptera Boreoeutheria Eulipotyphla Pholidota Mammalia Monotremata (5 species) Monotremata (324 species) Metatheria ANCESTRAL Metatheria MAMMAL Proboscidea Sirenia Tubulidentata Hyracoidea Afrosoricida Macroscelidea (5,010 species) Eutheria Xenarthra Rodentia Lagomorpha Primates Dermoptera Scandentia Carnivora Cetartiodactyla Perissodactyla Chiroptera Eulipotyphla Pholidota  Monotremata Monotremes are a small group (currently only 5 recognized species) of egg-laying mammals consisting of echidnas and the platypus. Once a more diverse and widespread group, they are today restricted to Australia and New Guinea.  Marsupials “Marsupials” include opossums, kangaroos, and koalas Named for the marsupium – the fleshy pouch in which the newly-born develops outside the mother’s body. They are distinguished from the “placental” mammals, where the fetus develops inside the mother’s uterus.  Metatheria Embryo develops in the uterus with a choriovitelline placenta. The fetus is born very early in its development – pregnancy usually only (a) A young brushtail possum lasts a few weeks. The fetus then completes its development outside the mother’s body. There may or may not be a pouch. (b) A greater bilby  Metatheria So: Many “marsupials” do not have a marsupium. “Marsupials” do have a placenta. The correct terminology is: “marsupial” → metatherian “placental mammal” → eutherian  Eutheria Compared with marsupials, eutherians have a more complex chorioallantoic placenta. Young eutherians complete their embryonic development within the mother’s uterus. Oldest eutherian in the fossil record dates to about 160 million years ago.  Orders Main Orders Main Mammalia and Examples Characteristics and Examples Characteristics Monotremata Lay eggs; no nipples; Marsupialia Completes embryonic Platypuses, young suck milk from Kangaroos, development in pouch echidnas fur of mother opossums, on mother’s body koalas Echidna Koala Proboscidea Long, muscular trunk; Tubulidentata Teeth consisting of Elephants thick, loose skin; upper Aardvarks many thin tubes incisors elongated cemented together; Extant orders of as tusks eats ants and termites African elephant Aardvark placenetal mammals Sirenia Manatees, Aquatic; finlike fore- limbs and no hind Hyracoidea Hyraxes Short legs; stumpy tail; herbivorous; dugongs limbs; herbivorous complex, multi- chambered stomach Manatee Rock hyrax Living eutherian mammals are Xenarthra Reduced teeth or no Rodentia Chisel-like, continuously Sloths, teeth; herbivorous Squirrels, growing incisors worn generally classified into ~15 anteaters, armadillos (sloths) or carnivorous (anteaters, armadillos) beavers, rats, porcupines, mice down by gnawing; herbivorous Orders. Lagomorpha Tamandua Chisel-like incisors; Primates Red squirrel Opposable thumbs; Rabbits, hares, hind legs longer than Lemurs, monkeys, forward-facing eyes; picas forelegs and adapted chimpanzees, well-developed cerebral for running and jump- gorillas, humans cortex; omnivorous ing; herbivorous These living mammal orders Jackrabbit Golden lion tamarin were largely in place by the early Carnivora Dogs, wolves, Sharp, pointed canine teeth and molars for shearing; generally Perissodactyla Horses, zebras, tapirs, Hooves with an odd number of toes on each foot; herbivorous bears, cats, Eocene Epoch, about 55 million carnivorous rhinoceroses weasels, otters, seals, walruses Indian rhinoceros Coyote years ago. Cetartiodactyla Artiodactyls: Hooves with an even number of toes on each foot; herbivorous Chiroptera Bats Adapted for flight; broad skinfold that extends from elongated sheep, pigs, fingers to body and cattle, deer, legs; carnivorous or Frog-eating bat giraffes herbivorous Bighorn sheep Aquatic; streamlined Eulipotyphla Cetaceans: Eat mainly insects body; paddle-like whales, “Core and other small forelimbs and no hind dolphins, insectivores”: invertebrates limbs; thick layer of porpoises some moles, insulating blubber; Pacific white- carnivorous some shrews Star-nosed sided porpoise mole Mammalia Monotremata (5 species) Monotremata (324 species) Metatheria ANCESTRAL Metatheria MAMMAL Proboscidea Sirenia Tubulidentata Afrotheria Hyracoidea Afrosoricida Atlantogenata Afrotheria Macroscelidea (5,010 species) Eutheria Xenarthra Xenarthra Rodentia Xenarthra Lagomorpha Primates Euarchontaglires Dermoptera Scandentia Euarchontaglires Carnivora Cetartiodactyla Perissodactyla Laurasiatheria Chiroptera Laurasiatheria Eulipotyphla Boreoeutheria Boreoeutheria Pholidota Afrotheria This is a group of Black and rufous elephant shrew Aardvark Orycteropus afer mammals, where the Rhynchocyon petersi members have traditionally been placed in many, very distantly-related Lowland streaked tenrec Rock hyrax groups based on their Hemicentetes semispinosus Procavia johnstoni morphological characteristics. African manatee African bush elephant Trichechus senegalensis Loxodonta africana Afrotheria Recent DNA Black and rufous elephant shrew Aardvark Orycteropus afer phylogenies show that Rhynchocyon petersi they form a coherent group of mammals. They are distributed Lowland streaked tenrec Rock hyrax mainly in Africa/ Hemicentetes semispinosus Procavia johnstoni Madagascar - TODAY. Fossil members of this clade are found outside Africa. African manatee African bush elephant Trichechus senegalensis Loxodonta africana Afrotheria Take the elephant clade (Proboscidea) for example. For much of the past 40 million years, proboscideans inhabited every continent except Australia and Antarctica. Mammuthus primigenius, Woolly mammoth on display at the American Museum of Natural History in New York. Gomphotherium productum Gomphothere on display at the American Museum of Natural History in New York. Xenarthra Nine-banded armadillo Pygmy three-toed sloth Linnaeus's two-toed sloth Dasypus novemcinctus Bradypus pygmaeus Choloepus didactylus Another group of mammals that were, until recently, placed among different groups. DNA phylogenies confirm that this is a radiation of eutherian mammals that is Giant anteater Myrmecophaga tridactyla endemic to South America. Xenarthra Gigantism is a common evolutionary theme in this group. Among just the sloths (Folivora), very large body sizes (in excess of 1000 kg) were achieved independently by at least 5 different lineages. Giant ground sloth Megatherium americanum In addition, there were the glyptodonts, giant relatives of armadillos. Glyptodon clavipes, a glyptodont Laurasiatheria Sunda pangolin Manis javanica A very species-rich, and highly morphologically diverse group. Today, this clade is Lion Panthera leo lives from pole to pole, on every continent. Giraffe Giraffa camelopardalis They inhabit every type of terrestrial habitat, as well as aquatic and areal habitats. European hedgehog Erinaceus europaeus Laurasiatheria Recent DNA phylogenies have resolved the whales into this clade. Whales are a fully aquatic-adapted clade of artiodactyl. These are the cloven-hoofed ungulates, which include species like sheep cows, pigs and (most closely related to whales) hippopotami. Laurasiatheria Bats (Order Chiroptera) have true powered flight – not just efficient gliding. This is the only tetrapod clade outside of the archosaurs where powered flight has evolved. The flight surface is formed by stretching a membrane of skin over the hand and stretching this back to the ankles. Euarchontoglires Sunda flying lemur Galeopterus variegatus Madras treeshrew Anathana ellioti Nilgiri langur Trachypithecus johnii Eastern chipmunk Tamias striatus Clade of mammals uniting the rodents, lagomorphs, treeshrews, colugos and primates. This is by far the most diverse mammalian group, due mainly to the rodents. (Rodents comprise ~ 40% of all living mammal species). European rabbit Oryctolagus cuniculus Euarchontoglires Rodentia is by far the most diverse mammalian group, with over 2400 extant species. The vast majority of rodents are small mammals – 77% are less than 250g, 55% are less than 100g. Despite this, several rodents are rather large, like the capybara at about 55kg. Capybara Hydrochoerus hydrochaeris Approximately 55 kg – so the size of a male Rottweiler. That is a 20,000-fold difference in body mass within this group. Wood mouse Apodemus sylvaticus Approximately 23 g – so about half the size of a golf ball.