Monotremes and Marsupials
description
Transcript of Monotremes and Marsupials
![Page 1: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/1.jpg)
Monotremes and Marsupials
Biol 455 Mammalogy
Jan 27, 2005
![Page 2: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/2.jpg)
Monotremata Prototheria, retention of various reptilian
features Two families: Ornithorhynchidae and
Tachyglossidae Monotremata = “one opening”
Cloaca, common opening of fecal, urinary and reproductive tracts
Rubbery-shelled eggs (permeable)
![Page 3: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/3.jpg)
Monotremata con’t
Eggs are small, incubated for 10 to 11 days
Neonates have well developed forelimbs and shoulders
![Page 4: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/4.jpg)
Monotremata con’t
No teats Pectoral girdle has coracoid, precoracoid,
and interclavicle bone (similar to Therapsid reptile)
Homeotherm - low Tb of 32 C Sperm are fiiform (threadlike) and testis
structures similar to reptile
![Page 5: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/5.jpg)
Pectoral girdle
![Page 6: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/6.jpg)
Morphology of monotremes Cranium - indistinct sutures Jugal bone reduced or absent Zygomatic arch made up of maxilla and
squamosal bones Dentary bone reduced Adults are edentate Elongate rostrum, lack of teeth, high-
domed cranium - birdlike
![Page 7: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/7.jpg)
Morphology con’t
Cochlea (semicircular canal of inner ear) are not coiled
Have epipubic bones Males have large medial spur on ankle Males have baculum, permanently
abdominal testes and no scrotum
![Page 8: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/8.jpg)
Epipubic bone
![Page 9: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/9.jpg)
Ornithorhynchidae Duck-billed platypus Semiaquatic, semifossorial Near freshwater lakes and rivers, east coast of
Australia and Tasmania Feed on invert., fish and amphibians Adult male 1.7 kg, female smaller Short dense fur covers all but bill, feet, and underside
of tail Bill is soft and pliable, with nostrils at tip
Has tactile receptors to sense electric field generated by muscle contraction of prey
![Page 10: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/10.jpg)
Ornithorhynchidae con’t
Has small eyes and ears Pentadactyle (five-toed) and manus
(forefoot) is webbed Long claws for digging burrow
![Page 11: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/11.jpg)
Ornithorhynchidae con’t Spur on hind limb connect to venom gland
in thigh Platypus has no pouch, female incubate
eggs in burrow Neonates have molariform teeth, shed
before emerge from burrow Keratinized pads
Milk is secreted onto tufts of hair
![Page 12: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/12.jpg)
Ornithorhynchidae con’t
![Page 13: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/13.jpg)
![Page 14: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/14.jpg)
Tachyglossidae Short-beaked echidna (Tachyglossus)
Australia, New Guinea, and Tasmania 6 kg
Long-beaked echidna (Zaglossus) Forested highland of New Guinea 10 kg
Feed on ants, termites, and insects - ground to paste between tongue and spiny palatal ridge
Have scooplike claws on feet to break anthills and burrows
Ankle spur not venomous
![Page 15: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/15.jpg)
Tachyglossidae con’t Beak contains electroreceptors Guard hairs modified to become spines Mucus that coat tongue to make it sticky No teeth at any stage of development Have a pouch for incubating eggs
![Page 16: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/16.jpg)
Marsupials
Characterized by marsupium Only 50% of species have permanent pouch
Litters that weigh 1% of mother’s body mass Eutherians: litters weigh 50% of mother’s BM
Have well-developed stylar shelf
![Page 17: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/17.jpg)
Marsupials con’t
Lower basal metabolic rate (BMR) - 70% of comparable sized eutherians
Slower postnatal growth Smaller relative brain size No true flight, no fossorial herbivores,
large marsupial carnivores are extinct
![Page 18: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/18.jpg)
Marsupial reproduction
Bifurcated reproductive tract (female) and bifurcated penis (male)
Choriovitilline placenta Limited intrauterine development time and
accelerated development of muscular forelimb Precludes forelimb from becoming hooves,
flippers, or wings
![Page 19: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/19.jpg)
Marsupial reproduction con’t Paired sperm in New World marsupials Marsupium - open anteriorly or
posteriorly, folds of skin Best developed in arboreal species, and
species that burrow or jump Neonate (no more than 1 g) climb to a
teat Once attached, teat swells, keeping neonate
in place
![Page 20: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/20.jpg)
![Page 21: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/21.jpg)
Zoogeography Living marsupials occur in NA, Central and SA,
Australasia Marsupials are thought to have originated in North
America Oldest fossils dating 100 mya
Panamanian land bridge developed 2 to 5 mya, major interchange of fauna
65 mya, marsupials moved from SA through Drake Passage to Antartica and Australasia
Australian marsupials evolved in relative isolation from eutherians
![Page 22: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/22.jpg)
Orders and Families 7 orders and 18 extant families Polyprotodonts - unshortened mandible, lower
incisors small and unspecialized Diprotodont - shortened mandible with first pair
of lower incisors enlarged to meet upper incisors
Didactylous - unfused toes, each in own skin sheath
Syndactylous - skeletal elements of 2nd and 3rd toes in common skin sheath
![Page 23: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/23.jpg)
Dentition
![Page 24: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/24.jpg)
Digits
![Page 25: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/25.jpg)
Didelphimorphia Single family, Didelphidae New World distribution Terrestrial burrowers, semiarboreal Solitary and opportunistic feeders Most specialized didelphid, water opossum (aquatic,
webbed hind feet, marsupium watertight during dives)
![Page 26: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/26.jpg)
Didelphimorphia morphology Paired spermatozoa Pentadactyly, with primitive metatherian
dental formula 5/4, 1/1, 3/3, 4/4 =50 Polyprotodont and didactylous Have sparsely haired prehensile tails and
opposable pollex (thumb on forefoot) Some have incrassated tail (store fat in
the base)
![Page 27: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/27.jpg)
![Page 28: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/28.jpg)
Paucituberculata
Single family, Caenolestidae “Shrew” or “rat” opossum Dense vegetation of northwestern
Samerica Nocturnal, insectivorous or omnivorous,
and terrestrial Paired spermatozoa
![Page 29: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/29.jpg)
Small, shrewlike Long rostrum, adult weigh 40g No marsupium Didactylous, only New World marsupial that is
diprotodont Lower canine vestigial
Paucituberculata morphology
![Page 30: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/30.jpg)
Microbiotheria
Single family, Microbiotheriidae One species, monito del monte (Dromiciops
gliroides) South central Chile in beech/bamboo forest Small, 16-30g Have prehensile tail and pouch Greatly inflated auditory bullar Called “colocolos” by natives, bad omen
![Page 31: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/31.jpg)
Dasyuromorphia Small to medium sized, incl. carnivorous
species (Tasmanian devil and quoll) Polyprotodont and didactylous Canines well-developed, have carnassial
dentition Tails never prehensile 3 families: Thylacinidae, Myrmecobiidae,
Dasyuridae
![Page 32: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/32.jpg)
![Page 33: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/33.jpg)
Numbat
![Page 34: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/34.jpg)
Dasyuromorphia con’t
![Page 35: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/35.jpg)
Peramelemorphia Bandicoots and bilbies - Australasia 2 families, Peramelidae and Peroryctidae Terrestrial omnivores Have chorioallantoic placenta (no villi) Short compact body with long pointed rostrum Bandicoots have well-developed patella
(kneecap) and no clavicle Polyprotodont Marsupium opens posteriorly
![Page 36: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/36.jpg)
![Page 37: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/37.jpg)
Diprotodontia
8 families, 116 species Diprotodont, syndactylous In arboreal diprotodonts, first two digits of
forefeet oppose the other three digits - schizodactylous Hallux (big toe) opposable (not in terrestrial
species)
![Page 38: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/38.jpg)
Phascolarctidae
Koala
![Page 39: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/39.jpg)
Vombatidae
Wombat - powerful burrower 30 kg Grazing herbivore, dentition open-rooted
![Page 40: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/40.jpg)
Phalangeridae
Brushtail possum, cuscus Long prehensile tail, excellent climbers
![Page 41: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/41.jpg)
Potoroidae
Bettongs, potoroos Weak prehensile tail Upper canine well developed Have embryonic diapause
![Page 42: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/42.jpg)
Macropodidae Kangaroos and wallabies Grazing herbivores Similar to artiodactyls Molar hypsodont, mesial drift of cheekteeth
![Page 43: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/43.jpg)
Burramyidae
Pygmy possum - smallest possum 7-50g Exhibit embryonic diapause
![Page 44: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/44.jpg)
Acrobatidae Feathertailed glider and feather-tailed possum New Guinea Stiff, featherlike hairs on side of tails Feathertailed glider - smallest gliding mammal
(10-14g) Both species nectivorous with brush-tipped
tongue Exhibit embryonic diapause
![Page 45: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/45.jpg)
Pseudocheiridae
Slow-moving, ringtail possum Feed on leaves, aboreal Molars are selenodont Schizodactylous digits Prehensile tail Have marsupium
![Page 46: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/46.jpg)
Petauridae
Striped possums and wrist-winged gliders Petaurus similar to NA gliding squirrels Prehensile tail, opposable hallux Have marsupium Diprotodont but molars bunodont
![Page 47: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/47.jpg)
Tarsipedidae Honey possum 12 g Nectivorous Long pointed rostrum with brush-tipped
tongue, small peglike teeth Prehensile tail, hallux opposable, pads on
digits for gripping branches Delayed implantation
![Page 48: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/48.jpg)
Notoryctemorphia Marsupial mole Secretive, completely fossorial, eats beetles and
larvar Similar to eutherian talpids and chrysochlorids “Swim” through ground, substrate collapse behind, no
permanent tunnels Spend time aboveground too, active both day and
night Fusiform, scooplike claw, thick keratinized nasal
shield (pushing dirt) Cervical vertebrae fused, no pinna, vestigial eye
![Page 49: Monotremes and Marsupials](https://reader035.fdocuments.us/reader035/viewer/2022062723/56813bf0550346895da522a1/html5/thumbnails/49.jpg)
Notoryctemorphia con’t
Epipubic bone reduced Molars zalambdodont (v-shaped) Eaten by aborigines